# G 0704 spindle speed increases



## carlbob (Aug 10, 2019)

Does anyone else who owns one of these machines have the same problem with the spindle speed increasing when the machine senses a bit of a load??  Is there a work around that I can do so that the machine won't do this or is it just the way it is and just have to live with the problem??
Thanks in advance for any info.


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## 1911man (Aug 10, 2019)

Don't have a fix for you, but this is one of the reasons I went with the G0716 machine. The lathe I had was 'variable' speed and while it's good in theory and for some things, it sucks for others. Plus, if the control box/parts gets damaged, it's a pain in the balls to get repaired. I had to get that done on the lathe since it was damaged in my last move. Even after it was repaired it was never quite right. I sold it to someone else (from another forum I'm on) and let it become his problem. 

IIRC, the load level on the machine shouldn't get the controller to increase it's speed. Provided you're not trying to hog out too much at a time.


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## homebrewed (Aug 10, 2019)

The motor controller most likely needs adjustment because the motor speed should NOT increase with load.  That's an unstable situation that needs to be addressed.  For starters, contact Grizzly's customer service, they may be able to tell you what needs to be tweaked.

If Grizzly can't help you, contact the manufacturer of the controller.  Many of the smaller variable-speed mills use KB-Controls motor controllers.


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## Ulma Doctor (Aug 10, 2019)

there are trim pots (potentiometers) on the controller that can be adjusted for best operation.


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## markba633csi (Aug 11, 2019)

Try contacting Pete at www.olduhfguy.com he might be able to tell you which adjustment- otherwise, mark each trimpot with a sharpie pen and start experimenting til you find the correct one- that's what I would do. Try one adustment at a time so you don't get too far off the track- the pot may be labelled "IR comp" or similar
Mark
ps be careful


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## RJSakowski (Aug 11, 2019)

If you are shotgunning with your pot adjusrment, mark each one with a Shatrpie to indicate the starting position.  If your adjustment doesn't have the desired effect, return it to the original setting. The effects of some adjustments are subtle.


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## carlbob (Aug 13, 2019)

Thanks y'all.  I did contact grizzly and they basically told me to suck it up and that's the way it is..I did just install the belt drive conversion on the mill and it has made a 1000 percent improvement in the performance of thee machine.  It's costly if you buy the conversion, but it's definitely worth the money.  The motor increasing speeds is not that great of an issue now that all those cheap plastic gears are removed..Sure it still increases when it senses load, but not as bad as when it had the plastic gears.


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## coherent (Aug 14, 2019)

I also put a belt drive on but I had the same issue when mine was still under warranty. It's been a few years now but Grizzly simply sent me a new controller board. I then found more info about the adjustments others mention (sorry don't remember where but a little searching the subject should find simular info) and played with the potentiometers  on the original board until the issue was resolved. Took a bit of trial and error as I remember and I gained not only stability under load but a few rpms.


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## carlbob (Aug 14, 2019)

Thanks y'all for all the info on adjusting the pots.  Looked on u-tube and of course there's a video on doing just that.  Im going to try to make the adjustment on the ir pot and see if that will keep the spindle speed from increasing dramatically.  I'm not cutting large amounts on each pass but it still revs up.  It's even worse when trying to drill a hole in anything.  The spindle speed increases unbelievably and then the bit binds..ugh..that's what stripped the plastic drive gear before I installed the belt drive..
Thanks again for all the input.


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## carlbob (Aug 15, 2019)

Great news..I ever so slightly backed off on the ir pot on the control box circuit board and the spindle no longer increases over 300 rpm when drilling or milling.  The rpm is actually dropping about 20 or 30 rpm now.  I much perfer it this way than the other.
Thanks for all the suggestions and for you tube videos.


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