Help identify Changewheels

I have a set of 17 useful changewheels but don't know what lathe they came from. Can anyone identify them from the following description?

Bore 19mm thickness 9.5mm keyway 3mm wide by 1.5 deep. Tooth pitch about 3.5mm.

The gears have a slight chamfer on each side around the the tips and have a circular marking within which is stamped the letters DB GL. On some of the gears there is also a number stamped within the circle (eg2 or 7) but some have no number.

The smallest gear is 31T and has a an o/d of about 40mm, the largest is 127T and has an o/d of 136.5mm

other gears are 35, 39, 43, 45, 50, 52, 53, 59, 60, 70, 73 77, 81, and 100 T.

Hopefully someone will be able to attribute the gears based on dimensions or the DB GL marking.I can then try and find a buyer with the right lathe as it seems a shame to break the set up (in which case I would hold back a couple for my indexing head)

Have you quoted metric measurements as gospel, or might they be Imperial (more likely 3/4, 3/8, 1/8 and 24DP)?

Thanks for the comment NDIY - I agree 19mm looks a lot like 3/4" etc.

Given that these have been tucked away in the back of a cupbpoard for some years awaiting a worthwhile application and came with a host of miscellenous bits and pieces alongside my old Boxford lathe, they could well be from a lathe with imperial heritage. The presence of 100T and 127T suggest a metric leadscrew. (isn't 100/127 the required conversion gear to give imperial threads?)

John

127T is the required gear to give metric threads with an imperial leadscrew. The tooth counts you quote are not a standard set of changewheels for a Boxford with an imperial leadscrew though.

Thanks Clive, stand corrected on the conversion gear. (I thought my old Boxford had metric feedscrew and it had a 127 conversion gear with it - which I am told does not work on the VSL with imperial leadscrew but that might be tpo do with the ratios already within the screwcutting gearbox.

Yes these gears are very different from the Boxford ones which came with my lathe - the teeth on these are somewhat finer and shallower and the finish is better too which makes me think they might be off a toolroom lathe.

John

eI have just uploaded a couple of photos of the gears

You need 127 whichever way you are converting.

Since several are non standard values and they are smaller than most lathes wheels they are probably from some other machine that needs a greater diversity of variable feed such as a hobbing machine or even a chart recorder.

Are you sure it isn't DSGL?

I guess this is they?

Neil

Edited By Neil Wyatt on 29/03/2018 18:33:33

Hi Neil, no it is certainly DB GL.

Yes that is them advertised but if I cannot sell as a set i shall pull out the ones I was originally minded to keep for my indexing head and maybe a couple for use on a steam engine.

It just seems wrong to split up a set though if someone needs them for their lathe.

I also have a set of Atlas lathe changewheels (rather crude alloy gears) but don't know which model they come from either. I think they will end up scrapped as they are not really high enough quality to be worth putting on any other machine.

Bazyle - not sure why a chart recorder would need the 128 gear but can see that a hobbing machine might have used them.

John

Can you upload a picture of the logo?

Neil If you look at the photo of the single wheel in his album you can make out the logo. It looks like DB GL in a circle

Roy

I have cropped down the logo from the earlier photo as it wasn't very readily seen at thumbnail size. Now uploaded.

"127T and has an o/d of 136.5mm" sounds like 24DP (check my calculations, I majored in English at college) with 3/4" bore. Might help narrow it down. Not a common DP on the usual hobby lathes. But must fit something out there somewhere. Maybe Tony at lathes.co.uk could give you a clue?

If they were lathe change wheels for imperial threads they would need to go in steps of a fixed number of teeth, usually four or five. So either some are missing or they are not for Imperial threads. On the other hand, while metric threads are not really designed for convenient screwcutting, I don't think they would normally require quite so many odd wheels. So I suspect they were for something other than a lathe.

John

Yes, an odd bunch of sizes to be sure. Not the usual steps of five or four teeth at a time. Yet, the 127 tooth suggests a metric/imperial conversion gear as used on lathes.

Could DBGL stand for David Brown Gears Limited - the worlds premier industrial gear manufacturer for everything from tractors to massive marine turbine reduction gears etc? So could well be industrial gears rather than lathe.

Thanks Hopper - that sounds like a lead worth pursuing - I hadn't heard of them before (yes I have lead a sheltered life!)

J

If I might chip in:

Coil-winding machines have change-wheels. They are set up to control the pitch of the winding as the former rotates under the wire feed. In a transformer, the pitch is such as to lay successive turns in contact. In a 'wave-wound' coil for radio purposes, the pitch is greater. There is usually a trip mechanism to control the width of each layer of the winding, reversing the feed when the edge of the winding is reached.

These change-wheels are usually smaller than those used on hobby lathes - 24 DP doesn't sound unreasonable.

See the following:  https://archive.org/details/AvoDouglasCoilWindingMachinesManual 

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 30/03/2018 10:29:10

Could be someone's personal mark?

Neatly done though.

Neil

How about a gear hobber? That might tie in with David Brown.

Rod