My first Double thread

[Jimsehr]

I think the caps on milk bottles are multi start.

 

[Janderso]

Looks grate Jeff. How did you start the second thread in the middle of the first thread?

The method I chose you just move the compound to the middle of the cut thread.
In my example, 16 threads, one inch divided by 16 = .0625"
I just moved the compound .0625" toward the headstock that amount.
I hope that makes sense.

Here is part one of a two part series on the double start threads by Mr. Pete.

 

[savarin]

Good one Jeff.
I did a 4x multi start on my focussers and was very pleased at how it came out.

How I cut a metric multi-start thread

I havnt worked out how to do this with those weird imperial threads so I will leave that for someone more erudite in maths than myself to do so. All the metric threads I cut on this lathe are done by leaving the half nuts engaged so the first attempt was done the same way. I wanted a quad...

www.hobby-machinist.com

 

[Janderso]

Not typical for fasteners, multi-start is very common for motion systems where you want to convert rotary to linear, etc.

Plumbing fixtures, soda and milk jugs

 

[pontiac428]

Plumbing fixtures, soda and milk jugs

How about this:

Bolt-action rifles. Anything with a rotating bolt and lug scheme is essentially a multi-start thread. Maybe why they're called bolts.

 

[OCJohn]

Ponchoguy gets my vote for best theory of the thread.