Flat belt pulley lagging

Trapper John · August 19, 2016, 01:22:15 PM

I am getting slippage on my drive pulley on my circle mill. I can only saw a foot at a time because the belt will slide off the pulley or into the engine. The belt is quite tight and tracks perfectly until into the cut. Has anyone any experience with pulley lagging (applying adhesive rubber strips or pads to the pulley)? It is a common practice for conveyor systems but a sawmill is a different story I am thinking.

Joe Hillmann · August 19, 2016, 01:33:41 PM

How much crown does the pulley have and are the two pulleys in line with each other?

Trapper John · August 19, 2016, 01:50:16 PM

The pulley has the standard crown of one eight inch per foot of width. I have tried pulleys aligned and not aligned. Angle of drive pulley makes the difference on whether belt comes off or slides into the engine.

DMcCoy · August 19, 2016, 04:19:38 PM

Is it possible for someone else to run the saw while you watch the belt, motor and shafts?
Under load is when problems will show up.
I would look at the slack side as being where your problems are beginning. Could be as simple as adding some guide bars or rollers to keep the slack side tracking properly if the problem is slight. Could be a shift of the motor or shaft holding the belts.
Loads can easily change things that seem solid and aligned.

Duck tape around the middle of the pulley will tell you if you have enough crown. I machine my conveyor belt pulleys with 1/16" + taper in 3.5". 1/3W in the middle flat, 1/3W taper each end. Never had a tracking issue.

Kbeitz · August 20, 2016, 06:19:45 AM

I collect old hit and miss engines and i play around with flat belting.
What I found is any load to large or to much drag will walk the belt
right off the pulley no matter what you do. Is it possible that your
blade it dull ?

Ron Wenrich · August 20, 2016, 06:31:52 AM

Have you tried belt dressing? When I ran flat belts, I always found that belt dressing helped with a lot of issues. I also remember that some of the mills had a belt tightener that floated on top of the belts to keep the tension on the belt when you put it under load. It was a weight that floated on top of the belts.

Kbeitz · August 20, 2016, 07:36:02 AM

Like this...

DMcCoy · August 20, 2016, 07:49:21 AM

I missed your opening comment about slippage. :-[
Diameters do matter on Hp transfer, and with that big diesel...
I think Ron has it right, try belt dressing first.
A slack adjuster as close as you can to the drive pulley will increase the wrap around it. Edit:if you have it outside the loop.
Your mill has been sitting a while if I remember correctly you had some concerns with rust. Hows the condition of the drive pulley surface? Rust-bumpy would only give you contact on the high spots which could also be a problem on Hp transfer. If belt dressing would fill the low spots I don't know. I used spray on belt dressing(very tacky) and some old giant 2" diameter stick stuff that needed warm belts to even begin to adhere. If I remember correctly the old stick stuff worked better as the tacky stuff collected sawdust from the air. Dusty belts slip.

Gearbox · August 20, 2016, 04:32:41 PM

DmcCoy has it . I run a 8 in belt with a twist and a 3 71 DD . You can't use all the HP it puts out . I can saw at full speed up to 10 inch after that I need to feather the stick .

Trapper John · August 20, 2016, 08:38:44 PM

The teeth are new and the pulley is also new. I will try the belt dressing first, also the duct tape trick (hopefully in a week or so as I had to buy an injection pump). I like the idea of the idler pulley right next to the drive pulley and use gravity to give me tension and more wrap on the pulley. Someone suggested using adhesive safe walk strip around the pulley for better grip, might try it but doubt it would last very long. I sawed my first log ever with a circle mill a few days ago and except for the belt slipping (and leaking injector pump) I was happy how the lumber looked. I was within 1/16 inch in 16 feet. I will try the dressing on my feed belt also as I really have to push on the stick and it is very tiring. I was also thinking of using a larger driven pulley on the feed to slow it down and give me more torque. Really appreciate the help and good ideas!

DMcCoy · August 20, 2016, 09:46:04 PM

John,
Is your feed works a double belt system?
I put a longer handle on mine to run the feed. More leverage and more movement but less strain than the ridiculous little handle it came with. I think I then had to upgrade the shaft and bearing the feed handle was attached to. Like chasing your tail!

The feed works run off your arbor/mandrel shaft?

