Scalloping & Lines

[angelosart]

I have had my Shopbot 32 Buddy for a little over a year. I bought it new and do not use it every day. Use it about 3x week. Mostly doing relief work, plaques etc. Just recently I started noticing some lines here and there when using ball nose on a finishing toolpath. I a couple of spots almost a little scalloping. My bits are new and I use an 8% stepover. I have not changed my cutting methods recently.

I checked my pinions today for the first time, but they seem ok, can't see wear and tear. I am tuning up the rest of the machine as well. If this doesn't solve the problem, what other possibilities could it be?

[angelosart]

All set. As I went through all areas of the machine the router set nut was loose.

[cowboy1296]

Where is this nut located?

[Red F]

Massachusetts...






I appologise, I can't let a setup like that go to waste.

[cowboy1296]

Oh man, even though i was being serious that was funny, i dont care who you are.

But 1600 Pennsylvania Ave would be more correct.

[mgarrett]

Angelo,

Were the scallops caused by changes in Z (up & down) or tilt about Z axis? I have something similar going on but can't find any loose hardware on the table. My spoilboard is only 1/2" MDF sitting on a vacuum clamp board machined out of UHMW poly which in turn is bolted to the aluminum plate. During flattening of the spoilboard I noticed some cuts were sometimes higher or lower than the adjacent cuts. The variation isn't consistent like a tilted Z axis would be. The variation is about 2 or 3 thousands so it really doesn't hurt for most profile and drilling operations that I have been doing. It just seems odd.

I'll start a new thread if this goes further.

MG

[cowboy1296]

I have been experiencing this for a long time. But typically on a 3-d plaque thats 16 inches tall i will end up with 2 or 3 line/cuts that run in the x direction just about the 1/32 of an inch width and that deep as well. Depending on its location I can usually sand it out. But there has to a cause. In the near future I plan on cleaning my gears which maybe overdue.

Now in this case you can see the horizontal line that runs thru the upper tips of the badge.

This is my first experience with Perfect Planks black walnut. They put out some pretty good product but to be honest with you I did not like their black walnut. This will be the last of the black walnut that i order.

[zeykr]

Rick,
Do the grooves happen around the same time periods that you lean over machine to check it's progress? I had a similar random problem on my old prt, 2 or 3 times in a carving I'd get a small groove - went on for quite a while. Looked and looked for the cause, the more I watched for it, the more it happened.

Felt rather stupid when I finally realized I was doing it when I put my hands on the edge of the spoilboard to check the progress. Just enough flex the way the machine was built to move the workpiece up just a hair and cause a groove. :eek:

[cowboy1296]

At first i was not buying into this idea, but the more i thought about it the more it made sense. Thanks. Just for grins i will check this out the next cutting.

[scottp55]

That's funny Ken! Thanks for sharing:)

[mgarrett]

It looks like Ken had is nailed. I flattened a new spoil board today and kept my mitts off the machine during the process - no random high or low cuts now. The machine needs a tiny tweak to the Z axis alignment as indicated by the repeating ridges in the x axis.

Thanks, Ken!

MG

[cowboy1296]

Its looking as if you had a simple solutions to my problem all along. 2 3-d cuttings since i followed you advice and i am batting a 1000 with no ridges cut into the plaques. Thanks for the advice.