High Voltage!

4x4American · October 03, 2015, 10:12:55 AM

Since my mill is setting still while I recuperate I like to go up to it every so frequent like and start it up and run it for a little bit. I had the diagnostic screen up to watch the battery voltage to make the difference between the controller and the batt wasn't too far apart. Well while I was doing that I was running the head back and forth. I noticed that when going backwards, once you get it up to speed, and let off the drum switch, the volts will rise pretty good size. The voltage would rise to 16V as the headrig slows down. I'm guessing it must be spinning the motor, acting like a generator? It doesn't seem to do it when I'm going forward. But I think that could be because I slow it down with the potentiometer instead of just killing the forward travel with the drum switch. How do you stop your head when it's going forward (pot. switch or drum switch)?

I also noticed that when I hit the drum switch into reverse, it twists the head a bit, I can see the engine pick up, and it seems that only in cases where I used the accuset's rounding feature to get the head to the nearest whole number, it will sometimes rise 1/16" from the back to the front of the mill. Prolly somethings just loose. Anyone run into this before?

Magicman · October 03, 2015, 08:54:33 PM

I would say that you are correct. When you release the drum switch with the power feed motor spinning, it should then become a generator until it stops.

When you reverse the entire 12vdc is applied in reverse to the power feed motor, and when the power hits the chain/gears, there is tremendous torque. I have never noticed any lift, but I have never looked for it either.

4x4American · October 03, 2015, 08:57:40 PM

Yea I'm sure it's nothing to worry about. I am kinda sorta really way the hell too meticulous lol

terrifictimbersllc · October 04, 2015, 04:20:41 AM

Sell the excess back to WM!

4x4American · October 04, 2015, 06:17:33 AM

That's a good idea!!! lol

Magicman · October 04, 2015, 08:53:11 AM

Quote from: Magicman on October 03, 2015, 08:54:33 PMI would say that you are correct. When you release the drum switch with the power feed motor spinning, it should then become a generator until it stops.

The above is not correct. After thinking, the drum switch puts a shunt (short) across the motor winding which serves as the brake to stop the rearward movement. Since the motor is shunted it can not serve as a momentary generator in this instance.

I have no idea where your 16 voltage spike is coming from unless maybe your drum switch contacts are not properly making. Does your saw head stop instantly or coast to a stop?

4x4American · October 04, 2015, 10:36:56 AM

It doesn't stop immediatly, but there is a braking effect going on. You can tell theres something holding it up. Also, if it's going forward, pretty fast, and I flip the drum swtch to neutral, it stops faster than if I kill the pot switch, then it coasts to a stop. I always figured it was a brake that wm integrated. Is it bad to be hitting the computer with 16v? I wonder if thats why my first control panel fried?

4x4American · October 04, 2015, 10:41:28 AM

I will summon @MartyParsons for his expertise!

MartyParsons · October 04, 2015, 11:35:56 AM

I do not have an answer. I know you can not push the saw head easily with the wires on the PF motor because of dynamic braking. If I need to push the saw head during service I remove the wires. Even if the motor was generating DC current I would not expect it to be 16V. I never looked at the voltage with the motor coasting.
Sparks would be the expert on that.

The movement on jerking the saw head is from the clearance of the pads on the mast. I would not worry about it. It will not effect lumber.

4x4 You need to heal and saw some lumber or have something else to think about.

.

If you have time come down to our training day in a few weeks. I will post later in the places to meet show ect.

Marty

Percy · October 04, 2015, 11:59:03 AM

JUst a thought about the momentary 16 volts....could it be the internal regulator in your alternator reacting a bit slowly to load changes on the system???

4x4American · October 04, 2015, 01:17:51 PM

not a bad thought percy. I just went and watched my friend 40 super running, his head jerks to a stop when comig back, whereas mine glides. something must be wrong! i do need to heal up marty im going crazy!!! sawmill fever!!

4x4American · October 04, 2015, 01:18:37 PM

will call rick lauman monday

deadfall · October 04, 2015, 02:43:47 PM

Since I got the worn out cam follower rollers sorted out, my carriage simply glides on return with no inkling of any braking mechanism. I can push it backwards with one finger when the drum switch is not activated. I assumed this was normal. I have learned to get off the switch way ahead of where I want the carriage to end up.

So, I guess I have to get this sorted as well.

4x4American · October 04, 2015, 04:47:15 PM

same here I get off the switch way before where i want it to stop. When I was watching my friends mill in action, it would stop almost as soon as he let off the drum switch.

ladylake · October 04, 2015, 04:53:33 PM

I'd be checking those cam followers if I was him. Steve

Magicman · October 04, 2015, 05:42:33 PM

Quote from: 4x4American on October 04, 2015, 04:47:15 PM
same here I get off the switch way before where i want it to stop. When I was watching my friends mill in action, it would stop almost as soon as he let off the drum switch.

As it should. The drum switch shunt applies some serious braking as noted in Marty's reply above. Removing a motor lead is normal practice during blade guide alignment, etc.

4x4American · October 04, 2015, 06:20:34 PM

They never should have stopped testing the new mills at Indy, imo.

Magicman · October 04, 2015, 07:50:29 PM

Just call Indy and let the tech walk you through the testing. At this point I do not know that anything is wrong with your sawmill. You should be able to remove a motor wire and look back for a short, but they would know for sure.

Kbeitz · October 04, 2015, 08:11:22 PM

You could a broken or disconected shunt...
Any DC PM motoer will work as a generator when the shaft is turned.

deadfall · October 04, 2015, 08:27:37 PM

Wouldn't this shunt/brake work in both directions when the switch is at center? While I can push the head backwards easily, forward is a different story. I have to lean into it to move it forward.

Kbeitz · October 04, 2015, 08:49:48 PM

Maybe not if there is a diode in the circut...

4x4American · October 04, 2015, 08:51:18 PM

or if your mill is not level lol

Magicman · October 04, 2015, 09:26:30 PM

The shunt "brakes" both ways, forward and back.

4x4American · October 04, 2015, 09:28:45 PM

Where should I start looking? I don't know what a shunt is or what it looks like when it comes to electrical!

Magicman · October 04, 2015, 09:33:58 PM

A shunt is a short. Since shorts are associated with trouble or an abnormality, an intended short is called a shunt. The two motor leads should read a short if one lead is disconnected from the motor. This is with the power feed lever in the "neutral" position.