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

[longy]

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.

[Boyan Silyavski]

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 .

-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

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 . 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

[Beone]

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

[EddyCurrent]

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

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

[Beone]

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

[EddyCurrent]

@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