My spur gears need a larger bore

[Simon HorsmanParticipant @simonhorsman68912]

[Simon HorsmanParticipant @simonhorsman68912]

Good morning,

This is a great resource and I'm looking forward – as a first time poster – to learning from it. I'm just wondering if one of you could help me out for the price of a bottle of wine.

I'm restoring a vintage radio set (Beomaster 1400). To add some heft to the dial tuning function it uses a small gearbox to drive a flywheel. The original two cogs have completely disintegrated.

I have sourced two spur gears (0.5 Mod 20T and 45T, the smaller of which is in brass, the larger Delrin). Unfortunately the bores are too small for my two axles.

Could anybody help me out by enlarging the smaller cog bore from 3mm to 4mm and the larger one from 5mm to 6mm?

The runout on my bench drill makes this operation impossible and I don't yet have a mini lathe.

The RS Component numbers are 5032052 and 5217124 if you want an idea of what's involved.

It would be great if one of you could solve this for me. I could post them with a tenner and a SAE.

Cheers,

Simon

[not done it yetParticipant @notdoneityet]

I wouldn’t do it for a tenner. Not even for a fiver!🙂. It’s a hobby forum.

Hope someone makes a better offer.🙂

[John BaronParticipant @johnbaron31275]

I agree ! Though I wouldn't refuse the bottle of wine

Where in the country are you simon ?

[Brian HParticipant @brianh50089]

Hello Simon, given that it is a vintage radio, are you sure that the shafts are metric?

Brian

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian H on 31/01/2020 08:35:50:

Hello Simon, given that it is a vintage radio, are you sure that the shafts are metric?

Brian

.

According to Wikipedia: Denmark introduced the metric system in 1907

… so, it does seem very likely.

MichaelG.

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[Simon HorsmanParticipant @simonhorsman68912]

Thanks for all your replies.

No wish to offend by offering cash, but posting a bottle of wine doesn't always end well.

I'm in South London/Croydon borders so could travel locally.

Cheers,

Simon

[Neil WyattModerator @neilwyatt]

If people don't want to accept payment for a job (or gift of bits etc.) I always suggest making a charitable donation.

Neil

[Howard LewisParticipant @howardlewis46836]

Presumably, you are not in position to be able to measure the shaft diameters, accurately; nor to enlarge the bores yourself.

This is not a "Can you just?" job. It requires some skill, and a lathe, to do properly.

The first task is to make a collet, specifically for each gear, and split it so that it can be gripped when the chuck jaws are tightened.

Then, when held accurately, can enlarging the bore begin.

The first job will be open up the bore of the gear, gently, with one or more drills (Taking into account the small grip available for the gears) followed by boring or reaming. A boring tool, is likely to need to be small,.

So, all in all, quite possible, but not a ten minute job.

More likely to be done for interest than financial gain, in terms of hourly rate.

Commercially, the labour would cost far more than the gears, I suspect!

Howard

[David NobleParticipant @davidnoble71990]

Hello Simon,

If you haven't had any takers yet, send me a pm and I'll do them for you

David

Edited By David Noble on 31/01/2020 12:31:37

[Simon HorsmanParticipant @simonhorsman68912]

Thanks to you all for your replies.

Having had a closer look at this, I can see that it's not as straightforward as I had thought.

There are two brass axles and mounting the larger gear is easy enough after the bore is drilled out.

The other axle which is pressed onto the flywheel presents a problem in that the gear has to be mounted from the flywheel side as there is a 0.5mm raised lip on t'other side over which the bored out gear won't fit.

I dare say the flywheel shaft could be drifted/drilled out of the flywheel – though it might be easier to turn a new shaft rather than bore out the gear.

One bottle of wine is looking rather cheap now, though I'm as happy to donate to charity.

Simon

[larry phelan 1Participant @larryphelan1]

Simon,

I doubt if you will be left waiting for too long for a dig-out.

This is what this forum is all about, and I don't think money is the name of the game !

If it was,I would be way-way out of pocket for all the advice and help I have received.

I am not near you, but rest assured, someone else is and will be willing to help

Have faith !!

[Simon HorsmanParticipant @simonhorsman68912]

Please disregard my previous post.

The axle tapped out of flywheel easily enough, so my need is only to enlarge gear bores as per original request.

Simon

[Former MemberParticipant @formermember19781]

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[Simon HorsmanParticipant @simonhorsman68912]

Bill,

Indeed, and I am touch with one of them.

Many thanks.

Simon

[not done it yetParticipant @notdoneityet]

This is not a "Can you just?" job. It requires some skill, and a lathe, to do properly.

Howard,

Would not simply fitting a 3mm dowel pin in the ER collet and gear, holding down the object on the mill table, exchanging the pin for a 4 mm end mill and enlarging the hole at that settingbbe a sufficiently accurate method to adopt?

That would be my approach to the job. Where would I be going wrong?

[not done it yetParticipant @notdoneityet]

This is not a "Can you just?" job. It requires some skill, and a lathe, to do properly.

Howard,

Would not simply fitting a 3mm dowel pin in the ER collet and gear, holding down the object on the mill table, exchanging the pin for a 4 mm end mill and enlarging the hole at that setting be a sufficiently accurate method to adopt?

That would be my approach to the job. Where would I be going wrong?

Edited By not done it yet on 31/01/2020 19:26:57

[Former MemberParticipant @formermember19781]

[This posting has been removed]

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