Change Wheels

[Julian GoodyearParticipant @juliangoodyear91963]

I have what I believe to be a set of change wheels.

 

They came with my ML7 when I bought it many(many, many) years ago.

 

But, now I have started to use the ML7 in earnest I found that the holes in the middle are too small. They measure approx. 0.5 inches.

Does anybody out there know what they could have come from.

 

I have now obtained a set of wheels for my ML7 so these smaller holed ones are now rather surplus.

 

Many thanks in advance,

 

Julian

[DC31kParticipant @dc31k]

You are being rather too thin on the information you provide. Telling us you have a gear-shaped object with a 1/2″ diameter hole in the middle does not help very much.

Tooth count, gear specification (DP/Module and pressure angle) or outside diameter plus any centre detail is required.

A gear with a completely plain bore can only rotate on a shaft. A gear with a keyway, a spline or other means of securing it to something is a lot more useful

[Julian GoodyearParticipant @juliangoodyear91963]

Many thanks for your response.

There are nine of them and they have:

56, 54, 52, 48, 46, 44, 36, 32 and 24 teeth. All have a keyway.

I’m not that confident on how I can ascertain the DP/ module or the pressure angle.

The teeth don’t mesh with the ones I use on my ML7.

Does this in anyway help?

[BazyleParticipant @bazyle]

Google DP to find out what it is which will tell you the missing piece of information to provide.

The tooth count suggests Boxford but their hole is 9/16″.

[Julian GoodyearParticipant @juliangoodyear91963]

Ta,

 

Will do

 

 

Julian

[Julian GoodyearParticipant @juliangoodyear91963]

Using the formula:

 

DP = No of teeth + 2)/ Outside diameter

I got 17.9998 on the 24 tooth gear

And 17.9799 on the 32 tooth gear

 

So I guess we’re looking at a DP of c. 18

 

Does this sound reasonable?

[DC31kParticipant @dc31k]

You can measure the outside diameter of the 54t one and tell us (or the 24t and 48t one, which should bear a 2:1 relationship). That will enable the DP to be calculated.

You will notice that in general the tooth count increases by four each time. If you look at your Myford ones, they generally increase by five each time. That can help a little to identify possiblities.

The thickness could also be useful to know.

[Julian GoodyearParticipant @juliangoodyear91963]

Yes.

Did the same calculation on the 48 tooth and I get 18.005…so: 18

The thickness is c. 3/8″

 

 

[Julian GoodyearParticipant @juliangoodyear91963]

The diameters are 1.445, 1.891 and 2.777 for the 24, 32 and 48 tooth gears respectively… by the way.

[Julian GoodyearParticipant @juliangoodyear91963]

Oh…and the 54 tooth is 3.1060″

[Howard LewisParticipant @howardlewis46836]

So you have some 18 DP gears with a 1/2″ bore (Obviously not for a Myford – which are 20 DP and 5/8″ bore)

Maybe someone can say what they would fit (If you quote the width), and offer a good home for them.

Howard

[Julian GoodyearParticipant @juliangoodyear91963]

Hi Howard,

How are you?

Yes, I’d like to know where they came from.

So perhaps I could get them somewhere where they can be used…instead of lurking in a drawer in my workshop.

 

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, they could quite possibly be for a mini lathe, but may need a bush to gang two together, or for single use. You say they are approximately 0.5″, which nay mean they are 12mm. So you need to say exactly what they are.

Regards Nick.

[Nicholas Farr]

On Nicholas Farr Said:

…they could quite possibly be for a mini lathe…

Please could you suggest a potential “mini lathe” that is made in a location that uses 18DP (i.e. imperial specification) gears.

It is good to read all the information and think a little about its implications.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi DC31k, I don’t know of any such lathe per se, and it was only a suggestion, but I guess most people think mini lathes are a modern thing, but my father’s old RandA lathe isn’t much different in size to my Chester Conquest one, and that has 20DP change wheels with a 5/8″ bore, and I think it’s only the term “Mini lathe” that is modern.

Regards Nick.

[BazyleParticipant @bazyle]

They are almost certainly Boxford/SouthBend.  Measure the bore accurately with a vernier calliper ( if you haven’t got one get a MANUAL one not a digital one as the batteries always run out).

Myford – 20DP. Randa and its many clones use Myford wheels with a tiny pin not key
Boxford – 18DP with keyway
Drummond – 14DP with larger pin

Mini lathes – 1 Module (Close to 26DP)
Bigger modern far eastern lathes often with a number like 1224 indicating sw-ng diameter and bed length 1.5 Module

 

[SillyOldDufferModerator @sillyoldduffer]

A photo might help Julian.  The more information the better please, there are many possibilities.  The excellent lathes.co.uk lists hundreds of lathe makers, many of whom sold several different models, with different gears.

Also possible that the gears aren’t change gears for a lathe.  Might be off another machine, collected in hope they could be adapted to add more ratios to your ML7, only to find the resulting threads are all non-standard!   Many workshops contain a few optimistic acquisitions that will baffle everyone after the purchaser has gone!

