Steel/Aluminium design/build, sorta smallish, cuts ali hopefully

Ok, here we go!

Name's Mart and I come from lovely boring rural Suffolk. Well I come from Down Under before that but its another story altogether...


I've been lurking around here for a while now, gathering ideas after going thru about 10 different design iterations. So, after gathering some ideas, comparing them with my metal stockpile and aluminium prices online, I've done another one :)

What I'm trying to achieve is a machine with a quesstimated work area of around 800x600x300. Why these measurements. Well, first of all, I had a look at a workbench I have here and thought "this looks about the right size" :) Then I tried to optimize the measurements with the steel stock I hold in the junk pile. And well, it felt about right :)

I have hardly any experience with CNC other than just sending DWG-s to suppliers, so its a proof of concept if you like for a bigger machine in the future. And also, hopefully I can actually fabricate the bits needed for the bigger machine then :)

So. The frame is welded out of 50x3 and 20x2 box section (just because I have too much of it) It's probably a massive overkill (in some ways but weak in others), but well. The massive amount of 20x20 box is just because I have so much of it kickin about. The green bits on the drawing, on top of the frame are 60x6 flatbars, stitch welded to frame to provide something more solid to mount the rails on.

Gantry is 120x5 aluminium box section. End plates are 15mm ali. Rails are planned SBR16. Ball screws 1610 for X and Y and 1605 for Z.


Attachment 9795Attachment 9793Attachment 9794



What else. Cheap 3Nm steppers. Haven't decided yet on direct drive or belts. Have no idea about drivers/PSU-s :)
Somehow I managed haggle myself Thisl from Zapp. Don't even know if it works but I got it free :)

Spindle. About 2Kw ish, China .


So, some quick pictures. I swapped computers lately and for some reason I can't open my z axis or drive assemblies. But I'll work on it and hopefully get more decent design up tonight.






All help would be appreciated, as I feel kind of stubid about these machines :)

Regards,
Mart

Hi - Which part of Suffolk are you in?...i'm just over the border in Norfolk.

Whilst i'm still in the process of designing my steel/aluminium build & am not as wise as many of the others round here, there are a couple of things that stand out to me.
I think you'll want to replace the middle side legs with 50mm box rather than the 20mm box.
The gantry looks to be uber chunky - the distance between the front of the gantry, the Y leadscrew & then the front Y plate all look far too big. It's also better to keep the Y leadscrew either behind the gantry or inside it to help keep gunk/chips away from it.

Good first draft though - much better than mine was :sulkiness:

Im near Stowmarket.

About the sides and rear end. I plan to fill the sides/rear in with some MDF to control dust a bit better and I actually hope it'll make it a good bit stronger from there as well. With all the triangulation and say ~15mm MDF it should be pretty strong. Bear in mind that the straight legs are only 250mm long.


As for the gantry and Z carrier, the gap should be 42mm. Thats 43mm high ball nut carrier sunken into the plate 3mm and 2mm for good old air. I have to check the drawing. There might be a horrible mistake there somewhere.

I'm not really fond of the idea of cutting a 120mm box section apart to fit the lead screw in there... and then starting to strengthen it :)
As I have understood it would be best to keep the lead screw as close to the Z as possible to minimize leverage?

I might mount some little brushes on the ball screw to keep it clean when this comes an issue. Someone has done it on my Bridgeport and seems to work pretty good.

Edit: oh, about the base and those 20mm box sections there. Base is going to be covered with 20mm ali plate. Should be plenty strong then?

That looks to me that it will be difficult to load the media, especially if full size and heavy. G.

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Originally Posted by GEOFFREY

That looks to me that it will be difficult to load the media, especially if full size and heavy. G.

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The work envelope is pretty small, so I can't see doing any heavy lifting :)
Front diagonals should be designed just so a "full size" 600mm wide sheet fits in between them.

Basically, the heaviest "full size" I can see myself working on, would be maybe a 25mm-ish aluminium plate. 800x600mm of that weighs in just over 32kg, so wouldn't be much of a problem to wiggle in even if the front diagonals would be in the way...

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Originally Posted by mart154

The work envelope is pretty small, so I can't see doing any heavy lifting :)
Front diagonals should be designed just so a "full size" 600mm wide sheet fits in between them.

Basically, the heaviest "full size" I can see myself working on, would be maybe a 25mm-ish aluminium plate. 800x600mm of that weighs in just over 32kg, so wouldn't be much of a problem to wiggle in even if the front diagonals would be in the way...