Adjusting feed rates adjusts your chip size. I was told to keep the chips at least 1/16" so with my 24T saw the feed rate was 1.5" per revolution. I could cut slower by feathering the feed handle but when it can to flat out sawing my max was 1.5" per revolution. 600 RPM or 900" or 75' per min. Very fast, had to wait for the sawdust drag to catch up.

You want your chip size big enough to keep the sawdust in the gullet for the majority of the time. Too much fine dust will prematurely wear the sides of your shanks.

steamsawyer · August 22, 2016, 02:35:25 AM

Hey Trapper John,

Here is an old video of my mill showing the drive belt and idler. I run an eight inch belt. You can find some pictures of the idler in my gallery, when it was under construction. I also use cane syrup for belt dressing. Just drizzle some on the inside of belt while it is running and in a few minutes it will get tacky and you can't make the belt slip.

Not much milling going on here, just a little edging after finishing up a log with the kids and grand kids there.

Alan

https://www.youtube.com/watch?v=Vts5vGr47ao

Trapper John · August 22, 2016, 05:38:33 PM

The feed is a double belt system and it runs off the arbor. I did a little research on "belt dressing" and cannot believe all the things people use. No sense buying anything expensive when you can go to the nearest grocery store and buy sorghum, cane, or corn syrup. Also pine tar, rosin, molasses, honey, bees wax, caster oil and raw linseed oil also used.

Trapper John · August 22, 2016, 07:39:52 PM

Anyone try simply roughing up the pulley a bit with a belt of disk sander? Or is that a bad idea? Cool video.

Kbeitz · August 22, 2016, 07:46:54 PM

I've seen people put hatch marks on there pulleys with a grinder...

steamsawyer · August 23, 2016, 12:07:14 PM

You really don't want a rough surface, it will eat the belt. A pulley will work best with a smooth shinny surface. Paint will hold up for a while but will eventually wear off. Even rust will shorten belt life and it will last a long time before it cleans up under use.

I agree with your research on belt dressing. Why waste money on the high tec stuff when there is something less in cost that will work as well. One thing about the syrup is that it will be noisy when it gets tacky. It sounds like continuously ripping a bed sheet on the other hand with all the other noise it's not that noticeable.

Alan

DMcCoy · August 23, 2016, 01:25:59 PM

John,
Take a look at the length on Steamsawyer's carriage lever.

Mine came with about a 24" lever which I changed to about 56".

steamsawyer · August 23, 2016, 02:54:42 PM

Thanks DMcCoy, that handle is original equipment. The extra length allows you to feather the feed a lot better and smooth the feed out more. It helps take the jerk out of the carriage. All the feed pulleys are counterweighted to trim out any excessive control pressures either direction.

I also rigged a small return spring to make sure that it always returns to dead neutral. Depending on belt adjustment these things can have a tendency for the carriage to creep a little... and that can not be allowed.

Alan

sparky · August 28, 2016, 12:01:54 AM

I needed to replace the pulley on the mill I run as some of the steam engines could not get up to the proper operating speed for the blade. My friend owns a company that builds gravel conveyors. He offered to build a pulley with the proper diameter, width and taper. He also said he would place a vulcanized rubber coating on it. I have used it for two years with no problems with slippage, etc. He said the vulcanized system has been used for application sup to 500 HP. No problem for me as I never get a power source over 120 HP.

Sparky

Old Iron nut · August 30, 2016, 10:10:05 PM

Trapper John,, last year I had the identical problem with the belts. Adding belt tack to the belt gathered sawdust and threw the belts off. Tightening them up just ripped the lacing out of the belts. Different types of flat belts also a no go. So, this year I bit the bullet and went full hydraulic on my feed system and have never looked back! What a difference. I can saw straight through now without having to push the carriage through by hand. I could have paid for my hydraulic system had I went that way in the first place. Happy sawing, cheers, Old Iron nut.

bandmiller2 · September 03, 2016, 09:00:10 PM

Trapper flat belts are a throwback to simpler times when they were all they had. I ran flats on my circular mill just long enough till I found Vee belts and sheaves that would fit. As suggested dressing and a weighted idler will help. You want the idler on the slack side of the belt. Alignment becomes more critical as load increases. Frank C.