Member postings for Peter Cook 6

Thanks,

Bernard - the next project is a screw cutting follower based on the one described by Keith Brooke (A Thread Cutting Attachment for the Taig Lathe (cartertools.com)) which itself is based on a Unimat version described in MEW. For that low speeds will be handy. The other reason is to improve the torque available at low(er) turning speeds. The DC motor has little power below 500rpm which with the original setup is about 200rpm at the spindle. I could actually have used the extra grunt when turning the 90mm billet of aluminium down to make the pulley - it was a lot of very light cuts to avoid stalling.

Mine has the ER16 spindle which I think is rated for 10,000rpm as standard, so now I can go from 50-10,000 rpm - should I feel the need.

Ady, I am already well down the slope I have high and low speeds on the Taig (see above), a watchmakers lathe and have already bought a micro mill - although not the Taig one. The roundtuit project list gets longer every time I step into the workshop!

I posted a question a few weeks ago about the best place to mount the bearings in a backshaft setup for my Taig lathe and the responses helped with the thinking.

The gadget is now finished(? are they ever!). In case anyone is interested in the approach, I have added a few photos in my Taig Lathe album.

It works as designed. Gives me a 10.5:1 reduction between the motor and the spindle, and gives good useable torque at the spindle down to about 50rpm.

Again thanks for the advice given here - I am learning a lot as I go along. I now have a new list of things "I wish I hadn't done that way" but must confess the lathe has become a project rather than a means to an end.

Smiths of Derby do a patented auto wind system (AW10) for heritage tower clocks. The system is in effect a remontoire which winds the weights at frequent intervals reducing the drop needed, and eliminating the need to wind manually. There are details on their website which might give you some ideas.

There is also a good paper by Mark Frank on tower clocks (speech_final_web.pdf (my-time-machines.net) which discusses various remontoire systems for tower clocks - from page 23.

Edited By Peter Cook 6 on 26/07/2021 21:03:34

That really brought back memories!

I was a DEC manager during the years (84-91) they sponsored the revival, and attended quite a few of the events. The flying was "lunatic" everything from Spitfires down to tiny single seat stunt aircraft. I remember the commentator, who was standing on the finish line, diving flat as someone undertook - literally underneath - another finisher. He was probably less than 10 feet off the ground! I even got to ride round the race circuit in Peter Crisp's Pull-Push Skymaster. I still swear I could see wake on the water surface from the wingtip vortex as he went round the nab tower in a breakaway turn below the top of the tower.

The logistics in suppling a first class black tie sit down dinner dance for pilots, customers and Dec staff in a marquee in the middle of Bembridge airfield was equally impressive.

edit typos

Edited By Peter Cook 6 on 20/07/2021 14:27:49

My view. A lot of what has happened in the last 30 years is down to the developments in computing technology - imagine designing and making that ball on a manual machine tool!!

The next 30 years will see yet more advances, but even more will we see biological development. Covid 19 vaccines have been made in months rather than years, in 30 years time it will probably be hours. DNA sequencing has come down from $3billion for the first human DNA sequencing ( 2003) to less than $1000 today.

You ain't seen nothing yet.

Edited By Peter Cook 6 on 15/07/2021 13:18:32

Thanks Martin,

The block will be 20mm wide and I will be using a couple of bearings in either case. A concern with the step and nut approach on the bearing block is where the axial squeeze forces applied by the nut would be carried. To avoid them being transferred to the sides of the ball races, I would need a spacer between the two inner races and the bearing block would need sufficient room for that to rotate. That also implies that all the radial loads caused by belt tension get transferred to the block via the ball races - so two 5mm supports at opposite ends of a 20mm block.

For bearings in the pulley the two bearing centres could be clamped together ( with a very small spacer to allow rotational clearance) giving in effect a (small and cheap) double row bearing. The radial loads get transferred through the whole length of the 20mm shaft set in the block.

I think I am convincing myself to go the pulley route. As usual dialogue here clarifies thinking in a way I can't do on my own.

Thanks Bernard for the ideas more to mull over.

