Thread count question

Cue Crazy

Cue Crazy

AzB Silver Member
Silver Member
My buddy has started replacing some of the older dufferins as they get broken with the valley supremes. I had one with a cracked ferrule. I noticed that They have a tenon that has a shoulder half the lenth, and the end/face half has threads. There are around 5/16 dia., and I laid a 5/16-14 thread on top of them, which laid in there almost perfect, but it seemed when trying to use a 5/16-14 that it wasnt' the exact same thread. The dia. seemed alright, but the threads cocked just a hair to one side and snugged alittle. I tried relieving the female a little by boring them a bit, but that didn't really help either. The glue is cleaned well so no problem there either. I guess the thread count could be used with only half a run, but the would rely on the center shoulder, shoulder faces, and so they would be fighting against each other.

Anyway, just wondering if anyone knows off the top of their head what the thread count of these ferrules are? I don't know If they are a bastard thread, or possibly metric? Aren't they imported from over seas these days?

Thanks Guys, Greg
 
There is a metric size that hits almost right on 5/16-20. Not sure if that would be it or not. 8mm is about .315" so it is a 8mm by 1.25 or something like that. I used to have to buy that size bolt and I can't remember what it was called if not 8 x 1.25.
 
cueman said:
There is a metric size that hits almost right on 5/16-20. Not sure if that would be it or not. 8mm is about .315" so it is a 8mm by 1.25 or something like that. I used to have to buy that size bolt and I can't remember what it was called if not 8 x 1.25.
Click to expand...


Thanks Guys,

It's not a standard 5/16-18, that was the first one I checked. A 20 count would be way too fine also. It's coarser then that. I stuck a 5/16-14 JP pin on top of the threads on the tenon, and the threads of the pin laid in as if that was the correct count, but when I made a ferrule up with that count, It just felt like it was a smidge off. Not much at all though, It was really close. The diameter didn't feel too tight either, so I don't believe that was My problem. It actually had Me a little baffled. I have a couple of thread gauges. I'll check it next time and see if I can figure it out.

I'll try to figure it out next time, and pass it on if I do. I'm sure it would be good info to know for anyone that does alot of house work.

Anyway, I do apprietiate you guys trying to help, Thanks Greg
 
I would be interested to know this information. I have replaced 6 of those ferrules in the last 2 weeks. Neither a 5/16x14 or 5/16x18 is a true fit to the threads on the tenon, although either can be made to grab enough to snug up to the shoulder.
 
Sounds like a 8mm by 1.75 if it is metric. That would be real close to 14 tpi but not exactly. It would only be off by about .002" or .003" per thread.
Here is a chart of inch and metric conversions:

PITCH CONVERSION TABLE
(Left) APPROXIMATE THREADS per INCH
(Middle) PITCH mm
(Right) APPROXIMATE THREADS per cm

338 1/2 0.075 133.33
317 1/2 0.08 125.00
282 1/4 0.09 111.11
254 0.1 100.00
203 1/4 0.125 80.00
169 1/4 0.15 66.67
145 1/4 0.175 57.14
127 0.2 50.00
101 1/2 0.25 40.00
84 3/4 0.3 33.33
72 1/2 0.35 28.57
63 1/2 0.4 25.00
56 1/2 0.45 22.22
50 3/4 0.5 20.00
42 1/4 0.6 16.67
36 1/4 0.7 14.29
33 3/4 0.75 13.33
31 3/4 0.8 12.50
28 1/4 0.9 11.11
25 1/2 1 10.00
20 1/4 1.25 8.00
17 1.5 6.67
14 1/2 1.75 5.71
12 3/4 2 5.00
10 1/4 2.5 4.00
8 1/2 3 3.33
7 1/4 3.5 2.86
6 1/4 4 2.50
5 3/4 4.5 2.22
5 5 2.00
4 1/2 5.5 1.82
4 1/4 6 1.67
 
Last edited:
the closest I can come up with without actually measuring it is 8x1.75 which is a bastard thread. Is the 5/16 x 14 too coarse or fine?
Chris where did you find that.. I have the trusty bible : 27th Machineist Handbook.
 
Last edited:
cueman said:
Sounds like a 8mm by 1.75 if it is metric. That would be real close to 14 tpi but not exactly. It would only be off by about .002" or .003" per thread.
Here is a chart of inch and metric conversions:

PITCH CONVERSION TABLE
(Left) APPROXIMATE THREADS per INCH
(Middle) PITCH mm
(Right) APPROXIMATE THREADS per cm

338 1/2 0.075 133.33
317 1/2 0.08 125.00
282 1/4 0.09 111.11
254 0.1 100.00
203 1/4 0.125 80.00
169 1/4 0.15 66.67
145 1/4 0.175 57.14
127 0.2 50.00
101 1/2 0.25 40.00
84 3/4 0.3 33.33
72 1/2 0.35 28.57
63 1/2 0.4 25.00
56 1/2 0.45 22.22
50 3/4 0.5 20.00
42 1/4 0.6 16.67
36 1/4 0.7 14.29
33 3/4 0.75 13.33
31 3/4 0.8 12.50
28 1/4 0.9 11.11
25 1/2 1 10.00
20 1/4 1.25 8.00
17 1.5 6.67
14 1/2 1.75 5.71
12 3/4 2 5.00
10 1/4 2.5 4.00
8 1/2 3 3.33
7 1/4 3.5 2.86
6 1/4 4 2.50
5 3/4 4.5 2.22
5 5 2.00
4 1/2 5.5 1.82
4 1/4 6 1.67
Click to expand...


Thanks Chris, maybe that's the one. The 14 laid in there pretty well, so it's got to be close. It's much coarser then 18 though.
 
RocketQ said:
the closest I can come up with without actually measuring it is 8x1.75 which is a bastard thread. Is the 5/16 x 14 too coarse or fine?
Chris where did you find that.. I have the trusty bible : 27th Machineist Handbook.
Click to expand...


I'm not really sure, I was in a rush and just slapped It up there to see how close It was. I may venture to say coarser, but could not be for sure, and It wouldn't be by much if so. Next time I get one in that needs a ferrule, I'll check It out better to see.:) Greg
 
You might be able to get away with cutting the internals of the ferrule bigger. You would have to get a 8 x 1.75 made special.
 
RocketQ said:
the closest I can come up with without actually measuring it is 8x1.75 which is a bastard thread. Is the 5/16 x 14 too coarse or fine?
Chris where did you find that.. I have the trusty bible : 27th Machineist Handbook.
Click to expand...
I just did a search for Metric Thread conversions and found that.
 
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