Am i asking for trouble?

[phantomcow2]

Well i am in the process of gathering material for my CNC router. This will be used to cut wood, wax, and butterboard. I doubt i will ever do aluminum, as I have a mill for that.

My plans were to have a router with 44" of the X, and 24" of the Y.
But i found a beautifully polished sheet of 3/8" aluminum that i snagged for 20 bucks at my scrap yard (still had the retail sticker on it, what a buy!) But the size is 40"x24". So it looks like travel might even be decreased to 38" X. Or somewhere around that.

I am going the skate bearing route. Except rather than have 3 bearings contacting at 6deg, i will have 4 bearings contact at 90. Going to be using 1.5" conduit pipe, which i sanded with fine grit paper so it looks pretty nice. Measuring with my calipers, i found all the OD measurements to be very consistent.

One idea i was wanting to jump on is to use aluminum extrusion heavily. However one part of that which makes me reluctant is to use 1x3" extrusion as the support for the entire moving gantry.
I know i can mount it okay, and I am confident my conduit will hold up fine. But i have never done anything with extrusion, and I am unsure of the ridgidity and strength of the 1x3.

Can somebody comment on this?

[phantomcow2]

One thing it might be worth adding, i dont expect the gantry overall to be very heavy. A rotozip or something of similar size will be used for the spindle. I have a 48x6x.5" piece of aluminum i will cut down to size to join the two columns for the gantry, and on which the shafting and all sits on.

[ger21]

Do you have any drawings of what you propose? Is the table with extrusions only going to be supported at the corners?

[phantomcow2]

I just switched to linux, so my drawing program is not working right now. BUt i will see if I can crank out a crude drawing in "GIMP"

[phantomcow2]

the table itself though will be supported on all edges. What i question is the column that supports the moving gantry slide.

[ViperTX]

I would opt for doubling up on the extrusion.

[phantomcow2]

Doubling up, thats something i could definantly do. Even if i could get away with 1, i might as well overbuild here...

When you say double up though, do you mean make it into essentially a 2x3 or a 1x6?

[phantomcow2]

http://home.comcast.net/~phantomcow3...rExtrusion.jpg

Okay theres my crude drawing and first attempt in GIMP. I know its ugly, but it should give some idea of what im talking about.

The black is the extrusion, the 1x3.
Green lines represent the shafting for the skate bearings
And blue is the ballscrew. Except my router would have a little belt drive actuator, but im not drawing that here

[ger21]

Do you mean for the gantry sides?

[phantomcow2]

Yes! Thats it. I think the all nighter i pulled is starting to have an effect on my brain

[phantomcow2]

Oh, i have one quick question for you Gerry. I saw your router, which i am very much impressed with. Looks strong, i like the conduit pipe, and it just looks elegant i guess with all the wood.
I see you used 2" diameter conduit for 60" of travel. Well for me there will be no supports, and i am looking at 40". Will 1.5" be enough? Or should i go for the 2", as its unsupported.

[ger21]

I haven't seen the 1.5", so can't comment on it. I can tell you that the 2" can flex quite a bit in 60" if not supported. You said you don't expext your gantry to be that heavy. Neither did I, and mine will end up about 75lbs.

The issues with using the 1x3 for the sides, is how you attach the bearings, and how do you keep it from wanting to flex side to side, and front to back.