Old Woodmizer Power Feed Issues

[Firegrass318]

This is my first time ever posting on any forums, so bear with me.

A couple years ago I bout a 1984 Woodmizer LT 40 that had been converted from a 3 phase electric motor to a gas motor, per the guy I bought it from.

It has had its moments of greatness and then sadness.  I don't really know how many board feet I have sawed with it, but I'd say I have put a couple hundred hours on it.  I just use it for personal projects and I just really like sawing.  Most recently I was having some problems with the power feed being very inconsistent.  I re-wired everything(just replaced the old wires that were in bad shape) and also replaced the drive motor(forward and reverse).  Now, when I first start running the mill, it runs great, but after some time, maybe 2 hours, I start to have to manually push the mill through the wood and pull back.  The power feed works, but will randomly stop or be very weak and I have to physically assist.

Let me be clear, I am a house builder, not a mechanic or electrical guru.  I am pretty good at problem solving with most everything and enjoy a challenge, but this is getting old.

I have ordered a new drum switch from Woodmizer, as the contact points are showing a ton of wear.  Some are paper thin where the connection would start when the switch is pushed in that particular direction.  Only thing I can come up with is these connections are just to weak to supply the right amount of power.  I must also note that the battery is very old, but cranks the motor every time with no lag.

Thanks in advance for any direction for a very frustrated hobby sawyer!!

[Old Greenhorn]

First thing to check: feed drive belt tension, its kind of important.

[Yamforlife]

I have a 1986 lt40 and went through all the same issues.  I had  to replace the actual power feed speed switch.   I believe it's called a pentameter ...or something like that.  It was an updated switch and the wiring was slightly different  I went back and forth with Woodmizer tech but we got it sorted.   I also replace the wiring harness and messed around with the drum switches ...it works fine now.

[Ben Cut-wright]

A couple years ago I bout a 1984 Woodmizer LT 40 that had been converted from a 3 phase electric motor to a gas motor, per the guy I bought it from.

  Most recently I was having some problems with the power feed being very inconsistent.  I re-wired everything(just replaced the old wires that were in bad shape) and also replaced the drive motor(forward and reverse).  Now, when I first start running the mill, it runs great, but after some time, maybe 2 hours, I start to have to manually push the mill through the wood and pull back.  The power feed works, but will randomly stop or be very weak and I have to physically assist.

Let me be clear, I am a house builder, not a mechanic or electrical guru.  I am pretty good at problem solving with most everything and enjoy a challenge, but this is getting old.

I have ordered a new drum switch from Woodmizer, as the contact points are showing a ton of wear.  Some are paper thin where the connection would start when the switch is pushed in that particular direction.  Only thing I can come up with is these connections are just to weak to supply the right amount of power.  I must also note that the battery is very old, but cranks the motor every time with no lag.

Thanks in advance for any direction for a very frustrated hobby sawyer!!

No problems with the forward-reverse drive before now?

 
If the drive motor won't run in forward or reverse, that probably takes the forward variable speed drive control out of the equation.  IF the motor attempts to run but doesn't have enough power that might be a bad contact or connection or a compromised wire.


No complaint of low battery so run time isn't depleting it. Is the engine dynamo charging the battery or has an alternator been retrofitted?

That drum switch could be suspect. Might be making poor contact because of corrosion and worn thin by no lube maintenance.  The later drum switches have different wiring schemes so be aware that the wires might have to be altered in the switch. If you keep track of the wire distribution of the old switch and can interpret the schematic for the new switch it is an easy job.


The auto reset breaker was an upgrade, perhaps not used originally on your mill. But it would pay to see if yours has one and install one if it doesn't. 

[Firegrass318]

First thing to check: feed drive belt tension, its kind of important.

First thing to check: feed drive belt tension, its kind of important.

I do have tension issues from time to time, but I simply push down on the power feed and it keeps the tension.  When trying to go forward there is no slippage of the belt and the motor makes a high pitched whine like it's not getting enough power.

[Firegrass318]

I have a 1986 lt40 and went through all the same issues.  I had  to replace the actual power feed speed switch.   I believe it's called a pentameter ...or something like that.  It was an updated switch and the wiring was slightly different  I went back and forth with Woodmizer tech but we got it sorted.   I also replace the wiring harness and messed around with the drum switches ...it works fine now.

I have replaced the power feed potentiometer because the old one was doing the same thing.... And now this one is too.  I am able to log my serial number on woodmizer and get the original part, which was a pre-94 maybe?   

[Firegrass318]

A couple years ago I bout a 1984 Woodmizer LT 40 that had been converted from a 3 phase electric motor to a gas motor, per the guy I bought it from.

 Most recently I was having some problems with the power feed being very inconsistent.  I re-wired everything(just replaced the old wires that were in bad shape) and also replaced the drive motor(forward and reverse).  Now, when I first start running the mill, it runs great, but after some time, maybe 2 hours, I start to have to manually push the mill through the wood and pull back.  The power feed works, but will randomly stop or be very weak and I have to physically assist.