If you are interested in what I am trying to do I have added an image in my "Taig lathe" album called "backshaft overview.jpg" which shows the general idea. It is based on the DC motor I have already mounted on the lathe. The backshaft is mounted on top of the headstock using the T slot. The smallest motor pulley drives the big pulley, and the small pulley drives the next to largest spindle pulley - hence the alignment. The bearing block will be made to slide (slot & tenon) on the part fastened to the T-slot for tension & belt change adjustment.

As designed it gives me about a 10:1 reduction (vs the 3.5:1 available on the standard pulley set). I can't see any reason why the design wouldn't work with a motor mounted behind the lathe if you adjusted the lengths of the belts.

Hope this is of interest.

I am making a small "backshaft" for my Taig lathe, and am wondering where is the best place to put the bearings. In the pulley with a fixed shaft, or in the bearing block with the pulley fixed to the shaft.

The large pulley is 80mm, the small one 20mm, the shaft is 8mm (or 10mm) steel, and will use a couple of 8 x16 x 5 bearings. Block & pulley will be aluminium. The Pulley profile is for a 3mm Gates belt ( as used on the lathe).

If I mount the pulley firmly on the shaft, I could use the shaft as a mandrel for turning the pulley and ensure concentricity - but I then need to work out how to stop lateral movement of the shaft in the bearing block.

Putting the bearings in the pulley would make it a bit harder to ensure concentricity, but makes lateral positioning easier - small step on the shaft, and a nut or similar on the small pulley side.

Could I ask the the wisdom of the forum for thoughts, ideas or gotcha's before I make yet more scrap.

Is there any theory/rule of thumb about the best diameter for the cotter compared with the shaft it locks. All the examples shown have the cotter smaller than the clamped shaft. Is it just convenience, or is there something about the clamping action that suggests a particular ratio of diameters?

I want to lock a 10mm steel shaft, and was planning to use a 10mm brass cotter. Would that be too big, or just unnecessary?

I would doubt it. The number of places where that sort of insulation comes into contact with household wiring will be enormous.

My roof is lined with 6mm ply. Not sure of the relative cost, but it sure is handy to be able to screw hooks etc in to suspend things for painting, drying etc.

Unless spares costs are "controlled" the manufacturers will make the cost well out of proportion.

Our 10 year old Bosch dishwasher died recently. Investigation (took apart) suggested that the control box was faulty. One small PCB in a plastic box with edge connectors £165 inc VAT. It's certainly no more complex than an Arduino Uno I can get for 1/10th of the price. Man to come and diagnose the fault £99. So total cost to repair by "approved" repairer £264 - about 60% of the cost of the dishwasher originally, and a new one is about the same cost.

Actual fault (Google is your friend) was a 100ohm 3W resistor (£1.99 for five) and a Regulator IC (£4.75 for four) both delivered by a well known auction site.1 hour with a soldering iron and it all works again.

But I have no idea where the average person might find someone to do such a repair. All the "engineers" these days seem to be trained just to swap components.

Thank you for the received wisdom of the forum. More Ideas for me to ponder and experiment with.

David, I did look for taper rollers - but with a 7mm ID they seem to be unobtainium and if do find any probably out of my price range.

NDIY - One option was to create a jam nut by cutting the nut in half, but I take the point about the difficulty of holding the preload still enough - especially with a 2mm pitch. 5 degrees of shift is 0.028mm change in the preload position.

Paul, I know will have some backlash on the running nut, but I can probably live with that on the little lathe as long as the leadscrew bearings don't add to it. The idea of a fine thread on the leadscrew to make adjustment easier is interesting. Perhaps thread the dog clutch on, adjust and lock with a grubscrew. A ballscrew is serious overkill for the purpose.

Thanks to everyone for the ideas. I have a couple of nuts on order with the leadscrew, so may try the grubscrew with a brass or copper slug, DC's approach with a slit in the nut and threading the inside end of the leadscrew. Just to see which works best.

Edited By Peter Cook 6 on 21/06/2021 12:51:48

My take on the backlash issue is always approach the positions from the same direction.

