[rcrank]

Hi all. I am finally going to take the plunge and do a DIY CNC router. I actually have need for a high end unit but I also just need to do typical wood routing. Should I go all out and build the CNC of my dreams or should I start with a simpler design. There are very cheap linear rails and bearings on EBay. These are all from China and I presume not the best quality. My question is are they good enough for a first machine that could at least carve wood?
Thanks

[ger21]

I actually have need for a high end unit but I also just need to do typical wood routing.

Are you saying the high end unit would be cutting materials other than wood?

There are very cheap linear rails and bearings on EBay. These are all from China and I presume not the best quality. My question is are they good enough for a first machine that could at least carve wood?

People have been building machines with home brew linear bearing systems for years with good results. If your talking about the round supported rails, than yes, they are fine. They're not as good as THK or Hiwin profile linear rails, but they're much cheaper.

[rcrank]

Thanks for your reply. Yes I would like to machine aluminum but am afraid such a machine my be a bit much for a beginner on a budget. Those ebay supported rails are probably cheaper than home brew if I did it, about $190 for all 3 axis. I will order soon and get the project going. I plan to do most of the construction using aluminum or welded steel.

[dmalicky]

I'd recommend not ordering anything until the design is completed and refined. Lots of people order parts early, then design it, then realize they have the wrong parts. Also I'd suggest at least a month of study reading the archives, then work up a design, then post it here for feedback. These are pretty complex machines--very cool--but lots to learn to make a good machine and lots of ways to make mistakes (in performance loss, mis-spent $, and simply the wrong machine for one's needs). Unless you really want to learn the background and design a machine, the best approach is probably to copy a known good design or buy the plans of one.

In your shoes, with what sounds like a need for 2 machines, a good approach might be to build a small and simple machine for wood first (probably from a standard plan), learn from that, then use that experience to build a better one for aluminum.

[adprinter]

As the old saying goes: "There's more than one way to skin a cat" Like you, I started out building my own machine not really knowing what I was doing yet. That was in October, 2008. A LOT has changed since then, as I have continued to add to my machine's capabilities, and sturdiness. But the basic linear rail design I came up with is still in use today (on my machine). It is constructed of 1.5" square tube steel rails, with 4" square tubes in use as the actual trucks. Inside the 4" tubes, are swing bolts (think heavy-duty Eye bolts,- the thing that makes them heavy-duty is the fact that they are machined from a single piece of steel). On the swing bolts, are cheap skate wheel ball bearings which ride along the surface of the 1.5" square tube rails. It makes for a VERY sturdy linear rail system, which would cost many times the investment I have in these, to do the same job. The arrangement of the swing bolts is pretty simple- Bearings are mounted on two all thread rods on the top side, a second piece of all thread rod is used to ride along the bottom side, suspended by the swing bolts, to form a four-sided clamping action around the perimeter of the 1.5" square tube rails. Hope this helps!

[RCWorks.com]

This is what I am using...

Well picture uploading is not working for me...

I am using bearings running on pieces of 2.5 x .25 cold rolled steel.