HELP! Removing a worm shaft

[Dr.Al]

About 8 years ago, I bought a long-in-the-tooth-then battered old bandsaw. It's served me well for those 8 years despite being it pretty shoddy condition for all that time, but I've decided it's time to give it some love and try to sort it out.

As part of that I'm trying to replace the bearings and oil seals (and I'll probably paint it while it's all out). I've mostly got it apart, but I'm really struggling to get the worm shaft out.

The problem is, I haven't got a scooby how to remove it. I'd wondered about using some brake caliper separators, but the minimum spread is 12 mm and the gap between the boss in the casting (which you can just about see above the worm shaft) and the end of the worm shaft is 6.1 mm. I'd also wondered about grinding that boss away, but I suspect I'll want it to be there for reassembly as I can reset the worm shaft to have that 6.1 mm spacing from the boss.

The only other ideas I've had have been coming up with something or other that clamps extremely firmly onto the flat on the bottom end of the shaft and then making some form of custom puller.

Any bright sparks on this forum got any bright ideas?

 

[Pete.]

Well, clearly that went in worm end first so the only way it'll go out is down (in the pic). What you need to know is, what is retaining it right now.

EDIT- A quick search suggests that there is a roll pin through the shaft of that gear. Does yours have a roll pin?

 

[Pete.]

It should look like this once removed:

https://s296.photobucket.com/user/sparky961/media/Metalworking/Miscellaneous Parts/IMG_4693.jpg.html

 

[Dr.Al]

Well, clearly that went in worm end first so the only way it'll go out is down (in the pic). What you need to know is, what is retaining it right now.

EDIT- A quick search suggests that there is a roll pin through the shaft of that gear. Does yours have a roll pin?

Can't see any sign of a roll pin. The diagram on page 26 of the manual for the latest version of the bandsaw (which may be very different from my ancient one) suggests that the worm is integral to the shaft.

The worm diameter is smaller than the diameter of the bearings that are supporting it on either end of the hole through the casting. I had assumed that it was retained in a similar way to the worm gear (which went through the hole you can see in the picture). This had a plate on the outside end (held in with three screws - you can see the equivalent screws at the bottom of the picture) and there were two bearings and an oil seal pressed in. The whole lot came out with a firm push on the worm gear, from the inside of the gearbox (into the page in the photo above) but there's no way I can think of to push on the end of the worm shaft.

 

[Dr.Al]

It should look like this once removed:

https://s296.photobucket.com/user/sparky961/media/Metalworking/Miscellaneous Parts/IMG_4693.jpg.html

Yeap, that looks similar to the one in the manual. Hopefully there will be enough clearance behind the bearings to pull them off once the assembly is finally out. It doesn't look like it from that picture though...

 

[jordan1]

Is there a large circlip or similar holding it in place?. Is that 'boss' part of the casting or a removeable 'plug'?.

 

[Dr.Al]

Is there a large circlip or similar holding it in place?. Is that 'boss' part of the casting or a removeable 'plug'?.

No circlips or anything else like that. The boss is part of the casting.

There was a retaining plate over the bearing at the bottom. The plate has been removed (the three screws hanging out at the bottom of the photo are just there so I don't lose them).

I'm pretty sure that what's holding it in is the fact that the bearings are a press fit in the casting, so I need to somehow find a way to press the whole assembly out from the top of the photo down.

Problem is: I don't know how to apply enough force in a downward (in the photo) direction.

 

[eLuSiVeMiTe]

Are the bearings ok?
Pop the seals in place. clean em up and repack em..save some hassle

 

[Dr.Al]

Are the bearings ok?
Pop the seals in place. clean em up and repack em..save some hassle

There is a bit of wobble in the shaft, so I suspect they've had it. I'd also like to paint it all, which feels like it might be easier with the shaft removed.

 

[eLuSiVeMiTe]

Blocks and wedges.have a few wedges made from tool steel and they have been invaluable.
Pack the gap with blocks. Drive the wedge in. Swap the blocks and wedge it again.
Tedious though

 

[fordman]

Try usin a hot air gun to heat the boss area and then try to pull/push the shaft out, complete withe bearings.

 

[Shox Dr]

It must have some mechanical fixing, otherwise the worm would walk out the casting

 

[Dr.Al]

It must have some mechanical fixing, otherwise the worm would walk out the casting

I presume that's the purpose of the retaining plate, although I don't know how the forces of the worm reaction compare to the friction of the press fit.

 

[m_c]

It must have some mechanical fixing, otherwise the worm would walk out the casting

Not necessarily.
As it's a bandsaw, it should only ever run the one way, so it could simply be relying on the force pulling everything against a boss.

@Dr.Al have you tried pressing the worm in, to see if it at least moves through the bearings?
If you've got somebody else to help steady things, another thing to try would be grip the shaft in a vise, then hit the housing.

 

[Shox Dr]

Not necessarily.
As it's a bandsaw, it should only ever run the one way, so it could simply be relying on the force pulling everything against a boss.

@Dr.Al have you tried pressing the worm in, to see if it at least moves through the bearings?
If you've got somebody else to help steady things, another thing to try would be grip the shaft in a vise, then hit the housing.

Pulling or pushing still needs to be held

 

[m_c]

Pulling or pushing still needs to be held

Very true, which is why I'm guessing the inside bearing will be sitting against a boss/lip at the end of the bore.

 

[eLuSiVeMiTe]

Very true, which is why I'm guessing the inside bearing will be sitting against a boss/lip at the end of the bore.

Umm. How did they fit the worm then.

Or do you mean a lip to stop the bearing pushing any further towards too of pic

 

[m_c]

Or do you mean a lip to stop the bearing pushing any further towards too of pic

That. Big enough so the worm can pass through, but small enough to stop the bearing from passing through.

 

[Kram]

Id cheat, drill a hole in the casting, inline with the shaft (itd remove the boss -so measure shaft to casting for reassembly). Peice of plate to fit in the gap with a m10 or m12 fine thread, screw a bolt from outside and you have a pusher. After, tap casting bigger and fit a plug.

 

[knighty]

got any more photos?

I'd knock it in first.... cut the inner bearing off with a grinder and then push it out... once the outside bearing is out it should pop right out?