Drummond M type drive and parts query

Hi,

I have a 1936 M Type which I am commissioning. Due to being a treddle machine it appears to have been used very lightly.

I have three immediate queries:

1. Having made up a new clipped balata belt I found the clip was snagging on the flywheel journals and traversing up to the next ring. I adjusted the edge of the clip which fixed it.

I then treddled to test the operation and foolishly engaged the back gear. The bull gear was disengaged, but the shock was enough to break a tooth off the spindle gear and a few off the back gear.

I'm furious with myself, but that doesn't change the fact it is broken.

Does anyone have a back gear and drive gear, to sell, alternatively, has anyone repaired these gears by either letting a tooth in, or welding them up and cutting new teeth?

Can the drive gear be removed from the drive pulley, it appears fixed, but not cast as a single item.

Second query.

I was going to use a treadmill motor to drive the machine, but due to curfew, the treadmill is now in use for it's intended purpose, so intend to use the1425rpm, 1/2hp AC motor I have.

My intention is to drive the original flywheel, probably by the outer ring, but as this flywheel is for a treddle, it has no machining on the outer flange.

The options appear to be to use a flat belt with guides for tracking, or cut a channel in the outer ring...or indeed a ring gear and make it a knee planer.

Is the outer journal crowned and would a flat belt run centrally, without any machining?

Would the flywheel need to be rebalanced if the treddle is removed?

The motor will need a 2" pulley/gear for the speed to be correct. I want to motor to be underslung as space is a premium, but also feel the flywheel will damp any single phase vibrations

Thirdly, if using the smallest flywheel drive pulley to the largest spindle pulley, should one use a second, shorter, flat drive belt, as the length is considerably different.

I could shorten the belt I have made and add a link belt to make it the longer length.

I am a DIY car repairs enthusiast with general fabrication equipment (grinders, welders), but don't have an engineering workshop, so cannt perform my own machining of the gears at present.

Sorry for the long post.

Shock? Whether engaging, or disengaging, Back gear, the machine should have been stationary, surely.?

When you motorise the machine, do disengage the treadle drive. You don't want to have a foot trapped under the treadle while it is moving up and downat a hundred or more times a minute!

When you get it sorted, you will have a lot of enjoyment from the machine.

Howard

Rule 1 before you start your Drummond. Always do 1 revolution by hand by moving the chuck

Always

Onto the next bit. Welding may be possible, if you have the welding skills

Build it up and file down by hand or with an angle grinder

Alternatively, make a new one, which is a major operation for a new user

**LINK**

You can probably buy a used back gear etc. There still seem to be parts around.

The main source used to be a Drumondlathes group on Yahoo groups but I believe Yahoo shut all the groups down. I believe it may have be migrated to here link

The old group used to have a very useful FILE section too, full of valuable M type info. I havent got around to joining the new group but assume its still all there somewhere.

Also there is a Facebook page for Drummond/Myford lathes that might be worth a look. And parts do come up regularly on eBay UK.

Welcome to the forum. There are a few of us M type owners on here. I think you are the lone treadler though. Sounds like a classic machine.

Edited By Hopper on 23/04/2020 02:02:58

The groups.io Drummond group Hopper linked is one of the most active I subscribe to . Often 2 or 3 posts a day.

Hi..I understand the spindle should be stationery when engaging the back gear, but having just built up the back gear components, it was on my mind and I foolishly flicked the lever round..

Edited By Dieselman on 24/04/2020 09:51:55

I don't have either the skills or equipment for casting a new one and believe a repair is possible as it's only the smaller (22t) gears teeth that are broken.

I have arc welded some material onto the hub and intend to look into a repair.

The options appear to be use freehand tools, or buy a gear cutter and make a suitable boring bar to use in the chuck, whilst the gear is held stationery on the toolpost/saddle. I believe the gears are 14DP.

It may be cheaper to obtain a replacement, or have it machined.

Hopper and Bayzle.

Thanks for the link to the new group, indeed the yahoo group has gone.

I have a pending registration for the Fb group...maybe I need a Union card, or something...

I will look out for a replacement back gear, but am more concerned regarding the spindle pulley gear, as I cant see how it can be removed, and the teeth butt upto the pulley, so restrict access.

It could be machined with a dovetail cutter and a pre-machined tooth slid in from the end, then affixed.

Edited By Dieselman on 24/04/2020 10:06:01

Hi Dieselman, you always adopt this idea from John Stevenson's Bodgers Lodge threads.

John Stevenson

Regards Nick.

Many years ago I brazed up a new tooth for a motorcycle gearbox where one was broken off. I filed it to rough shape and it worked for the time I had the cycle but the tooth shape wasn't perfect and it made a ticking noise. It was still working when the motorcycle was stolen.

Not sure either. I never had to remove mine. Had the pulleys and gear off to replace the belt but all as one unit.

There is a manual online with a cross section of the headstock on page 6 here LINK

Looks like the pulley unit and the gear are pressed on to a sleeve which then slides on over the main spindle. Check for a grub screw holding that gear in place. You may have to drive the sleeve out of the pulley unit, taking the gear with it. Not sure.

You may be able to buy the whole pulley unit with gear on the groups.io group or eBay.

