# What Are They Called



## Garththomas (Apr 8, 2016)

I am looking at these little dials on the control board that some wires from potentiometer are connected to.
They are black with a little arrow shaped slot in a white center that can be turned.


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## atlas ten (Apr 8, 2016)

Need to see picture.  Could be a few different things. I think it might be a potentiometer. 
Jack

Sent from my SGH-I337M using Tapatalk


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## Bob Korves (Apr 8, 2016)

Trim pot(?)


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## Garththomas (Apr 8, 2016)

Yes trim pot thanks, my chuck would slowly start tuning as soon as I hit the switch so I was looking at the picture in my manual and although most of mine matched the picture a couple were different so I adjusted one and low and behold my chuck stopped turning before I turned up the potentiometer.


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## Garththomas (Apr 8, 2016)

I think the pot marked ir is for torque and the min and max seem self explanatory but what about the pot marked cl and should my motor turn as fast in reverse as it does in forward


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## strantor (Apr 8, 2016)

CL means "current limit, do not touch unless you know what you're doing to the extent that you know that the result of your adjustment won't damage the motor. "

IR means "black magic, do not touch, and I don't care who you are or what you think you know."

If you think someone has fiddled with IR, turn it all the way down, and then back up a very tiny amount, like 2 degrees.

If you think someone has filled with CL, turn it to half way and leave it there unless your motor starts stalling prematurely.

Your symptoms sound like some nightshift hero with a tweaker screwdriver has given your IR pot a bit of love. 

I'm guessing you're looking at a KB drive, but even if not, the manual below should help. The terms and adjustments are pretty universal across MFGs


https://www.google.com/url?sa=t&sou...ggmMAI&usg=AFQjCNGBFFsBPjIUlnmwU2YZ3ugNnedxPQ


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## strantor (Apr 8, 2016)

P.S. IR does not mean torque. It stands for " current(I)...Resistance " and it's an adjustment that very few people understand.  It has to do with speed regulation with varying loads, and it's a very fickle adjustment. Getting it dialed in just right is a nightmare. As the manual says, it comes preadjusted from the factory and you should not be touching it unless you know for a fact that someone else has already screwed it up and you have nothing to lose.


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## strantor (Apr 8, 2016)

Oh, and yeah, your motor should spin equal speed in both directions usually. Unless it's a motor optimized for running one direction only ( with brushes angled). Possible bad adjustments in drive could be the culprit too. What model drive is it? Can you post P/N and a pic of the board with the pots?


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## Garththomas (Apr 8, 2016)

Thanks for the info I only tweeked two trimmers  very little 
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## mksj (Apr 9, 2016)

Use this in some of the Grizzly lathes. As mentioned, trim pots are used to adjust different control functions and motor parameters. There is a plug in resistor for the motor sizing. This looks the same as the KBC version, I would review the following manual which describes the functions and location of the trim pots. Probably changed the motor current trim pot, there is a red indicator CL if it is tripped. Hopefully didn't pop a fuse or something else. The MAX and Min set the speed range.
http://www.kbelectronics.com/manuals/kbic_manual.pdf


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## British Steel (Apr 9, 2016)

You may have an extra pair of contacts on the Fwd-off-Rev switch intended to reduce the speed in reverse, many Chinese machines do. As I understand it it's because the motor brushes aren't "symmetrical", being slightly offset to favour efficiency and torque in the forward direction (a bit like the spark on a petrol engine's ignition - I had a Bultaco that would run happily backwards, but didn't make as much power, a Very Good Thing when it stalled on a steep climb and fired up and ran as it ran back down again!).
Re the IR comp, if you have to adjust it, turn it up until the motor starts "hunting" under no load, then back off until it runs smoothly checking that a load on the motor doesn't slow it excessively and it should be in the right area.

Dave H. (the other one)


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## Garththomas (Apr 9, 2016)

What is "hunting", when I was into dirt bikes I wanted a Bultaco but I don't think they were sold in Canada.


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## British Steel (Apr 10, 2016)

"Hunting" is when the revs aren't stable, and you get a regular pulsing in the motor RPM - it's caused by the IR compensation being turned up too far to the point where its feedback loop starts oscillating - there's an inevitable lag between the controller sensing a change in load and adjusting for it, so at the right (wrong!) point the lag between matches the motor and spindle inertia and gets "in step" with how fast the controller accelerates the motor, kind of like the occasional but well-timed push on a swing sending your firstborn into the sky... Also how the majority of oscillators work in electronics and clockwork.

What the IR comp should be aimed at is "critical damping" where it can compensate for load changes in a timely fashion, but not cause the instability - at the other end from "hunting" too little IR compensation will see the motor slow excessively with a load applied to the spindle.

The IR compensation function is what makes it difficult to turn the stationary chuck opposite to the selected direction if you stop the spindle by turning the speed to zero without switching off the supply to the motor controller, voltage generated in the motor is seen by the controller as back-emf due to a load and the controller applies a voltage to compensate, resisting the backward movement. Forwards, the generated emf agrees with what it sees as a reduction of load so it reduces the voltage applied - which on e.g. a KBIC controller is already zero, so no change, the chuck's easy to rotate.

Hope that explains, rather than confuses...

Yeah, the Bultaco was great, not a patch on modern dirtbikes though - they're mad, I won't ride 'em 

Dave H. (the other one)


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## strantor (Apr 10, 2016)

British Steel said:


> "Hunting" is ...


Very concise and accurate explanation in easy to understand language. I struggle to convey ideas like you just did. That's why I'm not a very good teacher.


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## Garththomas (Apr 10, 2016)

One thing I noticed when I put a load on the chuck with my hand was that the rpm would increase past the initial setting for as long as I had the load by 100 rpm in some cases. Would that indicate the IR was set wrong. By the way I echo what strantor said about your directions thank you very much.


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