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View Full Version : Higbee cut for 1x28 TPI?



DaHui
08-01-2011, 08:05 PM
Hi all,

I've been making flashlights and tried an experiment the other day. I cut a double start thread on the section where the head threads to the body. The thread is 28 TPI and has about 10 turns. That a lot of twisting to get the head off to change the battery to I tried the double start.

It works great, but I also sell these lights, and the fine thread makes starting the head on a little tricky. As a mechanical person I have no problem getting the thread started correctly, but I suspect a heavy hand would bugger them up in no time.

So my question is, would a higbee cut work well one threads this fine? It's a little different that the thread on a fire hose, but I'm looking for a way to get more positive engagement so I can feel comfortable putting a double start thread in the hands of John Q Public.

Thanks!

Andrew_D
08-01-2011, 10:13 PM
I know what you mean...we've got some old 2" hose here at our fire station and it is VERY easy to cross-thread it!

My vote is Yes, a higbee start to the thread would help...the problem is that unless you have a CNC machine, it's pretty much a manual filing/milling job.

I had success filing when I made a 3/8" x 16tpi drawbar for my mini-mill. Makes it much easier to start the threads into a collet/whatever.

Andrew

Black_Moons
08-01-2011, 10:51 PM
Id wonder if maybe such a thread start could be made on a manual lathe by manualy rotating the spindle, using a parting tool and just stoping shy of the last cut.. Since its only one revolution * a few passes..

Alternatively, rotary table + mill would do it nicely, just adjust the Z as needed by eye?

Alternatively, live tooling (or grinder?) on the lathe would do it with manual turning the spindle.

Joel
08-01-2011, 11:04 PM
Nah, the easy way is to clamp up a little die grinder in the toolpost and rotate the thread into it by hand.

While a higbee sure wouldn't hurt, I suppose you are pushing it on that fine a thread. On a flashlight, why not redesign for a simpler (cheaper to produce) single start of less length? Just because you want to bury X amount of cap sure doesn't mean it all has to be thread. Go as coarse as you can also. Since there is minimal loading and sealing is usually done with an o-ring, full depth is not really required. Fewer machining processes equals more time and profit.

DaHui
08-02-2011, 12:28 AM
I'll be doing this on a CNC mill :)

I'm mainly wondering if a higbee will have the desired effect with a thread profile that is so small. (1x28 TPI)

Andrew_D
08-02-2011, 11:19 PM
I'll be doing this on a CNC mill :)

I'm mainly wondering if a higbee will have the desired effect with a thread profile that is so small. (1x28 TPI)

I don't have CNC anything, so I have a question...will it take very long to modify your program and try one? If it works, great. If not, oh well....

Andrew

DaHui
08-03-2011, 03:37 PM
I don't have CNC anything, so I have a question...will it take very long to modify your program and try one? If it works, great. If not, oh well....

Andrew

It wouldn't take "that" long but I have other things that need my attention if someone here already knows that it won't make much difference :)