Thread ID help needed

[DAN_IN_MN]

Hi guys

I have an old tire balancer (don't remember the brand at the moment) that I need the nut that holds the wheel on when the machine is in use. The guy I bought it from back in 2006 said "I'll look for it". He didn't find it so, I'm going to make one.

I don't have a pic of the thread, phone was dead.....takes so much more battery than my old flip phone.

Anyway, I digress....


The thread is like an acme thread being that it's not pointed.

The dimensions are.

INCH (MM)
Major 1.568 (39.8272)
Minor 1.370 (34.798)
Thread to thread .146 (3.7084)
7 tpi

Width of top of thread .048 (1.2192)
Width of bottom of thread .056 (1.4334)

I've done a fair amount of searching to ID this thread. Any help IDing these thead would be appreciated.


I also will be setting up a cutter to cut the internal threads on my lathe.

Here's the blank for the nut. (after short phone charge....) I cut it out after work today. 3/4 plate 1 inch starter hole

 

[Chuck K]

Dan, I can picture the thread your trying to make. Do you have an acme thread gage? I would be curious to know if that's what it is. In any event you're going to have to grind a form tool that fits the thread on the machine. If it were me, I would probably thread a scrap piece and see how it fit. But I have a habit of doing things the hard way and someone else will probably be able to give you better advice. Good luck.

Chuck

 

[Tom Griffin]

If I am interpreting your numbers correctly, 1.568-1.370=.099" high and .056-.048=.008" taper, it works out to a 5º included angle, so it's definitely not an Acme. It doesn't really matter what the thread is though, all you need to do is grind a tool that fits the existing thread and cut and internal thread at 7 TPI until it fits, plus a healthy clearance. Chances are it's not a standard thread anyway, a lot of machines like that had special threads made to suit the application.

It looks like you flame cut that hole in the center of the blank, so you're going to have a tough time machining it. Your best bet would be to use a carbide boring bar and take the first cut deep enough to remove all of the slag. Be sure to grind as much off of the surface as possible before machining it.

Tom

 

[ki4byz]

I made one of these for a local shop once, when I tried to screw it on it would not go.
That is when I realized it was a double lead thread.
Check closely

 

[DAN_IN_MN]

I made one of these for a local shop once, when I tried to screw it on it would not go.
That is when I realized it was a double lead thread.
Check closely

Were you able to go back and add the second lead?

Do you recall the thread size? Was it an acme thread?

Thanks for the heads up! If it is a double lead, that would be a reason why I can't find a thread with 7 tpi of this size. Could it be a double lead thread with a 14 tpi? I'll have to check.

 

[Tom Griffin]

If it's a two start thread at 7 threads per inch, the pitch would be .143 and the lead would be 1/3.5 or .286. That is basically two threads that are 3.5tpi and 180º out of phase, so no you can't turn a single start thread into a double start. It wouldn't surprise me if it was a two start since you would want the lock nut to spin on quickly on a tire balancer.

Tom

 

[DAN_IN_MN]

Here's a picture of the machine and thread. I think it's about time I get this thing out of the shed and start using it!

Oh, I did check the thread and it is a single lead.
Thread up close.

 

[OldMachinist]

If it a multi lead thread you should be able to look at the end of the shaft and see the starting points. Another way would be to take a sharpie, put it in one thread, move the marker around the shaft several revolutions and see what is marked. Normal single lead thread would have ink in every thread and with a multi lead thread it will skip one or more threads.

Edit:
I see you edited your post to add that it's a single lead thread while I was typing.

Do you think that it might be metric? 40mm x 4mm?

 

[DAN_IN_MN]

If it a multi lead thread you should be able to look at the end of the shaft and see the starting points. Another way would be to take a sharpie, put it in one thread, move the marker around the shaft several revolutions and see what is marked. Normal single lead thread would have ink in every thread and with a multi lead thread it will skip one or more threads.

Thanks Don

I just checked the thread and there is only thread lead.

 

[OldMachinist]

Metric 40mm x 4mm?