Thread Size Help With Starrett 196a Back Plunge Accessory

I just found that clamp in a pile of stuff and could not find any thread american or metric so I just retapped it to 10/24 not suggesting this but at least I can make use of this clamp. I can now make any bar with 10/24 to use with this tool
 
Bob,

I have the newer 196A Starrett set that has two different lengths of those posts and they don't have the ball ends on them. Mine are 12-28NF thread, 1/4" long. I don't know if they are a different thread than the older sets, but you could try a test fit with a 12-28 screw or tap. Or, you could try one of mine to see if it fits.

Ted
 
talvare said:
Bob,

I have the newer 196A Starrett set that has two different lengths of those posts and they don't have the ball ends on them. Mine are 12-28NF thread, 1/4" long. I don't know if they are a different thread than the older sets, but you could try a test fit with a 12-28 screw or tap. Or, you could try one of mine to see if it fits.

Ted
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Thanks, Ted. My thread is definitely smaller than that. It looks like it would be about a 9-32, if there was such a thing. This is old school Starrett, at least 50 years old, probably much older than that, so there is no doubt that it not metric. Starrett used lots of oddball thread sizes on their tooling, probably because they had always made them that way, so why change? It was also easy for them to get oddball tools because they owned Union Twist Drill, just up the river in Athol, Mass.
 
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Ed ke6bnl said:
I just found that clamp in a pile of stuff and could not find any thread american or metric so I just retapped it to 10/24 not suggesting this but at least I can make use of this clamp. I can now make any bar with 10/24 to use with this tool
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I could probably do that, Ed, but this is an antique tool holder in nice condition, with nice color case hardening. It would be a shame to deface it in the quest of a modern thread. I need to make the post anyway, and am quite sure I can make one that works well and looks near original, just would be easier to not be guessing at the size. Thanks for the idea, and I would probably do something like that if it was not an antique.

It is not the clamp that I am going to screw it into. My clamp has a permanently brazed rod on it. This is the bar that gets clamped into the tool post that I want to screw the post into. My old set is different than the newer ones.
 
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I think I may have one of those posts, Bob. If so, you're welcome to it. I'll look this afternoon. I never cared for the back plunger indicators but have a few pieces of a set.
 
Bob, I think something is amiss in your set. The rods you have should screw into that bar. The bar should say Starrett on it. The rod(s) should screw into the clamp and/or bar. It’s all interchangeable. If you need a replacement bar, give me some time to stumble across one in my shop and I will send it to you. If you want to make a bar anyway. I would just trial and error the thread until I got it correct. Shouldn’t take that long on the lathe…Dave.

PS: You can kinda date your Starrett tools by the kind of Starrett logo they used through the years.
 
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chips&more said:
Bob, I think something is amiss in your set. The rods you have should screw into that bar. The bar should say Starrett on it. The rod(s) should screw into the clamp and/or bar. It’s all interchangeable. If you need a replacement bar, give me some time to stumble across one in my shop and I will send it to you. If you want to make a bar anyway. I would just trial and error the thread until I got it correct. Shouldn’t take that long on the lathe…Dave.

PS: You can kinda date your Starrett tools by the kind of Starrett logo they used through the years.
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Dave, this is an older set and it does not have the removable bars in the clamp. I have seen others like it on the web. The clamp is configured in the reverse of the later models. My bar does say Starrett on it. My old set is different than the newer ones. My set is exactly like the one I posted above that I lifted off the web, just missing the post. These are older sets with the slide top box.
 
chips&more said:
Bob, I think something is amiss in your set. The rods you have should screw into that bar. The bar should say Starrett on it. The rod(s) should screw into the clamp and/or bar. It’s all interchangeable. If you need a replacement bar, give me some time to stumble across one in my shop and I will send it to you. If you want to make a bar anyway. I would just trial and error the thread until I got it correct. Shouldn’t take that long on the lathe…Dave.

PS: You can kinda date your Starrett tools by the kind of Starrett logo they used through the years.
Click to expand...
The tool post bar says "The L.S. Starrett Co./Athol, Mass. U.S.A." I think that only tells me it is made after 1896...
 
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