1220 × 2440 build

[HullMark]

Hi all, I'm Mark. I know many of you have probably heard it all before, but I'm hoping to build a CNC router big enough to take full sheets of ply or MDF and be able to cut nested parts. I'm in the process of enlisting the help of a local engineering firm to take care of the welding and fabrication, they will just work off of my drawings, I'm waiting to hear back from them after today.

I have a few grand to spend, hoping to keep the costs down as much as possible but don't want to compromise on the design. It needs to be strong, last the test of time and also be fairly fast and accurate. This is a business venture so it needs to cock on, no way am i paying 10k plus, not that id mind if I had the money, if I can build one for a fraction of the cost.

I have some design ideas and have been working on a basic draft, mostly incorporating ideas I've seen (will post a couple of pics later, if necessary),
but thought it best really if I get the advice from the pros. I've spent hours (days) trawling the forums and have read some great and useful stuff, the only problem is I've forgotten half of it and the other half is buried somewhere in fragments throughout different pages.

FYI I am completely new to CNC, but have some experience coding and can draw (a little) in CAD. Can't be much different to building a computer, can it? Hardware and software.

I have a few questions...

What pitfalls do you foresee with a machine this size? (1220 x 2440 x 100mm working area).

The steel and aluminium costs I have covered, it's the cost of the rest of the hardware and software I'm not 100% sure of. Can anyone direct me to a kit or the parts I need?

If you had 2-3k (2) to spend and you needed a machine this size, how would you go about designing and building it? Materials and hardware etc. Can it be done?

If there's any relevant (completed) builds you know of please send me the link.

Thank you.

[routercnc]

Hi Mark,

There are a few machines here, all self built. But they are not as large as you are planning:
http://www.mycncuk.com/threads/10066-Finished-builds-picture-menu

When the machine is that big (1220x2440) there are many things that come into play:
1. Ensuring the gantry is stiff enough to cope with the span
2. Ballscrews may want to whip at that length - I've not built anything that large but either look at fully tensioned ballscrews, rotating ballnut type, or rack and pinion drive.
3. Costs start to build as things get heavy and better motors are need to drive it
4. Be careful buying motor kits - they may boast Nema34 8Nm etc. motors but they throw in lowly 48V drivers and you would get more performance with Nema23 3Nm believe it or not.
4. Ensuring general alignment and straightness

I know Jazz and others have commented on big machines in the past based on first hand experience so I'm sure they will be here with some better specifics. Also some people settle for 1/2 sheets in the end to make something more manageable.


Another machine here but unclear if it ever went anywhere:
http://www.mycncuk.com/threads/6952-Advice-on-Mammoth-CNC-Router-Build-Steel-Framed-2440mm-x-1220mm-cutting-area%21/page5

[HullMark]

Hi thanks for replying.

1. Hopefully the gantry won't be an issue as the design uses 50mm by 100mm mild steel side rails for the x axis, with 50mm support structures welded to the bottom. I'd seen somewhere that dropping the bed instead of raising the gantry makes the structure stronger, makes sense. 10mm aluminium plate for the gantry in an L shape. In theory, this is sound I think?

2. Backlash, which sounds similar to slop in a drivetrain, was one of my worries here too. In my design I was looking at using ballscrews, I guess I need to keep reading some more on that issue. Are you saying that backlash can be eliminated by using those methods? I'm sure I've read somewhere it can. The structure itself I think should be ok, I tried uploading a picture from my phone a few tims but it failed.

3) Most of the weight would be in the bed and support structure below made from mild steel, the only moving parts would be made from 10mm aluminium plate to keep the weight down.

4.Again this is an area I need to look into more, but I'm thinking I need to finalise my design and see how much it's going to weigh before I decide.

4. Hopefully this won't be an issue and is why I'm not even going to attempt to weld this myself. The lower supporting structure will be separate from the bed, bolting together so I can use shims to get the bed as level as possible. Not 100% decided on whether the resin route will be needed, probably, Hopefully someone else will come and clear this up.

You mean that rather than having 100mm travel they leave it at just having 2 axis and using different router bits? I could make that work for some things, but not others.

Many thanks

Ps sorry if I've posted this multiple times!

[HullMark]

Thanks for that link too, I have seen this and was thinking very similar, I was hoping though as you'll see from the dimensions I've given, mine doesn't need to be as robust for cutting just wood ... or am I wrong?

[Clive S]

If you had 2-3k (2) to spend and you needed a machine this size, how would you go about designing and building it? Materials and hardware etc. Can it be done?With this budget you would be lucky to build a machine half the size you are after. I would suggest that you put some of your design idears up for other to critique. Also I would advise not to buy any parts or kits of parts until you have until you hav a good idear of what you require. Sorry for the doom and gloom but many have made the mistake of jumping in with both feet.

[JAZZCNC]

Hi Mark,

Ok first off let me say straight away that Clive is correct with 3K you cannot build the machine you describe or one that is any good.

When you get into 8x4 or above the game changes in lots of respects and cost is one of them.

Now regards your idea of farming out the welding to engineering firm then be careful because I've seen this done many times and fail.?
The problem comes from the fact most welding firms will weld the frame up as thou it's just workbench and CNC frame requires more careful approach.
They won't take the time or care to spread the welding so as to keep distortion to minimum. They also won't constantly monitor any twisting that might occur from the heat. And most certainly won't take the time to make sure the Rails surfaces are on the same plane.
Any distortion or twist will have to be dealt with later otherwise it will affect how the machine performs. So anything that can be done to lower this the better and this takes time and most welders haven't got the time to wait for welds cooling etc so will just weld it up in one go which will cause you issues down the line.

The rail surfaces must be on the same plane and will need careful attention when welding or they will cause you lot more work. Even then if carefully done your still going to have either Epoxy level or have the surfaces machined flat.
Don't be fooled into thinking Box section is flat because I've yet to see one that is and certainly not one nearly 3mtr long.!

Now regards Gantry and 10mm plate in L shape layout then forget it.! That's just not going to be strong enough for gantry that will be 1600mm wide.
To give some idea the last 8x4 I built which you'll see in pics uses 120x80 HD Aluminium Profile arranged in L shape and I consider that a Minimum for a machine this size.
It's not just the weight it's carrying but got to also think about resonance/vibrations that will occur from the cutting. Resonance will give poor finish, cause excess tool wear and shorten component life.