Let me be clear, I am a house builder, not a mechanic or electrical guru.  I am pretty good at problem solving with most everything and enjoy a challenge, but this is getting old.

I have ordered a new drum switch from Woodmizer, as the contact points are showing a ton of wear.  Some are paper thin where the connection would start when the switch is pushed in that particular direction.  Only thing I can come up with is these connections are just to weak to supply the right amount of power.  I must also note that the battery is very old, but cranks the motor every time with no lag.

Thanks in advance for any direction for a very frustrated hobby sawyer!!

No problems with the forward-reverse drive before now?


If the drive motor won't run in forward or reverse, that probably takes the forward variable speed drive control out of the equation.  IF the motor attempts to run but doesn't have enough power that might be a bad contact or connection or a compromised wire.


No complaint of low battery so run time isn't depleting it. Is the engine dynamo charging the battery or has an alternator been retrofitted?

That drum switch could be suspect. Might be making poor contact because of corrosion and worn thin by no lube maintenance.  The later drum switches have different wiring schemes so be aware that the wires might have to be altered in the switch. If you keep track of the wire distribution of the old switch and can interpret the schematic for the new switch it is an easy job.


The auto reset breaker was an upgrade, perhaps not used originally on your mill. But it would pay to see if yours has one and install one if it doesn't.

I've had to assist the forward and reverse off and on since I got the mill.  Can't seem to figure out what triggers it.
I'm fairly certain the motor charges the battery fine because it's only not cranked one time.
I have ordered the original drum switch, I'm assuming since woodmizer allows me to enter my serial number and they have a full list of original parts for my specific machine, from woodmizer.
I don't think my machine has a reset breaker, at least that I can find.
Thanks for the good info!

[Southside]

How are your cam follower bearings?  They will hitch up when going out and can cause issues like you describe.  

[Smallmill]

I dealt with the intermittent disfunctional forward/reverse for a while. Over time, replaced dc motor, potentiometer, drum switch, no luck. It was always tempermental I thought for a while it was the humidity or the phase of the moon. 

The only remedy was a good whack to the control box. When this remedy wasn't enough I would remove the cover to the box, the one the potentiometer is in, and blow the dust out. Most of the time cleaning the box solved the problem. One time while cleaning the box I had jarred the computer chip panel looking thing and a tiny wire came disconnected. 

There were two or three wires that were loose and simply needed tightened with a tiny screwdriver. Haven't had any problems since.

[Firegrass318]

How are your cam follower bearings?  They will hitch up when going out and can cause issues like you describe.  

It's hard to tell about the bearings.  They make some racket from time to time and it seems that when I grease them the problem gets worse.

[Old Greenhorn]

It's usually best to go at these problems in a decided path. Start eliminating each possibility completely by making sure it meets the settings in the manual. It sounds like you have a bunch of things that are 'iffy' and it's adding up to time to do a bit of a rebuild. Tackle one issue at a time and make sure it's fully up to spec then move onto the next issue. Eventually your problems will be all gone. But you can't keep skipping over that marginal stuff. Fix it.
 If you just want opinions, I think you need to replace the drive motor at least. It's got a lot of time on it. But opinions are like thumbs, everybody has at least two. Really, just start fixing stuff the right way.

[Ben Cut-wright]

Here's a few more general thoughts.


You "replaced the drive motor" yet the same problem persists. The drive motor exhibits the problem in forward and reverse.  You say the battery seems to start the engine with no problems.  Bearing "racket sometimes" is concerning,  " greasing makes it worse" is even more concern.  If you are able to push and pull the sawhead back and forth with NO hitches in the movement or extreme effort, it's doubtful the bearings are bad enough to cause the motor to stop working. The drive motor does provide a type of braking when not rotating so the belt should be removed when roll testing the bearings.  Removing the chain for test purposes will also eliminate a problem with the chain or sprocket.  The dust cover may be clogged or dry.  None of that is necessary if the sawhead rolls with little effort and no stopping.


Furthermore, the drive motor does not utilize the variable speed controls in reverse.  The drum switch is provided to 12 volts positive and switches that directly to the motor in reverse.  The two wires from the switch to the motor carry current both in forward and reverse. Thus a circuit problem in both directions is most likely a compromised wire or connection.  The contacts in the drum switch are a type of connection.  The ignition switch has contacts that can become faulty.  A "voltage drop" test, a test light, and/or a Multimeter are necessary in order to pinpoint the electrical fault. If the new drum switch doesn't correct the intermittent motor the testing instructions aren't that difficult even for someone with little experience.


I've installed a number of drum switches sourced from WoodMizer.  Others here have noted the wiring terminations in the retrofit switches are different in the new switches.  It's common for components to be upgraded or the OEM is NLA.  Good for you if you happen to get exact old stock.  Was attempting to make you aware there could be a difference. For example, the latest iteration of potentiometers have *operational characteristics which are vastly different than the originals.

