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WW1 Peerless lorry restoration


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Don't forget that when you consult your Zeus or whatever tables , the pitch in relationship to the diameter is just the  'preferred'   and this is what the automotive industry tend to work to.   In the real industrial world like machine tools - where large dia. tend to be screwcut on a lathe , the pitch is chosen best suited for the application when you get to dia. above abt. 2"     Things like locking collars for overhead travelling crane trailing wheel axles , multi-auto lathe spindles etc.

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41 minutes ago, ruxy said:

the pitch is chosen best suited for the application when you get to dia. above abt. 2"     Things like locking collars for overhead travelling crane trailing wheel axles , multi-auto lathe spindles etc.

Or, indeed for fun. I made an M14.75 x 0.95 thread pair once. Just because that satisfied a mathematical optimum. 

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I don't like to add unrelated links, but since the topic this week seems to be threading, I thought I'd introduce you to the world threading champion:

https://www.youtube.com/watch?v=cDfMI5ahbJI

... I didn't even know that was possible.

( Hit the box for subtitles if your Russian is a little rusty )

Edited by Gordon_M
added subtitle info
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1 hour ago, Barney said:

 1" 16-UN - Unified Extra Fine Thread, which is used for special purposes.
The flank angle is 60°.

But would a 1934 British car be using Unified threads? (Unlikely, Unified threads were invented during WW11) 

I just finished an M77 x 1 thread. I chose that size as I had a 76mm recess that needed a thread, and the 1mm threading tool was the one in the holder. 
If it had been the 1.25 insert then it might have been an M77.25 x 1.25 thread instead. 

 

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22 minutes ago, andypugh said:

But would a 1934 British car be using Unified threads? (Unlikely, Unified threads were invented during WW11) 

I just finished an M77 x 1 thread. I chose that size as I had a 76mm recess that needed a thread, and the 1mm threading tool was the one in the holder. 
If it had been the 1.25 insert then it might have been an M77.25 x 1.25 thread instead. 

 

Posted  21 hours ago

1934 Singer ,  what is the component  ?     If it is a  'fast-mover'   then it may be a post 1948 replacement part -  in that case a  16 UN  (National Extra Fine)  on 1" dia. would fit the bill.

-----

This sort of query - always best to get it on a shadowgraph.

 

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10 hours ago, ruxy said:

always best to get it on a shadowgraph

That takes me back, 50 years ago, Guildford tech was the last time and place I used one.  But brings up a the thought of where to get access to a shadowgraph should you want to check out your thread.

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6 minutes ago, rog8811 said:

That takes me back, 50 years ago, Guildford tech was the last time and place I used one.  But brings up a the thought of where to get access to a shadowgraph should you want to check out your thread.

 

7 minutes ago, rog8811 said:

where to get access to a shadowgraph should you want to check out your thread.

Any oilfield equipment place would have the casting dough and a shadowgraph to compare it.

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4 hours ago, rog8811 said:

That takes me back, 50 years ago, Guildford tech was the last time and place I used one.  But brings up a the thought of where to get access to a shadowgraph should you want to check out your thread.

I found a YouTube video of someone making their own: https://youtu.be/lw1b58kITxQ

 

I was wondering if the lead angle of a thread affects the apparent thread angle when projected, but after a bit of 3D modelling, I have decided that the answer is "not enough to cause confusion"

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21 hours ago, andypugh said:

But would a 1934 British car be using Unified threads? (Unlikely, Unified threads were invented during WW11) 

 

 

I feel you are overthinking this, Andy. Singer would have chosen the thread on the basis of material to be used, the duty that the component is to perform, and ability  to manufacture. Any comparison with a thread designation decided upon by the Americans nearly twenty years after the Singer components manufacture is can only be pure coincidence.

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54 minutes ago, Barney said:

I feel you are overthinking this, Andy.

Or you are under-thinking it when you suggest that an 1"-16 UN thread is an option. 

I am saying that it is unlikely that the thread form is UN, it is very likely to be Whitworth, and the two are not compatible. 

This has nothing to do with any of the standards, it has to do with the basic shape of the threads, which differ significantly. 

 

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On 12/18/2020 at 11:13 AM, Bill Coates said:

It's the gearbox primary shaft so it's possible it could be a replacement.  I hadn't come across UN extra fine before!   The things you learn on this forum!!!!