Next comes linear motion. If your wanting Ballscrews then you really need to know what you're doing and what to buy because when you get past 1500mm things get wobbly real quick.
First, you have the obvious thing to deal with which is screw Whip from the long length. But you also have to think about alignment because long screws are merciless when comes to alignment. The slightest misalignment and they'll turn into gyrating skipping rope which will cripple the machine performance.
Getting this right is a careful balance of selecting the correct ballscrew with regards pitch and diameter along with correct tensioning and alignment. Get anyone one wrong and your in for world of pain.

This why Rotating ballnuts are often used for long lengths but this gets expensive and complicated unless you can make them your self.
Rack & pinion is the common solution for machine this length but again this brings with it's own challenges and problems/costs.

Coupled with all these solutions comes correct selection Motors/drives etc and is one of the reasons why you cannot build a machine this size for £3k.
Long, large diameter screws require bigger motors which along with high power drives get expensive quickly.
Ballscrew or R&P there is no difference really here because R&P is less efficient so still requires large motors to compensate. You also then have more backlash to deal with from R&P. Also R&P will require gearing to give you the Torque and resolution required which adds another layer of costs/complexitys.

I Strongly advise you to think long and hard before you take this project one with No experience because it's very very easy to get it wrong and all the research in the world won't prepare you for just how much more of challenge it is building an 8x4 than say 4x4.
The extra length really does change things that much and the slightest errors get magnified.

But one thing I can 200% tell you is that cannot be done properly or legally for £3k.!!

Here's two for you one with R&P and other with Ballscrews and mounted vertical.!

238372383823839


https://www.youtube.com/watch?v=4STVbn_EMoc&t=17s

[JAZZCNC]

Thanks for that link too, I have seen this and was thinking very similar, I was hoping though as you'll see from the dimensions I've given, mine doesn't need to be as robust for cutting just wood ... or am I wrong?

Yes your wrong.!!
Don't under estimate wood because while it's softer than aluminium you have to cut it faster and often much deeper which requires strength/power.
Also don't just think strength but also think in terms of vibrations because resonance really does affect the machine in many ways, performance, quality of finish, tool wear and component wear.

Also just bare in mind CNC tends to open up other avenues and if machine is weak to start with then limits these avenues.!!

[HullMark]

It's not all doom and gloom at all, I appreciate the honest replies and is why I'm here. I don't want this machine building yesterday, sure it's going to take time, I'm not in a major rush but would like It to be complete in 6 - 12 months. It will take as long as it takes, any sooner the better, this is a side venture/ hobby and the time will give me the chance to research more and work on my CAD.

This is all sound advice, I won't be purchasing anything until until I have a fully itemised bill of materials, and like you say that will come once I have worked out a suitable design Clive. I've tried attaching photos to the posts I'm sending, but it says failed to upload.

It seems like The first and maybe most important things to consider are the strength and accuracy of all parts. The two companies I have in mind, I know someone who builds conveyors at one, and i know the owner of the other one. The other company manufactures all sorts of precision parts. There's no doubt in my mind that both of them will be able to achieve the accuracy, they both have decades of fabrication experience each. It's like jazz said though they are always busy so it'll be a case of finalising a design first, then fitting in the welding and fabrication around what they've got going on when I'm ready.

I thought first of all i'd draw a rough idea, get the structure looking solid for the bed, base and gantry before I go into any of the finer detail stuff. Then from there we can look at motors etc. I will look again at posting some pictures.

If it can't be done for that price, how much is more realistic Jazz? There's a few machines this kind of size on eBay for 7.5-11.5k with some offering training. I figure if they can sell them for that surely I can build one for less (hopefully, that's usually the case when you DIY as much you can) with the right kind of guidance and outside expertise. Maybe I don't know what I'm talking about? But that's why I'm here.

This thread as much as anything will serve as a reference for me so I can have everything I need in one place. Any links and information are much appreciated, I'm keen to learn as much as I can from the experts here and am not expecting things to happen over night.

Cheers guys for the comments, you've given me a lot to think about.

[JAZZCNC]

It seems like The first and maybe most important things to consider are the strength and accuracy of all parts. The two companies I have in mind, I know someone who builds conveyors at one, and i know the owner of the other one. The other company manufactures all sorts of precision parts. There's no doubt in my mind that both of them will be able to achieve the accuracy, they both have decades of fabrication experience each. It's like jazz said though they are always busy so it'll be a case of finalising a design first, then fitting in the welding and fabrication around what they've got going on when I'm ready.




If it can't be done for that price, how much is more realistic Jazz? There's a few machines this kind of size on eBay for 7.5-11.5k with some offering training. I figure if they can sell them for that surely I can build one for less (hopefully, that's usually the case when you DIY as much you can) with the right kind of guidance and outside expertise.

Ok well obvioulsy depends on lots of factors and how good job you want to do but £4k will be more realistic figure and that is doing everything your self, welding machine work for aluminium parts the job lot.
So straight off the bat your backs against the wall if paying these companys or even if working on mates rates you haven't got much room to play with.

Also you'll all most certainly have to buy all the major components ie: linear rails, ballscrews etc from china to do this for £4k- £4.5K.
Here's Little break done for you.

The Linear rails & bearings, ballscrews & end bearings will cost about £2k and that's working on 20mm rails. Really 25mm would be better for long axis. Then throw another £300-400 into things like Timing belts, pulleys, Cable chains, nut's bolts etc.

Frame materials will depend on design but You'll not have any change from £500 and that's working on steel prices at wholesale not retail. By the time throw aluminium into mix for Z axis and brackets etc and you'll be at £750+.
If you use Profile type gantry like I do then will be easily over £1000.

The electronics will cost best part of £1000 to be done properly. That's working on using Closed loop steepers and using Motion control card all done correctly in Steel cabinet. Including all cables relays, e-stops, limit switches etc.
Wouldn't use open loop steppers for machine this size because using slaved motors as there is lot of inertia and easy to loose position. Plus the difference is cost isn't massive so well worth little extra.

So
Rails/screws etc £2000
Rail/screw sundries £400
Steel/Ali £750
Electrics/Motors etc £1000

These prices are not OTT and based off prices I've paid from China so you don't have massive wiggle room. Plus there will be extra hidden costs like paint,Drills etc which could easily account for another £200-300.

