DONALD BLUDWORTH joint pin

ribdoner

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Tried getting a hold of Donald to find out what type of joint pin he uses/used to no avail, so, perhaps someone here can help me out.

Thanks in advance, adam
 

Thomas Wayne

AzB Silver Member
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It was a 3/8" stainless rod stock Leonard bought in bulk at an auction from a shipbuilding firm that had gone bankrupt. Initially, Leonard used short lengths of the thread rod itself to make his taps, but he may have had hardened steel ones custom made later on. He may also have gone to live tooling at some point.

For those of you who knew Leonard well enough to remember how he pitched this odd pin, his claim of having it specially engineered and analyzed to "provide the most wetted surface" (his words) was pure bullshit.

Because it was being used in a commercial application at the time he bought it you would think there'd be some sort of standard specs it conforms to, but I've not found that to be the case. In hand, it looks like a hybrid between a "stub ACME" at the minor and a British Standard CYCLE configuration at the major. The pitch angle falls somewhere between 55* and 60* (hand-polishing may have altered this slightly).

The pin was an 11 1/2 tpi, with a major of 0.346" - 0.348" (after polishing), and a minor of about 0.270" Live tooling with a lightly radius thread mill will easily provide a workable female thread, though I would recommend running a few test pieces to get it just right.

TW
 

MVPCues

AzB Gold Member
Gold Member
Silver Member


It was a 3/8" stainless rod stock Leonard bought in bulk at an auction from a shipbuilding firm that had gone bankrupt. Initially, Leonard used short lengths of the thread rod itself to make his taps, but he may have had hardened steel ones custom made later on. He may also have gone to live tooling at some point.

For those of you who knew Leonard well enough to remember how he pitched this odd pin, his claim of having it specially engineered and analyzed to "provide the most wetted surface" (his words) was pure bullshit.

Because it was being used in a commercial application at the time he bought it you would think there'd be some sort of standard specs it conforms to, but I've not found that to be the case. In hand, it looks like a hybrid between a "stub ACME" at the minor and a British Standard CYCLE configuration at the major. The pitch angle falls somewhere between 55* and 60* (hand-polishing may have altered this slightly).

The pin was an 11 1/2 tpi, with a major of 0.346" - 0.348" (after polishing), and a minor of about 0.270" Live tooling with a lightly radius thread mill will easily provide a workable female thread, though I would recommend running a few test pieces to get it just right.

TW

I appreciate the insight. I made a shaft for a local bludworth owner. I made the insert on my cnc machine. Actually, I made several inserts to find a good tolerance. One insert would fit nicely on one of his blud cues but be too tight on another. It seemed to me there was about a .005 variance between the pins.
 
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