New rails arrived!

[3Dsigns]

These rails came with four blocks and the hole patterns on the blocks are only1.375'' on center for each.

Will I need all four blocks: two on the top rail two on the bottom, to mount my z axis? Or will one on each rail work?

I plan to mount these to a 5' piece of 3.0x6.0 80/20 aluminum for my gantry. WOuld it be possible to mount each rail on a t-slot and get accurate alignment?

http://cgi.ebay.com/ws/eBayISAPI.dll...DME:L:RTQ:US:1

Thanks!

[mxtras]

Just a few thoughts:

I would imagine that both rails mounted to the same extrusion could be pretty well aligned. The extrusions are typically pretty straight - without twist or bow, and the slots are very, very parallel as are the sides.

I would suggest mounting the two rails on adjacent sides of the extrusion rather than on the same surface. Mount one rail on the top, rear corner and one on the lower, front of your gantry, for example, to form a more rigid arrangement. This would utilize more of the extrusion's structural stability and would also provide some harmonic dampening as you would be transmitting cutting harmonics in differing directions.

I would also recommend using all four bearings - two on each rail. At least use three of them - two on the rail closest to the work and the other on the rear, top rail. Three bearings would provide a decently stable platform.

Keep in mind that I do not know what you are planning to do with your machine.....

Scott

[Zumba]

80/20 is only flat within .010/ft or so. Yours could be better but you'll have to check it.

[3Dsigns]

Originally Posted by mxtras Just a few thoughts: I would imagine that both rails mounted to the same extrusion could be pretty well aligned. The extrusions are typically pretty straight - without twist or bow, and the slots are very, very parallel as are the sides. I would suggest mounting the two rails on adjacent sides of the extrusion rather than on the same surface. Mount one rail on the top, rear corner and one on the lower, front of your gantry, for example, to form a more rigid arrangement. This would utilize more of the extrusion's structural stability and would also provide some harmonic dampening as you would be transmitting cutting harmonics in differing directions. I would also recommend using all four bearings - two on each rail. At least use three of them - two on the rail closest to the work and the other on the rear, top rail. Three bearings would provide a decently stable platform. Keep in mind that I do not know what you are planning to do with your machine..... Scott

Thanks guys!
Scott,
This is to be a 4x8 router and will use it to cut dimensional signs out of wood, plastics and HDU.
I will be using 3.0 x.3.0 80/20 aluminum for the frame.
I intend to use 1125 in/oz servos and a 3.25 HP porter cable router.
Part of the z axis is a Thompson 12 linear slide.
Haven't found long enough rails for the long x axis yet.
Thanks
Wayne