So you see £4K soon gets eaten up and that's allowing for someone who knows what there doing and doesn't screw up. Which is very easy to do for resonably experienced builder and almost guaranted for new builder.!!

Regards the Ebay machines then I've yet to see one that is any good for under £10K and most are Chinese machines which have there problems like coming with DSP controllers which expire quickly and limiting to use or cheap nasty electronics which will need some fetteling costing more money still. Most 8x 4 that are any good are between £15K-£20k.

If you expect to spend £5K you'll end up with machine that will last for years cut everything you want and be very reliable. The same would cost you £20K+ to buy.

[HullMark]

5k sounds reasonable to me, thanks for the break down Jazz, that's helpful and exactly what I needed, a ballpark figure ... have you seen CKJCNC on eBay? They seem to be doing a lot of business selling CNC machines, sub 10k plus VAT for the 1325 model (1300 x 2500 x 200 working area). Certainly looks the part, at least to my untrained eye! About 11.5k inc VAT.

[JAZZCNC]

5k sounds reasonable to me, thanks for the break down Jazz, that's helpful and exactly what I needed, a ballpark figure ... have you seen CKJCNC on eBay? They seem to be doing a lot of business selling CNC machines, sub 10k plus VAT for the 1325 model (1300 x 2500 x 200 working area). Certainly looks the part, at least to my untrained eye! About 11.5k inc VAT.

They are just Chinese imports. If you notice they say Orders being Taken. You could import one of these your self for lot less money. Shit loads on Ali express.
https://www.aliexpress.com/af/1325-cnc-router.html?d=y&origin=n&blanktest=0&jump=afs&SearchText=1325+cnc+router&initiative_id=SB_20180227112841&isViewCP=y&catId=0

[malcolm01]

5k sounds reasonable to me, thanks for the break down Jazz, that's helpful and exactly what I needed, a ballpark figure ... have you seen CKJCNC on eBay? They seem to be doing a lot of business selling CNC machines, sub 10k plus VAT for the 1325 model (1300 x 2500 x 200 working area). Certainly looks the part, at least to my untrained eye! About 11.5k inc VAT.

Hi Mark
I’ve just finished building an 8x4 CNC. It works ok, https://uploads.tapatalk-cdn.com/20180227/1e31c716f6491083411b39ea039e449c.jpg
I fitted it with 25mm ball screws on x and y axis and fitted a ready made z axis. The guys above were correct about ball screws whipping or wobbling while running, the y axis is fine, but the x axis has vibration issues. I’m planning on changing the x axis drive to rack and pinion which I’ll be buying from America ready made, I would recommend if your building a machine to avoid ball screws over 1500mm like one of the other guys said.
It will cost around £5k, it did for me, but when you see that thing cutting out your parts you’ll be glad you did it. I love my machine, I hardly cut anything buy hand if I can help it.
Best of luck.
Malcolm, from Ayrshire, Scotland


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[JAZZCNC]

Hi Mark
I’ve just finished building an 8x4 CNC. It works ok,
I fitted it with 25mm ball screws on x and y axis and fitted a ready made z axis. The guys above were correct about ball screws whipping or wobbling while running, the y axis is fine, but the x axis has vibration issues. I’m planning on changing the x axis drive to rack and pinion which I’ll be buying from America ready made, I would recommend if your building a machine to avoid ball screws over 1500mm like one of the other guys said.

Hi Malcolm,

I wouldn't do that to be honest because R&P comes with it's own issues and I'm guessing you mean CNCrouter parts R&P which isn't the best thing in world. Ballscrews can work fine if done correctly.
The trick is to get the screw speed down. So to do this you use pitch that is higher than you need and apply a ratio. I'll guess you used 10mm pitch.?
If you had used 25mm pitch then applied 2:1 ratio you would half your screw speed. The ratio makes it the same as if having 12.5mm pitch so you have little more travel speed still with decent resolution. The ratio also increases your torque so little more grunt.

If you use Fixed end bearings both ends of screw and put under slight tension then you won't have any issues. If you watch the video of the Vertical machine it's using 2525 screws done this way and traveling at 15Mtr/min. In testing I had it upto 25mtr/min and still with little left.

[HullMark]

So it definitely sounds like building my own will be best option as I'll know exactly what I'm getting/ putting into the machine, so long as everything's accurate and I take into account all the issues learnt so far by everyone else. Oh and spend a little more too!

Jazz, that makes perfect sense. I was wondering how slowing down the speed of the screws would effect the whip that's been mentioned. Hopefully that'll be a cheaper fix for Malcolm! Thank you for sharing your progress malcom, ill be sure to keep in touch and up date with any developments ... Is the vertically mounted CNC one of yours jazz?

[Clive S]

Is the vertically mounted CNC one of yours jazz?


Yes it is I have personally seen it. Why not ask him for a quote? He is not to far from you.

[malcolm01]

So it definitely sounds like building my own will be best option as I'll know exactly what I'm getting/ putting into the machine, so long as everything's accurate and I take into account all the issues learnt so far by everyone else. Oh and spend a little more too!

Jazz, that makes perfect sense. I was wondering how slowing down the speed of the screws would effect the whip that's been mentioned. Hopefully that'll be a cheaper fix for Malcolm! Thank you for sharing your progress malcom, ill be sure to keep in touch and up date with any developments ... Is the vertically mounted CNC one of yours jazz?

I wonder how I’d go about fixing the other end. It has a floating bearing, it’s only held on by a sirclip, other end is designed to be fixed 🧐


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[HullMark]

Without seeing something Malcolm, with my inexperience, I'd find it difficult to offer any kind of solution. I've seen parts available on a uk website CNC4YOU ... seems to be a lot cheaper than I've been advised here for screws and bearings. Anyone used these guys before? There's fixed and floating bearing supports for sale on there Malcom if that's of any use.

[routercnc]

I wonder how I’d go about fixing the other end. It has a floating bearing, it’s only held on by a sirclip, other end is designed to be fixed ��


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I'm in the process of doing just that on my new Mk4 machine on the long X axis. Because of the arrangement in the design I will not use off the shelf parts - instead I will be re-machining the floating end to have a lock nut and thread, and then use a thrust bearing between the lock nut and radial bearing to vary the axial pre-load. I'm likely to need a spacer in there to ensure force lines pass through the right part of the bearings. Hopefully when I get the video out (could be a few weeks yet) it will be clearer, and in my case it should make a neat job of it.

