DIY Linear Rails - Building from scrap on a budget of next to nothing

Hi everyone, after having to put my 1500 x 1000 steel build on hold due to health and finance problems this summer, I still would like to built a cnc. Finance or the lack of any meaningful budget is something a lot of people who are wanting to build a cnc face. I would like to hear from other members that have gone that have gone down the roller skate bearings on pipes route, using wood or MDF how good or bad was your build ?


V-Groove bearings like the ones in the video below has anyone used them and will you be honest and say how good or bad they are ?

https://www.youtube.com/watch?v=3Oy6OeXmVo8

I have a shed full of plywood offcuts, steel pipe and tubes, plastics nuts bolts and the rest, I would love to explore more on building this way to make a machine to move one of my five routers around, does not need to accurate to less 0.05mm as I only want it to help with learning to use the design software and understanding mach3 better.

I intend to record and take as many pics as I can of the build so others looking to build can learn what's good and what's bad when on a tight budget.

Lets hear your views everyone.

Mike :)

I very much look forward to following the build, if you already have most of the stuff why not give it a go ?

Definitely worth a bash, the cheapest builds look like the most fun!

I have built and am currently using an MDF machine built, more or less, to the JGRO design. Plenty of info if you do a Google search. Pro - materials to build are cheap. I went up a size on steel guide tubes, but it still uses skate bearings and threaded rod so didn't cost an arm and a leg. I did spring for bigger motors than recommended and reasonable drive electronics so that I could reuse these later. Fairly simple to build with ordinary tools, although I also used my lathe, milling machine, and 3D printer to produce parts (home-made motor couplings, anti-backlash delrin nuts, etc). Cons - it warps like nobody's business, and it's really, really difficult to keep the bearings in adjustment. Use of M10 threaded rod as a leadscrew may be cheap but the critical speed is low, so my maximum rapid speed is only 900mm/min.

I've done some useful work with it; I was using it today to make drilling jigs for some MDF furniture I'm building (the cutting area is too small to directly CNC cut the cabinet panels) and it's fine for that kind of thing. I've learnt an enormous amount from it (including a long list of what not to do!) at not a very great cost and had a CNC router available for use while planning the Mk2, which is now being built. I wouldn't stop someone building a wooden machine, and I'm sure that you could build something stronger than mine, but just keep in mind that it is going to have limitations and go into it with your eyes open.

For learning sake then go for it and so long as you don't invest too much money or have too high expectations you'll be fine and should full fill it's purpose.

While V-Rollers are more resistant to dust and debris, the bearings have a small amount of play in them, so they're not really any more rigid than skate bearings. I've heard that the CNC Routerparts machine in the video is less rigid than their skate bearing model.
My wood and skate bearing machine has been running well for over 5 years now. I've used it for many things, from wood, to phenolic, and even aluminum.
Mine is much more rigid than the JGRO model mentioned above, though. I highly recommend supporting the pipes in some way, as it will greatly increase rigidity.

I think that the Joe2006 design is better than the JGRO as it provides much better support for the steel pipes. Downside is that it really needs a CNC router to cut the parts sufficiently accurately! I was thinking of building one as my Mk2, but then decided to go welded-steel instead.

Thanks guys, just what I wanted to hear not one of poo-pooed the idea of the scrap heap challenge. The budget is small and I'm not going to invest too much money in the build, the most expensive part will be the motors and drivers. I want to use it as a learning curve and then try to help others avoid the pit falls. Wood scraped for tests and trials that don't work will head for the wood burner that does my heating. I've got a feeling it might get a bit warm.

I've been looking at the Solsylva machines and watching vids on youtube of the builds plus reading other forums post along with this one. One thing that I have decided on is it's going to be a bench top machine and the dreaded mdf limited to the cutting bed, as it don't burn that well.

I have such a machine, with V bearings. Will work OK for wood and plastic. Aluminum-NO.

The good: Cheap and makes money if you are clever.

The bad:
-Man, i hate the V bearings and all their incarnations. Plus people who promise not achievable things with them http://www.picgifs.com/smileys/smile...ing-166975.gif.

