[gun_mike]

Hey Guys,

It's been a while since I've posted here. I've been quite busy lately revising my homemade 3-axis mill.
Previously It had a dovetail saddle and table, this new revision has THK 15mm rails in place of those lousy dovetails. The difference is incredible. The table is very rigid, and I've gotten the backlash down to under a thou in both X and Y axis (oversized ballscrew balls) The machines rapid is now 210IPM which is the most my G540 will support with 5tpi ballscrews. The old noisy geared treadmill motor for the spindle has been replaced with a HiTorque mini mill motor and controller and synchronous belt drive, which is controlled by Mach3. In the past I've always had problems with chip guarding on the rear side of the Y-axis. I solved this by using U-shaped accordion bellows from Mcmaster Carr. The front Y-axis cover is made from some 1/16" stainless that I tig'd together. The machine has full swarf guarding on the table and home switches for all three axis. Anyways here's a photo of the mill and a video of it doing a test cut.

Homemade CNC Mill 3/4" Bore Test - YouTube

Mike

[J S Machine]

This is cool man. Good job. I have thought about building a machine and using linear rails, but I imagine it isn't cheap.

[109jb]

You have done a great job on your machine. Looks to be about an X2 size machine. I am contemplating building a RF45 size machine with linear rails but don't know what size rails to use. How did you decide on the size for your machine?

[wizard]

This is cool man. Good job. I have thought about building a machine and using linear rails, but I imagine it isn't cheap.

This is where that phrase "it depends" comes in. Source used hardware and you potentially save a lot of money. Actually I don't see raw materials being a big issue relative to buying Chinese cast iron. Steel tubing isn't free of course but overall I don't see it as a significant expense. The big issue in my mind is access to a machine shop to actually machine all of the weldments to square up and flatten as required. Well that and stress relieving the weldments. If you can get that work done locally cheap enough the build might be cost effective.

If you look at what Shyfire charges for his small mill you will see that even something built in China is relatively expensive. A lot of scrounging can address the cost issues.

[gun_mike]

You have done a great job on your machine. Looks to be about an X2 size machine. I am contemplating building a RF45 size machine with linear rails but don't know what size rails to use. How did you decide on the size for your machine?

I chose the largest rails/block set I could find that would fit in my configuration. For an RF45 sized machine, I would use 20mm rails for X and Y and 25mm for the Z-axis. There are many different types of configurations for the blocks and rails. You can even get then with roller bearings (needle bearings) for ultra high rigidity. I just stuck to the basic THK SHS style rail. This has the contact area for the balls angled in at a 45 degree angle to achieve good support in all directions. All of my rails were purchased on Ebay for awesome prices. I got my z-axis rails and blocks for $38 (4 blocks and two 22" rails!!). I believe my X and Y axis were about $60 per axis.
One thing I would advise on is buy them in sets as there are so many types of rails and a lot of other companies making similar ones. It would be very easy to buy an incompatible rail/block combination.

Mike