Alternatively, and easier if it can be done on your machine, you can use the same fixed end bearing set (that you have at the drive end) with angular contact bearings in to apply the axial pre-load, but you would need access to a lathe to machine the floating end of the ballscrew to suit. Then to apply preload to the ballscrew depends on how it is bolted to the machine. If the bolts run through the vertical holes then you just need to pull the ballscrew tight and torque up the fasteners. If the bolts run through the horizontal holes you need some way of shimming it away from the mounting face to get the axial load applied.

edit: apologies, realised I've replied to a poster, not the OP. Malcolm, create a new thread if you want more.

[malcolm01]

Without seeing something Malcolm, with my inexperience, I'd find it difficult to offer any kind of solution. I've seen parts available on a uk website CNC4YOU ... seems to be a lot cheaper than I've been advised here for screws and bearings. Anyone used these guys before? There's fixed and floating bearing supports for sale on there Malcom if that's of any use.

That’s where I bought the lot from. Fixed at one end and floating at the other.


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[malcolm01]

I'm in the process of doing just that on my new Mk4 machine on the long X axis. Because of the arrangement in the design I will not use off the shelf parts - instead I will be re-machining the floating end to have a lock nut and thread, and then use a thrust bearing between the lock nut and radial bearing to vary the axial pre-load. I'm likely to need a spacer in there to ensure force lines pass through the right part of the bearings. Hopefully when I get the video out (could be a few weeks yet) it will be clearer, and in my case it should make a neat job of it.

Alternatively, and easier if it can be done on your machine, you can use the same fixed end bearing set (that you have at the drive end) with angular contact bearings in to apply the axial pre-load, but you would need access to a lathe to machine the floating end of the ballscrew to suit. Then to apply preload to the ballscrew depends on how it is bolted to the machine. If the bolts run through the vertical holes then you just need to pull the ballscrew tight and torque up the fasteners. If the bolts run through the horizontal holes you need some way of shimming it away from the mounting face to get the axial load applied.

edit: apologies, realised I've replied to a poster, not the OP. Malcolm, create a new thread if you want more.

Yes I understand now. Ooft they’re 2.6m long, I have little engineering knowledge I’m a joiner.


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[HullMark]

Malcolm is this all made from the aluminium profile stuff? I would love to hear a run down on the processes you went through to get to this stage.

[malcolm01]

Malcolm is this all made from the aluminium profile stuff? I would love to hear a run down on the processes you went through to get to this stage.

https://uploads.tapatalk-cdn.com/20180301/3230ef073a36ac4769ba1bd97478d100.jpghttps://uploads.tapatalk-cdn.com/20180301/c14ad3f3e328de579eb4221c99eb38a7.jpghttps://uploads.tapatalk-cdn.com/20180301/1f0345765276f52976219e2ca2ce0ddb.jpgl


Like you I was trying to build this cheaply and myself, made the mistake of building a torsion box as a base. It still sagged no matter how sturdy I thought it was. Then I just followed my instincts and built it. I used aluminium where I could, I’ve stuck in a few pictures, the gable ends of the gantry I had made from a local engineering firm, they cost a fortune.



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[JAZZCNC]

I wonder how I’d go about fixing the other end. It has a floating bearing, it’s only held on by a sirclip, other end is designed to be fixed

Hi Malcolm, As you have probably gathered by now the Ends will need machining to fit the Fixed type bearing. However, this alone won't make a massive difference it's the screw speed that is Key.


I've seen parts available on a uk website CNC4YOU ... seems to be a lot cheaper than I've been advised here for screws and bearings. Anyone used these guys before?

You will buy the same stuff from China a lot cheaper than he sells them.! . . .Where do you think he buys them.?
China at the minute is on Holiday but when you have the design nailed down and know lengths etc then Email Fred here for a quote.
https://bstmotion.aliexpress.com/store/314742

[HullMark]

Guys how will I upload some pictures?

[malcolm01]

Guys how will I upload some pictures?

The app has a wee photo symbol, click on it


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[malcolm01]

The app has a wee photo symbol, click on it


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https://uploads.tapatalk-cdn.com/20180302/0c7fdffcf6d9d15e61f3902edf57eb3a.jpg
Like so



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[JAZZCNC]

Guys how will I upload some pictures?

Start post Click on this icon in pic. Then on "From Computer Tab" Then "Browse" select pic then click on "Upload files" writing.

23861

[HullMark]

Thanks chaps, I've tried it that way. Don't know if it's because I'm on my phone maybe? I've downloaded the tapatalk app now anyway so I'll try with this a bit later when I get home. Cheers

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[HullMark]

Let's see if it works on this app. I just took some photos of the screen. I keep changing my mind about the lay out as I'm learning a few things from drawing. After all, my first drawings where based on scratch building.

I started out with the linear bearings actually on top of the aluminium profile (not shown in pics) but I was worried about the lateral forces when the gantry was in the middle of the x axis cutting along the y, what do you think? It's 90 x 45mm heavy profile. Looks like it would be pretty strong in the corners.

It seems using the aluminium profile for some parts makes getting everything square easier. That's why I was going with a separate structure for the base, but I seem to have gone a bit ott with the aluminium now.

After seeing the other picture though I've attached, this was another idea I had, although the one pictured looks a little weedy (I think?), I think maybe it could be beefed up a bit (lot). Pretty much by combing both designs

I've settled for less y axis travel, I want to be able to do 3d stuff on this machine too, do we think it's possible? It's down to the software I guess? Obviously they won't be coming from my drawings haha I'll be using a CAM program to import someone else's.https://uploads.tapatalk-cdn.com/20180303/42f62003feecb262790213b619792cd7.jpghttps://uploads.tapatalk-cdn.com/20180303/0b29ae2cf1044df19b697f8725581df1.jpghttps://uploads.tapatalk-cdn.com/20180303/a0970351aded0c1e6686226452c7913e.jpghttps://uploads.tapatalk-cdn.com/20180303/603bb693c1726c3a3525748456493c18.jpghttps://uploads.tapatalk-cdn.com/20180303/8988db5551b386340ebaf5239ff5505e.jpghttps://uploads.tapatalk-cdn.com/20180303/6b01873ce3e04b3e3b96a2a8682788b5.jpg

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[JAZZCNC]

If you was building a plasma machine I'd say that's perfect. But if you want a serious router then it needs lot more work.