There was also a number of articles in Model Engineer over the years on restoring M types with lots of useful info. If you search the online index for Drummond you should find them. Those articles used to be in the FILES section of the old group on Yahoo so you will have to scope around and find out if they are set up on the new groups.io group. Or someone there may have copies.

I bunged all my headstock photies in here in case anyone might find them useful

There is also some headstock setup information here

Edited By Ady1 on 24/04/2020 14:08:03

Thanks to all that have responded.

I do have the Drummond manual and on had only had a cursory look at the headstock setup.

When looking at the pulley shaft it appeared to be be a single shaft, with a flange on the Bull gear end, inside the large pulley.

On looking closely at the illustation, it appears to be a split shaft, pressed in from both ends. The bull gear end is probably  a centering journal for teh Bull gear.

The oil screw is just that, just to block the oiling port.

I'll have another look. I'm waiting on some new 1/8" balls for the thrust bearing..I only found 11 out of 16...

Edited By Dieselman on 24/04/2020 15:10:15

That is my backstop option. Turn the gear down and either fit a steel/iron blank, or gear. Using a hobbing tool to turn the blank is the obvious choice.

If doing a single or a few teeth, I would go for making a holder for the gear, that advances it a single tooth at a time, as I don't have dividing head.

I need to get the machine up and running first, to be able to use it to make it's own parts.  The Salamander lathe...

Firstly, I'll make a plastic mould to use as a guage and have a go at hand forming a tooth.

Edited By Dieselman on 24/04/2020 15:19:07

I'll have another look. I'm waiting on some new 1/8" balls for the thrust bearing..I only found 11 out of 16...

Hi diesel

You can buy a complete replacement thrust bearing from "simplybearings", fits perfect, stock number is FT 3/4.

Go to thrust bearings, search 3/4" bore and it will come up.

I would suggest that you go "V" drive with your headstock. Easy to do IF...... you can pick up a later drive pulley from a Myford built M type. Sadly easier said than done, but if you can get one it is a direct replacement for the Drummond cone flat belt drive pulleys.

Get a copy of Lawrence Spareys the Amateurs Lathe. There is a good chapter on setting up a lathe for motor drive. A good example is for a Drummond B type on a Drummond stand, same as your stand and a similar lathe. It's an easy set up which does not require specific engineering skills, easily built by a good mechanic.

Stick with it you have a great lathe, worth persevering.

Geoff

I think the teeth may be cut into the inner sleeve itself.

In looking at the link I noticed the weight - 1cwt 2qr and with treadle 4cwt 1qr 14lb. So the flywheel weights a fair bit and it is interesting that they didn't just give the weight in lbs or stone.

The V belt pulley conversion Geoff suggested while you are at it is a good idea. Otherwise, if you have to stick with the flat pulleys, a modern Poly-V "Serpentine" belt works very well, run with the V grooves in contact with the pulley. Much better than the old flat belts gripwise and never seems to stretch.

To come back on this.
I drew the gear and shaft partially out of the belt pulleys using a bush puller, which was a lot easier than I expected, which indicates the interference fit can't be supplying much load.
I then made a profile guage out of HDPE, ground back the single damaged tooth on the drive gear and welded it up with arc rod. Welding in very small steps, peening, de-slagging and wire brushing before the next weld. The weld apepars to have bonded perfectly. After grinding and filing that tooth it is nearly perfect. I drew the shaft back into the pulleys.

For the back gear, I have welded it similarly and cut the gear teeth. I've not made quite as good a job of the profiling, but the teeth fit and clear well.
Time and working this under load will tell if this repair has been successful, long term. Ideally, I will either cut new teeth, or gear, or replace the back gear.

The back gear guard was broken, so I have welded that too. The metal appeared more granular in this part, but the weld is strong. Once I ground into the gear bosses, the metal appeared to have a more steel like structure, not granular like cast iron.

Next query...
Can anyone please confirm the size of nut used to hold the spindle thread cutting gear on. It appears to be 5/8", but with 16 tpi, not 14 tpi, which would be BSF.



Does anyone have the required back gear and spindle nut and a single back gear guard screw to sell?

Hi Dieselman, the thread on my M type is 5/8", 18tpi, which agrees with the drawing in the files section of the [email protected] group. That thread is a bit of an odd ball to find on an old British lathe as it doesn't fit with the normal BSW or BSF series, but it is a recognised thread BSC - where the C stands for CONDUIT! T^he other near common thread of that size today is the 5/8UNF which is 18tpi but with a 60deg angle rather than the 55 deg of BSW or BSF. I've just tried a 5/8UNF tap in the spindle nut off my M type and it goes in easy with just fingers most of the way but starts to bind up just as it's about to reappear on the other side. I tried the tap through both ways and it was the same, so it isn't a burr causing the problem so I'm guessing it's the mismatch of thread angles and the nut and spindle are 55deg rather than the UNF 60deg.

If you look on the [email protected] website you'll see a section called files. On the second page of folders, fourth from the top is a folder with 34 documents in it, it's called "M-type arts drawings", most of the bits for the lathe are in there so you can see if anything has been damaged or modified. The archives on there are supposed to be viewable by anyone so you should be able to access them easily. If you can't send an e-mail to the group moderator to chase up your membership.