ISO fit for sprockets

[Brad93]

So I've had a bit of of trouble pressing together the shaft and sprocket combination.

17mm shaft.

Recommendation for bearings to be an interference fit was a shaft size of j5 tolerance = +2 to +5um. I thought that was a little loose so ended up at +7 to +9um.


Sprockets were heated to 150°C.

Bearings were heated to 110°C.

Bearings went on lovely with low pressure on the press.

Sprockets were bored to 17.01mm. Plus 10 microns. In my head I thought that was a good idea. I'm guessing this is where I went wrong.

What should my sprockets have been? Size of the shaft + tolerance?

Sprocket has galled the shaft slightly, it's not an issue to the final operation, but it's unsightly. Shame because it was all looking the mutts nuts.

 

[mtt.tr]

I would think your shaft is to tight at 110°c id expect the bearing to be a hand fit.

 

[mike os]

As above …

 

[pressbrake1]

Tolerate quoted is at a certain finish which isn’t a lathe surface finish hence parts can burnish and go loose or pick up and gall
Also material hardness is a big player

 

[daedalusminos]

I assume he used some abrasive on his shaft
But probably not on the sprockets.

 

[Brad93]

I assume he used some abrasive on his shaft
But probably not on the sprockets.

I did indeed

 

[Brad93]

Well the bloke does t need the parts till next week so I might end up remaking

 

[addjunkie]

A freezer is often a great help in these instances

 

[Munkul]

Will it work as designed, and will the owner care? It'll look fine when it's covered in grease

150deg is hot... it does sound like less a fit issue and more a surface finish issue leading to galling. What was your bore surface finish like?

 

[Brad93]

Will it work as designed, and will the owner care? It'll look fine when it's covered in grease

150deg is hot... it does sound like less a fit issue and more a surface finish issue leading to galling. What was your bore surface finish like?

The bore was as good as you could expect with an unknown make of sprocket. It was a nice smooth bore. I used a carbide boring bar with a very fine finishing insert.

Shaft is EN8 but was finished to a very smooth finish with emery tape and scotchbrite.

 

[Rkweld]

https://simplybearings.co.uk/shop/Info-Pages-ISO-Limits/c4746_4779/index.html?page=1

Is this any help?

 

[Munkul]

The bore was as good as you could expect with an unknown make of sprocket. It was a nice smooth bore. I used a carbide boring bar with a very fine finishing insert.

Shaft is EN8 but was finished to a very smooth finish with emery tape and scotchbrite.

Should have been good then.

Hang on. The whole shaft was turned to j5? So thats +5, -3 um. You turned it to +7 +9. Why didn't you just trust the ISO fits? lol