The Bottom Pic looks very much like Merchant Dice machine and just ask anyone about how well MD machine performs..:hysterical::hysterical::hysterical:

Your gantry design is week and far too weedy for decent router this size.

[malcolm01]

the gantry looks a bit too low to me, id say try to get this a rock solid as possible, I thought machine was solid but turns out the ready made z axis assembly is not solid enough, getting vibration when cutting 18mm mdf in one pass, It the only bit that hasn't got hiwin rails, will changing it soon and ill be changing my spindle for an ATC spindle

[HullMark]

If you was building a plasma machine I'd say that's perfect. But if you want a serious router then it needs lot more work.

The Bottom Pic looks very much like Merchant Dice machine and just ask anyone about how well MD machine performs..:hysterical::hysterical::hysterical:

Your gantry design is week and far too weedy for decent router this size.These were some earlier drawings I was playing with, when I mentioned earlier on in the thread about and L shape gantry, this was what I meant. Looks heavy. I realised though by sweeping back the gantry I can save a bit of room in the overall length of the machine.

It's just the weight of it all too is a logistal nightmare when you start using bigger steel.

Im going to make some time in the week to go see my guy and see what he says about just how much fabrication he wants to take on, show him some pictures.
https://uploads.tapatalk-cdn.com/20180303/dbffc0a8843d3c543308268b3f399f93.jpghttps://uploads.tapatalk-cdn.com/20180303/22efa4f070b24ed759a7c7fc2c06180d.jpghttps://uploads.tapatalk-cdn.com/20180303/b6847d18d13f6f6d2f6ef96737f39669.jpghttps://uploads.tapatalk-cdn.com/20180303/bb60022346061e9e839c66286164c6f4.jpg

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[HullMark]

the gantry looks a bit too low to me, id say try to get this a rock solid as possible, I thought machine was solid but turns out the ready made z axis assembly is not solid enough, getting vibration when cutting 18mm mdf in one pass, It the only bit that hasn't got hiwin rails, will changing it soon and ill be changing my spindle for an ATC spindleAh sorry to hear that, but thanks for letting me know. I was considering just buying theirs. I tried to keep the gantry as low to the rail as possible. Droping the bed lower instead of raising the gantry seems like it'd be stronger.

I need to go see my engineer now I have a little more idea about what I want. Doesn't seem too difficult to make the z axis from scratch.

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[malcolm01]

do you just use sketchup or do you use cad ?

[malcolm01]

the guy jazzcnc sent a link to an American site that looked good, they have a preassembled part that I really like the look of

https://www.aliexpress.com/item/CNC-Sliding-table-effective-stroke-400mm-guide-rail-15mm-ball-screw-1605-CNC-Z-axis-Linear/32741888942.html?spm=2114.search0104.3.152.6ab831b 0ZkP59s

[HullMark]

do you just use sketchup or do you use cad ?I haven't used AutoCAD for years, and even that was limited to simple furniture made in a caravan factory with someone I knew. Just started using sketch up more recently. I'm going to the local college on Monday to see the lecturer for this city and guilds course which hopefully will help me hone my skills.

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[malcolm01]

if you look at my c beam picture, I joined 3 bits of aluminium together, this is ridiculously rigid but very heavy! if I could do this again id use light weight aluminium profile instead! I have no doubt it would be still as rigid, keeping the weight down would be a good idea because the gantry is cumbersome and requires a lot of power to heave it about, the x axis struggles while the y axis flies
I'm not so sure keeping it so low wouldn't ending up causing you problems down the line. also when I'm making a new base for my machine I plan to make the underside suitable for sheet storage, my workshop is small and the machine swamps the place so sheets lying around are a real pain

[HullMark]

if you look at my c beam picture, I joined 3 bits of aluminium together, this is ridiculously rigid but very heavy! if I could do this again id use light weight aluminium profile instead! I have no doubt it would be still as rigid, I'm not so sure keeping it so low wouldn't ending up causing you problems down the line. also when I'm making a new base for my machine I plan to make the underside suitable for sheet storage, my workshop is small and the machine swamps the place so sheets lying around are a real painYeah I spent a little while trying to find one like it until I looked at the picture more closely! Nice idea about storage ... is the base of yours made from wood?

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[HullMark]

Yeah I spent a little while trying to find one like it until I looked at the picture more closely! Nice idea about storage ... is the base of yours made from wood?

Sent from my SM-G935F using TapatalkI think I'll maybe go with your c beam then, it's an option for sure

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[malcolm01]

yes I built a torsion box from mdf, stupid idea, my idea was to pivot the machine against the wall when not in use, terrible idea so I plan a new table, mix of steel and aluminium, I was thinking if you used Turbocad id have sent yiu my drawings of my machine, theyre a bit ruff but you might have seen something usefull

[HullMark]

If you was building a plasma machine I'd say that's perfect. But if you want a serious router then it needs lot more work.

The Bottom Pic looks very much like Merchant Dice machine and just ask anyone about how well MD machine performs..:hysterical::hysterical::hysterical:

Your gantry design is week and far too weedy for decent router this size.What would you recommend instead Dean? I keep thinking about the logistics of it, I don't have a forklift at home haha

http://www.ukcnc.info/forums/showthread.php?1259-New-Large-CNC-Router-Build-8x4ft-Progress-starting-November-2014

I was impressed by this one but haven't (can't) work out how much it'd cost.

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[Clive S]

The Bottom Pic looks very much like Merchant Dice machine and just ask anyone about how well MD machine performs..
Funny that I have to go and sort a MD machine on Monday. I actually think the MD machine is better :toot:

[JAZZCNC]

the guy jazzcnc sent a link to an American site that looked good, they have a preassembled part that I really like the look of

https://www.aliexpress.com/item/CNC-Sliding-table-effective-stroke-400mm-guide-rail-15mm-ball-screw-1605-CNC-Z-axis-Linear/32741888942.html?spm=2114.search0104.3.152.6ab831b 0ZkP59s

Wouldn't buy that either.? Those ball screw bearing blocks are not designed for this purpose and will almost certainly have some end float.
Also the price is ridiculous. You can buy all the bits and build your own better for lot less.

