Upgrading Drummond spindle

This topic has 7 replies, 4 voices, and was last updated 5 January 2019 at 11:01 by Bazyle.

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5 January 2019 at 08:22 #389438
Mike Waldron
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@mikewaldron61652
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
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5 January 2019 at 08:22 #19195
Mike Waldron
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@mikewaldron61652
5 January 2019 at 08:44 #389443
Michael Gilligan
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@michaelgilligan61133
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.
5 January 2019 at 09:07 #389447
Mike Waldron
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@mikewaldron61652
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
5 January 2019 at 09:35 #389449
Ady1
Participant
@ady1
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
5 January 2019 at 09:48 #389450
Michael Gilligan
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@michaelgilligan61133
Posted by Mike Waldron on 05/01/2019 09:07:25:

Michael:

My thought is … merely to make a larger nose register and thread.

.

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.
5 January 2019 at 10:09 #389455
Ady1
Participant
@ady1
You could probably squeeze a 2MT into the existing spindle

Then use an adaptor for fitting Myford bits
5 January 2019 at 11:01 #389481
Bazyle
Participant
@bazyle
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.
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