Left hand thread

[Dunc1]

I have an arbour spindle that is missing the retaining bolt. Afaik part is not available (very old tool). The arbour thread is internal; I have tried both metric & imperial bolts but no go - diameter seems appropriate but a bolt will not thread in. Either it is damaged or it is left-hand thread. Lacking left hand threaded fasteners to try, any ideas? Are there left hand fasteners available commercially? Thanks!

 

[140mower]

If you have a bent dental pick, or even a bent piece of wire will do...... Put the bent end into a thread and rotate the part or wire end in the thread, that will tell you which way it threads depending on the which way the wire goes, in or out... A bit of silly putty or plumber's putty pressed into the thread will make using a thread gauge to determine the pitch a bunch easier....

 

[140mower]

Btw.... Welcome to the forum from Lillooet BC....

 

[Arbutus]

If the part is pre-WW2 there's a chance the thread is Whitworth. This has caught me a few times when working on older British stuff. Whitworth threads are 55 degree vs. most others which are 60 deg.

 

[kstrauss]

I have an arbour spindle that is missing the retaining bolt. Afaik part is not available (very old tool). The arbour thread is internal; I have tried both metric & imperial bolts but no go - diameter seems appropriate but a bolt will not thread in. Either it is damaged or it is left-hand thread. Lacking left hand threaded fasteners to try, any ideas? Are there left hand fasteners available commercially? Thanks!

Yes, there are left hand fasteners available from vendors such as McMaster-Carr. See https://www.mcmaster.com/screws/thread-direction~left-hand/ for some examples.

If you need to find the thread pitch and thread form (in addition to handness) I've found that an appropriate sized piece of thin softwood screwed into the threads works well to get an impression from the thread..

 

[Former Member]

There is a casting material that you use to get accurate measurements from internal dimensions. Used in gunsmithing, forget what its called.

Basically, pour in fills to size as it sets it shrinks slightly to allow easy removal and then expanses to 100% original mould dimension after a period of time.

 

[Dabbler]

@Dunc1 you might have a thread with a custom pitch, but Whitworth is more likely.

To get an impression of your thread for for checking with a thread gauge, get some plastiscene and make a roll less than 1/4 of the size of the hole. Use a wire or stick to insert the roll and press it into the threads, just a little bit. You can then remove it from the hole and check it with a thread gauge.

I once had a problem like this, and the thread was 1/2-12 instead of the standard 1/2-13. The above is how I proved the pitch.

 

[kstrauss]

@Dunc1 you might have a thread with a custom pitch, but Whitworth is more likely.

To get an impression of your thread for for checking with a thread gauge, get some plastiscene and make a roll less than 1/4 of the size of the hole. Use a wire or stick to insert the roll and press it into the threads, just a little bit. You can then remove it from the hole and check it with a thread gauge.

I once had a problem like this, and the thread was 1/2-12 instead of the standard 1/2-13. The above is how I proved the pitch.

1/2-12 is a standard (BSW) Whitworth thread. If that is your situation remembers that it is 55-degree rather than 60-degree flanks.

 

[Dabbler]

1/2-12 is a standard (BSW) Whitworth thread. If that is your situation remembers that it is 55-degree rather than 60-degree flanks.

The 1/2-12 bolts were missing, and not too hard to replace. The hard part was figuring out what to get.

 

[Susquatch]

There is a casting material that you use to get accurate measurements from internal dimensions. Used in gunsmithing, forget what its called.

Basically, pour in fills to size as it sets it shrinks slightly to allow easy removal and then expanses to 100% original mould dimension after a period of time.

@Dunc1 - Degen is referring to Cerrasafe.

It's a great idea, but I wouldn't use it for that. It shrinks, but not enough to release from a damaged thread.

Of all the ideas floated here, I like @Dabbler 's suggestion. You could even use some chewing gum. Press it in place on one side of the hole and then stick it outside to cool. Fridge is better but divorce can be a very costly solution.

 

[Chipper5783]

I also ran into a 1/2”-12 on a milling machine stub arbor. Another way to measure thread pitch in a hole is with a bent piece of wire (similar to an o-ring pick): insert wire, with the tip in a thread root, mark depth, bump the wire out while counting a number of threads, then mark/measure the wire insertion again. Obviously you try to be over as many thread roots as you can.