[JAZZCNC]

What would you recommend instead Dean? I keep thinking about the logistics of it, I don't have a forklift at home haha

Well all can say is build it stronger or should say Stiffer. If your limited with logistics then build it sections so can be easily moved. It will add another level of complexity because still need to maintain accuracy which is harder to do with more pieces.
Going to say this again because cannot stress enough. Your Gantry design is WEAK and if you build this it will show in the quality of finish.

The Gantry and Z axis are key areas. Malcolm as already mentioned to his pain that Z axis is key area and soon shows any weakness in the cut.
I don't agree that is Gantry is over built and changing to lighter Section profile wouldn't give any better performance really and could potentially cause other issues with resonance when cutting deep or hard materials.
Better having strong gantry that is little heavier than light gantry that will flex when cutting hard. If higher feeds are required then better to size the screws or motors to suit rather than under build.

Under building because of Logistics or weight is just going to compromise the machine performance. Better to think smarter and design around any restrictions.

[malcolm01]

I recon my gantry weighs at least 100kg, surely reducing that alittle with a lighter profile aluminium wouldn't hurt??

[JAZZCNC]

I recon my gantry weighs at least 100kg, surely reducing that alittle with a lighter profile aluminium wouldn't hurt??

Ok I guess your main profile is 160x40 and top/bottom profile 80x40.? The weight difference between HD and light for 160x40 is 3Kg per meter and 2.5kg perM on 80x40.
So lets say gantry is 1500mm wide so in total your only saving approx 12kg and this won't make a huge difference in performance. The extra strength it provides will be more beneficial when cuttng hard than the any slight speed it may gain.

[HullMark]

Hi Mark,

Ok first off let me say straight away that Clive is correct with 3K you cannot build the machine you describe or one that is any good.

When you get into 8x4 or above the game changes in lots of respects and cost is one of them.

Now regards your idea of farming out the welding to engineering firm then be careful because I've seen this done many times and fail.?
The problem comes from the fact most welding firms will weld the frame up as thou it's just workbench and CNC frame requires more careful approach.
They won't take the time or care to spread the welding so as to keep distortion to minimum. They also won't constantly monitor any twisting that might occur from the heat. And most certainly won't take the time to make sure the Rails surfaces are on the same plane.
Any distortion or twist will have to be dealt with later otherwise it will affect how the machine performs. So anything that can be done to lower this the better and this takes time and most welders haven't got the time to wait for welds cooling etc so will just weld it up in one go which will cause you issues down the line.

The rail surfaces must be on the same plane and will need careful attention when welding or they will cause you lot more work. Even then if carefully done your still going to have either Epoxy level or have the surfaces machined flat.
Don't be fooled into thinking Box section is flat because I've yet to see one that is and certainly not one nearly 3mtr long.!

Now regards Gantry and 10mm plate in L shape layout then forget it.! That's just not going to be strong enough for gantry that will be 1600mm wide.
To give some idea the last 8x4 I built which you'll see in pics uses 120x80 HD Aluminium Profile arranged in L shape and I consider that a Minimum for a machine this size.
It's not just the weight it's carrying but got to also think about resonance/vibrations that will occur from the cutting. Resonance will give poor finish, cause excess tool wear and shorten component life.

Next comes linear motion. If your wanting Ballscrews then you really need to know what you're doing and what to buy because when you get past 1500mm things get wobbly real quick.
First, you have the obvious thing to deal with which is screw Whip from the long length. But you also have to think about alignment because long screws are merciless when comes to alignment. The slightest misalignment and they'll turn into gyrating skipping rope which will cripple the machine performance.
Getting this right is a careful balance of selecting the correct ballscrew with regards pitch and diameter along with correct tensioning and alignment. Get anyone one wrong and your in for world of pain.

This why Rotating ballnuts are often used for long lengths but this gets expensive and complicated unless you can make them your self.
Rack & pinion is the common solution for machine this length but again this brings with it's own challenges and problems/costs.

Coupled with all these solutions comes correct selection Motors/drives etc and is one of the reasons why you cannot build a machine this size for £3k.
Long, large diameter screws require bigger motors which along with high power drives get expensive quickly.
Ballscrew or R&P there is no difference really here because R&P is less efficient so still requires large motors to compensate. You also then have more backlash to deal with from R&P. Also R&P will require gearing to give you the Torque and resolution required which adds another layer of costs/complexitys.

I Strongly advise you to think long and hard before you take this project one with No experience because it's very very easy to get it wrong and all the research in the world won't prepare you for just how much more of challenge it is building an 8x4 than say 4x4.
The extra length really does change things that much and the slightest errors get magnified.

But one thing I can 200% tell you is that cannot be done properly or legally for £3k.!!

Here's two for you one with R&P and other with Ballscrews and mounted vertical.!

238372383823839


https://www.youtube.com/watch?v=4STVbn_EMoc&t=17sWhat dimensions are those gantrys Dean?

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[Boyan Silyavski]

When all is short , it looks very sturdy. In 3m length even the 100x100 box section feels like makaroni. If steel, i would say gantry will have to be minimum 100x200x3 beam at the very least. So for aluminum i dont know what Dean uses, but i think 2x 90x180 in L configuration will do the job.

If you want as cheap as possible you have to do all from steel. There is no escaping that. The bigger the steel you use, the simpler the structure will be. 100x100 will need no diagonal bracing, if done right. If you get your hands to 100x200x4 or thicker, that will simplify greatly the whole build. 100x100 is the maximum a Rage saw can cut, hence the maximum you could cut at home.

[JAZZCNC]

What dimensions are those gantrys Dean?

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Gantry is HD Item section 120 x 80.
Frame is 100x100x6

[JAZZCNC]

Here's design that will allow you to be more flexible with the frame. Although the base here is in one piece it could easily be made in 2 or 3 pieces and bolted together.
The important part is the full-length profile section running full length down each side. This will allow you some flexibility in adjustment so can get both rails on same plane without messing around epoxy resin etc. Must stress thou the accuracy will only really be good enough for cutting woods and softer materials. It will also take lot of setting up and tweaking until spot on.
In my experience profile is relatively flat and straight enough for wood router and does make fitting rails, ball screws etc much easier. The downside is cost so mixing steel and profile gives good balance of strength, costs and accuracy with ease of building which doesn't require too much machineing or timely and costly techniques for leveling etc.

