Drummond pre-B type bearings. Renewal time.

[GaunlessParticipant @gaunless]

Hi all.

I’m in need of new spindle bearings for my 1908 Drummond pre-B type lathe.

I think these may be beyond my current capability to make. Has anyone done this job, and if so, how did you proceed?

Cheers

 

Stew.

[Nigel Graham 2Participant @nigelgraham2]

I once owned one of these lathes but my memory of its details are hazy. I’ve also similar problems with refurbishing my dear little EW lathe, smaller and simpler than the Drummonds.

Nevertheless, are the bearings plain bronze bushes pressed into the casting? If so…

 

1) Investigate sintered bronze equivalents, made as standard commercial items. (“Oilite” is perhaps the best-known make; most transmission-parts stockists sell them, e.g. HPC Gears, or Bearing Boys.) The lubricant is an ordinary, light oil.

Note though that these cannot be machined, or not easily. Attempting to modify the bore will damage its lubricating abilities. Holding it safely without distortion or cracking would be problematical, and the material is quite brittle.

This may not work if the spindle itself is significantly worn. In that case it may best ground to suit the nearest smaller available bushes – which might need be metric (quelle horreur!) to minimise the reduction. This may also introduce difficulties of its own, with the diameters of the areas of shaft that hold the pulley, back-gears and change-wheel driver pinion.

…

2) You could probably make new bushes on the same lathe, with care!

Dismantle the lathe to measure everything.

Make a plug-gauge – brass, mild-steel or aluminium – to test the new bushes’ bores.

Use leaded-bronze; machine the outer and inner diameters without removing the material from the chuck so they are truly concentric; take light cuts to avoid problems from the wear making the chuck “jump” (you can see that happening if the wear is heavy).

 

[old martParticipant @oldmart]

Using a reamer to adjust Oilite bearings will smear the sintered grains and close up most of the pores which allow the oil to do its job. Boring with a sharp tool is the only method recommended by the manufacturers, not closing the pores to anywhere the same extent. If you can get some oilite, it would be worth getting a spare set to store for the future. aAs Nigel mentions, holding Oilite bushes without damage would be difficult, I would use a four jaw chuck or soft jaws and hold lightly.

[GaunlessParticipant @gaunless]

Hi Guys.

The bearings in question look like this (pic used courtesy of lathes.co.uk).

[old martParticipant @oldmart]

There is a small ammount of adjustability built in courtesy of the split has that all been used up? It might be possible to give the bearings a second life by several hacksaw cuts around the OD going 3/4 of the thickness, and filing the existing cut wider. This would allow the bore to shrink slightly.

[SillyOldDufferModerator @sillyoldduffer]

I’d be inclined to have a go at making new ones.   Apologies if I’ve missed something tricky, but the bearing looks fiddly rather than outright difficult.    Looks like a good middling-challenge to learn on!   One of the best things about owning a lathe is they can make their own spare parts.

I can describe how I would do it in outline, first step would be an accurate dimensioned drawing.  Which part of the job seems scary to you Stew?   The forum has many skilled machinists on tap.

This forum is annoying!  When I started typing at about 13:15, Nigel’s post of 10:54 wasn’t visible.  Now it is.   Had I not noticed, I’d have hit the send button, making it look as if I’d either stolen Nigel’s idea or ignored his post!

The main difference between me and Nigel is I wouldn’t bother with Leaded Bronze even though it’s the better option.  I’d make it in Brass, because I have some!  Won’t last as well as Bronze, but do we need a 1906 Drummond to last another century?

Dave

 

 

 

[old martParticipant @oldmart]

I always try the easiest option first and if that doesn’t work well then go for a more sophisticated solution. You can get thick walled leaded gunmetal cheaper than solid, and there might be a size that suits the lathe if the hole is smaller than the rear bearing bore.

The Smart & Brown model  has similar design bearings which are cut to look like er collets for adjustability.

[cogdobblerParticipant @cogdobbler]

What has led you to the conclusion these bearings are worn out?

Are they pushing so far into the taper the slit is closing up metal-to-metal? Or that the small end of the bearing is pushing up against something?

In either case, removal of metal from the slit or the small end  should remedy it. You might have to make up spacer rings to go under those existing rings so the bearings get pushed further into the taper now.

[BazyleParticipant @bazyle]

Further to above post note the conical oil hole. There might be an oiler bush fitted with a conical end to push the bearing open so check that.

[GaunlessParticipant @gaunless]

Hi chaps. Yup, the slit in the bearing is pretty much closed when all play is removed by tightening the two screws to draw in the bearing. The screws have to be pretty darn tight, so I think we’re at the end of bearing life. The suggestion to widen the slit (ooer) may hold the reaper at bay for a bit.

My concern is not that I can’t make a set of bearings, It looks to be quite possible, but the order of operations in order to produce accuracy is my main issue. How to make the things on a lathe with the minimum of faff.

It’s obviously an ancient machine, but I would like to use it for some basic operations, so I’d like it to be reasonably accurate. It’s never been motorised, it’s on the original treadle, so I can still play if the power goes out..

I get a lot of pleasure from cleaning up and tinkering with old machines.

Out of interest, take a look at ‘Find Hansen’ on YouTube. A Danish chap who uses his similarly ancient lathe to make worm gears for his miniature diesel engines. Watching and listening to him is very relaxing!

