Restoring a Vintage Saw

[Mark A]

Hi chaps,

Good news! The worm is out of the box!

Here's a picture to prove it.

It transpires the shaft upon which the worm is fitted is splined, and so to disasemble it was just a case of knocking the shaft through. I had actually tried doing that a couple of days ago, but was just not heavy-handed enough as I was worried about cracking the casing or damaging a bearing.

I did, however, discover after taking apart the gearbox that a small chunck of casing around the rear bearing (through which the shaft passes) has come off at some point in the last 70 years and the rubber gasket has started to perish. The gearbox oil has been slowly seeping through, and is the reason why the motor casing is so filthy.

I have a tube of gasket sealer. Is there any reason why I shouldn't use some in conjuction with the perished rubber gasket?

Mark

 

[dickm]

Hope it wasn't your hammering that dislodged the bit of the casing (been there, done that!).

Could you re-build that broken bit with epoxy? Presumably it doesn't take any stress? And re-make the gasket if you have the original as pattern and can identify the material.

 

[Mark A]

Hope it wasn't your hammering that dislodged the bit of the casing (been there, done that!).

Wasn't me, honest!

The screws securing the stator are worn, which suggests the saw has been dismantled at least once in the past.

Could you re-build that broken bit with epoxy? Presumably it doesn't take any stress?

How would I do that? Build up layer after layer and then grind back with a Dremel?

And re-make the gasket if you have the original as pattern and can identify the material.

I have some rubber matting which is about the right thickness. The original gasket isn't too bad; can I not just smear it with gasket sealer and be done with it?


I have a question about gearbox oil.
The original instructions for this "Ripsnorter" say to refil the gearbox with the official oil, but there are no more B&D service centres around. My "Tarplaner" came with a little tin of extremely viscous oil, and while searching online for worm drive saw gearbox oils I came across a forum post which suggested SAE 140. I have been using an EP80W-90 but I'd rather get it right. What do you think?

Thanks,
Mark

 

[CHJ]

If 80-90 gear oil is good enough for a car differential I'm sure it will do for the light loads in a tool gearbox.

You are not after high performance, just something that will stay on the mating surfaces to prevent metal galling.

Most modern formula gear oils are a better performers than the older single viscosity spec. oils sold by tool firms under their own brands.

 

[Mark A]

Hi Chas,

Initially that was my thought too - if it's good enough for a diff etc.

However, with both my "Tarplaner" and "Ripsnorter" after flushing out the gearboxes with kerosene and refilling with fresh EP80W-90 I noticed some seepage pooling below them. This is what made me then think about using a more viscous oil, as the manufacturers intended.

Truth be told I'm trying to get out of replacing the gaskets...

Mark

 

[Shrubby]

To repair the gear housing degrease it thoroughly and build walls from plasticene to support the filler. Use a metal loaded epoxy like Devcon , Loctite or JB weld
Hold the part in a vice or prop it up on a sandbag at the right angle whilst it cures
Matt

 

[dickm]

Exactly what I was going to say, Shrubby!

W.r.t. to oil there used to be one called Hypoy which went into the diff housing of my elderly Volvos. Not sure what was the viscosity, but it might have been heavier than 80.

What do you see as the problem with replacing the gaskets, Mark? Material/shape/access? Gaskets are usually pretty straightforward.

 

[Mark A]

Hi chaps,

Thanks for the plastercine tip, that's handy to know!

Accessing the flange could be a bit tricky, however.

Here's some pictures of the gearbox housing.

(this is looking at the flange from behind)

Chas - The original gaskets aren't just rubber disks or rings. See pictures below

The smaller of the two is the perished gasket which fits into the recess behind the broken flange. Here's a close up

Mark

 

[Mark A]

Apologies for the rubbish pictures, it's the best my phone can do!

 

[CHJ]

I would not refer to those as Gaskets, they are shaft oil seals, some at least spring loaded and should have a knife edge inner face bore against the shaft to reduce friction and provide a positive pressure enhanced seal against oil leaking along the shaft.

You should be able to find replacements, possibly at a bearing suppliers or motor factors, it's years since I've rebuilt engines so am out of touch with sources. I know Simply Bearings have some.

 

[n0legs]

They're Radial Shaft Seals.
A good engineering supplies should have them, if not as stock but could be ordered.
I doubt whether instant gasket/sealer would work against a rotating part.
Well built machine though, I can't imagine many being built like that these days.
Good luck

 

[Mark A]

Proves just how little I know!

Just found this company which looks promising, and as luck would have it I'm driving past tomorrow (collecting a dinky Myford planer)

Cheers,
Mark

 

[CHJ]

When you refit any new seals of this type (or the old ones for that matter) make sure you replace them in the same orientation as originally fitted.
Their design is such as to increase the sealing force as face pressure is increased from heat/pressure expansion of the oil containing compartment.

Not so critical in a tool gearbox perhaps but it is best to make use of the 'self closing' aspect of the design where possible as wear takes place over time. (don't think that will be a problem in our lifetimes in this instance though )

 

[Mark A]

Hi Chas,

I dropped the oil seals at the place mentioned above and now it's just a case of waiting for a call to say if they can supply them or not. In the meantime I'll begin cleaning up a 40-odd pound beast of a circular saw (yes, another one!)

 

[dickm]

Ah, those seals take me back! Repairing/rebuilding all sorts of machinery, from garden stuff to classic Volvos. But much dirtier than woodwork!

 

[Mark A]

Hi chaps,

How can I clean the accumulated grime off the motor? The stator windings can hardly be seen beneath the layer of crud.

Bearing in mind this motor is almost 70 years old I don't want to use solvents in case it damages the varnish.

Thanks,
Mark

(I've changed the title of the thread since the gear issue is solved (hammer) )

 

[dickm]

First off, gentle physical removal with soft brush/plastic or wood spatulas? Then maybe some carefully applied washing up liquid, worked into the crud with the soft brush and then washed off with hottish water? Though it's quite possible that the insulation is shellac, which might not even take kindly to getting wet, and would certainly soften with most organic solvents (I think)

(you had me puzzled with the change of title for the thread - before doing that sort of thing, think of us slightly senile septuagenarians )

 

[Mark A]

Sorry 'bout that, Dick!

What then after brushing, washing and rinsing? Dry in oven and reapply varnish stuff?

I've seen electric contact cleaners recomended online and found these on the Maplins site. Some state they're safe for use on plastics. What do you think?

Thanks,
Mark

 

[CHJ]

I would not use any solvent based cleaner, as Dick says could well be shellac on the windings, it's what we commonly used in the days when we rewound soldered comutator Black & Deckers and similar small motors.
They were usually placed in a cool oven for a few hours when re-coated.

Might be a good idea to have a look at the comutator segments while you are at the cleaning stage, burnt/scored or carbon glaze across the segment gaps.
We invariably re-cut the insulation a few thou below the segment level (old hacksaw blade with ground hooked end)
But the above may be a step too far if you have never refurbished an armature before.

 

[Mark A]

Hi Chas,

As far as I can remember, the commutator is in pretty good shape. Just dirty like the rest of the motor.

Would I need to reapply shellac after cleaning and drying?

Thanks,
Mark