pwm controller

[kelLOGg]

Here is a PWM controller kit for $17.95. I would like opinions as to its applicability to sawmilling.

http://store.qkits.com/moreinfo.cfm/qk166

Bob

[woodbowl]

The specifications have lost me already. "Slabs" is the man to get in on this. I'll give him a heads up and maybe he can post soon.

I think in terms of HP. My Woodmizer has a 1/2 hp feed motor. The newer ones are 3/4 hp. If it is compatable, for $17.95 it sounds like a dream come true.

[Radar67]

Olen, you did notice it is in kit form didn't you?  :P ;)

Stew

[Gary_C]

I suspect the current requirements for the DC motors on a mill would exceed the capabilities of that kit. DC motor controllers usually have to be matched to a specific motor size.

[jackhdn]

I'm looking to do the same thing on my LT 40.  Search ebay for PWM controller and there is an 80amp one listed.

jack

[Jason_WI]

The traces on the board are only rated for 5 A. It mentions using other MosFets but if the board isn't heavly modified you will see smoke!!!

You want to buy something that can handle the current and voltage for your application. You also don't want to run at max output of the controller as it wont last long. So if you need 40 Amps get a controller that can handle 60 amps continous.

Jason

[woodbowl]

I will attempt to speak for the non-electronic type folks since I are one.  : I have a tough time understanding how to match up the right pwm to the right motor as well. However, I do have a reference point to understand from.

Woodmizers use a couple of different feed motors. 1/2 hp on the lesser model and 3/4 hp on the Super model.

     1/2 hp=  10 to 60 amps,   1700 rpm

     3/4 hp=  10 to 75 amps,   1700 rpm

What is the relationship of pwm controllers to these specs? Thanks.

[Slabs]

Checkin in upon request here.

I did a bench test on one of the WM up-down motors but am not sure of the HP rating.  It's got to be about 1/2.   Free-running current (no load) was 5 amps.  I put a small pulley on it and started loading it and the current quickly ran to 50 amps and would have gone more on "locked rotor".  The current figures for similar motors from Grainger show compatible values.

I've also got one of the older control boards from WM  on the bench and they use 4 transistors (TO-220 case and a bonded frame heatsink) as outputs though no emitter resistors.  I guess that somewat cinches it about the after-market 5-amp unit.  A solid-state amplifier for the up-down motor might be a project I could get interested in too.  It should extend the life of the drum switch almost indefinitely.

Good to see you in here Jason.  I had already referred to you on a pm.  I found some 51 amp power mosfets in Hosfelt and will probably get some to experiment with.

Good luck all.

[pineywoods]

The 80 amp (peak) pwm controllers on ebay are made by Curtis. Do a google search on motor speed controllers. I bought one to use for speed control on my wife's handicap scooter. It runs a 2hp 24 volt motor just fine, should be ok for 1 hp on 12 volts.