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Belt Driven Hacksaws -

Kennedy Pulley/Belt Problem

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Old Elan22/08/2018 19:14:54
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87 forum posts
31 photos

I have a Kennedy 60 powered by the original; Hoover 1/6 HP motor. It used to work fine (I think!) until the belt began to slip. I purchased a new belt but no matter what I do the belt slips to the outside.

I say I think because I'd never taken the guard off before getting the fitting the new belt.

kennedy drive 1.jpg

I have tried all permutations of pulley positioning on the spindles to no avail. According to the manual, the pulleys outer edges should be in line. I can get close but the belt still rides off to the same extent.

I have not loosened either the motor, a no-no according to the manual, or the saw body itself although I suppose the new belt may have pulled the shafts out of parallel.

Calling Kennedy owners, is your motor pulley like mine?

Any ideas as I'm getting cross now!

kennedy drive.jpg

Muzzer22/08/2018 20:11:56
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2904 forum posts
448 photos

Look about 2:48 into this video. I would suggest your motor and pulley are not parallel. Possibly one of them has become misaligned.

Murray

Clive Foster22/08/2018 20:35:32
1840 forum posts
59 photos

Odds are its been running misaligned for years 'cos last person to change belt loosened the motor instead of just working the belt on. If so the large pulley crown may have worn asymmetric and need correcting before the belt will run true.

These little flat belts seem either to just go straight on and behave or turn into a total nightmare. Had the nightmare with my Clarkson. Pulleys measured OK but it flat out refused to behave. Ended up making two new ones which worked just like that after a simple ruler alignment of the pulley faces.

That said I think I'm one nightmare out of five.

Clive.

Old Elan22/08/2018 20:37:28
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87 forum posts
31 photos

Thanks, Murray. That is sort of the conclusion I came to, too.

Thanks, Clive. I hope mine is not that much of a 'mare! I must say that the motor pulley is a strange shape but is in steel whilst the driven is aluminium. I don't think the motor would have been worn by the belt.

It will be difficult to work out which if any bit has moved. The motor to base or the saw unit to base. Or maybe both!

I would still appreciate any input from fellow Kennedy owners.....

Roy

Edited By Old Elan on 22/08/2018 20:43:10

Mike E.22/08/2018 21:15:36
192 forum posts
1 photos

I have the larger model 90 Kennedy saw which had belt slippage when I acquired it. Oil was part of the problem, but slippage all but disappeared when I roughed up the small motor pully with coarse sandpaper.

peak422/08/2018 21:45:20
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851 forum posts
71 photos

Mine's a nightmare to keep the belt in alignment.

Loosening the motor would make little odds, as mine's held in place with 4 allen bolts in minimal clearance holes through the base casting, so no adjustment there.

That only left aligning the saw body, but the bolt slots weren't long, or wide, enough.

I think some of the issues are that the bushes for the crankshaft are worn slightly oval, so setting the motor and crankshaft parallel goes to pot when the very tight belt stresses everything.

Bill

Robbo22/08/2018 21:47:25
1504 forum posts
142 photos

Roy

The motor pulley is noticeably "barrel-shaped" intentionally, so as to cause the belt to ride to the middle of the pulley. It's called "crowning" and the big pulley is similar but not so noticeable. Bandsaw wheels are the same.

Would suggest that your 2 pulley shafts are not parallel. Don't forget that the belt needs to be really tight (known as "bar-tight" in my day). I use a short length of wood batten as a lever between motor and saw base to tension mine.

lfoggy22/08/2018 21:52:53
72 forum posts
6 photos

I had one of these hacksaws and changed the belt and pulleys to 'V' belt. Much better than the original flat belt which was forever slipping or falling off.

Pete Rimmer22/08/2018 21:55:56
423 forum posts
18 photos

Remove the motor pulley and turn the shaft so the keyway is not pointing towards the big pulley. Place a straight edge across the edges of the big pulley so that it extends up to the motor shaft. Put a small square on the straight edge and check if the motor shaft is truly perpendicular to the straight edge, which will make it parallel to the big pulley axis. If it isn't, loosen the motor and adjust it until it is. If the pulleys are now aligned and parallel, the belt will run true.

Once you have the motor pulley parallel to the big pulley use a marker pen to draw marks on the base along the motor feet. Then if you have to adjust the motor to tension the belt you have a visual reference to keep the shafts aligned, you just eyeball the gap from the line to the motor foot.

peak422/08/2018 22:16:41
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851 forum posts
71 photos

Also, If you've not come across This Link before, you might find it useful.

