Okay, squaring the X rails...

[johnm]

Folks -

Allright, I've got the holes drilled in the top of my c-channel for the x rails, and I was going to set a light behind them to look for low and high spots between - but in the book they show the rails being fitted without the rack. With the rack in place, you can't really see the low spots as well, if at all. So, what's the process? I unscrewed the racks, but then saw that they'd been taped as well, and didn't want to disturb that setup... I suppose I could try to slip a feeler gauge inbetween the x rail and the top of the channel, but think that there's probably an easier way that I am missing.

I'll start in again tomorrow; tonight I was happy enough to get the holes drilled for both sides. I deburred the holes and hit the high spots with my belt sander and that made the tops of the c channels smoother. They do have a slight crown to them, but don't think that there's a whole lot that I can do about it.

I'd appreciate any input y'all'd like to give about setting those rails flat and true.

Thanks!

John Moorhead

[mikejohn]

John
As I remember it went like this.
Attatch the centre bolt of one rail.
Attatch the ones either side.
Check with the straight edge.
Shim and adjust where necessary.
Wonder why ShopBot supplied so many shims.
carry on attatching bolts either side.
Check with the straight edge.
Shim and adjust where necessary.
Check, shim, adjust.
Check shim adjust.
Have coffee.
Check shim and adjust.
Worry that you haven't got enough shims.
Check,shim and adjust.
When you have finally got it to where you feel it is impossible to improve, do the same on the other rail, only this time keeping it absolutely parallel to the first rail.
At the end of a few hours, roll the carriage up and down, with help, making sure the V-rollers stay seated along the whole length of the rail, front and back.
Then adjust the stop blocks at one end,on one side so the carriage touches both at the same time.
Do this at the other end.
Then sit back and feel smug.
(You may need to keep a small boy handy to keep fetching coffee
)
.....................Mike

[gus]

Mike has it about right. I would add:
Go to hardware store and buy a bag of washers.
Measure and then mark the thickness of each washer with a felt tip pen.
Look around and find where you put your feeler gage.
Now you can mix and match washers to fill the gaps and finish off with ShopBot shims.

[gerald_d]

In addition to the above, have a few beer cans and a tin-snips ready, so that you can cut coarse shims and save the SB supplied ones for fine-tuning. (I don't know if SB still supplies plastic shims. If you stack the plastic too high it becomes spongy - rather make up the bulk of the stack with beer can metal)

Also remember that if you put a shim only on one side of a bolt, you can force a small bend or twist - very useful.

[mikejohn]

Don't start the day with full beer cans

...............Mike