Drummond Tailstock

[BazyleParticipant @bazyle]

M-type tailstock barrel key

[BazyleParticipant @bazyle]

Some time in the last 90 years.

Able seaman Henry have you used the Drummond to make a new spindle for itself?
Yes Chief, nice and smooth down here at 20 fathoms below, but could only drill it 4 inches deep with the half inch drill.
What about the MT1 taper? oh never mind. How did you get 4 inch deep the tailstock only has 3 in travel?
No Chief, it does 4 in but was a bit stiff for the last inch. Just needed some extra force on the handwheel but they don't call me Heavy Handed Henry for nothing.

Conveniently for HH Henry the tailstock barrel is threaded externally so the anti rotation key was being forced through the threads giving space to squish the metal out of the way.

My question is about the key. On the outside it doesn't have a screwdriver slot; it just seems to be plain. Is it supposed to be a push fit? It might be held by having been partly smeared over on the inside. So I just want advice on whether I can push it inwards, or outwards without damage.

[David George 1Participant @davidgeorge1]

Hi Bazyle

I believe that it is screwed in from the outside and you can only remove it outwards. I will check in the morning but I believe that you can turn it with grips. You may have to cut a screwdriver slot on outside.

David

[David George 1Participant @davidgeorge1]

Here is drawing of spindle.

David

[not done it yetParticipant @notdoneityet]

I like the story, but when was the drilling depth ever limited by the tailstock travel? It would have been more spectacular if the drill used were only 1/2” long!

[BazyleParticipant @bazyle]

Thanks David. Your drawing shows the keyway extending into the threaded section where I have about 3 clean threads then about 6 beyond that which have been mashed. Interestingly before the damage the length of threaded section means the barrel can be retracted well inside the housing which I haven't seen in a lathe before. I imagine if the key is screwed in they didn't put a slot at the outside to avoid having people try to unscrew it and sheer off the key.

[BazyleParticipant @bazyle]

NDIY. I did wonder if anyone would pick up on that. However the cross slide is a little over 4 in wide which uses up some space. I will find out more about the practicalities one day when I do drill it right though (not 1/2 in of course).
Also before you mention it the time period would hopefully be somewhat less than its entire life and might have happened after it was demobbed probably in 1971.

[HopperParticipant @hopper]

Just had a look at my M-type and refreshed my memory from when I rebuilt the tailstock years ago.

There is a tiny 1/8" grub screw that holds that key in place. The grubscrew descends vertically down from the top of the tailstock casting, directly above the key. Original probably had a screwdriver slot in the grub screw, I replaced mine with a allen type grub screw, so must have been 1/8 BSW (or more likely UNC that will fit right in.)

Once you scrape the 25 layers of paint off the tailstock right above the key you should be able to see the grub screw and either screw it out or drill it out.

The the key can be tapped inwards until it falls out. Dont tap it outwards as the mashed end will score the hole in the tailstock.

The key is a piece of 1/4" round bar with the end machined down into a tang that fits into the slot in the tailstock quill. The tang is the width of the slot, minus a thou or so clearance, and it runs across the full width of the 1/4" diameter bar. I made mine by filing down the end of a piece of bar to suit.

Will try and take a pic with my phone and post it shortly.

[HopperParticipant @hopper]

Here's a pic showing the grub screw partly retracted for demonstration purposes. In use it sits flush and is well camouflaged by paint.

[HopperParticipant @hopper]

Her's what the key looks like in its unmashed condition. Disregard color – some weird lighting autocorrect thing. It's just a piece of silver steel bar, unhardened.

I don't know how Heavy Handed Herbert managed to drive the key through the very coarse threads on the tailstock quill with that tiny handwheel on the Drummond tailstock. I coiuld not even get enough purchase to comfortably drill small holes so I made and added two Myford-style crank handles as below.

The little divot on the rim of the handwheel is worth adding too. Previous owner did that with the tip of a drill bit. Acts as an index mark to count the turns of the wheel and thus depth of hole drilled. One turn = 1/8", half turn = 1/16", quarter = 1/32", eighth = 1/64" etc. Surprisingly accurate depthing is very easy.

[not done it yetParticipant @notdoneityet]

Not a Drummond, but my tailstock wheel has no handle, so I am aiming to change the wheel for one with a handle. Then easy to count revolutions using the handle as a datum – even though the tailstock is engraved/etched with distance markings.

[geoff walker 1Participant @geoffwalker1]

Bazyle,

You could use one of these. The pre war drummond longbeds had a much longer tailstock barrel presumably to compensate for the wider cross slide. I've been meaning to fit this to my post war Myford M but never seem to get round to it.

This is because I have a lever tail stock and it would require some mods to the linkage for me to really benefit from the extra barrel length.

Hopper, I remember Ed Maisey drilled holes around the circumference of his hand wheel and inserted short bar lengths so it resembled a ships capstan. Nice job on yours with the two crank handles. To me they look more like drummond cranks than myford cranks, more rounded on the end.

Geoff

[BazyleParticipant @bazyle]

Very clear photos Hopper. Thanks.

A longer barrel might be an option some day. Meanwhile I can't find the locking screw which might have been introduced after 1926 when mine was made. I also can't see a thread on the sidewall of the hole where it is visible inside. I think the key may have been pushed outwards a bit by its encounter so will try persuading it in a bit after a soak in release oil, file off the burs, then push it outwards.
The photo shows how the extra part of the slot was very slightly tilted off-centre.

By the way the picture colour doesn't show that the paint is a sort of washed-out greenish which seems to be the only layer, no grey or black underneath. I've seen this sort of colour on a few steam engines in museums so might be the original requested shade.

Edited By Bazyle on 04/11/2019 13:36:33

[HopperParticipant @hopper]

Ah yes Bazyle. Mine is a modern one, 1937, so maybe a bit different.

Still marvelling at Heavy Handed Harry's efforts. He must have had the four-foot Stillsons on the handwheel to do that, surely? And I wonder if your lathe's paint is ship's engine room colour?

Hi Geoff, I did not fancy Maisey's capstan version. Looked to me like you'd be forever catching sleeves etc on the spokes. And yes my crank handles are a copy of the Drummond cross slide handles so it looks as original as possible, just located in the ML7 etc position. They were an interesting project with my homemade ball turning tool adapted to turn the concave section. It's a great mod though. Totally got rid of my major niggle with the old girl. Been meaning to do the lever conversion for years though…

Edited By Hopper on 04/11/2019 21:56:16

[Howard LewisParticipant @howardlewis46836]

The ML4 that I helped sort out had a Tailstock Barrel that rotated.

Judging by the Handwheel Retaining Plates, Heavy Handed Henry had been using it.

Having removed and flattened the plates, found that the key was a 1/4 BSF slotted head screw, but the actual key was too fat for it to fit into the barrel.

After some filing and a few trial fits, the key was screwed in until it just did not jam against the bottom of the keyway in the barrel. Cue reassemble. The key cannot unscrew because the key/keyway prevents it rotating..

As J.S. would have said; job's a good 'un.

Howard

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