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If you have so many steel, why don't you move the supporting braces outside or think of something else.

Correct me if i am wrong, but when you design a thing from scratch there shouldn't be any compromises. Thats the whole point, yes?

You are correct. There shouldn't be any compromises and I can't see the front supports being an issue with the work I plan to do.

I will have a crack designing outside supports but it seems to complicate frame I planned to bolt the machine on to have it higher.

Been busy with other things recently and finally decided to have another crack on the design.

The work area has increased a bit and gone a bit beefier.

The work area is now 890x1000
The cutting area should be about 670x780 now.

Main frame is now 50x50x3 box. The rails bolt on to 60x60x5 (blue)
The green bits are 30x30x2 box to support the baseplate.
The gantry is still 120x120x5 ali box.

So any feedback is greatly appreciated before I start cutting the steel :)

Attachment 10153
Attachment 10154

Looks ok to me but I'd change the way the bed is constructed to help keep side frames from being pushed while welding and cut down on steel.

You won't need mesh that tight so I'd drop 2 of the long rails and flip other around and take rail across machine from each side in centre, this will hold sides together better and lessen chance of welds pushing/bending side rails. I'd then run the others up the machine and space outer ones so they land on the edge of the planned cutting area, they will support whole cutting area better. You will probably have a lower bed that goes right up to the sides but you'll also have a spoil board that is the size of your cutting area so ideally you want the edges of this to land on the supports and not rely on the bed underneath which isn't supported.
This also means you could drop the green bits because the bed will be supported where it matters, in the cutting area, and the small overhang which is a cantilever won't matter has it has no forces acting on it.

Other than that then fire up the saw. . :encouragement:

Oh forgot to spot this but was more looking at the frame than the gantry.! . . . . Mentioned this before many times .!! Wouldn't have the Y axis like that with a rear piece so basicly creating a box with no sides. It's just adding weight and costing money it gives very little strength. Get your self a card box and cut sides out and see what it does.?? . . .Same principle.

It also adds other complications in the build because if the edges are not machined perfectly 90deg it skews the box making it parallelogram which will cause bearings to bind and stick when bolted together.

Thanks! Got it on the frame. Makes absolute sense! :) I was already designing some jigs in my head to keep weld distortion under control. Now I can probably ditch those.

But with the Y. I basically just copied some designs I found here and there and I don't really have any more ideas. :(

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Originally Posted by mart154

I was already designing some jigs in my head to keep weld distortion under control. Now I can probably ditch those.

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Jigs to stop distortion are not practical really.? Heat cause's distortion and stress so to restrain these forces would need massively strong Jigs which for a one time machine just isn't worth the trouble. If you stitch weld in short runs and spread welding around so not to create heat build, Take your time and don't try to weld frame in one go let it rest and come back to it then you won't have much trouble.

Tips to help with stress relieving are Stitch weld and balance the welds IE: If you weld for half inch on outside face of steel box then immediately weld half inch on inside face opposite to keep balanced stress's. Don't weld all of one side up then turn over and do other, Also Don't weld in one spot for long but Move around and try to weld with minimum heat.

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Originally Posted by mart154

But with the Y. I basically just copied some designs I found here and there and I don't really have any more ideas. :(

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I'd just move the rails on Gantry closer towards front and just have narrowest top and bottom brackets possible you won't need any thing more than that and they will be more than strong enough. Edit: When I say narrow I mean looking from side not narrow bearing spacing.!!

I noticed your Z axis plates look on the thin side what thickness did you have in mind.? For the front and rear Z axis plates I wouldn't go less than 15mm and 20mm is best balance of strength and cost.

I make my living with welding and have big strong (200ton tested) jigs I could use and know how to hold weld distortion to minimum :)
But still I like your idea for the bed more. The massive amount of steel I designed there was in a hope that I could maybe use 15mm ali bed and stop excessive movements with the frame underneath.

So with the Y you basically suggest a structure shaped like a PFC?

Z axis plates? You mean the plate where the spindle and Z axis rails mount to? It is intended to be 20mm. At least in my head, have to check the drawing tho :)

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Originally Posted by mart154

I make my living with welding and have big strong (200ton tested) jigs I could use and know how to hold weld distortion to minimum :)

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Well your sorted then and you'll understand why I said what I did thinking your DIY welder with minimal resources.

