Ok, i have decided to compleately restart my cnc project. i strted out building a solsylva 24" x 48" rack and pinion set up.

I have decided to move compleately, or almost compleatley to 80/20 1530 extrusion. I have built my z axia using the parts from cncrouterparts.com and they worked great.

Working on my design i plan on having a cutting area of about 54" x 33". I plan on running raised rails for the x axis, and run dual lead screws for it. My z offers just over 5" of travel. With my raised rails, my gantry my only stand 6-9' tall. I want to keep it as short as possible. Now, for my y axis, and i use a single piece of 4" cold rolled steel of my rail with a car on top and bottom? most i see use 2 seperate rails, but i want my ganrty to be low profile. I plan on cutting mdf w/ my 3.25 hp PC router.

Any ideas on this? I just dont like th plans thathave the leadscrew under the table centered, as this looks like it could rack, where are the dual lead screw, though costing more, should have the ability to slef square them selves

Yes, you can do a single piece of 8020 for the gantry. One way is how GlacialWanderer did it. He has pics here and on his blog. Just make sure the design provides the deflection you want. I'm doing something similar on my router (still designing). I'm also doing two screws on the x-axis. This also offers double the force to push the gantry around.

A dual lead screw setup is definitely a good way to go if racking is a major concern. Run the screws on the side, and you'll be in good shape using my system. Definitely a monolithic gantry is the way to go -- I wouldn't split the rails. If you have a lot of z travel, you can go with a taller piece of extrusion for your gantry (1545, or even 3060) -- this will give you a large y rail for your z to ride on. However, for 5" of Z, you're probably fine with a 3030 gantry and a 4" steel rail. Looking forward to seeing pictures of your build!

Ahren
www.cncrouterparts.com

yeah, i have actually managed to squeeze a lot of trave out of my z. the extrusion is only 11.5' long. i cut holes in the 1/2" plate to allow the low profile bearings to pass through, so the cars can travel about 1" further either direction

here is a post of my machine that I built using 8020 extrusions.

http://www.cnczone.com/forums/showthread.php?t=52453

Let me know if you have any questions.

Rich

I opted for a different approach:
http://www.cnczone.com/gallery/showphoto.php/photo/210/cat/500/ppuser/1938

Mounted the router between 2 80/20 rails to reduce racking of the gantry. Only downside is it takes an extra minute or 2 to change bits - no drama.

:cheers: Jim