If your gears can’t be identified as belonging to a particular lathe, describe them accurately in full so potential buyers can judge how useful they are.   Not unusual for secondhand lathes to arrive with change-gears missing, so there are always folk looking for replacements.   Original gears being rare, they often modify the bore and keyway of similar gears to match their lathe, and a good description of the gear will confirm if that’s possible.

Dave

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I don’t know about other Boxford Lathes, but my Boxford CUD change wheels have 9/16″ bores.

Regards Nick.

[Nigel Graham 2Participant @nigelgraham2]

There are two clues to them being lathe change-wheels rather than, umm, just gears wot ‘appened to be in the box.

1) The tooth-count stamped or engraved on them.

2) Some means to key them to each other and to the spindle and lead-screw. That could be a keyway as on yours, or a small hole in the face, near the bore, to take a simple pin.

A third clue, but not infallible, is that their counts will increase by a single integer such as 5 per step; though there may be two of certain sizes, or some odd one to allow peculiar prime-number or metric pitches. (BSP thread for example, include 11tpi.)

 

This does give a further clue to finding if these are even lathe change-wheels anyway. It’s safe to assume if they are, and they are to Imperial dimensions, they were for a lathe made to Imperial dimensions (so British or American make) with a leadscrew 8 or, perhaps, 10tpi.

So see if improper-fractions of 2 of those numbers multiplied by 8 will give common thread pitches. E.g., the 24 and 48T wheels give [48/24] X 8 to produce a 16tpi thread. I tried others and very few gave integer values; but I did not try compound trains.

I wonder if these gears were not screw-cutting change-wheels in the ordinary way, but for something like a speed-change gear-box, gear-hobber or coil-winding machine.

…..

Even if you find orphaned gears whose pitches are the same as your Myford lathe’s change-wheels, I would recommend not using them unless you can be sure their pressure-angles are also the same. Mixing wheels of differing PAs can rapidly damage them because they will not mesh properly.

[Bazyle]

On Bazyle Said:

They are almost certainly Boxford/SouthBend.  Measure the bore accurately with a vernier calliper ( if you haven’t got one get a MANUAL one not a digital one as the batteries always run out).

Myford – 20DP. Randa and its many clones use Myford wheels with a tiny pin not key
Boxford – 18DP with keyway
Drummond – 14DP with larger pin

Mini lathes – 1 Module (Close to 26DP)
Bigger modern far eastern lathes often with a number like 1224 indicating sw-ng diameter and bed length 1.5 Module

 

I’ll just add they are not Raglan, either.  They were 16 or 14DP.

[Nigel Graham 2]

On Nigel Graham 2 Said:

…

This does give a further clue to finding if these are even lathe change-wheels anyway. …

So see if improper-fractions of 2 of those numbers multiplied by 8 will give common thread pitches. E.g., the 24 and 48T wheels give [48/24] X 8 to produce a 16tpi thread. I tried others and very few gave integer values; but I did not try compound trains.

I wonder if these gears were not screw-cutting change-wheels in the ordinary way, but for something like a speed-change gear-box, gear-hobber or coil-winding machine.

…..

 

Nigel’s hypothesis is that these aren’t change gears, and I agree with his reasoning.    To test the hypothesis I ran the compound permutations on a computer to see if any of the ratios produced by this gear set would produce metric, BA, or imperial threads. (Wrote a program for this years ago.)

My results say these gears cannot be combined in a way that would produce standard threads on any lathe.  Done correctly, maths is far more reliable than guesswork.

Unfortunately, I don’t entirely trust my gear program.  About 18 months ago I ‘improved’ and never fully retested it.  Whilst results are correct for my metric WM280, that doesn’t prove much.  Looking at the code today, the way I handle imperial lead-screw pitches is suspicious.  As I don’t have time to test it properly, is anyone else able to confirm Julian’s gears don’t make useful threads?   Or show that they do!

So far:

• Nothing physical confirms these are lathe change gears.  Gear features like bore size, keyways, DP, PA and width aren’t peculiar to lathes, and there are thousands of other machines with gears in them.
• The maths suggests these aren’t change gears because they don’t generate standard threads.

The case is still open.

Dave

 

 

[Michael GilliganParticipant @michaelgilligan61133]

I don’t have time to explore it further at the moment, but someone else might like to …

I’ve just put the following to ChatGPT

Gear Puzzle: 56, 54, 52, 48, 46, 44, 36, 32 and 24 teeth

and it gave a useful & conversational reply

 

MichaelG.

[halfnutParticipant @halfnut]

Fancy computer programs and ChatGP to the contrary,  Boxford use such 2 and 4 tooth increment counts. See chart below. Their imperial charts also use the same 2 and 4 tooth steps. Many many other old lathes used similar sets based on 2 an 4 tooth steps rather than Myford’s 5 tooth steps.

Perhaps twos and fours were the American way and crossed the pond with the Southbend from which the Boxford was copied?

 

[halfnutParticipant @halfnut]

[Author]

Posts