Linear Rail Alternative

[m1911bldr]

I've been lurking and building for the past several months. I have a 3' x 4' foam cutter almost finished and have built a welded aluminum rect. tubing frame for a heavier-duty CNC engraver/router. The foam cutter is a collection of various components I've collected over the past two years; MDF table/base, IGUS slide rail X (horiz) axis and DRILL ROD towers for the Y (vert) axis. The drill rod is an excellent alternative "rail" material for anything of less rigidity than the more serious metal-cutting engravers/ routers. It's exquisitely straight, dirt cheap, machines nicely and is available in 3' and 6' lengths from MSC, Enco and other metal suppliers. Straighter, heavier, and more consistently sized than pipe or EMT - also available in more diameters! I'll post some pics when I get the chance - holiday craziness is intruding on my endeavors!

[dandydon]

What type of linear bearings do you use with the drill rod and where do you get them?

[m1911bldr]

Don,
I'm using Igus Drylin 1/2" pillow blocks (slippery nylon type material as the bearing surface) on the drill rod towers. The drill rod is very straight, very smooth and very concentric and round. It's almost the same quality as the hardened "rails" sold for linear bearing usage, just 1/8 the cost. You can get it in 6' lengths but 3' lengths are more the norm. I've tried the "traveling ball" pillow blocks off actual linear motion rail/slide systems on the drill rod and the difference in smoothness and drag is so small as to be practically undetectable. If properly supported (it's not hardened so not quite as "stiff") it should work just fine for routers and such.

[fatal-exception]

Real ball bearings will quickly roll grooves into drill rod, I tried it quite awhile back. Regardless, drill rod is a very nice material to work with and can easilly be hardened if your making tools out of it.

Let us know how the drylin bearings work. They should work well with the drill rod because of all the surface area. I've also read that those types of bearings are prefered for low noise and dusty applications, like cutting MDF...

Paul

[m1911bldr]

I'm using the Drylins on a hot-wire foam cutter, so dust, etc won't be an issue. The drill rod has a hard-coat dry film applied (coatpro.biz is the applicator). The pillow blocks fall down the entire length of the towers with about a 35 deg angle of slope. I never thought about the grooving effect on unhardened drill rod- you're absolutely right! For Drylin and "sliding bushing" applications, the drill rod should live a long life, don't you think? I'm building a CNC router and using VXB's hardened rail and ball-bearing pillow blocks. They are very nice! Should get good utility out of them.

[fatal-exception]

Hard coat dry film? I didn't know such a thing was possible. It wouldn't help with real bearings, but yeah, it should help with the Drylin bearings. I think they will work well, especially in your environment, it's a bonus that they will very little stress on them, should glide forever....