Restoring a Vintage Saw

[Mark A]

Hi chaps,

How can I extract this gear? There's a smidgen of forwards and backwards play on the shaft, so I reckon it's just a case of pulling it off - must be, because there's no other way to seperate the gear housing from the rest of the saw without removing the helical gear first.

Cheers,
Mark

 

[Mark A]

Forgot to add I don't possess bearing pullers etc.

 

[Monkey Mark]

Without pullers you may well struggle.
If it was me I'd place the shaft into a vice protecting it with soft jaws/rubber/similar and gently tap the body.

Edit: hard to tell from the pics but it looks like there could be a reraining bolt/grub screw on the outside of the casing holding the helical gear in place. If the bolt is removed perhaps the casing can be separated without removing the gear pictured?

 

[Mark A]

hard to tell from the pics but it looks like there could be a reraining bolt/grub screw on the outside of the casing holding the helical gear in place. If the bolt is removed perhaps the casing can be separated without removing the gear pictured?

The bolt you are referring to on the right side is the threaded end of a shaft upon which the worm gear is fixed. It passes through a bearing and is secured with a nut.

I've already tried pulling the casing away from the saw but it wouldn't budge.

Mark

 

[spinks]

Could you drill and tap the gear (say m6 ish) and use 2 bolts and a small steel plate to pull it out?

 

[Monkey Mark]

What make of saw is it?

 

[Graham Orm]

Looks like it's a throw away to me, not designed to be replaced. I really can't see anything pulling that off.

 

[Graham Orm]

Can you get the worm gear out from above it? In the top picture I can just see the end of it.

 

[rxh]

What are the diameters of the hole in the tool body and the gearwheel (to the tips of the teeth)? Also, how far is it from the face of the gearwheel to the outer face of the hole?

 

[Mark A]

Many thanks for your help so far!

What make of saw is it?

It's a Black & Decker "Ripsnorter" circular saw.

Could you drill and tap the gear (say m6 ish) and use 2 bolts and a small steel plate to pull it out?

In theory I could as I have a drill press and a cheap tap and die set; though I really wouldn't like to in case I messed up.

Can you get the worm gear out from above it? In the top picture I can just see the end of it.

No, the only way to access the inner workings of the saw is to remove the helical gear first.

The motor turns the worm gear, which meshes with the bronze helical gear and transmits the power perpendicularly to the blade. Forcefully pulling the casing away from the motor would mean everything working in reverse and it doesn't want to.

What are the diameters of the hole in the tool body and the gearwheel (to the tips of the teeth)? Also, how far is it from the face of the gearwheel to the outer face of the hole?

I'll measure it when I'm home a bit later today. What did you have in mind?

Looks like it's a throw away to me, not designed to be replaced.

No chance! :shock: It's from a time when things were manufactured to last and not thrown away when a fuse blows like we do today. The castings are a tiny bit rough in places, but mechanically it's very well made - even the lower blade guard has a thrust bearing to ensure it retracts smoothly...This saw is precious!

 

[Graham Orm]

Is it pressed onto the shaft or floating? You say there is slight movement.

 

[woodpig]

Without actually seeing it in the flesh it's hard to be sure but it's probably not designed to be taken apart so looks like there was little interest in making it easy to get the gear out. The manufacturers may well have had a suitable puller for it though. You may have to make up a puller if you can't buy one slim enough to do the job? Then again, getting the gear back on may not be straight forward either! Good luck with it though and let's here how it works out, it may be of use to others.

 

[skippy75]

Does look like you would have to make something just for the job. No normal puller would get in there.

 

[CHJ]

I would say that gear is trapped by the pinion, you need to dismantle the device enough to wind the pinion out of the gear (like a screw thread.)

That would explain the side movement, just the clearance play in the assembly.

 

[dickm]

A couple of things to note with worm/pinion pairs like that. When pulling the pinion out, it needs to be twisted slightly at the same time, as the teeth are not parallel to the axis. One other possible difficulty is if the pinion is not a cylinder, but "waisted" (bit like a squashed cooling tower) which makes it even more difficult/downright impossible, as the worm sits within the waisted bit and this stops the pinion pulling out. The rotor gearbox on the old Howard Bullfinch rotavator was like this, and from memory, it was necessary to pull out the worm, by effectively unscrewing it from the engine side.
It might be possible to do this if you can get at the armature to rotate it while pulling on the gearbox housing. (Aha - just seen CHJ has already suggested this). Further thought - where does the gearbox split from the motor housing? If it splits at right angles to the motor shaft, it might work to rotate the gearbox to unscrew it off the pinion.

But at that date of manufacture, it was almost certainly designed to be disassembled if wear had occurred. Maybe try asking on one of the US forums, where there seem to be folk who do this sort of thing routinely.

 

[Mark A]

What are the diameters of the hole in the tool body and the gearwheel (to the tips of the teeth)? Also, how far is it from the face of the gearwheel to the outer face of the hole?

Diameter of hole - 44mm

Depth of gear - 19mm

My digital calipers aren't able to reach the gear to give an accurate reading of its diameter, though it looks to be a smidgen less.

Thanks for the advice everyone - I'm in my garage as I type this trying out what's been suggested.

Mark

 

[rxh]

This special puller I have is for a gear wheel of about 39 to 40 mm overall diameter and up to 20 mm thick. The diameter of the locking barrel is 47.6 mm so sadly it looks like it would clash with the hole in your case.

 

[Graham Orm]

I think as mentioned earlier you'll have to drill and tap the gear, if it will drill that is. A piece of thick flat bar with a bolt through it will work then. Just get your bits organised and take your time.

 

[Mark A]

Hi chaps,

I managed to separate the gear casing from the motor housing with a pair of wedges.

Almost 70 years worth of dust and leaking gearbox oil built up inside of the motor housing. It looks like a sewer!

Chas and Dick - You are both correct; on very careful inspection with a torch the helical gear is indeed waisted, so it must be removed after the worm. I tried unscrewing the gear from the casing by rotating the armature, but so far it hasn't worked. I'll search forums and youtube in the morning.

Thanks,
Mark

 

[dickm]

Hi chaps,

I managed to separate the gear casing from the motor housing with a pair of wedges.
Almost 70 years worth of dust and leaking gearbox oil built up inside of the motor housing. It looks like a sewer!

Chas and Dick - You are both correct; on very careful inspection with a torch the helical gear is indeed waisted, so it must be removed after the worm. I tried unscrewing the gear from the casing by rotating the armature, but so far it hasn't worked. I'll search forums and youtube in the morning.

Nice to be proved right! A good job you didn't start drilling holes in the end of the pinion shaft and trying to force it out with a puller .
Is there any sort of collar or something on the end of the worm shaft that is stopping it coming out? The other possible (actually, thinking about it, it's a probable) is that the worm gear is actually pinned on to the shaft, and is too big to go through the bearing in the end of the motor housing, Can't see a pin in the pics, but worth a look.