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Davidhcnc
05-28-2011, 05:59 AM
And todays problem is...

http://homepage.ntlworld.com/david.hull35/Other%20Images/shaft.jpg

The motor shaft measures .748" and the pulley is .752" so that is .004" clearance. The motor is metric 19mm and the pulley 3/4".

I can bore the pulley and sleeve and re bore but really I am looking for other ideas to make this fit. I should say that the key will not be used and some loctite will do the driving.

No huge loads but true running is important.

What tricks have you got up your sleeve?

Boostinjdm
05-28-2011, 06:05 AM
Maybe .0025" shimstock? Then warm the pulley and drop it on. No need for locktite then.

winchman
05-28-2011, 06:21 AM
Why have such a big motor if there's not much torque load on the pulley/shaft?

Davidhcnc
05-28-2011, 06:31 AM
Why have such a big motor if there's not much torque load on the pulley/shaft?

Yes, that is valid. This is the motor I've got and would like to stick with it.

DougA
05-28-2011, 07:12 AM
Doesn't look like enough material at the ID of the pulley to bore it out and put in a new center. If running true is important as you say I would be looking for another motor and save this one for the next project.

Westline
05-28-2011, 07:29 AM
Double post sorry...

Westline
05-28-2011, 07:30 AM
This may be a bit stupid and I'm not sure if it will work but here goes.
Take the motor's shaft out and kurnl the part that goes into the pulley.
Don't do a full diamond knurl .... do just enough to form the surface that the peaks of the kurnl takes up the clearance
Some loctite retaining fluid and press it on......comments???

Kobus

wierdscience
05-28-2011, 08:22 AM
Or take the shaft out and shrink fit a sleeve on it,or weld it up and remachine more than on way to do it.

A.K. Boomer
05-28-2011, 08:42 AM
Maybe .0025" shimstock? Then warm the pulley and drop it on. No need for locktite then.


This is the simplist fix and takes advantage of the aluminum pulleys expansion ratio --- the two surfaces are in perfect cond. just the wrong size so go for it,

- just take the time to build your shim to fit perfectly and don't wrinkle it when you press/put it on, If you want a slip fit yet don't want to use heat then use .002" and locktite,

I saved an entire 4wd mitsubishi transmission by mapping out all the internal bearing bores and boring them oversize while moving them closer to each other - then installing the appropriate shim stock with locktite to hold the bearings (and therefore previous loose fitting gears) in their new geographical location:D

Bill McLeod
05-28-2011, 10:56 AM
with no key I would shrink an oversize sleeve on and turn it down, dead easy.

winchman
05-28-2011, 11:04 AM
I doubt you'd have much luck turning down a sleeve to the point that it's only 0.002 thick. It would just tear from the cutting loads.

Aren't there some Loctite gap-filling products for this situation?

aboard_epsilon
05-28-2011, 11:07 AM
put a thick sleeve in the pulley ..loctited in ..then bore the sleeve whilst its in the pulley ..should work fine .

all the best.markj

Mcgyver
05-28-2011, 11:11 AM
I doubt you'd have much luck turning down a sleeve to the point that it's only 0.002 thick. It would just tear from the cutting loads.

Aren't there some Loctite gap-filling products for this situation?

agreed that turning a sleeve down to .002 doesn't sound good. I'd turn down the shaft slightly, sleeve the shaft and turn to the required OD. gap filling loctite is also a good idea, I'd probably sleeve though so i know its aligned and I don't have to buy another bottle of over price loctite stuff that mostly will just sit a drawer until it expires :). Working with .002 shim stock might work, might be a frustrating thing to get together with lots of nasty words....you want a fairly tight fit between pulley and shaft and thin shim stock isn't much fun in cylindrical assemblies do to tearing etc. I wouldn't go knurling on an AL pulley, the steel knurls will cut the AL too much and mess up the bore

A.K. Boomer
05-28-2011, 11:17 AM
with no key I would shrink an oversize sleeve on and turn it down, dead easy.

yes like others stated - what you would end up with is a dangling oversize ring even if it was shrunk to start with - too thin to pull that off.

Evan
05-28-2011, 11:40 AM
First machine a piece of aluminum rod to .765". Then mount up the pulley and bore it to .765. Use a pointed tool to make some regular axial scratches indexed around the inside of the bore. Nothing critical about spacing or depth, maybe 15 or 20 scratches. Then apply loctite to the inside of the bore and press in the .765 plug you made using the tailstock as a press. Let it set in place on the lathe, then bore it to the correct dimension.

jkilroy
05-28-2011, 11:45 AM
Weld an aluminum plug into the pulley bore, face on both sides and rebore to fit, broach for key and use the key. Loctite is not going to work well in that application with a steel shaft and aluminum pulley.

Turn end of motor shaft down and thread for nut.

You are now fixed, correctly without bs fixes and it should last for years and years, or at least until the aluminum part wallows out.

bytewise
05-28-2011, 11:49 AM
However, if you permanently attach a sleeve on the motor shaft, you will never be able to disassemble the motor to replace the bearing!
Hugh

Evan
05-28-2011, 11:56 AM
The pulley is probably Zamac, not aluminum. It isn't weldable.

