[nicko17]

I would be interested in building up a cnc milling machine to do steel/aluminum.

From all the ones i have seen they have taken a bench mill and converted it to cnc. I haven't seen anyone done from scratch. There probably is i just havent came across any.

My main concerns are the linear rails (strength) , and a head that i can put r8/ other holders in. Linear rails are easy to get , but how well will they work when you have more torque on them/ consistency.

[kling8]

Why don't you look into a used CNC machine that already works rather then spend all the time and money in building one. I read alot of people building there own and it is probably a fun project, but I'd rather get something that works that can start making me money sooner than later. Just my thought...

[nicko17]

Why don't you look into a used CNC machine that already works rather then spend all the time and money in building one. I read alot of people building there own and it is probably a fun project, but I'd rather get something that works that can start making me money sooner than later. Just my thought...

I have seen older cheap cnc for sale for decent price.

But i do not have the space for such big machines. Nor do i have the power for it. I need something that can fit on a table and can run off 220 or 110v 1phase.

I have seen units like this but im not going to spend 5K on one. Unless you have seen ones cheaper , i haven't.

[thebodger@roger]

If the basic structure of the frame of the machine is sound, then linear rails will work fine. Many modern machine tool builders use this system

[nicko17]

If the basic structure of the frame of the machine is sound, then linear rails will work fine. Many modern machine tool builders use this system

I was thinking of putting down some 1/2 thick + by 4" bars as the main frame. Its the slop in the bearings i would be worried about , even though if i have 4 bearing blocks per axis.

For 2 axis , 2 feet by 2 feet with bearing blocks its going to cost me over 200$. Ball screws seem pretty expensive too , probably atleast another 250$. This isnt going to be cheap , i'm going to reconsider on this.

[serriadh]

For 2 axis , 2 feet by 2 feet with bearing blocks its going to cost me over 200$. Ball screws seem pretty expensive too , probably atleast another 250$. This isnt going to be cheap , i'm going to reconsider on this.

You'd also need access to a relatively large machine to build the structure for any new build; getting your linear rails, ballscrew and table all perfectly colinear and coplanar where they meet the bed/saddle is a non-trivial task and exceptionally hard to do without time on a larger mill.

Few examples of some really high quality builds that are worth looking at if you've not already done so...
http://zealcnc.wordjot.co.nz/
http://www.5bears.com/cnc.htm

There are a few others about on here, small to large, but I can't remember who started them or what the threads were called.

To summarise; expense is only one aspect of the problem! Converting an existing benchtop is significantly simpler, and cheaper in term of equipment required. That's one of the reasons it is so popular.

Best of luck with your planning.

[nicko17]

I was thinking some nice solid flat bar would be flat enough to use as the base , drill holes where needed and ready to go. But then again once i get into im sure it wont be the best.

I guess this isnt going to work so well. Thx for the links

[serriadh]

I was thinking some nice solid flat bar would be flat enough to use as the base , drill holes where needed and ready to go. But then again once i get into im sure it wont be the best.

I guess this isnt going to work so well. Thx for the links

I'm not sure quite how coplanar and parallel linear rails need to be, but they're best kept to tight tolerances... I think THK have some good information about installing rails, and I would imagine that other manufacturers (eg Hiwin) do too. Worth a quick read. All projects I've seen here using linear rails have the base machined using (at the very least) something Bridgeport-sized and set up to a high degree of accuracy. Grinding and sometimes scraping in by hand is also used in many cases.

Something like cast aluminium tooling plate (MIC6 is one brand) might well be flat enough to use as-is, but without a nice straight reference edge to line the rails up against, keeping them parallel will be awkward. Surface plates would also work, but chunks of flat bar are a bit more of a gamble!

Few links I thought I'd put in the last post, but which somehow went astray:
http://www.cnczone.com/forums/showthread.php?t=30262
http://www.cnczone.com/forums/showthread.php?t=71652
http://www.cnczone.com/forums/showthread.php?t=51688

[nicko17]

I'm not sure quite how coplanar and parallel linear rails need to be, but they're best kept to tight tolerances... I think THK have some good information about installing rails, and I would imagine that other manufacturers (eg Hiwin) do too. Worth a quick read. All projects I've seen here using linear rails have the base machined using (at the very least) something Bridgeport-sized and set up to a high degree of accuracy. Grinding and sometimes scraping in by hand is also used in many cases.

Something like cast aluminium tooling plate (MIC6 is one brand) might well be flat enough to use as-is, but without a nice straight reference edge to line the rails up against, keeping them parallel will be awkward. Surface plates would also work, but chunks of flat bar are a bit more of a gamble!

Few links I thought I'd put in the last post, but which somehow went astray:
http://www.cnczone.com/forums/showthread.php?t=30262
http://www.cnczone.com/forums/showthread.php?t=71652
http://www.cnczone.com/forums/showthread.php?t=51688

I work as a machinist , so this isnt new to me. As for the flat bar , im not sure how flat they come off the mill. Thickness wise they always seem to be pretty close. Sure it wont be perfect. Scratch that idea.

I cant seem to find a place that sells mill spindles. I'm not going to use a router.

I will continue to research , i doubt i will ever do this though. It would be cheaper to buy a used bridgeport and convert it , wish i had the room.

[serriadh]

I cant seem to find a place that sells mill spindles. I'm not going to use a router.

Little Machine Shop sell Sieg spindles... you can get a whole X3 spindle and column assembly or complete or partial X2 mill heads. Beyond that I only ever seem to find high speed spindles that would be fine for aluminium work, but not so great for steel. Keling sell some moderately powered high speed spindles, and over this side of the Atlantic you can get various moderately sized Suhner and Elte spindles, though they're not cheap.

Again, probably the easiest way to get a moderately priced spindle is to get a mini-mill of some kind... the Weiss models seem to be quite popular right now (G0704, BF-20, WM-25, and a dozen other distributor-specific names...) and have the advatage of being a wee bit easier to move around than a Bridgeport.

Plus, once you've got once CNC mill, converting the next one will be so much simpler :bat:

[nicko17]

Little Machine Shop sell Sieg spindles... you can get a whole X3 spindle and column assembly or complete or partial X2 mill heads. Beyond that I only ever seem to find high speed spindles that would be fine for aluminium work, but not so great for steel. Keling sell some moderately powered high speed spindles, and over this side of the Atlantic you can get various moderately sized Suhner and Elte spindles, though they're not cheap.

Again, probably the easiest way to get a moderately priced spindle is to get a mini-mill of some kind... the Weiss models seem to be quite popular right now (G0704, BF-20, WM-25, and a dozen other distributor-specific names...) and have the advatage of being a wee bit easier to move around than a Bridgeport.

Plus, once you've got once CNC mill, converting the next one will be so much simpler :bat:

I saw that at littlemachineshop , they want 300$ for a head assembly. Plus shipping to canada probably at least another 100. I wish there was harbour freight here in canada then i would buy the whole mill. Here in canada princess auto sells them but they want a grand for one.

[serriadh]

Here in canada princess auto sells them but they want a grand for one.

That's not far off the going rate for that sort of machine though, right? MTW sell the Weiss mills (which are a little better than the Sieg ones, apparently). Course, if you're in the wrong end of Canada that won't help much either. Oh, and if 900-1200CDN is too much for you, I have no sympathy because that's what Warco sell the equivalent machines for in the UK :-)

Sounds like there's maybe a profitable venture in smuggling cheap US machine tools across the border for desparate zoners.