Help with setting up a KB controller.

Stryder

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I’ve been making some changes to my HF mini-lathe and one of the changes was to replace the FC250 controller bd. I ended up going with a KBLC-19. I can’t find a manual for that model so I was using the manual for the KBIC as a reference. My motor is the 250 watt version so I used the #9840 horsepower resister (1/3 HP at 90VDC). Wired it up and turned power on. No smoke and spindle spins but fast. What is a good/usable RPM to set max speed to? I can figure out max & min but how should one go about adjusting IR and CL?.
 
I was using that procedure but I'm not sure I was doing it correctly. Using my hand to brake the chuck I don't think that there was much of an improvement over the FC250. Also had the question on a good RPM to set Max Speed to.
 
max speed is alright to around somewhere in the 2500 rpm range.
you aren't changing the motors hp, so the KB controller should act very similar to the FC250 overall,
although you can play with the settings to facilitate other conditions or parameters .

what type of improvements are you looking for?
 
Stryder,

There is no correct answer to your speed question. But I'll give it shot. First off I am a certified Drive Dirtball been applying them since the early 70's. Designed the drive used on the early 3rd party DC drive conversions for the Bridgeport Mills.

First 1/3 hp is 1/3 hp the drive can't change that. at 1800 RPM 1/3 hp will deliver 12 inlbs of torque, with a 900 RPM motor its 24 In Lbs and with a 3600 RPM motor its 6 inlbs. You will still need to use the belt drive to optimize the torque delivered to the lathe.
What is the rated RPM of your motor? I am assuming that it is a PM motor which is usually 1800 to 2000 RPM at its rated voltage. so I going to assume its 1800 RPM at 90VDC you should set the max voltage (speed) at no load to 90 VDC. It does not pay to set it higher as the maximum RMS Voltage you can convert from 115VAC is a little over 90 VDC. For the sharp guys reading this ya you can get more but you need a drive with a swinging choke in the DC filter.

Now here's the hard part DC drives are rated at constant torque. Torque is equal the current flowing through the motor. This tells us when the motor is overloaded so you cannot exceed the rated current of the motor without damaging it. this also means that if you run the motor at half speed you only get 1/2 the HP (work) out of the motor (HP ~ Tq* RPM) or ( Amps*Volts). if you use your belt drive to cut the speed in half with out the drive you will get twice the torque delivered to the lathe spindle. so in the end find a workable speed when the drive speed is set for around 75% using the v-belt drive as the course adjustment then you can adjust up and down from that set point and have a good range of torque.

What the drive can do for you is control how much the speed drops off as the current increases. this is to me the big advantage of using VS drive. If the CL and the IR have not been changed from the factory setting best to leave them alone. If they been changed here is how to go about setting them. I'm going to assume you have a DC amp meter and a volt meter (analog would be best don't ask why that's another issue). Set the motor up secured to your bench with the pulley on the motor. Use the volt meter to measure the voltage across the armature leads and the amp meter in series with the motor. Put a thick leather glove on your favorite hand. Run the drive up to full speed (90VDC) carefully grip the pulley trying to slow down the motor. you will see the amps go up hold the glove so that you are reading the amp rating of the motor (should be around 2.7 - 2.9 Amps amps for a 1/3 HP motor) look at the voltage adjust the I/R pot until you see the voltage go up to 96 VDC. This sets up the boost (Gain) so that motor will not bog down under a heavy load.

To set the CL grab the motor pulley and stall out the motor adjust the CL pot until the voltage starts to drop measuring 1.5 times the motor rated current.

That's about it, good luck and be careful.

Jim Nunn
 
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