23873
23874
23875
23876

[HullMark]

Here's design that will allow you to be more flexible with the frame. Although the base here is in one piece it could easily be made in 2 or 3 pieces and bolted together.
The important part is the full-length profile section running full length down each side. This will allow you some flexibility in adjustment so can get both rails on same plane without messing around epoxy resin etc. Must stress thou the accuracy will only really be good enough for cutting woods and softer materials. It will also take lot of setting up and tweaking until spot on.
In my experience profile is relatively flat and straight enough for wood router and does make fitting rails, ball screws etc much easier. The downside is cost so mixing steel and profile gives good balance of strength, costs and accuracy with ease of building which doesn't require too much machineing or timely and costly techniques for leveling etc.

23873
23874
23875
23876Thanks for that, this is exactly the route I'm looking at now. Makes sense to use the profile for exactly those reasons.

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[routercnc]

Nice machine Dean - have you made one before ? :)

Out of interest do the profile rails down the side also bolt horizontally into the steel sections or just on the support brackets?
Would the ballscrew be drilled and tapped in the ends to bolt through the supports ears? Or the supplier may prefer to machine external threads and use a nut to tension.

Mark, as you are starting out then study this machine as it contains lots of nice features that would be missed be the casual observer. At all the critical interfaces there is scope for alignment and adjustment so you can dial it in.

[HullMark]

And how are the motors driving the x axis?

[Neale]

That's one of the details that you might miss! Looks like rotating ballnuts fixed to the gantry sides, with fixed ballscrews up each side.

[JAZZCNC]

Nice machine Dean - have you made one before ? :)

No not made one using this technique because I've got large Granite surface table so use different methods to get surfaces on the same plane. Mainly to save costs because the profile is expensive compared to steel.
However, I know from experience using lots of profile this technique will work great and would certainly use it my self if needed.

The Model shown is just basic layout to give some idea of the concept and that all fit together without any hidden surprises. (Which if got keen eye will see this model does have one in gantry area which would be pain unless corrected.?)
The original design was actually setup to be R&P but also did Configuration for ballscrews which shown.

When I actually build then I model to the last detail and actually use dimensions for cutting list etc.
This way I know 100% there will be no hidden surprises or costly cock up's. Only need to be off few mm's in some key areas and can cause your whole world of pain or worse still compromise the machine.


Out of interest do the profile rails down the side also bolt horizontally into the steel sections or just on the support brackets?
Would the ball screw be drilled and tapped in the ends to bolt through the supports ears? Or the supplier may prefer to machine external threads and use a nut to tension.

The plan was they would bolt in both directions. This would allow more setup adjustment.
The ball screw would be threaded on the ends so can put tension on them. The brackets allow adjustment for alignment.


Mark, as you are starting out than study this machine as it contains lots of nice features that would be missed by the casual observer. At all the critical interfaces there is scope for alignment and adjustment so you can dial it in.

Adjustment is Key at the DIY level and the more you build in the easier and quicker you'll dial in the machine. Unless you have large Gantry Mill to machine surfaces flat, parallel etc then the only way to achieve accuracy is with adjustment and lots of patience tweaking as you go.

[JAZZCNC]

Here's another simpler to make design. Warn thou it's heavy. Those lower beams are 300x200x6.

23879
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23881

[JAZZCNC]

And how are the motors driving the x axis?

It's using rotating ballnuts which are fastened to gantry sides.
Could if you wanted use conventional ball screw setup but the end brackets would need changing and you'd fasten the ballscrews to profile using BK blocks.

[HullMark]

It's using rotating ballnuts which are fastened to gantry sides.
Could if you wanted use conventional ball screw setup but the end brackets would need changing and you'd fasten the ballscrews to profile using BK blocks.Yeah I've just been looking at some of those ... what size rails and screws will i need, both 25mm?

http://www.mycncuk.com/threads/6997-Rotating-Ballnut-Design-MK3

These seem fairly straight forward to put together

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[JAZZCNC]

Yeah I've just been looking at some of those ... what size rails and screws will i need, both 25mm?

Yes 25mm for both. Thou could actually get away with 20mm Rails if wanted but for the little extra then I wouldn't.

[Desertboy]

the guy jazzcnc sent a link to an American site that looked good, they have a preassembled part that I really like the look of

https://www.aliexpress.com/item/CNC-Sliding-table-effective-stroke-400mm-guide-rail-15mm-ball-screw-1605-CNC-Z-axis-Linear/32741888942.html?spm=2114.search0104.3.152.6ab831b 0ZkP59s

Looks a lot like my Z axis but I have BK12/BF12 fittings

23883

Cost me ~£100 to build but I recovered the Hiwin's.

[HullMark]

Looks a lot like my Z axis but I have BK12/BF12 fittings

23883

Cost me ~£100 to build but I recovered the Hiwin's.Yeah that's nice and simple looking, is it meaty enough Desertboy for your uses?

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[HullMark]

Here's design that will allow you to be more flexible with the frame. Although the base here is in one piece it could easily be made in 2 or 3 pieces and bolted together.
The important part is the full-length profile section running full length down each side. This will allow you some flexibility in adjustment so can get both rails on same plane without messing around epoxy resin etc. Must stress thou the accuracy will only really be good enough for cutting woods and softer materials. It will also take lot of setting up and tweaking until spot on.
In my experience profile is relatively flat and straight enough for wood router and does make fitting rails, ball screws etc much easier. The downside is cost so mixing steel and profile gives good balance of strength, costs and accuracy with ease of building which doesn't require too much machineing or timely and costly techniques for leveling etc.

23873
23874
23875
23876I guys hope all is well. So much to do with so little time! When I've been looking at doing something like this, I've been concerned about how to attach the profile to the steel so it's strong and minimises lateral forces. Are you really sure just bolting it on the bottom via those brackets is strong enough?

