Why can one not use their thread gauges to cut thread?

Not to disquade ( not sure if this a true word ) , you from the purchase of a Machinist Handbook , but try this . If you have a tap supplier you use regularly , ask them to provide you with a thread form and limit book . I have them from Greenfield and OSG . It will give you ALL your limits on 1-4 class ID and OD threads , pitch diameter limits , tap classes ( GH1-5) etc . Best thing is they are free and much easier to read than the handbook . ;)
 
mmcmdl said:
Here is a home project you can easily make . I posted this years back . Maybe the 2nd one down . 60V and Acme thread grinding jig .

https://www.hobby-machinist.com/thr...wn-as-g-or-government-jobs.43057/#post-369160
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Thanks for that.

Sorry to all for posting this in the wrong sub. I honestly looked for the correct subforum for a good while before throwing this in the general chat area. It probably shoulda went into the metrology subforum.

Thanks to all.
-Fixxer
 
fixxer said:
Thanks for that.

Sorry to all for posting this in the wrong sub. I honestly looked for the correct subforum for a good while before throwing this in the general chat area. It probably shoulda went into the metrology subforum.

Thanks to all.
-Fixxer
Click to expand...

I moved it to the General section. It is a machining subject. :encourage:
 
If you have a sample of the thread you are to make it's real simple. Find a small drill that will fit the flanks of the thread. Measure the OD of the thread you are duplicating then measure the distance over the drill and OD. When getting close to finish measure the OD of your part and then measure the distance over the drill and OD. Compare the differences in OD and make appropriate adjustments to your over the drill distance.
 
BtoVin83 said:
If you have a sample of the thread you are to make it's real simple. Find a small drill that will fit the flanks of the thread. Measure the OD of the thread you are duplicating then measure the distance over the drill and OD. When getting close to finish measure the OD of your part and then measure the distance over the drill and OD. Compare the differences in OD and make appropriate adjustments to your over the drill distance.
Click to expand...


Simple yes . Accurate ? NO ! Why ?
 
It is only as accurate as your sample and as close as you can make it. Do most projects require the utmost accuracy? I doubt it.
 
We cut a lot of threads measuring on the fly using spring calipers, these threads were fairly coarse and large diameter, a loose fit did not hurt the application.
 
I problem I had when NOT measuring pitch diameter was making the threads too loose. If you don't have the proper flat on the thread crest it drags in the sample nut, giving the false indication that the thread is too shallow. If this is the case by the time you've deepened the thread enough for the sample nut goes on smoothly, you've cut too deep. Measuring pitch diameter eliminates any guesswork.
 
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