High temperatures on drive belt and pulleys of combo Planer/Thicknesser - PT-310 HH

G'day all.

I am seeking any guidance possible from the brains trust.

Background -
I have a Sherwood PT310 with Helical Head- one of the generic machines basically identical to the various offerings from different manufacturers/retailers - Woodman PT310HH , Woodfast PT310A, Jet JPT310, carbatec etc.

It's a new machine, nearly one year from new purchase and has served me well.

Issue -
I recently started hearing a clicking sound when the machine was switched on and upon investigation I found that the drive belt was damaged with a small chunk sticking out, hence the clicking.

I was also surprised to find that the pulleys and drive belt itself were too hot to touch.


I put in a warranty claim for the belt thinking it was strange to fail so soon after reasonably light use but in the meantime purchased another replacement A47 V Belt locally in order to get me up and running to finish the current project.


I’ve reinstalled and retensioned the new belt but was surprised to find that I was still getting the same heat issues. The pulleys and belt would get to 50+ within a minute or so with no load (just running, no planing). I left the machine running for 10 minutes and the temp climbed to 80!


The machine seems to be running fine, planing fine and no unusual noise, however everything I know about drive belts tells me this is too hot.


I have attempted the following:
1) carefully cleaned pulleys with isopropyl alcohol in case there was any oily residue causing slipping.
2) carefully checked the alignment of the pulleys - they seem close to co planar, however precise adjustment of the motor seems very hard to do. Any tips?
3) tested with higher or lower belt tension - same temp issues.
4) checked profiles of the belt and pulleys to ensure both are the same (yes 40 degrees)


I am seeking advice about whether this is an actual issue or not. If the belt hadn't started clicking I probably wouldn't have noticed the high temperatures... I would appreciate any guidance to reassure me that the behaviour is within tolerance or suggest next steps.

I have reached out to Timbecon as well - the first person on the phone couldn't offer any insight so I have sent a more detailed email query in the hope of getting onto a technician.


If anyone has a similar machine or experience with it
1) could you please run your machines briefly and feel or measure the temp after a short running time? How hot is normal for belts in this context?


2) I would appreciate any suggestions you might have about how best to adjust the position of the motor within its slots? Both for belt tension and pulley alignment. It seems very difficult to actually add precise tension or to adjust the angle of the motor. At first I was simply using a screwdriver wedged into the slot to lever the motor down. This would add belt tension but the rear of the motor would sit too low and face of the pulleys would sit out of coplanar. I have made up some small brackets to try to allow me to pull or push the front or rear end of the motor up or down - however this too is imperfect as the motor mount itself is not very rigid... The lack of precise motor position adjustment leads me to think that some degree of out of plane is to be expected?


3) on my machine the outside of the belt sits basically flush with outside edge of the smaller driven pulley on the end of the cutter head, however it sits proud of the edge of the lower drive pulley by 2.5mm. I wonder if this is contributing to the heat as the lower pulley is transferring the load over a smaller section of the belt. Any thoughts?


4) Can anyone with a similar machine confirm A47 is the correct belt spec? This appears to be right based on the text printed on the first damaged belt. And it seems to fit ok (aside from the fact that it is flush in one pulley and proud of the other...) The Timbecon warranty person has told me that they have posted out a belt replacement but that they do not know and cannot tell me the length/profile.

Some pics below -

Initial damaged belt:
Attachment 535126

Initial damaged belt showing wear at one side:
Attachment 535127

Thermal image after 2 min run time -
Attachment 535128

Thermal image after 10 min no load run time:
Attachment 535129

Top pulley - belt sitting flush:
Attachment 535130

Lower/Drive pulley - Belt proud by 2.5mm:
Attachment 535131


Many thanks in advance for any guidance that anyone can offer! Perhaps just a storm in a tea cup and these temps are normal? Thanks for patience with the long winded post but hopefully it can help others who might run into similar issues. :)

50°C is running hot, 80°C is excessive. Even in a car motor which is expected to run hot.

V-belts are generally rated up to about 60°C, which is where they start to degrade. (A very rough rule of thumb is for every 10° above expect roughly 1/2 the life-span.)

My suspicion would be that the pulleys are not aligned, not coplanar or both. That generates a lot of heat.

Air flow is also a factor, as it's what keeps them cool. With limited airflow and high ambient temps (in the cabinet) you can expect belt temps to increase.

But 80°? I can see why you're concerned.