Bill

Old Elan23/08/2018 13:41:39
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87 forum posts
31 photos

All useful information, thanks all.

I will check for parallelism this afternoon.

I don't really want to change to V belts if I can avoid it.

I will just have to be very patient setting it up but as Bill says, there's not a lot in the way of adjustment.

Thanks for the link too.

Roy

Trevorh23/08/2018 14:47:03
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272 forum posts
70 photos

There is an easier way to align or check the pulley

simply re fit the belt and trap a piece of string under one end - it does not matter which end, now rotate so that the string is pulled across the face of both pulley's

move off and bring it back onto both adjust until it touches all 4 contact points

for example if it touches both sides of the motor's pulley and not the large pulley then move the motor

keep adjusting until the string just touches both

if you want to check the correct tension then simply down load Gates Carbon Drive - its an app that measures the frequency of the belt when "plucked"

you enter the belt details and it has a proffered frequency attached to that belt size and distance between centre's

enjoy

Kiwi Bloke24/08/2018 06:18:40
256 forum posts
1 photos

I have a love-hate relationship with my original model 60. Perhaps part of the problem is that both pulleys are manufactured crowned. It should only be necessary for one to be crowned, in order for the belt to track correctly - assuming parallel shafts. Perhaps misalignment makes them fight one another. I remember swearing fluently at the thing as I wrenched the motor's alignment around, with the thing running, until the belt behaved. The belt has to be TIGHT. Once done, it's remained stable, but the language required was quite advanced...

john carruthers24/08/2018 08:41:48
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595 forum posts
172 photos

Absolutely nothing to do with the OP's problem but...
I once helped 'Old Mo' in renovating Crabble corn mill.
A huge long flat belt was called for, almost the length of the building.
The lads couldn't get the pulleys set right so Mo was called upon (did his time as a mill&engine wright).
He ordered all the windows and doors shut, then rigged a little motor to spin up the driver pulley.
He took his trusty oil can and squirted a dose of oil onto the spinning pulley.
A line of oil shot down the shop along the floor and up the far wall.
"just line up on that lads", and walked out

David T24/08/2018 08:53:25
71 forum posts
14 photos
Posted by john carruthers on 24/08/2018 08:41:48:

He took his trusty oil can and squirted a dose of oil onto the spinning pulley.
A line of oil shot down the shop along the floor and up the far wall.
"just line up on that lads", and walked out

That's genius! laugh

Clive India24/08/2018 09:28:12
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186 forum posts
Posted by lfoggy on 22/08/2018 21:52:53:

I had one of these hacksaws and changed the belt and pulleys to 'V' belt. Much better than the original flat belt which was forever slipping or falling off.

Me too - the complete cure.

Wait for it!

Clive Foster24/08/2018 09:42:30
1840 forum posts
59 photos

Multi groove rather than Vee belt pulleys would be better if you are changing pulleys. Motor pulley will be far too small for effective power transmission into a Vee belt. That small pulley and drum tight flat belt was used because its a more effective system when paired with a wimpy 1/6 th hp motor. For Vee belts you really need a countershaft and two stage reduction to get decent drive. Official minimum diameter for pulley A section belt is around 4" PCD. Bit less for notched belts and link belts but proper figures re hard to come by. Multi groove seem to be happy down to 1" or less.

Whatever the theoretical shortcomings the factory system works well for many years. Usually under maintained by neglect rules. What always amazed me was that the main bearing didn't wallow out in short order under the heavy loads. The one we had at work stood up fine to over 20 years of uncaring, albeit intermittent, operation to my certain knowledge. On the original belt too.

Clive.

not done it yet24/08/2018 10:26:48
3357 forum posts
11 photos

A lip, bolted to the shaft would prevent the belt from moving off the driving pulley at all. OK as long as the alignment is close. An endless flat belt was driven from a lipped pulley on a Wisconsin VE4 to a flat pulley on our MH701 baler. Worked OK on that scale

Old Elan10/09/2018 15:27:31
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87 forum posts
31 photos

Update largely prompted by the other Kennedy thread.

Managed some workshop time and got the pulleys running parallel and the belt is now centralized and runs fine.

I had to machine the end of the crank though as it was just tapping the motor casing.

It might have been better if I had bought a 540 belt. The 530 is very tight!

kennesdy crank.jpg

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