[stryder99]

I have a HF 7X14 lathe that I would like to get a little more performance out of. I have read many threads, here and elsewhere, about motor changes; gear reduction systems; etc. I believe that my machine has the 250W motor and the motor control board FC250. Will upgrading to a KBLC, KBIC motor cont. bd. give me some additional performance from the existing motor?If yes, is there a difference between the two KB boards and do I need the PECO speed controller add-on bd. Thanks for any help you can shed on this subject.

[Al_The_Man]

If you can find one of the KB PWM versions it would be better for quieter and better lower end speed control.
Rather than the SCR bridge types.
Al.

[stryder99]

Thanks Albert. I know that the PWM technology would be better but it is quite a bit more expensive.

[CS900]

I'm not an expert on the 7x14 by any means, but I currently run an MC-60 treadmill control board to run the DC motor I put on my taig mill. It's super cheap ($60ish) and is a great PWM controller. So just FYI, might be something worth looking into.

[stryder99]

Thanks for the info. I'll take a look at it.

[G59]

Thanks Albert. I know that the PWM technology would be better but it is quite a bit more expensive.

It's not just better, it extends the life of the brushes in the motor 10 folds, and reduces heat in the motor by a factor of 2. It is much quieter and low end torque is enhanced and noticeable. That's what you want if you do any threading. My advice is spend a few more bucks now, save yourself some headaches down the road.

[stryder99]

Do you think something like this would work??
6-90V 15A DC Motor Speed Controller Pulse Width PWM Speed Regulator Switch 16KHz. Once again I was just trying to get a little more performance out of the original/stock motor. I don't see any need to go the treadmill route at this time.Also, I have already received a KBLC-19 (SCR) controller that I had planned to use, but the PWM tech looks good.

[G59]

Yes, but not reversible and no mention of continuous duty.

[stryder99]

The reversing should be handled by swapping the motor leads via the FWD-OFF-REV sw. I don't know about the continuous duty but the specs claim 1000w and the motor on my lathe is only 250w. That should be enough reserve capacity that this controller is not operating anywhere near it capacity. Of course I am aware that all these specs (motor included) are based on the somewhat inscrutable Asian measurement system.

[Al_The_Man]

The ebay unit is fairly bare-bones and does not have the features that the KB versions do, even the SCR type, you generally get what you pay for.
Al.

[stryder99]

I don't think I've ever seen the specs on the FC250 contoller that came in the lathe, except that it might only supply 50VDC to the motor on the high end. I have seen posts calling it the weak link, so I don't think it is very feature rich either. There was a post on here years ago by Harrison regarding the KBLC-19 but the attached pictures are no longer available. I was planning on ordering a 4" chuck and thought it would be nice to have a little more low speed torque.

[stryder99]

All the KB controllers using PWM are considerably more expensive. I was trying do do this on a budget as I don't know if the gains will be that noticeable. If you have any recommendations on a reasonably priced PWM solution I would be more that happy to try to find one..

[G59]

You know, for what it's worth, it's only $9 + shipping. If you did some research on it and it could potentially fit the bill, then by all means do it. Who knows, maybe it's all that you want.
I mean for 9 bucks. If it don't work, just scrap it and lesson learned, right?
For myself, too many open questions about that eBay controller. First, what is the voltage in from your power supply. Last I remember on those lathes, it's something like 115-120V AC direct to the control board. So the eBay thing won't work unless its stepped down from mains voltage, by a transformer, and then through a rectifier circuit. Second, no reverse polarity protection, this could be a problem if not familiar with electronics. Third, no adjustment possible of any kind.
For myself it's too simple and probably won't last.

Oh and BTW, I also have one of those toy lathes and I ended up having to install a KBLC-19 controller, and I can tell you, that the power output is double the old board and Yes it will cook the little motor if doing heavy continuous cuts. Thankfully my nose is still capable of recognizing the smell of an overheating motor.

[Al_The_Man]

Normally on those drives, the current limit in conjunction with the correct H.P. resistor should prevent motor burn out due to over current.
Al.

[stryder99]

Thanks to all who replied. I'm thinking that though it's not PWM I will be trying a KBLC-19 on my mini-lathe since it's what I have on hand. I have a question on the correct Horsepower resistor to get. I used a watts-to-HP conversion formula on 250 watts and get a HP equiv. of .335. in the KB data sheets it looks like I could use their P/N 9840 for 1/3 HP. I did the same calc. on my X2 mini-mill moter which should be 350w and get a figure of .469 HP yet the label on the motor says 4/5 HP. Which would be closest the the real value? Are they really that overly optimistic on their specs.?

[Al_The_Man]

It is usually best to err on the lower HP resistor, the worst that can happen is that it goes into overcurrent a little sooner, if a problem, then one size up in HP can be fitted.
Another symptom is if it O.C.'s for rapid acceleration.
Al.