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question for the machinists


yellowrosefarm
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I have a Wisconsin engine that was used on a pump and the crankshaft is 1 1/4 with a threaded section. The crank is normally 1 7/16 with a keyway. Would it be possible to make a bushing to go over what I have to return it to the right size? Maybe threaded inside with the key made into it on the outside?  I really have no clue what can and can't be done.  The step on the crank next to the end plate is 1 7/16.

HPIM4472.JPG

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My cousin made a sleeve for increasing a crankshaft years ago for a twin Magnum 18 Kohler engine. The key is the tricky part 

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There is normally a step in the crank just before the pan seal.  Not all engines have it but most do.  The shoulder on the crank is what the either internal or external threads would pull against.  1-1/4” is a more normal size than 1-7/16” anyway.  If you sleeve it up to 1-7/16” there is nothing to pull against so any attachment on the crank would depend on a set screw or taper lock system to keep it in place.  Set screws don’t work reliably.

If you do have to sleeve up, you will have a sleeve of 3/32” thick.  That is quit thin.  So thin that the keyway would probably just have to be cut through the sleeve and use a custom key that fits in the parent keyway of the crank and is taller than it is wide.

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3 hours ago, bitty said:

My cousin made a sleeve for increasing a crankshaft years ago for a twin Magnum 18 Kohler engine. The key is the tricky part 

I.ve done this with a Honda that was on  pump.  I turned up a sleeve with an internal thread.

The sleeve wasn't thick enough to cut a keyway so I welded a bead big enough to file into a key.  Still working.

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we did it for a 1972 craftsman tractor

the shive has 4 different diameters for attachments

had to bump it up 1/16 and cut a key way threw it

also the new key was 1/4 x 5/16

mounted on a 16 hp Vanguard twin

worked great till we moved the 16 hp over to the IH 185 to run the blower for snow

Mike

 

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What is the application you are wanting to use it on now? Pics of what is involved with that might help to decide what to do.

I assume there is a keyway on the non threaded part of the shaft. You could make a bushing and as already suggested mill a slot over the existing keyway and make a tall key and even a step key if slot in crank isn't correct width. I would consider a spacer behind what ever is going  on the shaft (looks like a step in the crank before the seal?) as well as a nut /large washer /spacer In front if needed as well. I'm thinking pulley or sprocket application here? As long as your bushing I trapped inside something and the load isn't sever I think it might work. 

Or it might be simpler to get a new pulley/sprocket the right bore for the crank?

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I would like to use it to replace the engine on my stump grinder. Same VH4D, but with the 1 7/16 shaft and a 4 groove keyed pulley that is long enough to cover the threaded portion in the picture. The shaft in the picture has no keyway at all. The pump impeller was threaded on to it.  I doubt this engine from the pump has 100 hours on it. The paint isn't burned fully off the exhaust manifold yet. The stump grinder engine could pull double duty as a mosquito fogger.

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These guys make up shaft adapters but without a key I don't know how much torque they could transmit. I don't think a pump requires the shock loading a stump grinder does and the load just tightens the nut. Perhaps one of their keyed type and get a machine shop to cut a keyway into the crankshaft? They have keyed and non keyed.

https://shaft-collars-couplings.staffordmfg.com/viewitems/rigid-shaft-adapters/step-up-shaft-adapter-without-keyway

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A horizontal boring mill could, I think, cut either a standard square key or a woodruff key seat in the crank shaft of the ex pump engine without removing the crank.  Then buy a pulley to suit.  

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get a pulley to match the 1.25 shaft.

 pulley needs to have set screws.

 after setting up new pulley, tighten set screws, till they make a mark on the wisconsin's output shaft.

 Grind a small flat on the shaft where the set screws land.

 re install, tighten set screws till they take a good bite, you should be good.

 If you can run the pulley tight against the 1-7/16" step, using the threaded end and a nut, so much the better.

 

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1 hour ago, supermechanic said:

get a pulley to match the 1.25 shaft.

 pulley needs to have set screws.

 after setting up new pulley, tighten set screws, till they make a mark on the wisconsin's output shaft.

 Grind a small flat on the shaft where the set screws land.

 re install, tighten set screws till they take a good bite, you should be good.

 If you can run the pulley tight against the 1-7/16" step, using the threaded end and a nut, so much the better.

 

 

Quote

 

Alloy Steel Cup-Point Set Screws

92313a537-@halfx_637341252965763331.png?
 

Made from alloy steel, these set screws have a thin edge that digs into hard surfaces for a secure hold. Length listed is the overall length.

Black-oxide alloy steel set screws resist corrosion in dry environments.

Zinc-plated alloy steel set screws resist corrosion in wet environments.

 

 

I have seen where two set screws were 'stacked' one on top of the other, to act as a jam 'nut'.  (Just remember to remove BOTH screws, if you need to remove the pulley).

You should also be able to find them with a patch of nylon on the thread to keep it from loosening.

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Another type of "grip point" allen screw

Quote

Alloy Steel Knurl-Grip Cup-Point Set Screws

93445a427-@halfx_637341253094873000.png?
 

Made from black-oxide alloy steel, these set screws resist corrosion in dry environments. They dig into hard surfaces for a secure hold and have serrations on the cup edge that grip the material surface to resist loosening. Length listed is the overall length.

 

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There will be a lot of shock in that new application, I would consider taper bore bushing and sheave, they have set screws for the bushing but once it's tightened together I doubt you need them 

@AngrySailor

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3 hours ago, yellowrosefarm said:

Where does this one come from?

You can Google them. Shop where I was having an alignment was trying one on their air compressor but it didn't work as the motor they were trying to use didn't have the power. I'd never seen one before but remembered it and just looked for one on the web.

I have my doubts about using set screws. They're OK on fractional HP stuff but I don't think they'll hold on such a higher torque requirement, especially with the potential shock loading.

Hardtail's idea probably holds the best chance of using set screws although I've never seen one without a key. Taper locks really do grip the shaft. Having someone cut a keyway and using a taper lock pulley certainly will work as there's any size available to fit the hubs.

 

 

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The other problem is length. The stump grinder shaft is 6" and the pump a little over an inch shorter, including the threaded portion.  What if I had a machine shop start with a 6" long solid 1 7/16 round stock, bore for the 1" 14tpi thread all the way through, thread 3", then bore the other end to 1 1/4, then cut a 3/8x3/16 key way starting 3/4"from the 1 1/4 end all the way to the other end. It would cut all the way through the big bore, but would leave 1/32 above the threads. I'd have to do a shallow cut on the big part of the crank to match once the new bushing was screwed tight on to it.  Then I could use the existing pulley and 3/8th key.  If the taper lock collar was over the thin threaded section at the end, I could screw in a piece of 1" - 14 threaded stock so it wouldn't collapse it.

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I think Angry Sailor covered something like this in one of his projects and stepped it and welded, you could do a custom pulley that is sunken bore to deal with the shorter shaft but you are starting to rob from a few different areas on a tough application, there are ways but which is best and will last

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In this application it sounds like a key way would be a lot better than not. Could the crank be switched out of the old engine into this one? Or a key could be cut into this crank. We have taper locks on overhead hoist wheels at work but as NE said they have keys in them. 

Not sure sets screws even with flats would be stout enough long term. Would probably work for a while but sooner or later you might have problems with it. In fact I'm guessing probably would. 

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