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Brass_Machine:
Ya know, for all I do on the lathe... I have NEVER threaded on it. Except using taps and dies anyway. Anyone want to do a thread on it with pictures?? Please?

Eric

spuddevans:

--- Quote from: Darren on August 01, 2009, 02:51:15 PM ---Tim, I don't know how others get on, but I find single pointing produces far better and squarer threads than dies.

Don't be in too much of a hurry to get those dies in......not for precision work at least.... :thumbup:

You're doing a grand job as always...thanks for the write-ups.... :thumbup:

--- End quote ---

Thanks Darren, I believe you are right about single pointing producing far more accurate thread forms. I probably will continue single pointing after I get the tailstock die holder doo-dah made, probably start the thread off single pointing, get it near total depth and then just finish off with a die to get the right form and depth.

By the way, does anyone have a link or know of a publication that has a nice list of thread depth's, I have a couple of charts that give the OD of the different threads along with drill sizes for various %'s of thread depth, but I would really like a chart that tells me what each standard thread depth is, especially for metric threads as that is all I work in at the moment, ie M3 thread depth is ?? M4 is ... and so on and so fifth forth

I keep meaning to pick up a Zeus handbook, maybe it has something like that in it? I'm willing to buy a book that has the relevent details in it, I just dont want to buy a book thinking that it'll have it in it, and then find out it doesnt. So can anyone point me in the right direction please?

Tim

edit,

I just read your message Eric, I'll take even more pics than usual tommorow afternoon when I remake and thread my packing gland nuts screws and try and post up a new thread about it.

Darren:
Good question Tim....I have no idea, but assumed with metric threads depth was the same as pitch?

I just keep going till the part fits snugly.....but if you have to make both parts I can see that being difficult.
The other way I have done it is by judging with a thread gauge.

kvom:
A copy of machinery's handbook might be a good investment. I got a used copy online for about $15.

For the small threads we use in modeling I have been cutting partial threads on the lathe and finishing them with dies. Even with no undercut at the shoulder, you can use the die to thread almost to the shoulder as Bogs says. the partial threads cut with the lathe will keep the die straight.

Definitely turn the boss and drill the glands with the same setup on the lathe. You want the piston rods and valve stems to be dead center going through.

rleete:

--- Quote from: spuddevans on August 01, 2009, 02:42:52 PM ---But then again, there is great frustration in single pointing...(multitude of ways to mess it up)
--- End quote ---

Yeah, we've all had our share of screwing up. In fact, threading is probably one of the easiest to ruin, as there are so many ways to do it. You didn't mention the one that's my most common, which is running the tool into the shoulder by not disengaging the leadscrew, and either snapping off the pointing tool, or messing up the shoulder. Then there's the "forgot at which line to engage the leadscrew", thereby cuttting an entirely new groove right over/through your almost finished threads.

I think that's why I derive so much personal satisfaction in doing it right.

As to the thread depths, someone posted a chart for imperial threads here or over at HMEM. I printed and laminated it for hanging on the wall, and it's a very handy reference. Not sure if they did one for metric, but it's worth a look. If not, you can probably find one on-line with a bit of searching.

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