Think about it. The lathe is very likely less than 500W.

How much of that available power is used by the lead screw drive?

Can you drill a hole without breaking a drill bit of that size?

Is that short pin, in shear more, or less, likely to break than a long drill bit, of similar size, waving around?

Do you have the skill to drill a small hole in these change wheels, at the appropriate position, bearing in mind that they all line up at the same distance from the centre line?

The answers to those questions may well lead you to the correct conclusion – as to whether the pin-drives are a cheap and practical drive option.

Edited By not done it yet on 16/05/2022 07:23:56

A reminder that the original Drummond/Myford pins were tapered and only fit from one side.

I would be tempted to not do this with your new pins but use parallel pins held in place with loctite or similar.

My Raglan LJ used pins to connect together change wheel combinations. Those I made, as I recall, were drilled only part way through at the pin size, so there was no chance that they could ‘fall out’.

I Also took the obvious precaution of completing the hole at a slightly smaller diameter, to enable easy removal of the pin, if required.

Pins were (sensibly?) derived from the appropriate sized shank of cheap/blunt/broken drills.

These pins have worked perfectly adequately for the last several decades. KISS Principle in operation, as usual, I expect. That, or the age-old adage “If it ain’t broke, why ‘fix’ it?” applies.

When I helped a chap to get his ML4 up and running, one of the things that was needed was another 60T gear.

The only one available was from a ML7.

One of the existing gears was mounted on a stud and drill through to act as a jig for drilling the 3/32" hole into the 60T gear, opposite the keyway..

Once this was done, by using 20T gears as drivers, it was possible to arrange a fine feed, 20:60 / 20:65 / 20:60

The 20:65 intermediate Idler ensured that there was no clash between the 20:60 compound meshes..

With the 8 tpi Leadscrew, this gave a mechanical feed rate of about 0.004" per rev. This provides quite a good surface finish on finishing cuts.

Howard

Apologies – I was thinking of the Myford M-Type (a Drummond design) and not the ML series – but why might you ever need to remove a pin? – I thought each wheel had two holes in it one with the pin fixed in and another empty for the pin of another wheel to fit into when compounding.

I have converted some keyed gears to the Drummond-style tapered pins on a number of gears that came in a box with the Drummond lathe. No problems at all. Just used an existing pinned gear as a drill guide. Never found the need to remove a pin. They stack easily because each gear has a pin and a hole set at 180 degrees so they fit together. For an idler gear, I always put another gear on the stud with it as a spacer anyway.

Making my own tapered pins was an interesting exercise but they worked well, as I had the correct reamer in the box with the gears. (And I even domed the ends in the proper way!) That said, parallel pins and Loctite is defo the easier way to go! And less likely to cause cracking in the very small 20 tooth gear where there is not much "meat" and the tapered pin can wreak havoc if tapped in too hard.