Identifying an odd thread.

[Susquatch]

Perhaps it was your measurment rather than your math, .787 is almost exactly 20mm.

It's a very difficult measurement to do. It's a threaded shaft down inside a casting hole. I can't get a mic or a caliper in there. I had to make a gauge that just fit and then measure that.

Regardless, you were correct - it's an M20-1.25 thread.

Lots of great ideas here. When the dust settles, I'll write this all up and post it separately in tips and tricks with attributes to those who contributed.

 

[terry_g]

An employer of mine had a nice dial type bore gauge. I needed a longer extension rod for it to measure the cylinder bore taper in an engine block. It had an odd thread it appeared to be a 1mm thread pitch but cut on a .250" diameter rod as far as I could tell.
Our lathe could not cut a metric thread so I took it to a local machine shop and they made me the parts I needed. And yes it was a 1mm thread pitch cut on a .250" shaft.

 

[Dabbler]

here' what I'd do ' find a friend with a disassembled Hartford mill of similar vitage, and get a second set of measurements...

 

[Susquatch]

here' what I'd do ' find a friend with a disassembled Hartford mill of similar vitage, and get a second set of measurements...

It's an M20 1.25 for sure.

You mean to say that Hartford of yours is still sitting in pieces in your shop!!!

I love what priorities do to us! Pretty sure I have shared that old saying of mine with you before. "Don't tell me that you don't have time. That has nothing to do with it. It's just not a priority for you."

Sometimes I think you spend 10x as much time helping other folks than you do working on your own stuff!

 

[ChazzC]

Sometimes I think you spend 10x as much time helping other folks than you do working on your own stuff!

What’s so bad about that? The last 4+ months I’ve been spending almost all of my available (i.e., not sleeping, eating, exercising/PT) time “helping” (entertaining?) folks on four forums.

 

[Susquatch]

What’s so bad about that? The last 4+ months I’ve been spending almost all of my available (i.e., not sleeping, eating, exercising/PT) time “helping” (entertaining?) folks on four forums.

Sometimes my back handed humour doesn't come through. It was intended to be a huge compliment to @Dabbler.

 

[Downwindtracker2]

Humour and partying are two things Canadians do well.

 

[ChazzC]

Sometimes my back handed humour doesn't come through. It was intended to be a huge compliment to @Dabbler.

I, too, was being droll: we all know that John would do anything to help any of us.

 

[Dabbler]

Thanks for the compliments. It boils down to Your projects are shinier and more interesting than mine!

 

[Garyt]

Thanks for the compliments. It boils down to Your projects are shinier and more interesting than mine!

Dabbler certainty helped me to spend money to buy a hole into which I could pour more money.
Thanks I am having a great time learning.
Gary

 

[TorontoBuilder]

Seems a repeat problem for me is properly identifying an odd thread.

Is it metric or imperial?

Thread gauge can be difficult to use.

Custom threads make everything difficult.

My standard process, is to make an educated guess, then use thread checkers and fastener gauges. But if that doesn't work, I mic the OD or ID, use threading charts to identify possibilities, and test fit if possible.

But quite often it doesn't seem to work very well.

What process do you use?

I find it pretty easy to identify odd threads.

If within the first page or so a thread drifts into a discussion on plucking chickens, I immediately think, "This is an odd thread"