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Alignment issue observed when cutting spoil board

Posted: Sat Dec 01, 2018 11:47 am
by Hockeyhead
If you see the attached picture it shows that there seems to be some misalignment of the z-axis to the cutting surface.

spoil board.jpg
spoil board.jpg (57.87 KiB) Viewed 349 times

I noticed this when surfacing a piece of plywood for use as a spoil board. In the picture the plywood highlights the problem. Essentially there are small ridges formed on each path rather than a nice smooth surface. To me this seems to point that the router bit is not 90 degrees to the spoil board surface, there is some theta rotation. To clarify, if you were standing at the front of the machine, think of rotating the spindle toward you or away from you, that is the direction of rotation I'm talking about.

Has anyone else experienced this? If so, how did you correct it? It may not be a big deal overall as far as affecting the work done on the machine, but it doesn't seem to be ideal. Thanks.

Re: Alignment issue observed when cutting spoil board

Posted: Sat Dec 01, 2018 9:52 pm
by pearcrl
Hi, Just a guess, it looks like you used a 1.5 or 2 inch tool to cut the surface. Unless you usually use a large tool or you make deep cuts or need to cut precision slots, it probably wont make a difference. As a retired toolmaker I checked my spindle as soon as I got my Comet. The easiest way to square the head is attach a dial indicator to the spindle and set the diameter of the sweep to touch the high points of the cut. Use shims on the left or right or front and back of the spindle mount to get the total indicated runout as close to zero as possible. If you have access to a precision flat plate you can place it on the spoil board so it rests on the two ridges for a more accurate check.

Re: Alignment issue observed when cutting spoil board

Posted: Tue Dec 18, 2018 8:22 am
by 4DThinker
Old post, but I'll chip in anyway. We have a Meteor where I work that produced similar lines when milling off the spoilboard with a 1" end mill. A quick check of the Z axis against the perimeter frame showed Z was tipped back about 2 degrees.

To fix this we took out the front bolts holding the gantry beam to the gantry risers. We opened up the through hole with a slightly larger drill bit. that let us rotate the beam so Z axis was square to the frame, then tightened all the bolts.