-The biggest pain is to tighten equally all carriages. Though CNCrouterparts solution seems more clever than on my machine. Usually have to over tighten them so there is no play. That means the motors are always on big strain, so you need good high voltage drivers

-You will need on the gantry 3rd or even 4rth way to support the Z from behind. Additional rails i mean, at the back best done with roller bearings

-Dust resistant-Not at all if you don't use aspiration. I don't use and have to clean regularly the rails and bearings, not a big deal though. Though clever design will eliminate the problem.

I learned CNC on my V bearing machine, i paid my machine and earn money for living on it. If i see in person the engineer who made it i will http://www.picgifs.com/smileys/smile...ing-820903.gif

So how to make it:
-Make sure you buy the biggest V bearings you can afford
-make sure you use NO V bearings on the Z
-support the Z also at the back of the gantry/ 3-4 points of support/ . If not sure, will send you photos of my machine if you need ideas there.
-use belts
-No plastic V bearings
-design it easy to tighten the carriage. And accessable.
-There are by the way 608 roller bearings that are 0 clearance and are good for CNC. Just don't be fooled by ABEC this or that. VXB has them and other sellers at ebay. 2 of them can go in a V casing, then you change only the bearings, not the V. One guy sell these on ebay.


When i bought my V bearing machine there were no cheap Chinese machines, no other options. Also i was very :stupid: . No MYCNCUK forum, only overexcited Americans at the Zone. Me with cash in the hand and nobody answering correctly or truthfully my questions on the forums.

But honestly, now in 2015- i will rob innocent children of their savings but not buy or make V bearing machine. In fact i would buy 4 supported rails with blocks and make all else around them from scrap if a cheap build is desired.


PS. Honestly-V bearings http://www.picgifs.com/smileys/smile...ing-527413.gif

I built my router in 2006 and have run it hard since. Built from 1/2 ply, I used torsion box construction so my rails are well supported. I have very few problems with the machine warping. Skate rail x and y. And v bearing on the z. Skate rails work great! Just be sure to get sealed bearings, not shielded. Over the years shielded will get crammed up with dust. I have had it to as much as 250 in/min but best cutting is at 30-40 in/min si I keep the rapid at about 150. Cuts about anything including AL at slow speeds and light cuts using woodworking carbide bits. The v bearings seem to work great on the Z.
Skate bearing and ply works great for me in a router and true linear bearings are just a waste of money.
Dave

Quote:

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Originally Posted by Beone

Skate bearing and ply works great for me in a router and true linear bearings are just a waste of money. Dave

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You are correct there, true linear bearings would be just a waste of money on a ply machine.

Yep, ply and skate bearing and yet in spit of that I maintain accuracy of better than .005 inches.
Dave

@Beone. It would be great if you could do these tests and add your results to the end of that thread. If you read the posts it says how to perform the test.

http://www.mycncuk.com/threads/7155-...ight=stiffness

Neale, thanks for your honest opinion and advice. I had a look at the JGRP designs and did learn something from them. I'm not going to use much mdf only for the bed as I guess you mdf can swell as much as 4% even if sealed, left unsealed in damp conditions then 20% is not uncommon before it ruptures.

JAZZCNC, I don't intend spending much as I ain't got much to spent on the build.

Ger21, thanks for your input I would be interested to see some pics of your machine if you have any to post.

Silyavski, thanks for your input and advice. I have not seen the V casing on ebay can you post a link please. Also please post the pics of your Z axis please, yes I was thinking of using belt drives for the X and Y axis with liner round supported rails or profiled + blocks on the Z axis. NOTED your comments of V bearings LOL
Having costed up some stainless steel angle today as an alternative to round tube which I've several 4ft lengths I might as well buy supported rails as it would be cheaper.

Beone, thanks for your input. I know what you mean about shielded bearing and dust, as I was looking at a vertical panel saw with problems today and part of the problem was the bearings sticking apart from the resin build up on the rails, no wonder is was jumping out of the track. Can you post some pics of your machine please.

EddyCurrent, thanks for your input, yes I'll do some test and post them to the thread once I've got a machine built.

Mike :)