Need Help!- Aluminum angle and bearings

[Drools]

When making a linear rail using aluminum angle and bearings how far should the bearings over-hang the edge of the aluminum angle?

[Jack000]

I spent a surprising amount of time thinking about this problem when I was building my machine, dunno why, it seems simple now..

without further ado, voila! my illustrated guide to aluminum angle bearing alignment!



just roll it on the table, if it's flat it's not low enough.

[BobF]

Originally Posted by Drools When making a linear rail using aluminum angle and bearings how far should the bearings over-hang the edge of the aluminum angle?

What are your rails going to be? More aluminum angle? I would use steel for the bearings to roll on instead. Pipe?, see the joe2006 forum for good use of pipe and dimensions for bearings.

[Steven S]

I bought a piece of aluminum angle to do some tests and I noticed that the angle is slightly sharper than 90 degrees. This causes the bearings to ride on their edge rather than on the flat part. Check yours to see if it has that problem.

Steve S.

[jam5295]

How will aluminum wear?

[Drools]

I'm using 3' 5/8 steel rod as the X axis rails. I sanded and polished them and the result is quite nice. The surface on one has some small pot marks on one side but I can rotate the rod so that the pot marks are not in contact with the bearings.
The hard part is making sure both bearings on the sides are drilled exactly the same.
What will happen if the holes are even a fraction of an inch off?

[ger21]

Originally Posted by Drools The hard part is making sure both bearings on the sides are drilled exactly the same. What will happen if the holes are even a fraction of an inch off?

Clamp a board to the drill press table to use as a fence. That should get them as close to the same as possible.

[budP]

Your 5/8 steel rod is not strong enough unless it is supported, it will flex and you will lose a lot of accuracy.
budP

[Drools]

I would imagine Joe's or one of the other builds would have examples of supports needed for the 5/8 rod?
Also I'm looking for examples of DIY adjustment blocks, the kind used to adjust the rods to be perfectly straight and even with each other.

[Drools]

Would the 5/8 rod work for the 2' Y axis?
I found some 1" hardened steel rod that I hope will do for the 3' X axis.

Thanks

[Northboy]

Originally Posted by Drools Would the 5/8 rod work for the 2' Y axis? I found some 1" hardened steel rod that I hope will do for the 3' X axis. Thanks

I am very far from expert, I just started my own machine a couple months ago, but I have built many things through the years.
5/8 rod will definitely flex a lot even at two feet. Try supporting the rod and put a dial indicator on it. You will be surprised I think at just how much it will flex with not much pressure at all.


Northboy

[Drools]

Maybe I should just use the 1" steel rod for both the X and Y axis.
Take back the 5/8 stuff.