Upgrading Drummond spindle

Good morning all:

I am a member of both the Drummond and Myford Yahoo groups, so anyone else who is will probably be already acquainted with this topic.

I am currently considering upgrading my Drummond M spindle from the lean 1MT provision to ML7 thread + 2MT socket.

Has anyone else done this? I would be interested to hear of your exploits.

Also - in and around November 1960 to January 1961, a certain Mr Jennings rote a 5 part article about his upgrade of a Drummond Admiralty model, using his other one!

I guess he is no longer with us, but did anyone know him?

Mike

Mike

It wasn't a Drummond, but that's probably of no importance

Way back ... I did something similar:

I made a screw-on boss for the existing nose and fixed that in place; then [in situ] turned a vee groove at the joint line. ... Then dismantled the lathe and took the spindle to be mig-welded ... reassembled the lathe and finished the machining of the new nose.

Stepping things forward just a little did help make room for the 2MT socket without weakening the spindly spindle.

MichaelG.

Michael:

My thought is not to go the whole hog and enlarge the spindle, bearings and bored as Mr Jennings did, but merely to make a larger nose register and thread.

A slight enlargement of the front journal can be accommodated - just - apparently, so that’s my course of action once the weather gets a bit warmer.

Mike

It's a huge job and an interesting project but considering the amount of work involved I would just go out and buy a Boxford

The spindle is the "easy bit"

Absolutely everything has to be upscaled to back it up, a new pulley would need to be cast etc

A 1 inch bore would need what? a 2 inch spindle?

Myford have a big bore so that could give you the basic dimensions

Probably easier to adapt and bolt an atlas 10 inch headstock to a drummond bed

But even the mighty atlas 10 inch only has a 25/32" bore

.

Which is what I did ['though the exact details are a fading memory]

I just shifted the register face a little [towards the tailstock] to avoid weakening the spindle by enlarging its MT size.

May I suggest that you first draw a sectional view of the current arrangement, and overlay 2MT, to identify any potential weakening.

MichaelG.

You could probably squeeze a 2MT into the existing spindle

Then use an adaptor for fitting Myford bits

There is a pdf drawing on the Yahoo Drummond files section for an M spindle. Scaling that on my screen to be lifesize I held a M2 taper over it and there is room for 3 inches of depth so may need to look at the thin end.

For anyone wanting to try drawing their own the critical dimensions are: Nose 1in threaded x 0.5 in long, register 1.125 x 0.375 long, then flange 1.49 x 0.28 long, then journal 1in x 1.833 long. After that it gets a bit tight at 0.873 dia which needs to have the pulley keyway so you could modify this bit to give half an inch of extra length.