How to adjust Desktop Z axis?

[joelschuman]

Can anyone point me to a doc or thread that describes adjusting the Desktop to make the Z carriage travel perpendicular to the table? Can't find anything...

I found the problem when surfacing the spoilboard on new-to-me Desktop with a 1-1/2" Amana 2248 insert tool. Big digs on every pass toward the left and rear. Looks like I can loosen the spindle mounting bolts to do the side-to-side (X) direction, but how do I adjust the fron-to-rear (Y) tilt?

Thanks,
Joel

[Brady Watson]

The only adjustment you can do is to the clocking spindle mounting plate. A dial indicator is very helpful to get it perfectly parallel to the table. I used a piece of heavy steel bar to bolt to table extrusions so the indicator base magnet would work. Set the indicator against the plate and move the Z up and down tweaking it until it reads the same throughout the stroke. You should be able to get it within .001" or better even with a cheap indicator. Gradually tighten all fasteners like a cylinder head. Check and recheck the stroke via keypad mode.

Front to back *may* fix itself after you loosen and tighten the bolts. If you take the spindle and plate all the way off, inspect the bolts that hold the YZ car to the bearing blocks and make sure they are both seated properly and snug. If when you indicate it shows it's still out, you may have to shim it. This is pretty uncommon though...and front to back can be something as simple as the gantry to bearing blocks are loose or fastened out of square. Take it one step at a time to find out where it is out. Pop a good (unmangled) square on the extrusions and against the X rails. Is it square? If so, all the slop is in the spindle mount.

Don't indicate/square off the spindle...it is not truly 'square' and the reading will be off. Go off the spindle mounting plate and YZ plate when you test.

-B

[joelschuman]

Thanks, Brady. I'm slow and clumsy with a dial indicator. I got a lot of practice on my big table, since I had to swap the spindle far too often due to dumb mistakes. I found that I could get acceptable results quickly with a pencil mounted at the end of a horizontal 12 inch arm chucked into the spindle and rotated manually to just touch the spoilboard high spot. I'll try a shorter arm on the Desktop. Hope I don't have to shim.

[scottp55]

Hey Joel,
You can get pretty close even with a Fred Flintstone rig like shown in pics....no dial indicator when I discovered my X-rail bolts had loosened after 1 year, and thrown trueness off..all I had on hand was a $2 12" length of brass rod cut and bent to 9" radius, but got it close enough so only a minute with 220G gets rid of mill marks.
I did Z-upgrades with both Desktops with the same rig with very acceptable result when surfacing all my woods with a 1.25" Whiteside Mortise bit.
With bolts all uniformly tightened on both Desktops, I only had to adjust in the X-axis though.
Hope you don't have to shim.
scott

[Brady Watson]

I mentioned using a dial indicator because it doesn't rely on the already stair-stepped table surface as a reference. It's the ultimate tool for dialing in tools in the shop including the CNC, table saw, rotuer table etc. You can usually find a whole setup with base for $20-30. Once you use it & understand what you are looking for, its mystique will fade.

Not saying the chicken stick is 'wrong' - it'll get you in the ballpark but sometimes 'ballpark' just isn't good enough.

-B