spoilboard surfacing has ridges, spindle not plumb or perpendicular to spoilboard

[bbortnick]

Hi,
I have recently re-surfaced the spoilboard on our PRS Alpha 48x48, and found there are significant ridges (on the order of 0.02") in the Y direction. Much less so in the X direction. Cutting pattern is the standard clockwise decreasing spiral.
I have reviewed the Shopbot handbook, trouble shooting and maintenance section, but it only covers correction to the left/right of the spindle, whereas my problem is front to back. I understand the way to correct this is by loosening the 8 bolts on either side of the gantry, but this has very limited movement available, if I recall. I am seeing 3/32" gap on the spoilboard over the 16" of a framing square resting against the spindle.
Can someone please point me to the correct Shopbot procedure to plumb the spindle, front to back?
Thanks for the help!

[scottp55]

I found tramming by a square on spindle housing was WAY off.

I made a 9" "Z" shape mounted in the spindle the best for me.
(using a Starret plate on spoilboard"

Look up Tramming on Vectric Forum and there are a number of tips.

My X adjusted easily, for Y adjustment, it took .002" Starret shims.
Only Shopbot I easily found was this;
https://www.talkshopbot.com/forum/showthread.php?25391-Tramming-my-spindle

[bbortnick]

Thanks! I have asked Shopbot if they have a tramming procedure. Our spindle is held on with 6 bolts, only 4 of which are accessible from behind the car when the spindle is all the way down. Note that some of these bolts were loose, but tightening them made little difference as the spindle needs to tilt the other way, i.e. shims needed at the bottom of the spindle (and shimming 6 vs 4 seems problematic.) Maybe I am missing something here?

[jerry_stanek]

Mine came with plastic shims to help with tramming

[scottp55]

https://www.talkshopbot.com/forum/showthread.php?16866-Z-axis-Plumb

may be something here....pay attention to Brady.

[bbortnick]

Shopbot support recommended shims, although you cannot easily access the top 2 of 6 bolts. Nonetheless, accessing the lower 4 bolts with the yz car all the way down was enough to provide access. I ended up with 4x.003 brass shims resting on the top of the bottom two bolts. Got a pretty close to flat on the spoilboard, still can feel the passes with my finger, but good enough for what we do.
In hindsight, I wonder if using the eccentric wheel adjustors on the gantry would have been easier? The gantry extrusion also shows a similar cant as the spindle.

[MikeS]

bbortnick,

Getting the gantry square to the bed and getting the spindle trammed are definitely different. If you tram your spindle, but your gantry isn't perpendicular (or your z-axis isn't perpendicular) your cut will vary in location base on z axis position. This can be VERY annoying if using a variety of tool lengths in the same job. It's challenging to square these up without some very special machinery, but possible with patience. Also, Tramming indicators make tramming so much easier.

Mike

[bbortnick]

I think next time we flatten the spoilboard, I will use the eccentric gantry wheels to make it perpendicular, then adjust the spindle with shims to make it also perpendicular.
That sound about right?

[scottp55]

That's the order I would do it in.