best TPI for a twisty

archer6817j · Oct 6, 2010

Hi all,

I made a twisty with 28TPI, mostly to keep the thread depth shallow, but it seems like the thread pitch is a little fine. Sometimes I get a "false on" when twisting the head down and I think this is happening because my spring is not perfectly flat. It also means I have to give it 2-3 turns to make sure it doesn't turn on accidentally.

Does anyone recommend and ideal thread pitch? I'd like to keep the threads as shallow as possible but have solid engagement when activating. I'm not sure if 24TPI will make enough difference and 20TPI is starting to get a little deeper than I want...but it might have to do.

Mick · Oct 6, 2010

Use a multiple lead thread.

precisionworks · Oct 6, 2010

My McGizmo Ti PD-S seems perfect (in the rotation needed for On/Off). Crudely measured with a plastic ruler, it looks like 16 tpi.

Would have used my China Junk digital caliper but the battery is (once again) dead

(The brand is actually SPI, sold by MSC Industrial. It is not industrial, or even usable). Rant over :sick2:

archer6817j · Oct 6, 2010

Doh! A double start thread is a great idea but I don't think my Hardinge HLV will handle that since there is no threading dial. I think only the newer electronic versions will do a multi start...unless anyone has a trick. 16 sounds too coarse for me but I wouldn't argue with McGizmo

Maybe I'll try a 20 and see if that isn't a good compromise. The tube stock I got is a relatively thin wall so threads eat up the wall thickness pretty fast.

TranquillityBase · Oct 6, 2010

Gizmo PD's are 20tpi

PEU · Oct 6, 2010

it depends on the thickness of the wall that you have available, small flashlights use 24 or 32 tpi, bigger 16 or 20 tpi or the aproximates in metric.

Pablo

PhotonFanatic · Oct 6, 2010

archer6817j said:
Hi all,

I made a twisty with 28TPI, mostly to keep the thread depth shallow, but it seems like the thread pitch is a little fine. Sometimes I get a "false on" when twisting the head down and I think this is happening because my spring is not perfectly flat. It also means I have to give it 2-3 turns to make sure it doesn't turn on accidentally.

Does anyone recommend and ideal thread pitch? I'd like to keep the threads as shallow as possible but have solid engagement when activating. I'm not sure if 24TPI will make enough difference and 20TPI is starting to get a little deeper than I want...but it might have to do.

The thread pitch should have no effect on how well the electrical connection is made. If you are having problems with that, then, yes, it is a problem elsewhere, i.e., you mentioned a spring.

I use .5mm pitch thread all the time and it takes less than 1/8th of a twist to disengage/engage the electrical connection.

precisionworks · Oct 6, 2010

Gizmo PD's are 20tpi

I appreciate the correction. Under so-so lighting, using one of those cheap plastic rulers that clips into a 3-ring binder, 4 threads per quarter inch & 5 threads per quarter inch look a lot alike.

Which is why thread gages were invented :nana:

The thread pitch should have no effect on how well the electrical connection is made.

+1

Most twisty lights have some spring preload that pushes the battery (or batteries) toward the head & at the same time pushes the battery tube toward the rear. The threads are always in a loaded condition, which assures good electrical contact (assuming no anodizing or other insulator is present on the threads).

gadget_lover · Oct 7, 2010

Multistart is not that hard. I had to think about it a lot before it made sense.

For a 2 start 28 TPI . Set the compound parallel to the ways. Use a straight in feed.
Set up for 14 TPI and cut to the depth for 28 TPI. Then move the compound left or right 1/28 of an inch. The next cut will fall between the 14 TPI cuts.

Daniel

best TPI for a twisty

archer6817j

Enlightened

Mick

Newly Enlightened

precisionworks

Flashaholic

archer6817j

Enlightened

TranquillityBase

Flashlight Enthusiast

PEU

Flashlight Enthusiast

PhotonFanatic

Flashlight Enthusiast

precisionworks

Flashaholic

gadget_lover

Flashaholic

Similar threads

Latest posts