Spindle jumpy when slowing down.

Hello,
Sorry I couldn’t think of better terminology but I’m new to diy cnc and I bought a Emco PC Mill 55. It’s in great shape so I put a Mesa 7i76 on it . Got some help from my name is mike on YouTube with his wiring videos .

Everything’s going smooth except when it slows down from day 3500 rpm to 2500 itslows down jumpy like ABS on a car. If I slowly go down there no problem but going from a high rpm to low/stopped it’s jumpy .
It also constantly spins slowly in reverse while it’s supposed to be stopped .
Not sure if this is a common problem or if I can just edit the Hal code to have it slowly slow down as a quick fix. By the constantly turning at like 10 rpm concerns me.
Thank you and here’s a video of the sound

As far as slowing down goes, do you have a braking resistor? if not there will be limits to how fast you can stop smoothly

Slowly spinning when the spindle is supposed to be off sounds like a problem in the spindle enable wiring or hal file connections

Note: Older versions of pncconf mistakenly wired spindle enable to machine-on in the hal file so that's also a possibility.

Edit: Yes you can set the acceleration rate on the hal file by using the limit2 component but you can also typically do this in your VFD setup

thank you, i did some research and i think my wiring to the spindle might be messed up. ill reconfigure it today.

i reconfirmed my wiring but my spindle still spins backwards at about 10 rpm when its supposed to be off.
i attached pictures of my wiring and what the connections are in the manual.
Just wanted to confirm that im not wiring it wrong. i cant get it to work in open loop mode either.
Thank you

can you post your hal and ini files? Older versions of pncconf wired spindle enable to machine on rather than spindle on

I just copied the whole folder.
thank you

Your spindle enable is wired to machine on:

net machine-is-enabled => hm2_5i25.0.7i76.0.0.spinena

This is a bug in older versions of pncconf and should be changed to:

net spindle-enable => hm2_5i25.0.7i76.0.0.spinena

that fixed me, works perfectly now.
when i go less then 1 rpm - 17 rpm it spins backwards, is that anything to be concerned about?
at 0 rpm its stopped
thank you, i wouldn't have ever figured it out.

You could either zero the offset in your VFD or set the ini file spindle PID bias setting to 17