First threads!

[DavidR8]

Great looking work!

You'll find that the extension ratio for well supported stock to be even more critical in threading because the forces are pretty high. That second example would have benefited from some live center TS support.

You're really getting the hang of this! Congrats.

Next up is trying a metric thread. Requires you to have understanding of the change gears on your lathe and how to reverse the chuck out of the cut without undoing the half-nuts. Also in that bucket is internal threading and internal threading away from the chuck against a shoulder.

I do want to try metric as well as internal as I want to have the full repertoire of skills.
I did forget to reset the cross slide once last night and I just reversed back to the start so I didn't have to wait for my mark on the thread dial to come back around.

Come to think of it, if I pick a certain number on the dial do I always have to wait for the same number or can I engage on its opposite.
Say I start on the '1', can I also engage on the '3'?
Likewise start on the '2' and also engage on the '4'?

 

[ErichKeane]

I do want to try metric as well as internal as I want to have the full repertoire of skills.
I did forget to reset the cross slide once last night and I just reversed back to the start so I didn't have to wait for my mark on the thread dial to come back around.

Come to think of it, if I pick a certain number on the dial do I always have to wait for the same number or can I engage on its opposite.
Say I start on the '1', can I also engage on the '3'?
Likewise start on the '2' and also engage on the '4'?

That depends on your lathe and the TPI that you're cutting. For some lathes that is true, for some 'even' threads can be on any number, odds only on opposing, etc.

Mine for example (as an oddball!) I can engage whole thread numbers on ANY number or hash, "1/2" TPIs on only the numbers, and "1/4" TPIs I have to leave it engaged ! Most lathes however don't support 1/2 and 1/4 threads (like 1 3/4 TPI!)

 

[macardoso]

I do want to try metric as well as internal as I want to have the full repertoire of skills.
I did forget to reset the cross slide once last night and I just reversed back to the start so I didn't have to wait for my mark on the thread dial to come back around.

Come to think of it, if I pick a certain number on the dial do I always have to wait for the same number or can I engage on its opposite.
Say I start on the '1', can I also engage on the '3'?
Likewise start on the '2' and also engage on the '4'?

For reference only, my lathe has a nameplate with this chart... Yours will likely be different.



It states where on the thread dial I can engage. My thread dial has 4 major ticks (1, 2, 3, 4) and 4 minor ticks not labeled. The SCALE section above means this:

• "1-8" Engage on any major or minor tick
• "1-4" Engage on any major tick
• "1/3 2/4" Engage on ticks 1 & 3 OR 2 & 4 (Engaging on 1 then 2 would ruin the thread)
• "1" Engage on any major tick, but then only use that tick going forward
• "/" Do not disengage half nuts

All metric threads and any imperial threads not in the table are assumed to be "/"

 

[ErichKeane]

I do want to try metric as well as internal as I want to have the full repertoire of skills.
I did forget to reset the cross slide once last night and I just reversed back to the start so I didn't have to wait for my mark on the thread dial to come back around.

Come to think of it, if I pick a certain number on the dial do I always have to wait for the same number or can I engage on its opposite.
Say I start on the '1', can I also engage on the '3'?
Likewise start on the '2' and also engage on the '4'?

Assuming the 10k is the same as the grizzly one now, see Page 50: https://cdn0.grizzly.com/manuals/sb1002_m.pdf

According to that doc:
TPI divisible by 4: Any line (numbered or not)
12/20/28/36/44/52/92: Non-numbered only. [0]
10/14/18/22/26/46: Any numbered.
9/11/13/23: 1, 3, 5, or 7
11.5 TPI: 1/5 OR 3/7.

[0] This is confusing to me... a number of those examples ARE divisible by 4...

 

[DavidR8]

For reference only, my lathe has a nameplate with this chart... Yours will likely be different.

View attachment 320144

It states where on the thread dial I can engage. My thread dial has 4 major ticks (1, 2, 3, 4) and 4 minor ticks not labeled. The SCALE section above means this:

• "1-8" Engage on any major or minor tick
• "1-4" Engage on any major tick
• "1/3 2/4" Engage on ticks 1 & 3 OR 2 & 4 (Engaging on 1 then 2 would ruin the thread)
• "1" Engage on any major tick, but then only use that tick going forward
• "/" Do not disengage half nuts

All metric threads and any imperial threads not in the table are assumed to be "/"

That's a really helpful chart. I'm pretty sure the chart on my lathe doesn't have that extra info but I'll check.
Edit: no such luck. My chart has threads per inch and feeds in thousandths.

 

[macardoso]

That's a really helpful chart. I'm pretty sure the chart on my lathe doesn't have that extra info but I'll check.
Edit: no such luck. My chart has threads per inch and feeds in thousandths.

That chart is tacked on to my thread dial directly. Unfortunate yours doesn't have it. Check a manual for something similar.

At a minimum, for any normal imperial pitch, you should be able to engage/disengage on the same mark and it will be OK.

What lathe do you have?

 

[DavidR8]

That chart is tacked on to my thread dial directly. Unfortunate yours doesn't have it. Check a manual for something similar.

At a minimum, for any normal imperial pitch, you should be able to engage/disengage on the same mark and it will be OK.

What lathe do you have?

I have a 1975 SB 10K
I'm just in the process of making an Excel version of the threading chart so that I can read the feed rates. It's in excellent condition but brass numbers on a red background are not the great.

 

[ErichKeane]

Mine has the thread dial on a apron right next to the thread dial. You might just need to consult your manual. The Grizzly one I found above is clearly not the right one for you. I don't see the manual to a 10K even on Vintage Machinery, which surprises me!

Hopefully someone else more familiar with the SB can chime in.

 

[SLK001]

Take this chart and print it, then go to a stationary store and get it laminated. Place above your lathe.

 

[mikey]

mikey: Unless I'm reading it wrong, isn't your equations backwards? For 30 degree angle, I think it should be:
Estimated thread infeed using compound = 0.75/tpi
Estimated thread infeed using cross slide = 0.75/tpi X 0.866

No, don't think so.

Besides, I do it like you - I don't rely on calculations. I start checking early, and the more critical it is for that thread to be right, the earlier I start to check. You know how that flat at the peak of the thread starts to narrow? I tend to watch that and when it starts to look like I'm close, I pull the thread mic out and start measuring. I cannot tell you how many threads I've overshot using formulas!!