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Help.....don't know my lathe thread chart

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Suzuki4evr

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#1
I feel sort of stupid posting this,because I kind of feel I don't know my own lathe. I have to start by saying I am not a qualified fitter and turner,but qualified automotive machinist so everything I know about lathes and what goes with it is self taught and stealing with my eyes.

That being said,can someone help me with my lathe thread chart. I know how to do basic threads,metric & imperial, and know how to use the chart for that. I have never done ACME thread before so that is something I must still conquer. 20180111_114959.jpg
This is the chart
First I want to know what does the 45÷2000 & 45÷355 at the top of the chart mean. 20180111_115038-1-1.jpg
What does the symbols in these two rows mean. The funny looking thing with the m and the same thing with the DP. These are marked on the gearbox knobs. I know what the 1" and mm represent,but not those two. 20180112_194200.jpg
20180112_194054.jpg
And on the right side of the chart underneath the 45÷355 there is more numbers. Are these coarser threads if you change the gear ratios as symbolized on the left of them or am I wrong about that. Or are they used for cutting ACME threads? Like I said,never done ACME before.
20180111_114959-1.jpg
One last thing. There's this plate around the back of the spindle bore,but does not really look like an indexing plate.
20180112_194255.jpg
20180112_194308.jpg
This is just the gears at the back.
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20180112_194522.jpg
Can anyone help please.

Michael
 

Ulma Doctor

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#2
Hi Michael,
the columns I and II signifies the change gears necessary to cut the given thread pitches.
the upper left next to I is for metric threading, the top column to the right of column II is for imperial threads
the acme pitch is Imperial , you'll select the correct thread change gears for this operation 65 teeth for the top gear, the next gear is the 95 tooth, then the 55 tooth and finally the 57 tooth gear.

DP is diametrical pitch, you probably not be using those unless you are cutting worm gears on the lathe

i'm not exactly sure what the 45/2000 and 45/355 means
 

Moper361

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#3
Don't worry Michael I was the same ,I had had my lathe about five years before I even looked at the thread chart.I had no idea either and was lost a bit when first looking at it but if you stand back and not get to perplexed by it .it all fits into place and makes sense .My only regret was not using it five years previously as it's very handy to know what it all does now .its only the last six months I've really taken to enjoy hobby machining and I'm making things I would never have thought I could make five years previously .I did quite a bit of machining when I was a kid on the farm but it was no were near the level of what I have discovered I could achieve now .

It was the same with my mill and indexing head it was all just sitting there until just recently and now I can make up gears and all kinds of stuff ,I only wished I had been using it sooner rather than it collecting dust .

I Do really thank the guys on this forum for all the advice I have requested in the past as it's been a really good last six months totally filling my brain with new ideas and being able to carry out the tasks I want to .So don't feel silly in asking as the people on here are very helpful and seems they get some satisfaction out of helping of they can .

YouTube is a really good friend also and what I have picked up of mrpete222,Keith Fener ,Doubleboost with John the Gordy has been invaluable there are also others on there that I've learnt from but they are the few main players

I'm not familiar with your lathe but it appears Ulma is on the correct path .
 

jcp

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#4
The ring at the back of the spindle is for indexing the spindle to cut multiple start threads (2,3,4,6). The shop I worked in had a Summit 30 x 120 lathe that had up to 10 on the ring! I made a couple of 2 start threaded shafts for bowl lift screws on commercial food mixers and they were aggravation enough. Can't imagine doing a 10 start thread.
 

Suzuki4evr

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#5
Hi Michael,
the columns I and II signifies the change gears necessary to cut the given thread pitches.
the upper left next to I is for metric threading, the top column to the right of column II is for imperial threads
the acme pitch is Imperial , you'll select the correct thread change gears for this operation 65 teeth for the top gear, the next gear is the 95 tooth, then the 55 tooth and finally the 57 tooth gear.

DP is diametrical pitch, you probably not be using those unless you are cutting worm gears on the lathe

i'm not exactly sure what the 45/2000 and 45/355 means
I am going to have to make up some gears,but in order to do that I must first make an indexer for my lathe and gear cutters and all of that. I guess I have my next project. Just have to find some time trough all my work. Thanks for your thoughts guys.
 
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