[Southside]

When you say that greasing the bearing makes things worse sounds like you do have a bearing issue. The grease may be pushing the needles or balls out of place because the cage is damaged or some are missing. Enough grease falls back out for things to "settle" and it sort of runs. Being they are slow speed they may not grenade even though they have failed. 

[Firegrass318]

Here's a few more general thoughts.


You "replaced the drive motor" yet the same problem persists. The drive motor exhibits the problem in forward and reverse.  You say the battery seems to start the engine with no problems.  Bearing "racket sometimes" is concerning,  " greasing makes it worse" is even more concern.  If you are able to push and pull the sawhead back and forth with NO hitches in the movement or extreme effort, it's doubtful the bearings are bad enough to cause the motor to stop working. The drive motor does provide a type of braking when not rotating so the belt should be removed when roll testing the bearings.  Removing the chain for test purposes will also eliminate a problem with the chain or sprocket.  The dust cover may be clogged or dry.  None of that is necessary if the sawhead rolls with little effort and no stopping.


Furthermore, the drive motor does not utilize the variable speed controls in reverse.  The drum switch is provided to 12 volts positive and switches that directly to the motor in reverse.  The two wires from the switch to the motor carry current both in forward and reverse. Thus a circuit problem in both directions is most likely a compromised wire or connection.  The contacts in the drum switch are a type of connection.  The ignition switch has contacts that can become faulty.  A "voltage drop" test, a test light, and/or a Multimeter are necessary in order to pinpoint the electrical fault. If the new drum switch doesn't correct the intermittent motor the testing instructions aren't that difficult even for someone with little experience.


I've installed a number of drum switches sourced from WoodMizer.  Others here have noted the wiring terminations in the retrofit switches are different in the new switches.  It's common for components to be upgraded or the OEM is NLA.  Good for you if you happen to get exact old stock.  Was attempting to make you aware there could be a difference. For example, the latest iteration of potentiometers have *operational characteristics which are vastly different than the originals.

I have now replaced the drum switch and the exact same problem persists.  I may have forgot to mention that when I have the speed above 5 it seems to run just fine, when it is below 5 is when I have the problems.

[Stephen1]

I have a 1986 lt40 and went through all the same issues.  I had  to replace the actual power feed speed switch.   I believe it's called a pentameter ...or something like that.  It was an updated switch and the wiring was slightly different  I went back and forth with Woodmizer tech but we got it sorted.   I also replace the wiring harness and messed around with the drum switches ...it works fine now.

As above, Potentiometer is probably the culprit. They do not last long and is a spare you always want to have. You need to rule out what you been looking at, drive belt and motor, contacts, A new battery and or alternator  can work wonders. Might be enough for the motor but not the hydraulics or power feed especially once your sawing and depleting the battery, 

[Ben Cut-wright]

Here's a few more general thoughts.


You "replaced the drive motor" yet the same problem persists. The drive motor exhibits the problem in forward and reverse.  You say the battery seems to start the engine with no problems.  Bearing "racket sometimes" is concerning,  " greasing makes it worse" is even more concern.  If you are able to push and pull the sawhead back and forth with NO hitches in the movement or extreme effort, it's doubtful the bearings are bad enough to cause the motor to stop working. The drive motor does provide a type of braking when not rotating so the belt should be removed when roll testing the bearings.  Removing the chain for test purposes will also eliminate a problem with the chain or sprocket.  The dust cover may be clogged or dry.  None of that is necessary if the sawhead rolls with little effort and no stopping.


Furthermore, the drive motor does not utilize the variable speed controls in reverse.  The drum switch is provided to 12 volts positive and switches that directly to the motor in reverse.  The two wires from the switch to the motor carry current both in forward and reverse. Thus a circuit problem in both directions is most likely a compromised wire or connection.  The contacts in the drum switch are a type of connection.  The ignition switch has contacts that can become faulty.  A "voltage drop" test, a test light, and/or a Multimeter are necessary in order to pinpoint the electrical fault. If the new drum switch doesn't correct the intermittent motor the testing instructions aren't that difficult even for someone with little experience.


I've installed a number of drum switches sourced from WoodMizer.  Others here have noted the wiring terminations in the retrofit switches are different in the new switches.  It's common for components to be upgraded or the OEM is NLA.  Good for you if you happen to get exact old stock.  Was attempting to make you aware there could be a difference. For example, the latest iteration of potentiometers have *operational characteristics which are vastly different than the originals.

I have now replaced the drum switch and the exact same problem persists.  I may have forgot to mention that when I have the speed above 5 it seems to run just fine, when it is below 5 is when I have the problems.

When did the motor BEGIN operating correctly at pot settings above 5?  You began by describing the motor stopped working in both directions.