Disston Bevel Gauge - locking rod thread type ?

[pianoman]

HI, I've been grubbing around at the local junk...........er antique shop again. I picked up this Disston bevel gauge for a couple of dollars. The thread on the locking rod (?) is damaged and the other end is cactus too. I would like to make a new rod for it . Does any one know which thread gauges Disston used ? Or can someone narrow it down to a couple of types? I am trying to avoid buying 6 or 7 thread gauge sets just to find out what it might be . I have no idea of the age of this thing I'm sorry. I've added a photo or two just in case my descriptions of the thing I am talking about is not clear.

Thanks ,

Alasdair

[Bohdan]

Take it in to a nut & bolts shop. Tell them that it's US made and I'm sure that they can match the thread and supply you with a suitable die.

[Treecycle]

Hard to tell from a photo as to which diameter it is. Looks like 1/4", but maybe 3/16". If it is it will be 3/16" or 1/4" UNC or BSW but a nut of either type will fit even though there is a slight difference in the thread angle which won't make any difference for what it has got to do in this case. The only diameters that these threads are not interchangeable is 1/2" and 1" as they have different TPI's to each other but that won't be a problem here.
Must be a common problem judging by this ad.

[russ57]

Hard to tell from a photo as to which diameter it is. Looks like 1/4", but maybe 3/16". If it is it will be 3/16" or 1/4" UNC or BSW but a nut of either type will fit even though there is a slight difference in the thread angle which won't make any difference for what it has got to do in this case. The only diameters that these threads are not interchangeable is 1/2" and 1" as they have different TPI's to each other but that won't be a problem here.
Must be a common problem judging by this ad.

If that is 1/4, then the handle is nearly 1 1/2".
Id expect more like 1/8".


Can you take a close up with a ruler. The thread pitch should give it away.




Russ

[pianoman]

Russ
The locking rod has a diameter 13/64" . Although this is measured with a metric micrometer (5.13mm) and then converted online . I can't find my inch micrometer at the moment. As far as I could work out the thread is likely to be UNC . There is 0.71 of an inch of thread and there are 17 threads in it which works out at 24TPI according to the UNC standard there are 24 TPI which fits more or less. the only thing is this puts it between #10 - #12 major diameter sizes . To qualify I am 90% certain of the rod diameter, but I am not sure of the exact number of threads because of (lack of) experience and the damage to the threaded end. I am treating this as a first time experience in cutting new threads and making an attempt at rescuing a tool that might otherwise be thrown away. Do you think my estimations are close? The only thing that is throwing me is that neither Whitworth or UNC have an thread count given for 13/64" Measuring error? . Enough story, here's a pic.lock-rod_thread_ruler-16ths.jpg Alasdair

[Bohdan]

There used to be a 7/32" x 24 UNC thread which would be close to your measurements and is now obsolete.

This size may be unobtainable so I would suggest using a #12 x 24 UNC which is almost the same.

[dubrosa22]

I have no idea of the age of this thing I'm sorry.

Sometime after 1907 according to the patent date in the 1918 Disston catalogue:

IMG_20180314_064007.jpg

V

[IanW]

There used to be a 7/32" x 24 UNC thread which would be close to your measurements and is now obsolete.

This size may be unobtainable so I would suggest using a #12 x 24 UNC which is almost the same.

7/32" is a pretty common size on older US stuff, and a bolt is usually nominal size minus some clearance. Tolerances on an item like your locking screw are probably generous, that's most likely what it is. I think Bohdan's suggestion is right on the money, the nominal diameter of #12 is just 2 thou smaller than 7/32" so I doubt you'd notice any difference.

Cheers,

[Chris Parks]

Let me have a look later on, I am sure I recently bought a die that is 13/64 - 24tpi for my router plane adjuster.

[Chris Parks]

I just checked mine and it is 1/4" x 24tpi bought from Ebay

https://www.ebay.com.au/itm/1-4-24-R...72.m2749.l2649