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Originally Posted by mart154

But still I like your idea for the bed more. The massive amount of steel I designed there was in a hope that I could maybe use 15mm ali bed and stop excessive movements with the frame underneath.

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Yep it would have been but personally I'd only buy enough to cover the cutting area has Ali plates expensive and even with ali plate you'll want the edges supported. My steel Bed frame is larger than yours with less supports than you first drew and with 16mm ali bed and I don't have any probs with movement. Unless your throwing engine blocks on it then there's very little forces acting in a downward direction while cutting and you really want to limit plunge cutting to a minimum for spindle and machines sake has it knocks shit out of them.!!

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Originally Posted by mart154

So with the Y you basically suggest a structure shaped like a PFC?

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Yep just like a PFC ( Parallel Flange channel for those wondering.!!)

Ok, I updated the drawing a bit.

Did the "PFC mod", tho, now I have to fit the Y ballscrew somehow between the gantry and Z I suppose, so this is still going to change a bit.

Redesigned the bed a bit also. Didn't save any steel tho :)
Decided to have the extra steelwork under the bed just in case. Who knows, maybe I'll mill myself an engine block :)

Now the bits that could introduce side distortion are in one piece and there's a box everywhere under the edge of cutting area.

Left the green 30x30 bits in place. If I decide to have the bed only as big as the cutting area, these will help to mount "cutting fluid collection / mess containment solution"

I plan to cover the sides (and the edges then) with plywood or mdf or 1mm mild steel or something similar.

Attachment 10167


Now, couple other questions have risen as well.
First, on this picture below theres a 15x60mm riser plate under the gantry. I was wondering if it might be worth extending it and put the X ball screw mount straight to it instead of the gantry endplate?
Attachment 10168

Secondly. At the moment my Z rails are spaced 75mm apart, is this going to be enough or should I widen it?


I must thank anyone yet again for feedback. And for this forum in general! Amazing source of information!

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Originally Posted by mart154

Now, couple other questions have risen as well.
First, on this picture below theres a 15x60mm riser plate under the gantry. I was wondering if it might be worth extending it and put the X ball screw mount straight to it instead of the gantry endplate?

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Swings and roundabouts really, both will work. The extended version will possibly make fastening and alignment easier.
Take some time to think about ballscrew alignment because little adjustments can make a big difference to performance and it doesn't take much to go from working fine to stalling motors, esp at higher speeds. So anything you do to make alignment easier you'll be thankful for when setting up.

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Originally Posted by mart154

Secondly. At the moment my Z rails are spaced 75mm apart, is this going to be enough or should I widen it?

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Not 100% sure what your meaning with the apart bit.? Do you mean 75mm between bearings in vertical direction or 75mm between bottom bearings and top bearings.?

Anyway here's my take and way of doing it. The Z axis width or space between rails and bearings doesn't matter so long has you can fit everything like ballscrew between them. So you can make it just the minimum width if you like.!! . . . . What far more important is the bearing spacing on the Y axis and the more(within reason) you have the better it will be, obviously this comes at the cost of cutting width so it's a balancing act and personally I won't go any less than 200mm with 300mm being better. I tend to make my Z axis width 180mm or minimum 160mm.
I only ever really use profiled rails/bearings if can help it and these are much stronger so can get away with 200mm but if using round type rail I'd be looking for more.

I've also noticed you have the X axis bearing spacing very close together.? Same applys here has well but not quite the same with you running twin drive but I'd still try and get the widest foot print you can afford, even if it means extending the top rails past the ends slightly.!

Ive tried to design most of the precision critical components with oval holes and left provisions for shims here and there.

Here's a picture of the new "PFC" to explain the "apart bit."
Attachment 10169
Tho I just realized that the number "75" should be actually 100. So many errors. Embarrassing.... :blue:

So I gather that would be fine?

For bearing spacing on X and Y I do agree, tried to save some cash there but I'll increase it from 150 to 250.

Or would it be any good if I leave the bottom bearings on the gantry with 150 (or 200) spacing and do the top one say 300? (just to get the cutting area that little bit bigger?

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Originally Posted by JAZZCNC

profiled rails/bearings

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I just realized that profiled rails might actually be in my price range. Have to think and choose.


I wander if 15mm might be too small?

Have to do some more research :)
Oh damn you! :)

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Originally Posted by mart154

Here's a picture of the new "PFC" to explain the "apart bit."