 

[Proxule]

@Dunc1 - Degen is referring to Cerrasafe.

It's a great idea, but I wouldn't use it for that. It shrinks, but not enough to release from a damaged thread.

Of all the ideas floated here, I like @Dabbler 's suggestion. You could even use some chewing gum. Press it in place on one side of the hole and then stick it outside to cool. Fridge is better but divorce can be a very costly solution.

I use sulfur, Heat it until it melts and pour it into the rifle chamber. It does not shrink and I am unsure how it would act if it was poured into a thread, Food for thought.

 

[Susquatch]

I use sulfur, Heat it until it melts and pour it into the rifle chamber. It does not shrink and I am unsure how it would act if it was poured into a thread, Food for thought.

I infinitely prefer cerrosafe. It fits perfect as it solidifies, then shrinks a bit for removal, then returns to the same dimensions it had when it first solidified. So you can use it to measure exactly what a given dimension is. If you leave it for a very long time, it will change a bit, but they provide exact aging information so you can easily correct for its age. In most cases, I use it right away so I get exact results.

You can reuse it over and over.

Sulphur can be nasty stuff. Great for keeping ticks and chiggers off your pants though.......

 

[Proxule]

I infinitely prefer cerrosafe. It fits perfect as it solidifies, then shrinks a bit for removal, then returns to the same dimensions it had when it first solidified. So you can use it to measure exactly what a given dimension is. If you leave it for a very long time, it will change a bit, but they provide exact aging information so you can easily correct for its age. In most cases, I use it right away so I get exact results.

You can reuse it over and over.

Sulphur can be nasty stuff. Great for keeping ticks and chiggers off your pants though.......

I used what I was taught to use and had on hand.
Sulfur wont stick to any oily surface and melts at a low temp. I enjoyed it but I have no other exp to compare to.

Good enough for gunsmiths, good enough fof me.

Thanks for the cerrosafe tip.

 

[Susquatch]

I used what I was taught to use and had on hand.
Sulfur wont stick to any oily surface and melts at a low temp. I enjoyed it but I have no other exp to compare to.

Good enough for gunsmiths, good enough fof me.

Thanks for the cerrosafe tip.

Hey Proxule, I think maybe I was a little too emphatic about Cerrasafe. I hope I didn't offend you.

If you ever wanna try some I can send you enough for a chamber casting to try.

You can also buy it from Brownells in the US. No problem shipping to Canada. You can even specify USPS....

Shop All Shooting & Gunsmithing Supplies | Brownells Since 1939

Brownells offers Free Shipping over $49 through July on all products including ammunition, firearms, reloading, handgun and rifle parts, AR15 supplies, gun cleaning products, and more!

www.brownells.com

And I was dead serious about using sulphur to repel ticks and Chiggers. It's hard to find though. I paid through the nose at my pharmacy. Where do you get yours?

 

[JustaDB]

Great for keeping ticks and chiggers off your pants though.......

Susquatch's wear pants?!

 

[140mower]

Susquatch's wear pants?!

From what I have been able to gather, I think the bride might get those......



..... Ducking for cover....

 

[Proxule]

Hey Proxule, I think maybe I was a little too emphatic about Cerrasafe. I hope I didn't offend you.

If you ever wanna try some I can send you enough for a chamber casting to try.

You can also buy it from Brownells in the US. No problem shipping to Canada. You can even specify USPS....

Shop All Shooting & Gunsmithing Supplies | Brownells Since 1939

Brownells offers Free Shipping over $49 through July on all products including ammunition, firearms, reloading, handgun and rifle parts, AR15 supplies, gun cleaning products, and more!

www.brownells.com

And I was dead serious about using sulphur to repel ticks and Chiggers. It's hard to find though. I paid through the nose at my pharmacy. Where do you get yours?

No my friend you didn't offend me, thanks

I never ordered from brownells before, but will keep the USPS shipping option in mind. That helps a lot!
Thanks for the idea and offer for the cerrasafe.

Bought my sulfur from a lab, It was lab grade and not cheap. Should be enough for a wile!