[Paulds]

Here is an idea that i came up with to use some 8020 aluminum to make bearings that will fit on 1/4" steel plate or angle iron(i'm using 1 1/2"x 1/4" thick angle for my new build).I have also tried these on other things like 1/2" drill rod and they seem to work i also think they would work on gas pipe ect.. Would like to have some input pros / cons for use of this on say a 30''x40" size router table. I did a mock up of the assy. on the rails and it seem to work good. 5-12-09 Finally got the gantry mounted and made my own delrin lead screw nuts i am using 5/8" by 8 acme rod and found that if i run only 1 lead screw(plan on using 2 lead screws) i get some, what i'll call shaking (vibration) in the gantry as it moves. note: that i have not cleaned the rail or anything they still have the scale on them. (they will need to be sanded or even better - sand blasted. I have attached some pictures of the bearing assy. and a mock up of the gantry. Will add some more photos if there is any intrest in this build.

[jalessi]

That looks like a very primitive version of Ahren Johnson's Linear Carriage.

Cutting the slot's in the 8020 may sacrifice a lot of its strength and rigidity not to mention its structural integrity.

[tobyaxis]

8020 is no where near the tensile strength of steel ground ways nor the wear resistance.

[Paulds]

I have added some more photos of my build .
Jalessi & Tobyaxis thanks for the replies. You both are right about the strenght
and i had thought about that too. On the gantry i add some 1530 80/20 pieces
(1.5 x 3")just behind the bearing assy. for added strenght. I think that will be very strong the way that i have designed it and plus i can adj. the gantry height to fine tune the height to the table for the "Z" I think that once i get the lead srews on both sides of the gantry it should work ok. What do you all thinks. Is there something i am missing.

[LeeWay]

I think the design is okay.
I would have put some adjustments at least on one side if you intend to only use a single screw. You will get racking for sure without a way to load up the sides. This will also mean you need some good still table slats.

Driven with dual screws would do away with the need to preload as long as you have them snug.