Single point threading

Given the need to thread right up to the end of the stud section, and the generous length of the knob section, I would make a properly central hole in the knob, tap it, and screw in a length of studding. This can be stuck in place with eg Loctite, and offers significant advantages -
a) the need to cut a long thread on a thin part is removed,
b) the strength is improved as the thread is rolled and so work hardened, and will not be made of free-cutting steel
c) the thread is smoother and will wear longer,
d) a small stud uses less material than turning most of a bar away.

Other advantages are available

Cheers, Tim

Edited By Tim Stevens on 30/05/2020 18:08:44

@Tim Stevens - that sounds very sensible.

To complete this exercise in threading, I made 3 different fixings for this little project. This was thrown together "free hand" with whatever bits I had to hand...

The parts...

assembled...

Installed...

Apologies that the last photo is rotated. I can't seem to change it however much I pre-rotate the photo before uploading.

Anyway, it attaches to the end of my aero-bars on my bike to hold my phone...

My first thought was as other have said - use a half-centre, turning the top-slide round to bring the tailstock in close, as Duncan suggests.

Also, I cut the run-out with the threading-tool itself as that gives a slightly less stress-raising groove.

Lessen the depth of cut as you go deeper, but note Martin's point about avoiding rubbing.

Also, and I do this on any material, take a spring-cut at intervals (a repeat cut at the same depth). It's surprising how much metal that sometimes removes - but again, don't overdo that on a work-hardening material.

Ronald - Yes, a mandrel handle as you describe is a well tried and trusted attachment, and quite a few designs have been published over the years, though tend mainly sized for the Myford lathes.

There you go Jed, courtesy Photoshop.

Sam

Jed, what holds the phone in (is there a layer of double-sided tape ) If that was on my bike the first bump and the phone would be long gone!

John

The phone has a soft silicon case, which friction fits into the holder. It's a nice fit and works well, but to be clear, the bike is for indoor training only, I wouldn't take this out on the road

@Sam thanks for that. I was rotating the photo in windows (right click, rotate clockwise or counter-clockwise). I assume this just changes the metadata for the photo, rather than the pixel data, and the forum software ignores the metadata. I'll try doing a proper rotate next time(in paint I guess, I don't have photoshop).

Edited By Jed Martens on 08/06/2020 10:08:26

Ah! That makes sense. If you want a good photo editor try *** GIMP *** it is free and works on most platforms. Does everything that Photoshop can do but a bit of a steep learning curve beyond the basics.

John

Edited By Journeyman on 08/06/2020 10:19:14

Jed, try rotate and save a copy. Post the copy to the album. I think that is what has worked for me in the past.

Martin C

Take two pics - one in portrait and one landscape. One will load in your album the right way up (hopefully).