Tho I just realized that the number "75" should be actually 100. So many errors. Embarrassing.... :blue:

So I gather that would be fine?

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Apart from it looks like there's not enough room for the ballnut.? . . . Have you accounted for it.?

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Originally Posted by mart154

Or would it be any good if I leave the bottom bearings on the gantry with 150 (or 200) spacing and do the top one say 300? (just to get the cutting area that little bit bigger?

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Yes I'd have the top wide because you can and it will help and have the bottom most you can spare.

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Originally Posted by mart154

I just realized that profiled rails might actually be in my price range. Have to think and choose.

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Well if they are within reach then stretch to them because they are in another league to round rail. 15mm will easily handle the loads but the bearings are not always ideal due to there smaller size but they will easily do the job.

Am I looking for the right things?
100% genuine original HIWIN BRAND Linear Guide1lot 2pcs HGR15 L=400mm rail with 4pcs HGH15CA carriage-in Linear Guides from Industry & Business on Aliexpress.com


If so, I'll redesign everything for profile rails!

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Originally Posted by mart154

Am I looking for the right things?
100% genuine original HIWIN BRAND Linear Guide1lot 2pcs HGR15 L=400mm rail with 4pcs HGH15CA carriage-in Linear Guides from Industry & Business on Aliexpress.com
If so, I'll redesign everything for profile rails!

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Yep those are profiled rails.
If you can find 20mm for not much more then go with those has the slightly larger height and bearing size makes things a bit easier.
Thou 15mm will be fine but you'll need to put raiser blocks between back plate and bearing to give clearance between front and rear plate for ballnut. 20mm mean you just machine a shallow channel in plates for clearance.

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Originally Posted by JAZZCNC

What far more important is the bearing spacing on the Y axis and the more(within reason) you have the better it will be, obviously this comes at the cost of cutting width so it's a balancing act and personally I won't go any less than 200mm with 300mm being better.

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Dean - could you confirm this for me.
If Y supported rails are mounted to the top/bottom of the gantry - do you mean the height of the gantry itself ie, the distance between the rail mounting surfaces?
I think my design is at 175mm currently so may need to extend it.

Mart....try these people NSK LS20 Linear bearings & rails L400mm cnc thk router | eBay. Both Wobblycogs and I have had rails off them and they came quickly and seem genuine good quality although they are used. I also got some rails from YASKAWA, MITSUBISHI items in PK-USEDPARTS store on eBay! these people, ordered Thursday received Monday.

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Originally Posted by CraftyGeek

Dean - could you confirm this for me.

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Yep no problem but I like pretty pictures to save my fingers typing so that should show better what mean when say spacing between bearings.
Attachment 10170

I think Dean means the spacing of the Y rail mounting bearing mounting blocks horizontal should be spaced wider ..Clive

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Originally Posted by Clive S

I think Dean means the spacing of the Y rail mounting bearing mounting blocks horizontal should be spaced wider ..Clive

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Yep I think he does has well. .:loyal:

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Originally Posted by JAZZCNC

Yep those are profiled rails.
If you can find 20mm for not much more then go with those has the slightly larger height and bearing size makes things a bit easier.
Thou 15mm will be fine but you'll need to put raiser blocks between back plate and bearing to give clearance between front and rear plate for ballnut. 20mm mean you just machine a shallow channel in plates for clearance.

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Here is a "right " place to buy everything. The guy is called Fred , here is his email. Very helpfull and good price. I bought last week from him rails and ball screws and am waiting for them. Apart from the ball screws being the cheapest around./when making big order/ he can provide you with 3 types of supported rails and carriages:
1.LG /chinese/ cheapest, the minus is that they don't have long bearings like Hiwin
2.TBI , same like Hiwin, more expensive than Chinese, have long cariages, no dedicated double lip dust seals
3.Hiwin/more expensive than the before mentioned, from EU can be bought the dust seals/

I bought all ballscrews+Hiwing long carriages and rails + shipping+ customs???, a bit cheaper than the Hiwin would cost me here in EU.

Still waiting for the rails, but some guys here bought before from him.

After his detailed offer about your specific need, you will have much clearer view about everything. If cheap is what you search, i believe going with the chinese square rails is better idea than going with round supported rails

I have cut a bunch of steel meanwhile. And started laying out the bed frame yesterday evening.

In other news, I have to find a new job soon, so it might put everything on hold for a little while.
And if anyone has any leads on a mechanic / fitter / fabricator line of job, I might be interested :)