Odd thread size info needed

[djm77]

Hi All,

Working on reverse engineering a component for a client. We have a mating part for an internal thread but it doesn't seem to tie in with any thread that I can find data on, whether that's online or in the Bible.

It seems to be a 3/8" x 22 TPI thread.

Does this ring any bells with anyone? It would be nice to know what angle thread we are playing 55*/60* so that we can reproduce correctly.

Failing that we are going to have to do a few dummy runs until we hit it correctly.

Thanks in advance for any help in the right direction.

 

[Phil in Montana]

Make dummy thread and see what fits with blueing...Phil

 

[BT Fabrication]

are you sure its not a deformed M10x1.25?

 

[AlfaGTA]

If you have the mating internal thread you can use a product called "Facsimile"to make a gauge....Comes as a kit , its an epoxy style plastic, that is relatively free flowing and when cured will not shrink.
Use the mold release on the ID threads, stop off the depth and fill a few threads with the material, insert a small screw or piece of steel in the center of the mix ..when cured, unscrew it using the inserted material and measure on comparator for size and thread pitch and angle.....No guess work.

Cheers Ross

 

[L Vanice]

My huge list of threads only has two with 22 TPI and there is no close metric pitch: 16-22 ASME machine screw and 5/16-22 BSF. In the UK, I would suspect a madly ill-chosen variation on BSF, like splitting the difference between 3/8-20 BSF and 3/8-24 UNF with heaven knows what thread angle, maybe 57.5 degrees?

At least you said you have a sample male thread ("mating part for an internal thread"), so it should not be difficult to determine the thread form.

Larry

 

[L Vanice]

If you have the mating internal thread you can use a product called "Facsimile"to make a gauge....Comes as a kit , its an epoxy style plastic, that is relatively free flowing and when cured will not shrink.
Use the mold release on the ID threads, stop off the depth and fill a few threads with the material, insert a small screw or piece of steel in the center of the mix ..when cured, unscrew it using the inserted material and measure on comparator for size and thread pitch and angle.....No guess work.

Cheers Ross

An old-school trick is to cast melted sulfur into a female thread or tapered hole. I have used bismuth alloy that melts at 156 degrees F in the same manner.

Larry

 

[Limy Sami]

What is the component, no need to reveal too much, but purpose approx date of manufacture and country / brand source of origin will help.

 

[mhajicek]

In medical device prototyping I get wacky custom threads all the time. They're always 60°. I threadmill and use the tolerance of the nearest standard thread. Do the male first, measure with threadwires, then make some more male parts at the limits for the female, to use as go/nogo gauges.

 

[michiganbuck]

An old-school trick is to cast melted sulfur into a female thread or tapered hole. I have used bismuth alloy that melts at 156 degrees F in the same manner.

Larry

Another quicky with having the female is to screw a wood dowel into a bore to get the TPI.

yes, might have to turn the dowel to ball-park size.
We used to make segmented grinding wheels by pouring sulfur..it got rock hard at cooling.

 

[L Vanice]

Another quicky with having the female is to screw a wood dowel into a bore to get the TPI.

yes, might have to turn the dowel to ball-park size.
We used to make segmented grinding wheels by pouring sulfur..it got rock hard at cooling.

I use a knife to make the end of the wood dowel triangular. It screws into the threaded hole easier than a solid round and still marks the pitch clearly.

By the way, be careful melting sulfur and don't get the sulfur hot enough to burn. Sulfur dioxide smells bad and is poisonous if you breath too much of it. Got my first Gilbert chemistry set when I was eight or nine and used up the sulfur and powdered magnesium real quick. It was a few years later that I read a book on the history of fireworks and the Chinese recipe. I found the drugstore sold cans of saltpeter. Garden supply store had bags of sulfur and we had a charcoal grill...

Larry

 

[Georgineer]

I use a knife to make the end of the wood dowel triangular. It screws into the threaded hole easier than a solid round and still marks the pitch clearly.

I wish I'd thought of that!

George B.

 

[djm77]

What is the component, no need to reveal too much, but purpose approx date of manufacture and country / brand source of origin will help.

It's some sort of manifold block for a pressure test system, that's all the info I have unfortunately. The mating male part has a sprung loaded ball on the end to seal on the port. I think we are going to have to do a few dummy runs guessing what thread it is and when we get the right feel go with that one.

 

[Limy Sami]

I'll stick my neck and say its M10 x 1.25, ........ fine / none preferred threads are very comon on test equipment and M10 x 1.25 used a lot on car hydraulic braking systems.

Re 22 tpi = 0.04545'' pitch. .......1.25 mm = 0.0492'' pitch

 

[michiganbuck]

With the wood dowel method, one can count the thread turns over a few inches in length and so get a very accurate count.

 

[Erich]

Get one of the male fittings from your customer. Measure that.

 

[michiganbuck]

One could even put the part in a mill vise or lathe chuck, put in the wood dowel, and then set an indicator at the but and make a turn or number of turns to get pitch reading.