[DroopyPawn]

I've been collecting stuff to build a CNC router for a few years now. I'm just not sure how to start putting it all together. And I think I need to sell some of the stuff and replace it with other stuff.

Here's a partial list of what I have...
2 0.75"x53" supported round shafts with 2 short bearings each
2 1.25"x40" unsupported round shats with a 5.5" bearing each
2 8.5" rails with 2 small bearings each

2 6' acme rods 1/2 - 10
2 1/2-10 delrin nuts
at least 2 .5" bearing blocks for the rods (can't find them but they're here somewhere)

For tools to work with, I have...
Hammer drill
bench top drill press
Taig CNC mill (that I killed the driver board on. I ordered a new one, just haven't ever gotten around to hooking it all back up)
Table saw (I broke an ear of the fence last week doing a new kitchen floor, grrrr)
Skill saw
Reciprocal saw
Small air compressor
Basic hand tools (hammers, wrenches, etc.)

I'm thinking I might like to order some aluminum extrusions to start on a project similar to http://www.cnczone.com/forums/cnc_wo..._steel_al.html
As I have it figured, the x, y, and z axes will cost me about $300 plus some shipping.

Before ordering, I have some questions...
1. He used square rails, I have a set of round ones. Does it matter? I'm thinking of replacing all of my rails with supported round ones of the right length.

2. Can the entire machine be build from the extruded aluminum pieces? He used aluminum plates for the gantry. I'm thinking of going with all 1020, etc. Will it be string enough that way?

3. Does my gantry need the cross piece on the bottom? I've seen gantries with just an up-side-down U shape. Is there any reason to use the rectangular shape instead?

4. I'm assuming that using the extrusions will make it easier to square up everything on my machine's frame compared to MDF or welded steel. I also think it will be easier to keep my rails parallel with this system. Am I fooling myself or did I get it right?

5. I plan to build the machine with about a 5' x 4' footprint. Do you foresee any problems with chatter, binding, or issues I haven't thought of? I plan to use dual drives on the x-axis.

Thanks in advance for any help.

[ger21]

Honestly, I'd get rid of everything you have and start from scratch.

The 53" unsupported shafts will flex like a wet noodle.
And the 1/2-10 will be very slow, and at the lengths you want to use, will whip badly.

Check out these plans using all extrusions.
CNCRouterParts

You might also want to look at Fine Line Automation.

[DroopyPawn]

I think I AM going to sell the stuff but you missed that the 53" rails are supported - not unsupported. Maybe I'll keep those for something later. Anyway, thanks for the tips. I'm planning to build one of the FLA kits now. Much less collecting.