If you use the wiggler to find the LH edge of the part, you will be moving the table from right to left. When you move into the part from that position (you did remember to allow for half the diameter of the wiggler) you will still be moving the table right to left and dimensions should be ok.

However if you overshoot, and need/want to move back towards the LH edge (i.e. move the table left to right), then simply go past the point you want and come back to it so that you approach the position with the table moving right to left.

Same principle applies front to back.

Try Peatol (Peatol Machine Tools). Currently offering the Taig ER16 adapter P/N 1045ER for £42.00 plus £4.00 post and packing. The price list was updated on the 18th May this year.

I haven't used them - I got my lathe ( with the native ER spindle) direct from Taig in the US - they are very helpful but carriage can kill you.

Thanks DC. That Idea looks useful and potentially easier. I was a bit worried about positioning the grub screw so that it fitted either between the threads of the lead screw or on a land and didn't end up half and half.

You are correct ( I just checked) the thread is trapezoidal not ACME - my mistake. But the nut(s) and rod are all matched from the same source, so (hopefully) no issue.

I am in the process of adding a 10mm LH ACME leadscrew to my Taig lathe.

The two thrust (and one roller) bearings for the motor end of the screw are mounted in an aluminium plate. On one side (left in image) is one half of a small dog clutch which is pinned to the leadscrew (turned down to parallel).

On the other side (right) of the bearing set I have an ACME nut on the leadscrew that can be used to preload the thrust bearings to eliminate backlash.

To lock the preload, I will drill the ACME nut and put in a grub screw to fix it once loaded. The alternative is to saw the ACME nut in half and use the two halves as conventional locknuts.

The grub screw looks easier to do, but before I go too far, can the combined wisdom of the forum see any gotcha's I have not spotted? Or a better idea for the preload, ACME LH Nyloc nuts seem a bit rare.

Edited By Peter Cook 6 on 19/06/2021 17:45:06

Get or make a sensitive/micro drilling attachment with a small chuck. ARC & WARCO both do one with a 1/2" shank, and there are instructions on the web as to how to make one. Hold that in a suitable collet in the machine. It will give you the ability to down feed the drill by 10-15mm as well as holding it. Although the speeds will still be slow.

Just had delivery of a cheap HSS 1/4-20 UNC tap and die set (with a die holder) from Amazon.

Package was flagged as a Bladed item and the courier wanted age verification ID before handing it over.

It appears to be the only set on Amazon's site so flagged - guess someone ticked the wrong box. The courier found it strange - she said she delivers Chainsaws without needing verification!

Thanks everyone. Some diligent searching online has revealed several images of identical headstocks. One (withdrawn from sale) at

Wolf Jahn Watchmakers Lathe Headstock For Sale in Glasnevin, Dublin from steve2011 (adverts.ie)

shows the headstock disassembled and the shape of the spindle is identical to mine. It also shows the same nose to the pulley and has one of the dust caps. I think Michael is (as usual) correct and the intention was/is for the pulley nose to run against the back of the front bearing. Bearing preload is simply by squeezing the pulley up against the front bearing while holding the spindle in the double taper - then tighten the four grub screws. That would also explain the groove inside the front bearing from the oil hole to the back of the bearing (see the picture in the original post). At first I assumed this was damage - but now it seems more likely to be designed to lubricate the faces where the pulley bears on the back of the bearing.

As Michael also suggests this may be clever production engineering for a low cost product that could be badge engineered by wholesalers and suppliers. My headstock has no markings on it, only the tool rest and foot into which the headstock fits have the Wolf Jahn mark.

I have fixed the alignment of the oil hole, so I guess I should trust the quality of Wolf Jahn's engineering design, and reassemble it the way it was made.

Thanks again for all the ideas and thoughts - as always dialogue with someone else clarifies things.

Edited By Peter Cook 6 on 09/06/2021 13:39:14

Thanks Michael,

However if that is the case, then looking at the nose of the pulley

I think there is a bearing plate missing. Now to find out the shape of, or design, a suitable thrust washer.