Newbie new build

[Clive S]

What Neale has said.
Plus:-

You could go with supported rails but if you do you will wish you had gone of proper profile rails, although 15mm rails will do and are plenty strong enough the 20mm are much easier to mount and are not much different in price.

For a machine that size I would go with ally profile 90x45 The holes in the ends of them can be tapped M12 use two pieces for the gantry arranged in an L config and three for the main frame with ally end plates 20mm thick. Check out Joe Harris on here and see his vids all built with simple hand tools.

Start a build log to keep all the questions in one place

[Heliox]

Can you weld? Or do you know someone who can and will for free. This will save you a lot of money.

You will need slides
https://www.ebay.co.uk/itm/15-1500mm...oAAOSwyi9aJP-x
This is the cheapest I've found them and I have this exact set very happy with them, you will not find them cheaper than this new.

You will need a drive as well, ballscrew is your best choice here Ebay is your friend but expect £250 and maybe some import tax.

3. Variable frequency drive it's a inverter that drives the spindle. Spindles are not running 240v single phase they are 3 phase and need the VFD to drive them you cannot connect a spindle directly to either single phase of 3 phase otherwise you get the magic smoke. Water cooled spindle are much quieter if you need a water pump pay postage I'll send you one for free I have a box of them. £200 for spindle with VFD.

4. Everyone seems to go for 3nm Nema 23's ~£30 a motor, I have 2nm on my machine £20 a motor. You definitely don't want less than 2nm.

5. Breakout board to connect to parallel port on a PC, this means you need a desktop PC to drive the machine but it's the cheapest possible way (Yes even cheaper than arduino)
https://www.ebay.co.uk/itm/Mach3-CNC...AAAOSwhqhaRkJb

Buy 2

Think about how your going to control the machine you can buy Mach 3 £200 or use linuxcnc free I chose linuxcnc ;) You need to generate Gcode for the machine most of us are using fusion 360 for this but there's many ways of doing it depending on the job.

The best thing you can do first is learn! Read people diaries ask questions. If the job you have for it is profitable you can probably find someone on here to make them for you and still make money giving you a cnc fund ;)

But once you've done it you're in a special club for sadists that only members can ever understand lol.

It's also highly addictive ;) Most of us on this site would rather get 2 3m lengths of 25mm Hiwin's with carriages for Xmas than a new Iphone, which is the way it should be to ;

Now I built one I can say you build must start in cad! I thought I could build one without cad I was so wrong lol I was being idle. I could have worked it out on paper but damn it would have be sadistic and expensive with mistakes.

1.That's a good size. Big enough to be useful, but not so big that you start to give significant construction issues.

3. As said, water cooling means that the spindle is quieter, and can run for hours without problem. So can air-cooling, but you need to be a bit more careful about dust management so that it doesn't clog.

4. to be pragmatic about it, NEMA23, 3Nm or 4Nm. Might as well go for the more powerful.

6. You will be astonished at how fast and how violently a decent machine can shake itself around. That table will hold the machine while static but it's going to need quite a bit of bracing to handle dynamic loads.

Keep asking. Don't get upset if you get your leg pulled from time to time. Goes with the turf! But you'll get plenty of useful info as well.

What Neale has said.
Plus:-

You could go with supported rails but if you do you will wish you had gone of proper profile rails, although 15mm rails will do and are plenty strong enough the 20mm are much easier to mount and are not much different in price.

For a machine that size I would go with ally profile 90x45 The holes in the ends of them can be tapped M12 use two pieces for the gantry arranged in an L config and three for the main frame with ally end plates 20mm thick. Check out Joe Harris on here and see his vids all built with simple hand tools.

Start a build log to keep all the questions in one place

Guys what can I say, thanks I'm off to a flying start already with all those suggestions, many thanks.

re: preferring Hiwins to a new Iphone,,,lol,,,I totally get that angle ;-)

You've thrown me with the "can you weld" question? I can as it happens (I used to be a coded welding inspector offshore, among other things) but can't think what you'd be welding on a CNC machine, unless your talking about welding some of the Ali (or Steel) sheets/brackets/side plates? And to be honest I'd probably get someone else to do it as I haven't in a long time, other than a bit of mig and stick on various bit's in the workshop. (oh and I don't have roof on my workshop at the moment).