Mcgyver
05-28-2011, 01:08 PM
However, if you permanently attach a sleeve on the motor shaft, you will never be able to disassemble the motor to replace the bearing!
Hugh

that is a very good point, however if the sleeve was loctited on it is still removable with a bit of heat

John Stevenson
05-28-2011, 01:39 PM
Just going from the pictures and info given plus I have done the odd motor before - once :rolleyes:

Looking at the pulley with it's very thin sleeve and the fact it's probably Mazak or similar I'd leave that alone.

This now leaves the motor, and we have two choices, turn a bit under size and weld up then turn to 0.752" or turn down more to get a decent sleeve, say 17mm bore , press and loctite on and turn down to 0.752"

Don't worry about a bearing change as the motor is more than likely to have a 20mm bearing anyway.

Notice the small step at the end of the 19mm shaft ?, plus 19mm isn't a standard motor bearing size. I'm betting it has a 6204 bearing in there or possibly a 6304.

MichaelP
05-28-2011, 01:51 PM
If you can live with the puley being more away from the motor, you can make a simple adapter that will extend the motor shaft.
Something like this: http://i966.photobucket.com/albums/ae148/MPdisp/adapter.jpg

Davidhcnc
05-28-2011, 05:23 PM
I appreciate all the ideas. So it is a choice between doing it right or doing a hack:D .


I am very confident that loctite will hold and transmit the power....but to keep things true until it hardens.

to swell the shaft by knurling is no good because there is a key in it. It is there if you look closely.

We had this before. Who made the internal knurling device, a knurl wheel spinning on a bolt? So it would be easy to touch the inside of the monkey metal pulley to 'swell' the bore. Loctite, push it on and the rest is history.


Need to sleep on it and see if any more brainwaves come.

A.K. Boomer
05-28-2011, 05:26 PM
If you can live with the puley being more away from the motor, you can make a simple adapter that will extend the motor shaft.


this can not only compound run-out errors and cause major imbalances it's also not good practice as it shortens the life of the motor bearings due to putting them under more loads from the leverage of extension.

snowman
05-28-2011, 05:43 PM
Use a speedy sleeve

http://www.vsm.skf.com/en-US/HeavyDuty/KitsAndTools/SpeediSleeve.aspx

It's .011 thick. Put it in place with JB Weld or loctite. If you have a surface grinder it should be easy to fixture up the motor, spinning, on the surface grinder then slowly lower the grinding wheel onto the sleeve to reduce to finish diameter. Prior to doing this, mark where your key is at. Now cut out the key (but probably not all of it)

It'll at least be a precise thickness shim.

If you don't have a surface grinder, it's still possible, but you are going to have to work out a way to feed the spinning motor into a spinning grinding wheel, shouldn't be too difficult.

Use coolant to keep the sleeve cool so that you don't have to worry about expansion.

MichaelP
05-28-2011, 06:00 PM
this can not only compound run-out errors and cause major imbalances it's also not good practice as it shortens the life of the motor bearings due to putting them under more loads from the leverage of extension.
Well, you can shorten the motor shaft if desired.

darryl
05-28-2011, 08:30 PM
I would probably start by heating the pulley in the oven, then measure the bore before it cools. This will tell you how much room there would be for a shim. Seems like 3 thou would be the target thickness, but maybe that's too much. I would add the shim to the pulley (cold) then nose it up to the motor shaft and wobble it around a bit. With about 1/16 inch of shim sticking out of the pulley bore, you'd be able to get a slight flange on the shim, and this would help to prevent the shim from bunching up inside of the bore when you push it onto the motor shaft.

I would not use a press fit, but a shrink fit would give about the best grip with the least damage. You could apply a very thin ring of loctite around the motor shaft almost at the end, but I doubt it would do much good between the shim and the pulley bore. Correct me here, but I believe it needs contact to steel to cure.

Bazz
05-28-2011, 10:09 PM
shrink the dam pulley

compress the small OD in a press .010 and check the diameter then bore if needed

or spin the edge of the small OD of the pulley in the lathe and bore
or slip a hot bushing on the pulley small OD diameter and let it cool
or shrink it the blacksmith way with heat and cooling half of it at the time

Davidhcnc
06-30-2011, 03:30 PM
Easy.

http://www.youtube.com/watch?v=GTtlU5WDiM4&feature=player_embedded

Thomas Staubo
06-30-2011, 05:54 PM
He-hey! Looks like it worked.

Is that (http://www.youtube.com/watch?v=B_WAsDVo1Ec&feature=related)some kind of kit you can buy, to put on the grinder? Looks like you have one bench grinder and one standard motor with the same kit on.


.

Davidhcnc
06-30-2011, 06:15 PM
It is a Blue point/Snap on multitool attachment.

http://www.youtube.com/watch?v=se-zZnD2DXY&feature=player_embedded

This is for a UK forum that I inhabit, we got a load of these attachments in a job lot and distributed them to the troops at cost. We can't get decent grinders in UK. Then I've put together this kit to make them fit a 1 hp motor.

http://img.photobucket.com/albums/v76/rapidboy1/grinder%20attachment%20fitting%20kit/davidspics246.jpg

http://homepage.ntlworld.com/david.hull35/Other%20Images/adapter%20plate%20assembled.jpg