Best place for parts for CNC?

Hi everyone,
My name is Wayne and I own/operate a small sign business, am also compulsive tinkerer and jack of all trades, and would like to build my own 4x8 router for the shop. I will be routing mostly HDU(high density urethane), but also some other plastics and wood. You can see some of my work at webbsignstudio.com

I have over 1000# of 80/20 t-slot aluminum in various sizes, including one 3''x6''x60'' piece which I hope is long enough and sturdy enough to be used for the horizontal beam of the gantry.
There are also two 60'' steel Thompson linear rails but they have no slide/bearings. Could bearings be matched for these?

Should I use rack and pinions for the X axis?
Are the "threaded rod" thingies (name?) with the bearings etc, the best to use for the "linear actuators"?
What about servos vs stepper motors? Is 600 in lbs enough torque? Are 4 motors enough and would they need to be all of the same size?
I will run at least a 3.5 HP Porter Cable router on it.

Where would be the best place to get what I need?
Also some plans would be a bonus!

Thanks for helping.

Sounds like you are in the same boat as a lot of us at the start. Lots of things to think about and just about as many examples to follow..

One thing depends on the next depends on the next it seems.

I have a few threads on my build (which I have been very happy with how it custs. So I'll point you to them..)
http://www.cnczone.com/forums/showth...t=wcarrothers1
http://www.cnczone.com/forums/showth...t=wcarrothers1

Examples of things done on the cheep. and a mix of using both rack and ball screw drive. some reasons why I went one way or the other.

Design was a combo of ideas out of my head, avaliable bits, and stuff from the zone..

If it isn't in the threads some where. I went with rack on the long axis (Y) due to length and I also got a 10:1 thompson planetary for under 100 bucks on ebay that was perfect for the job (actually it could have been a higher ratio)

didn't do rack on the gantry axis 1 because gearing a screw was easier, and didn't want the weight to be out on the gantry for the (X) my 1100oz servo motors are 10+ lbs each. Figured the gantry would move nicer the lighter it was. Course that choice results in a max jog of around 200ipm on X where I can do 400-600 or even 800 on Y with the rack..

Also limited to the max rpm I can run my servos before they fault out with the voltage my power supply runs..

i'm running Gecko 320's for my servo drives. I don't know much about other alternatives but they work very well and I'm happy with them even if they happen to be more expencive then some others. Also eaier to buy the supply in kit form from camtronics although there might be a cheeper way to do it. You have to get the motors from some where and he is probably as cheep as anyone else and friendly..

Also in my case I would have been curious about mixing the motor sizes between the different axis. I'm pretty sure that I didn't really need a 1100oz motor on the Z for example but done mostly in an effort to maintain a balance. but I'm pretty sure I could have saved quite a bit of money mixing the sizes..

mcmaster car has most of the smaller bits you would need.
Pretty sure my thread says where I got my steel bar and stuff as well (for pretty cheep) Ebay is a good place for that stuff to. Lots of deals to be had if you have time to wait.

Don't know if any of that helped..

Anywho..

That's a wealth of information to to get me started!
I'll look at all of that.
Thanks again.

Misumi www.misumiusa.com has good prices on some stuff. Ball / Lead screw support bearings for example. Many of their parts are custom configurable, and many are available for download in 2D and 3D cad formats. Good Luck!

Thanks dansutula.

Any one looking at building a 4 x8 router should at least have a good look at the Mechmate.

Free plans and even support if you decided to go with that design.

And if it is not exactly what you want you will learn a lot there just by reading and looking.

http://www.mechmate.com/index.html

Greg

Thanks Greg!

This is a pic of the rails that I have. They are somewhat rusty sxo I don't know if they are any good. I tried cleaning this one with a wire wheel. I'm sure that sandblasting would probably be not a good idea.

http://www.webbsignstudio.com/assets...near_Rail1.jpg

How do these compare to the round rails in accuracy, strength and durability?


If I use the supported round rails for the 8' long (y??) axis, would this be too much of a span to use ACME or ball screws to drive it?


Thanks