Software: I have been using Sketchup for a number of years, so no issues with a bit of CAD, I was about to download Fusion 360 a few days ago, haven't got round to it yet, but I did see you can use it free as a small business or hobbyist/student so that's good.
I also downloaded a few weeks ago a plugin for sketchup that produces G code 'SketchuCam'
I got that here http://phlatforum.com/xenforo/

I do have a question on designing the CNC machine in Cad though, I can't see the benefit in designing in CAD, what I mean is am I missing something? because to design a CNC m/c in a CAD program you have to know the accurate Dimensions of each part, or box profile and then Draw each into the program. Which means unless your provided accurate drawings of each individual part before buying it, then you have to have the part in your hand and take a vernier to it, which means you have probably already bought the part? I can see how while your building it it might be helpful to make a drawing of it so you can add parts or modifications, but I can't see how your accurately going to draw it before building it? That's not me being awkward, I just don't get it? can you elaborate how you found it helpful?

Re: The controller/PC,,,,,,it just so happens I scrounged a windows XP (or vista) desktop tower off my father in law about 3 yrs ago, and funny enough I wanted it for the parallel port as I have an old laptop with a parallel port that I use to send files to a large A0 A1 printer plotter I bought off eBay a few years ago, the laptop screen is dodgy sometimes so I got the tower for that as backup,,,it's sat in the box just in case but I took it out a few days ago and powered it all up,,with the intention of possibly using it as a dedicated CNC computer, but I also bought a 3d Printer last week that I thought I might use it dedicated for that too. (Tronxy x5s, not arrived yet).

BOB's,,,,,,,,,,familiar with the concept of them, and why opto isolation etc.

Re: the table and how violent the machines can be, I get that Neale and agree with you, many moons ago I worked installing multitool CNC machines in Cosworth in Northampton and I also worked for Sony in Bridgend and Festo pnuematics, so I totally get where your coming from re: the forces, In fact anyone who has had a run-off with a decent hand held plunge router knows when you bolt something like that down and start cutting things there's alot to go wrong and fly about and all round alot of harnessed energy. (I'd thought about bolting the table down, adding a decent slab of something on top to give it a bit more mass and some form of diagonal bracing and beefing up the legs).

Dust management,,,,,mmmm yes that has been in the back of my mind as an issue, not for clogging a spindle but just the sheer pain in the rear factor of capturing it all, I have an axminster dust extractor for a Jet table saw, but extracting carbon fibre dust is going to be a different ball game, I'm contemplating a glass fibre wet tray into the design so the parts are submerged in water during the cutting, something similar to a wet tile cutting machine, has anyone seen anything like that on a CNC on this forum?

I see you all recommend the linear profile rails opposed to the round supported rails, why is this? are the profile rails less susceptible to play? or wear? less vibration? what's the negative issue with the round supported rails?

Thanks again guys,,,off to do a load of reading on here.

[Desertboy]

Cad models aren't so bad, you can download dxf's from KJN aluminium if using aluminium profile, Hiwin cad models are available from their website make sure you get the right model (It's the carriages you have to watch mostly) I never cad the ballscrews out I just did the maths using the datasheets but you could cad them if needed the thread is irrelevant. I certainly never picked up a pair of verneirs during my build lol

The information you need on the ballscrews are on the datasheets for BK12/BF12 and dsg16 if using 16mm ballscrews.

Further to what clive said about 15mm being harder to mount you need spacers see below.



also greasing 15mm rails is also a PITA.

If you have trouble finding cad models grabcad is good but I always grab the models directly from manufacturer or reseller if I can as accuracy is important.

Lots of people makes their frames from welded steel box section and then use epoxy resin to level the box section where you fit the linear slides. Steel is a lot cheaper than aluminium extrusion, it's also popular to mix steel everything with an aluminium extrusion gantry which is my plan for my next build.

