Standard for spindle nose thread

[Mayhem]

For some time now I have been wanting to make a copy of the spindle nose on my lathe, to use as a standard for making a backing plate for my 3 jaw chuck.

The thread is 4" 6tpi and I haven't had much luck in finding a suitable chunk of steel to use. I did see some off cuts of Delrin but they wanted $120 for a suitable piece

I managed to pick up a slug that had been flame cut from a 4" section of pate. For facing, I eyeballed it in the 4 jaw but for turning, I will need to be very close as there isn't much material to play with, diametrically speaking.

   

First thing I need to do is cut a shallow recess so I can weld in a section of an old drill coupler, which will then be used to hold the slug for turning, as it isn't long enough. I used a centre finder to locate the centre of the slug, which I then centre drilled. It was shortly after this that I remembered that I hadn't actually built that pump centre that I had planned on, to enable me to centre it accurately in the 4 jaw. So I rectified that problem!

   

Hopefully I will get to finish of the standard next week.

[Highpower]

(07-08-2012, 02:34 AM)Mayhem Wrote: I managed to pick up a slug that had been flame cut from a 4" section of pate. For facing, I eyeballed it in the 4 jaw but for turning, I will need to be very close as there isn't much material to play with, diametrically speaking.

I'm confused (as usual). Is that piece slit down the side?

Willie

[DaveH]

DaveH

[Mayhem]

Yes. They start the flame cut in the slug (off centre) and then move it to the edge before making the final cut. I will probably run a bead to close it up but I doubt it would really make much difference to the end result. Although, I could be wrong.

[TomG]

Darren,

It sounds like a lot of work to make a thread gauge that large for a one time use. Why not just make a rod with a 60º point on each end to use as a gauge. You could size it to the pitch diameter of the thread in your 4-jaw or face plate. As a final check, you could unscrew the chuck and check the fit of the newly cut thread before removing it from the chuck.

Tom

[Mayhem]

Hi Tom - Sorry but I'm not sure I follow. I'm having a hard time visualising what you have described. Is it a 4" long rod with a 60º point on both ends?

[TomG]

(07-08-2012, 09:48 AM)Mayhem Wrote: Hi Tom - Sorry but I'm not sure I follow. I'm having a hard time visualising what you have described. Is it a 4" long rod with a 60º point on both ends?

Yup, roughly 4" long. You'll need to fit it to an existing thread to get the exact length, then you can use it as a gauge to cut a new thread with the same pitch diameter.

Tom

[dallen]

interesting concept using a rod pointed on both ends to gauge a thread with, I can see how it will work with the tapers on both ends being the same degree as the thread

[TomG]

I got thinking about this a bit more (even though I'm still on vacation ) and the length of the rod would need to be less than the major diameter of the thread so it doesn't bottom out, say 3.95". You want the angled surface of the point to be the gauging surface, not the end of the rod. The pitch of a 4"-6 thread is .144", so any rod with a diameter greater than that would do for the gauge.

Tom

[Mayhem]

(07-08-2012, 06:58 PM)TomG Wrote: I got thinking about this a bit more (even though I'm still on vacation ) ...

Don't tell me the serenity is wearing off Tom? Thanks for thinking of me - I'll buy you a beer (or two) in September