I don't know how clear it is in the pictures I've sent, but I've used 90mm box section with 160 x 40 profile sat on the top. This gives 35mm overhang either side and would allow me to bolt the profile from the top down on the inside and outside edges of the outer steel lengths. Also does the gantry look strong enough now? Cheers.https://uploads.tapatalk-cdn.com/20180305/60c68bcd96b0a1e2ab8b172454c09ebf.jpghttps://uploads.tapatalk-cdn.com/20180305/faa217ff8e09e8c2e3ca4875c52d9067.jpghttps://uploads.tapatalk-cdn.com/20180305/c2bc64fddeea788641b9a3580d600c7e.jpg

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[HullMark]

Oh jeez I just worked out this base structure would weigh over 300kg!

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[HullMark]

Like thishttps://uploads.tapatalk-cdn.com/20180305/5070be59e5ac5453f7a776d5bf1219b0.jpg

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https://uploads.tapatalk-cdn.com/20180305/7bc1a4ca59ad2bc965cf698b7ec80cba.jpghttps://uploads.tapatalk-cdn.com/20180305/b2999551ddb7068e9c9b33f8f2287abd.jpg

[JAZZCNC]

I guys hope all is well. So much to do with so little time! When I've been looking at doing something like this, I've been concerned about how to attach the profile to the steel so it's strong and minimises lateral forces. Are you really sure just bolting it on the bottom via those brackets is strong enough?

Never said was just bolted to brackets. In fact, it's not that simple.!
There would be adjustment bolts between profile and steel to get the two rails parallel because couldn't rely on the frame being perfectly square.

These are the hidden things which cannot be seen but make a huge difference to how well the machine performs. Again can't stress enough always think adjustability when designing.

[HullMark]

Never said was just bolted to brackets. In fact, it's not that simple.!
There would be adjustment bolts between profile and steel to get the two rails parallel because couldn't rely on the frame being perfectly square.

These are the hidden things which cannot be seen but make a huge difference to how well the machine performs. Again can't stress enough always think adjustability when designing.Thanks for getting back to me. Ahh I see! So how would you go about fixing those adjustment bolts to the steel frame? Showing my inexperience here. I was wondering about how with my design I could get the profiles lined up along the x axis (this is why I want ott with the aluminium in the earlier design), adjusting the height along the length wouldn't be a problem with those cleats, could just use shims ... I had an idea for the x axis, but it isn't empirical or anything, just basically a bit of measuring and trial and error.

I appreciate what you're saying about being able to make adjustments, i can imagine all of the that could go wrong if things aren't aligned properly, and making things adjustable will allow me to get everything dialled in.


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[HullMark]

Having considered the logistics and cost etc. I've decided to go with a smaller machine. This will fit in a brick shed that's already in my garden with ease. Should make things a lot easier and cheaper in terms of the build. 1220 x 1220 I can make work for what I want it for. Thanks for all the input so far from everyone it's been a lot of help!

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[malcolm01]

Having considered the logistics and cost etc. I've decided to go with a smaller machine. This will fit in a brick shed that's already in my garden with ease. Should make things a lot easier and cheaper in terms of the build. 1220 x 1220 I can make work for what I want it for. Thanks for all the input so far from everyone it's been a lot of help!

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Good idea mark! For a long time I thought I had built mine too big. 90% of the time I’m cutting stuff no bigger than A3


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[HullMark]

Good idea mark! For a long time I thought I had built mine too big. 90% of the time I’m cutting stuff no bigger than A3


Sent from my iPhone using TapatalkThanks for the reply Malcolm. The way I figure it, if I build a smaller one with the same budget, I could make a better quality machine too. If I make it robust enough to work on aluminium, I'll be able to machine my own parts if I ever need to build a bigger machine.

It's looking like September will be when I start the actual build process. I'm hoping to have everything together by then so I can get it done ASAP, without any errors and not skimp on costs.

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[malcolm01]

Thanks for the reply Malcolm. The way I figure it, if I build a smaller one with the same budget, I could make a better quality machine too. If I make it robust enough to work on aluminium, I'll be able to machine my own parts if I ever need to build a bigger machine.

It's looking like September will be when I start the actual build process. I'm hoping to have everything together by then so I can get it done ASAP, without any errors and not skimp on costs.

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Sounds like a plan pal [emoji1][emoji106]


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[Boyan Silyavski]

Good idea mark! For a long time I thought I had built mine too big. 90% of the time I’m cutting stuff no bigger than A3


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Me too, but from time to time a friend would come with 2.5 meter model boat parts for 3d machining:


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[GrahamWhite]

I'm in exactly the same position as you are in that I want an 8x4 router for full sheets.
Looking around I decided to go with a Joes CNC hybrid design- comes in around the 2-3K price or more! ,all upgradable from the basic model which starts out with a mix of materials -MDF ,HDPE ali and steel , right up to his new design which is called the evolution 2.0 which is all made from 20mm plate aluminium.
It is a paid for plans/forum which I have bought but you do get access then to all the upgrades available.
I have my base made now and just waiting on my aluminium profile rails to get started on the actual machine.
I will post up my build on here in case anyone would be interested.

[sebcbien]

I'm interested :-)

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[Boyan Silyavski]

Year 2018 at the prices of square linear rails, ball screws and electronics, i would not even think of making a MDF, V bearings, Rack and Pinion machine. That's it. Better make a small well made machine than a big joke. if people need following plans, there many machines in the forum to copy from, i have uploaded the plans of my 1st machine in Sketchup. And if need be i sell custom plans for a specific purpose pro machine like the one that i use.

So in short the free plans of my 1st machine are 10 light years away from Joe's 10 years evolution machine.

Read forums, learn and save money. There are so many wonderful builds and ideas in the forum, so there is no need at all of anything new to be invented.

[Desertboy]

V wheels are crap get linear rails
https://www.aliexpress.com/item/HG-linear-guide-2pcs-HGR20-1500mm-4pcs-HGW20CA-linear-block-carriage-CNC-parts/32855353668.html

Even the cheapest clones are going to far superior to v wheels.

[GrahamWhite]

a quick reply would be linear rails ...yes please but £400 for linear rails or £30 for v bearings?
I've started my own build log so if you would like to direct any comments on my build choices please post on there :)
I'm not looking to hijack Hullmarks thread.
http://www.mycncuk.com/threads/11777-8x4-Build-based-on-plans-by-Joescnc-Hybrid-R-P?p=100938#post100938