Very probably ,  say renewed  1954 ,  20 full years of active service that could have included being a Home Guard troop bus  !       Late 1970's - I remember going to local scrap yards after  BMC  "A" Series  stuff,   complete engines/gearboxes/radiators to repower Morris Minot.  There was still quite a lot of pre-WW2 motors still active locally until abt. 1970 ,  40 years with chassis welding was the norm.   I couldn't shift my old man away from Ford.  I still have a expanding reamer for doing his 1938 Ford Prefect king pins , it had been laid-up since post WW2 petrol rationing , it was reactivated 1965 in prep. for me to learn to drive on ,  somehow I did that with a  A30 ,  however a 1963  Morris Mini Minor pulled the tallent better   LoL

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Thinking more about this ,  a gearbox primary shaft would almost certainly be threaded in a centre lathe .  It as a LH thread , if I were doing it - then I would prefer that to a RH thread , as I would be working towards the tailstock (away from the step).  I would not bother trying to use a tool inverted (leave that to Alfred Herbert).   The draughtsman would probably consult the turner or planner - both IMHO would say avoid a Whitworth form.  It would greatly add to production costs.  The thing is the crests have to be rounded , today a toolpost mounted chaser would probably be used  but try getting a LH one.  A 16 tpi hand chaser will have a handle like wood turning tool/scraper and be at least 2 foot long (and some poor B has to use it) ,  a LH one would not be unobtainium  even going back 70 years +

https://www.jeadonengineering.co.uk/index.php?route=product/product&path=20_62&product_id=2978

Getting a good look at the crests with a pocket magnifier would be worthwhile, you may see the scraped crests against the turned thread marks.

It could even be 25mm x 1.5 pitch ,  the .003" difference with 1/16" would not be so easy to determine , and should be eliminated.   First check I would do would be with a 0-1" micrometer - is the dia.  1"  or  16 thou. under  ??

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53 minutes ago, ruxy said:

The draughtsman would probably consult the turner or planner - both IMHO would say avoid a Whitworth form.  It would greatly add to production costs. 

They would cut the thread that they had tooling for. In 1934 that would have been BSW / BSF. They wouldn't have randomly chosen (pre-ISO) metric or UN / Sellers just because it is theoretically cheaper to single-point. 

They might well have chosen to forego the crest rounding for the reasons you mention,  but the thread angle is still rather more likely to be 55 than 60 (or 47.5, or 80). 

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12 hours ago, andypugh said:

They would cut the thread that they had tooling for. In 1934 that would have been BSW / BSF. They wouldn't have randomly chosen (pre-ISO) metric or UN / Sellers just because it is theoretically cheaper to single-point. 

They might well have chosen to forego the crest rounding for the reasons you mention,  but the thread angle is still rather more likely to be 55 than 60 (or 47.5, or 80). 

Even now  firms don't buy machine tools / tooling unless they are contracted to do a very long run.  Shorter batches they would make do with what they have or contract out some operations - the threading  may have been such a case with these primary shafts.  Whitworth form IMHO would always be done the proper traditional way = pride.  Tool rooms I have worked in always had a shadow-graph  &  even  55 or 60 degrees would call for second opinion(s) on a small dia. like 1"  .   With power presses jammed on the bottom (common event on thin oiled material being hand fed), we used to use every trick in the book to save the pitman screw from the gas axe ,  I have known some odd possibly modified special pitman threads on ancient British & foreign presses , older were often a knuckle .  Modern always a buttress - that was a joy infeeding the toolpost set at an angle followed by the ball to a template and then final lapping-in to the seat.

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btw.    I don't know the production runs of these gearbox primary shafts , but even short , the machining would be done , threads probably just roughed.  Any heat-treatment - then any grinding to finish and that would include the threads.   The best way to finish the threads would be on a centre-grinder fitted with a crusher,  when LAL had their factory at Newton Aycliffe , that was how they did their taps inc. L.H.  and they would be just short-runs.   Using a hand-glass - it will be possible to confirm if threads turned/scraped  or ground to size.

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14 hours ago, ruxy said:

A 16 tpi hand chaser will have a handle like wood turning tool/scraper and be at least 2 foot long (and some poor B has to use it) ,  a LH one would not be unobtainium  even going back 70 years +

If you can find them at a decent price, this style of threading tools make a lovely whitworth-form thread in a single operation. 

https://www.ebay.co.uk/itm/284087318863

 

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  • 4 weeks later...

Little progress of late because of the "Lockdown" where the team has not been able to get together for some weeks. So much was planned to be done over the Christmas and New Year break which came to nought - but Steve has completed the Dennis Radiator patterns at his home whilst Tim has continued with his writing - several articles completed for various magazines and lodged with them for publication. Tony managed to remove 18 of the rusty 21 Coach Bolts securing the Brake Drum to one back wheel and now awaits some help to finish the job. He has also stripped down and cleaned the brackets to hold the Radiator to the chassis. The situation is very frustrating!

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Well if it makes you feel better, I have not been able to do anything really to my Range Rover for well over a year. Been in storage for ages, find a workshop near where I live then Covid.

Small successes are successes nonetheless.

Still in awe BTW

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