[old martParticipant @oldmart]

You can certainly use the lathe to make better bearings, nothing should be critical. Measure the bearings first, don’t forget the taper will work even if it is not exact, and the new bore will be concentric with it. After measuring, you should try the tricks of getting the bushes to close up a little before making the new bearings out of brass or gunmetal, they both turn nicely. Somebody may come up with some drawings if you are lucky. It may pay to clean up the spindle before boring the replacements.

[Martin of WickParticipant @martinofwick]

Try widening the slot with a hacksaw and clean up with emery, otherwise plan B is make some…

….It looks to be quite possible, but the order of operations in order to produce accuracy is my main issue. How to make the things on a lathe with the minimum of faff….

Welcome to the world of precision engineering. Perfectly possible, simple even, unfortunately to accomplish you will have to expend some effort exercising the organ with which you think you think to plan the job sequence.

But after all, that is why most of us do this hobby. The actual cutting of the metal is usually trivial, messy and rather boring, (which is why CNC is such a hit).

 

[GaunlessParticipant @gaunless]

I totally take on board those comments. Thank you for your time spent in replying. I will have a go and see how I get on. My spare time is cheap at the moment, and materials cost is trivial. I like a challenge, and yes, the brain exercise is part of the reason I got into this hobby.

The lathe was cheap, the challenge was there, so why not. I wonder how the Drummond factory chaps did it? And what they used? To be honest, having taken the rest of the lathe apart to it’s bare bones, it strikes me as more ‘blacksmith’ than any kind of precision engineering. Relying on the skill of the operator, rather than the precision of the machine.

Stew.

[Martin of WickParticipant @martinofwick]

it strikes me as more ‘blacksmith’ than any kind of precision engineering. Relying on the skill of the operator, rather than the precision of the machine.

A hundred years ago that was the reality – relatively crude machinery by todays standards, highly skilled workers, operating by hand and brain, as they say. Sort of the exact opposite of practice today.

Individual finances differ and will depend on component size but not sure the cost will be trivial exactly, especially if you want to use bronze. I think brass would be better anyway as the spindle will not be hardened steel, but pricy enough even in brass. Was going to suggest doing a trial pair in Delrin as prototypes and to refine your workflow (saves buggering up a big lump of brass, not suggesting you will or casting nasturtiums etc.  but just sayin’… shit happens!).

In case you haven’t been..   https://groups.io › drummondlathe   may be useful.

 

 

 

 

[David George 1Participant @davidgeorge1]

I have made new bearings for an M type Drummond lathe. You should make them from Phosphor bronze as brass will wear in no time at all. You should strip and check the spindle for wear and measure the lengths and diamiters of both ends of the taper before finnishing turning. You should only cut the slot through with a slotting saw after finnishing turning etc. I make a expanding mandrell which i finnish to size of the bore in the chuck before finnishing the outside to size and taper to match the headstock to ensure it runns true.

Pictures of my bearings which although tapered on the outside work diferantly.

Tighten the screw which has a taper on the head expands the mandrill which has a similar angle in the end.

David

 

[BazyleParticipant @bazyle]

A passing thought. How much gap was there initially and hence what range did they think it would wear over in the bearing’s life. Assuming the initial bearing diameter was an imperial round figure it will be interesting to hear what the current diameter is.

My guess  the gap was about 1/16″ or 3/32″(nice imperial slitting saw) and it has gone down by 1/16″ or 60 thou. So around 20 thou on diameter. Would it be viable to fill the bore out with a strip of brass shim?

[duncan webster 1Participant @duncanwebster1]

With unhardened mandrel you’d be better using leaded bronze. It’s easier to machine as well, and you can get it cored, which is cheaper

[Nigel Graham 2Participant @nigelgraham2]

My thought too.

Mild steel running in phosphor-bronze tends to transfer the wear to the shaft rather than bearing.

Plain brass would probably be fine for this application, too, if kept well lubricated.

[David George 1Participant @davidgeorge1]

Steel manufacturing was at a higher state mainly because of arms and motor vehicles manufacturers, the use of special steels were at a higher use than thought.

The spindle on most lathes was probably made from EN24T which was around in the mid to late 1800’s but under a different name by many steel manufacturers.

Manufacturer
Brand name for their nickel chrome moly steel EN24

B Huntsman Ltd                                    NCM1
Samuel Osborn Ltd                               NF
A Balfour & Co Ltd                                SD20
Richard W Carr Ltd                               Plutonic553
English Steel Coprpration Ltd             PLMB/1
Thomas Firth Ltd                                  NCM1
Samuel Fox & Co Ltd                            FOX171
Hall & Pickles Ltd                                  Versatile
Jonas & Colvar Ltd                                SGWI
Jessop Saville Ltd                                 G5 Special
Sanderson Brothers & Newbold Ltd    Sanbold 21
Kayser Ellison Ltd                                   KE805
Watson Saville & Co Ltd                         CNC0H3
Spear & Jackson Ltd                              Spear 524

I had the old spindle for my M Type lathe checked, before making a new one, by a steel supplier I used whilst at work and although 40 years younger it was EN24T steel. It is most likely that such parts were made from a higher grade of steel.

David

 

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