V carving stars

I’m attempting to v carve the stars of an american flag union. The First star cut ok, but the next star the bit went into the wood shallower, next star shallower, next shallower until eventually the bit never touched the wood. I’ve checked to make sure the bit is secured in the router. Any ideas what might be going on?

Several possibilities

  1. You’re skipping steps on the steppers when it plunges, and just keeps getting worse. Solve this by slowing down the feed.
  2. MORE likely - the baseboard isn’t square/level to the machine x and y axis (and 90 degrees to Z) . I’d say likely the left side is higher than the right rear. It’s about even across the front left and right, but not front to back. You probably zero’d somewhere on the left, probably around the second star down.

I need to check being level with the x and y axis. I zeroed in the center of the stock. The first star cut was far left center then moved on an angle to the right, across the bottom then up to the top.

I am using an Amana RC-1145 V bit 45 degree. Feed rate 40 ipm and plunge 20.

My first impression is that the Z belt tension is too loose and you may be skipping a tooth when plunging. If that is not it maybe the set screw is not on the flat allowing the gear to slide on the shaft of the stepper motor.


I’ll check this too. Thanks

Spindle is about 1/32 out left to right.

The frame is out a bit too.

Any suggestions for correcting this?

The Y and X rails are square to the waste board.

We have a bit on this on the wiki:


The big thing is to work from large component to small and adjust, then check again, readjusting if need be, moving on to the next component otherwise.


Just reread the tutorial for squaring. I will repeat this procedure.

The more I’m thinking about this, it seems that maybe the belt is jumping a tooth. I realize it’s better for the squareness to be spot on, but I can’t see it putting the bit that far out. The first star had a depth of cut at 5/16" and eventually the bit didn’t even touch the board. If the squareness was the problem, shouldn’t there have been a pattern to the squareness issue?

I know I can adjust the tension pulley. Are there any other adjustments for the plunging? Also, when I manually move any of the axis, very gently and slowly, it’s smooth and then a “bump” feeling every few inches or so. Is this normal? Is that skipping a tooth? Should it be smooth all the time?

Assuming the power is off, that’s normal and is caused by the steppers.

I’m curious how far down in Y are you working? If you are very low, when the Y carriage is at the extreme of its movement, belt skips are more likely.

If that’s the case, put some scrap 3/4” mdf on top of your wasteboard and try milling your part on that.


Yes, power is off. I’m using 3/4" material on top of the factory waste board. New Carbide T track board is sitting on the bench waiting to be installed. Maybe that will take care of it.

As @mikep said above, I’m pretty sure you are skipping steps as you descend Z. The fact that you eventually get to the point where the cutter barely contacts the work tells us multiple step skips.

You can hear this happen, I know it well, I describe the sound as a slight “clunk”. If your away from your machine but still in your shop the first time you hear it you think “now what the heck was that”. Then you go watch the machine cut until it makes the same noise again, and you see the cutter happily spinning along above the work, cutting air.

So re-check the set screws, tight and on shaft flat. Z belt tight. Oh, and idler pulleys tight, I found this once too.

Good luck

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After double checking things, it all checked out ok. I added a 1/2" waste board (it’s what I had on hand) but that didn’t change anything. I called Carbide and they suggested tightening the Z belt to guitar string tight. I tightened it up and it helped. I tightened it more but I wasn’t getting good results. Was getting a lot of vibration when the bit engaged the wood, thought it was because I kept making the same paths in the same wood. Decided to call it quits on this board and try again tomorrow on fresh wood. Before I shut it down I decided to make a tool change and test cut the union perimeter to see if I got the same vibration.There was a little, but it was cutting good…until things got squirrely. About 3/4 through the second plunge pass I noticed an odd movement, then the spindle got all jacked up. Turns out the router bracket bolts backed out. Shut it down and left the darn thing as it sat.

Got everything put back together and tightened the belt up good. After communicating with Carbide more, I found out that Carbide creates rpm and feed speeds are set for a different machine. Increasing the spindle speed did the trick. Everything is functioning properly now. Thanks for all the help!

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Looks like the Z stepper motor is underpowered and you’re losing steps when plunging.

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