There's £600+ in aluminium and fittings in my router if I'd paid retail for it and I have 120cm * 70cm travel. You could certainly do something in steel a lot cheaper than that and of course it's stronger.


Accuracy with a steel a frame is nowhere as important as you think depending on how you fit the hiwin's the most important thing is they are level and parallel to each other. I'm going to weld mine together myself but have the steel cut by someone else (Who will be super accurate and square) to make things easier then you need a level working space and so decent magnetic clamps should be fine.

This is a quick mockup I did in fusion 360 for my next router, see how I'm planning to mix steel with extrusion. The cost of those 2 pieces of 9090 extrusion is £240 alone! My design is a nightmare because I want the Hiwin's sideways on so the frame does have to be very accurate and epoxy levelling for the Hiwin's will be difficult as I'll have to turn the router 90° to level each side. Mount the Hiwin's on top and you can don't need the frame to nearly as accurate.



That's not a ballscrew it's a cylinder I extruded with BK fitting's I downloaded the important bit is the DSG ballnut housing as this is your mounting point.

Prices add up quickly I've spent over £80 just on T nuts to fit the Hiwin's to the extrusion and M4, M5, M6, M8 & M12 bolts. If you use corners it becomes even more expensive.

[Heliox]

Ah ha,,,,,welding now it makes sense.

I see now, yes for sure if your including a frame there would be alot of welding, and I see that shimming out the rails with epoxy etc will give you the alignment accuracy where needed.

Lot of interesting points in your post, I'll digest that some more later.

Out of interest why are you choosing to mount the rails on the side rather than on top? is there an advantage or is it to do with working width?

Also to reduce materials; at a cursory glance if you wanted side mount rails I wonder if you would gain strength and reduce flexing movements by putting those rails on the inside of the frame?
(Though no doubt you'd probably lose some working width).

[Clive S]

Also to reduce materials; at a cursory glance if you wanted side mount rails I wonder if you would gain strength and reduce flexing movements by putting those rails on the inside of the frame?
(Though no doubt you'd probably lose some working width).

If you go the steel route mount the rails on the top as it is much easier, the way the epoxy works is that you make a moat on the two rails with a bridge between them this way the epoxy will flow around and give you the flat plane you require.

You use the very slow curing epoxy made by Wests 205 - 109 fluid for about 8 hours.

Search of the forum for epoxy levelling

[Heliox]

Thanks Clive

I would have thought there are other benefits to mounting the rails on top too, like the slider bearing are being worn either side rather than all the weight and action being applied to topside...................Although it is probably negligible over time anyway.

I like the Frame, neat job, is it 75mm box section your using or is that 100mm? ( I was trying to guess from the clamps and mdf).

Epoxy, I haven't specifically looked yet but I did see some where making Epoxy square pads, but what you have done there is much better, less chance of the epoxy shattering with long strips like that too as opposed to isolated squares.

I got a load of Epoxy here...and I guess besides a slow cure pre warming will make it like water to get the level, in fact you can get laminating epoxy which is quite thin and you buy the slow activator...(I repair boats occasionally). I buy from East Coast Fibreglass supplies, and CFS fibreglass suppliers.

How are you sealing the MDF mould to stop the Epoxy running out underneath? have you stuck it down with a grab adhesive or some sealant?

I make grp moulds occasionally and I use modelling clay (the GRP suppliers sell it) to make fillets around edge. you never see square edges with GRP parts, always rounded,,and it is done with modelling clay and a wooden spatula,,,or finger to make smooth radius. (Though in the case of what you have done there it wouldn't be applicable because the radius would create a lip in the epoxy down the edge). Anyhow just thought I'd pass that on as the clay is handy for various temporary shaping and sealing once you have used it for that kind of thing.

Some polyurethane glue like gorilla glue, or even an expanding foam gun would make a good seal too,and be easy to peel off afterwards.

[Clive S]

My frame is made out of 60x60x5 box, what is not shown is the table bed as that is adjustable in that it can be moved to different positions but in reality I have never moved it.

I sealed it with decorators caulk the epoxy is 5mm thick it came from East Coast Fibreglass. You have to be very careful with the sealing. It was left for about 8 days before removing the mdf