Thanks very much for the reply! Glad to hear I am not being toooo much of a perfectionist and perhaps rightly concerned.

It's a good point re the airflow - these tests were performed with the cabinet fully open - hence much more airflow than during normal operations. I will try testing again after having the cabinet shut for a bit.

I will try tinkering with the pulley alignment/coplanarity some more but the mechanism for adjustment is very rudimentary :/

UPDATE - Timbecon technical support came back with the following advice:
"If there’s clearance & the motor & spindle pulleys have no imperfections and there are no obvious noises then it's not easy to say why there’s a build-up of heat.Is the motor hot?
Just make sure when the motor is tensioned it only needs gravity (no overloading tension).

Install the belt & let us know if there are any wear issues in the future."

The motor is not hot, at least compared to the belts which reach 50C in the first minutes..

Tensioning the belt using gravity alone does not seem to align with the instructions in the manual and definitely results in a low tension belt. The rear of the motor also hangs lower under gravity than the front end (which has the belt tension acting on it) - this seems to make the pulleys non coplanar.

My search for knowledge continues..

Is there any chance the belt touches the bottom of the V on the pulley?
My understanding is there should be slight clearance. Only surfaces touching are the sides?
You'd checked pulley but is there a very minute deformity in either?

That first photo looks like misalignment or something a pulley issue.
I know you said you'd checked alignment.

Just read your comment re motor mount.
Any flexing would not help.
I'd be looking at making that solid

Hard to properly comment with complete ignorance of the machine

Thanks @Avondale - I’ve checked the belt for clearance at the bottom of the pulley and there is still a couple of mm, so should be all good there.

I have checked the pulleys simply by hand, no obvious surface imperfections etc. They visually appear to spinning true on their shafts.

re the first belt and pulley misalignment - I think you are right, pulley misalignment likely contributed to the issue - particularly as the wear is worst on one side. Upon buying a replacement belt I was much more careful try to align the pulleys. Despite these best efforts the new belt is still getting very hot..

it turns out to be very difficult to align the pulleys as there is no fine adjustment of the angle of the motor which simply can be moved vertically in loose fitting slots riding on the treads of some bolts.

If any other owners of a similar machine have figured out any better methods I would love to hear them!

It sounds like it's still misaligned to me, but given the nature of the cabinet I'm pretty much at a loss for any suggestions to get them correctly aligned.

Is there any way you can hold a good, known straight edge across both pulleys faces? Perhaps, if they're coplanar, you may be able to remove a pulley and use washers/shims to move it to a more suitable position? (If they're not coplanar, then that opens up whole slew of other problems.)

Whatever, if the new belt isn't already showing obvious signs of wear you could probably get away with just using it as is for a while, but personally I'd want to keep another spare belt or two conveniently to hand just in case.

Thanks again- yep I have tested with a made up straight edge - basically a piece of straight hardwood with four screw heads protruding, all on the same plane (confirmed with reference surfaces). When holding this up against the face of the pulleys it shows clear angular misalignment of the faces. Even putting a basic digital level on the two faces of the pulleys shows a clear 1.5 degree misalignment.

i have found it surprising that the retailer Timbecon has basically not offered any insights into the issue - aside from suggesting to position the motor under gravity alone. I guess this suggests that it’s not the biggest issue in the world.

I now have a few spare belts on hand so should be able to keep running if another burns out.

Of perhaps greater concern I’ve now noticed that it seems like the motor is also getting quite hot after a period of use, presumably influenced by heat transferring from the drive pulley into the shaft. This concerns me for motor longevity but I admit I don’t know how hot these motors typically get during use..

If the machine wasn’t under warranty I would probably consider fabricating a new method of mounting and adjusting the motor position. A similar Hammer combo machine uses a vertical adjustment screw to help with this for example.

in any case I’ll update the thread if I learn anything new.

once again if any other owners of these machines have overcome similar problems please let me know :) …or tell me that it’s nothing to worry about…

I believe they're telling you to just let the motor hang by gravity is so that you're not putting tons of tension on the belt. a heap of extra tension is just resistance and heat that everything has to over come.

to me it sounds like they're saying hang it by gravity to get the tension and then tighten everything down.

A photo of how your motor is mounted may help to visualise all of what you are saying. Many machines run with the belt tension applied by gravity so I don't see that being your main issue. At my wood club they have a 380mm Thicknesser and the motor is free floating and doesn't have any overheating issues even used continuously for some time.