AV40S speed oscillation

1

I got an AV40S spindle a while back and this week I did a little milling with a 2.5” slab slayer bit. I noticed during the spindle warmup and then during use that around 16k rpm the speed oscillates pretty noticibly. I have never seen this with a bit that doesn’t have a lot of angular momentum like this one.

I’m not too concerned, just wondering if others have seen this, or I have something to look into here. I am also using the old VFD that came with my original 3hp spindle, but the 3hp and 4hp spindles I had before never did this with any tooling.

2

Jim, you probably have an early control from us. We started putting capacitors on across the analog out for the spindles to eliminate this in certain noisier environments for folks. Look at your Acorn board, see if you have a capacitor across the analog out to the spindle, if you don’t we can get you one.

3

Ah, a little low pass filter to stabilize the output. I don’t see anything on the output at the Acorn.

I’ll send a note to support to get the cap.

Thanks for pointing that out.

4

Just a followup for closure.

I received the capacitor from Ahren today and installed it and now my spindle rpm is stable at all speeds.

5

Awesome!

7

Hi. Could you post a picture of where this capacitor should be? I received my kit in february of 2025 and will be adding the AVS40 shortly. I want to make sure my EX controller is ready when it arrives. Thanks so much Eric!

8

Your best bet is to open a support ticket so that if you do not have one (and you need one) they can get you setup.