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  #31  
Old 01-31-2021, 09:28 PM
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Shawn. Would you be so kind as to take a picture of the gear train under the cover on the left hand side of the headstock?

Thanks in advance.

BTW, do you have a thread pitch gage? If so, check the pitch of your lead screw..
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  #32  
Old 01-31-2021, 10:12 PM
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Last time I used a thread dial was high school machine shop. Every one since then has been by reversing as Keith describes.

Using carbide threading tools, it is pretty quick to cut the bulk of the thread out with a few passes, then a few more to finish it up.


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  #33  
Old 01-31-2021, 11:48 PM
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I use the reversing option too when cutting threads, at least 90% of the time at work. If the thread is longer than 2”, then I will disengage the half nut and move carriage back by hand or which traverse feed, unless it is a metric thread, which then in that case I can’t, since the threading screw is imperial pitch thread.

The thread engage lever slips in easy enough, but does not disengage easy on my work lathe, so I have gotten used to leaving it engaged. But my lathe has a lever that changes the spindle rotation and I can do that on the fly quickly. I do feather it out so it is going slower before reversing completely, but I do like it.

But, on my home lathe, an old south bend, it would be a pain to reverse the carriage back. I would have to hand crack the spindle backwards, since it does not have reverse. So, it would be good to learn using the thread dial, so you can be comfortable doing either way.


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  #34  
Old 01-31-2021, 11:50 PM
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Quote:
Originally Posted by greywynd View Post
...Every one since then has been by reversing as Keith describes...
It's been so long since I tried I honestly don't know if I could cut a thread using the dial. My current (Chinese) lathe came with a pretty good looking thread dial but it still had a lot of slop in it. I just knew that if I used it I would eventually pick up a thread on the wrong number and mess up. Not a huge deal on something simple but if threading is your last operation on a part that you've already got some hours into screwing it up doesn't go over well...
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  #35  
Old 02-01-2021, 12:16 AM
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Quote:
Originally Posted by ShawnR View Post
Maybe my technique is wrong?

Here is what I am doing...
1 set tool bit using gauge so it is square to stock
2 set compound slide at 30 degrees (or 29.5) and zero it
3 adjust cross slide to just scratch stock, then zero cross slide dial
4 pick a threading number to use
5 with cutter at right of start of thread, engage carriage feed when your number comes up
6 make first scratch (or cut) till end of thread
7 release carriage feed,retract cross slide to clear stock, and run carriage back to position for start of thread
8 put cross slide back to zero
9 advance compound a little (not doing this today cause just scratching)
10 when your number comes around, engage carriage feed
11 goto 6
12 repeat till thread is cut or stock is ruined, which ever comes first...

Cheers,
Shawn

Yes that is the way I do it with a US lead-screw with gears selected for "threads-per-inch"


IF
Looks like you have a metric lathe
so
select gears for a metric pitch and try cutting metric the same as above.

as for using the dial I always use the same number, had issues with the odd-even thing.
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  #36  
Old 02-01-2021, 12:42 AM
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Quote:
Originally Posted by Ironman View Post
Bill, didn't your machine have an interlock? I couldn't do that with mine, because the feed lever is locked solid when the half nut is used.
Not real sure, it was only last week but it seems eons ago. There is a position on the head stock for threading and a position for turning. I probably had the turning engaged when I tried to thread. It made a mess and another piece of scrap. A little re-education on threading was an immediate response and I finally cut threads where they should have been.
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  #37  
Old 02-01-2021, 05:58 AM
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I’m like Keith, I leave it engaged, fast wind out and stamp on the brake at the same time, then reverse. I think it’s quicker. My Chinese lathe was made for the US market and is imperial but I leave the 127 in the train all the time, alters the feeds slightly but not much and the only time I have to take it out is the rare occasion I cut an imperial thread. I cut between 600-800 off 12mm x 1.75 threads a year using the reverse method and the only time I have problems is when I get too cocky and careless. What brand and what model lathe is it? We can look up the manual maybe.
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  #38  
Old 02-01-2021, 06:21 AM
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Wow, lots of replies since yesterday. Thank you all.

It sounds like I should not be so stubborn so will work on the threading without disengaging the nut. As many things that I have resisted learning, once I try it, it will probably become the norm.

At one point in my day yesterday, after changing all gears out, tightening the belt drive, looking for any other issues, I ran about 8 passes, all perfectly in line. Figured I had it! Then the twin showed up again!

So today, my goal, is to run some metric threads and see if the consistency I expect is there. Then, I will practice some threading without disengaging the half nut. This has been an exercise to learn something new and it has certainly done that for me, so, despite the frustration of not "mastering" a new skill, I know my lathe much better, got it cleaned up, got more comfortable with swapping out gears, and was an active member of a very informative thread!

Thanks again all!!!

To answer a couple of recent questions, the make (Craftex B2227L) and manual are posted a little earlier.
I only have the carriage engage lever, not two levers.
I can measure the lead screw too, but after 4 pages of posts, I am finally accepting that it is not that straight forward....
Gear box and thread chart from front of machine pic attached. The one from the manual is very different and, I think, incorrect.

Cheers,
Shawno
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  #39  
Old 02-01-2021, 08:36 AM
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Shawn, the first picture clearly shows the 127 translation gear. There is your issue. To thread with it in place, you will be forced into leaving the half nut engaged and doing a reverse procedure.

As others have mentioned, you will still have to retract the thread Tool while reversing to prevent damage regardless of whether you use carbide tooling or HSS, or carbon steel. If the work will allow, threading to a full depth recess might make things easier.

Another question. What type of chuck mount does your 1227 use?
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  #40  
Old 02-01-2021, 09:37 AM
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Quote:
Another question. What type of chuck mount does your 1227 use?
The one big thing I dislike about this lathe, the spindle has a plate on the end and the chuck mounts with 3 screws. Again, not a big deal but a threaded chuck would be nice. Although I did a small job for a friend last year and needed to put the 4 jaw on. I fought to get more comfortable with it but have since grown to be fond of it. Easy to dial things in whereas the 3 jaw is what it is for being concentric. Now I can't see going back to the 3 jaw.

I am thinking this threading thing will be the same. As Shrek says, "change is hard Donkey" but I will work on not releasing the nut today and maybe someday I will be on here telling some new guy that this is the best way to do it! ....

Off to the shop, will report back
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