The triple tap and die Diameters to use

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mredburn

mredburn

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I have received a few requests for the sizes that are needed for the triple tap and die sets that were sold in the first group buy and the current group buy.

I talked with Mike Roux to double check what he used against my findings and it comes down to this.

The hole is made with a 7/16 drill bit for the female threads and the outer diameter for the male threads is .465 or 11.8mm

I Drill and tap a piece of material to use as a chaser die to check the threads on Pieces I make later. usually a 1/4 (6mm) thick 3/4 (18mm) round piece of brass Ive cut off some brass stock. You can use other material. Then when I make the male threaded piece I can use to to check how well the threads are formed without busting up the cap.

I then make a male test piece and try two together this lets me adapt the die to match the tap. There is a set screw in the die that by tightening or loosing it will make the threads cut slightly larger or smaller. This way you can make the kind fit that suits you best.


IF you have any different answers or any question feel free to post them.
There are a lot of members that have either bought in the first buy or are buying in the second one that could use this information.

Hope this helps

Mike
 
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mredburn

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You turn the outer diameter of the rod to 11.8mm or .465. I have edited the original post so hopefully it is a little clearer. Like mud. Sorry about that
 
skiprat

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Not to be picky, but are you guys sure?
The tap and die threads are metric M12 x 0.8
The theoretical perfect hole would therefore be 11.2mm (12 subtract 0.8)
This is called the minor diameter. The teeth on the tap will then cut the threads inside the hole at 0.8mm deep. The bottom of these female threads will be the major diameter.
The theoretical perfect turned diameter would be 12mm.
This is called the major diameter and this surface will be the peaks of the threads.
Once you run the die over this shaft, the teeth on the die will cut the threads at 0.8mm. The bottom of these male threads is the minor diameter

Remember that a hole will ALWAYS be a bit bigger than the drill size.

Aim for perfect sizes and the polishing will make for a nice fit without being sloppy. :wink:
 
Timebandit

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skiprat said:
Not to be picky, but are you guys sure?
The tap and die threads are metric M12 x 0.8
The theoretical perfect hole would therefore be 11.2mm (12 subtract 0.8)
This is called the minor diameter. The teeth on the tap will then cut the threads inside the hole at 0.8mm deep. The bottom of these female threads will be the major diameter.
The theoretical perfect turned diameter would be 12mm.
This is called the major diameter and this surface will be the peaks of the threads.
Once you run the die over this shaft, the teeth on the die will cut the threads at 0.8mm. The bottom of these male threads is the minor diameter

Remember that a hole will ALWAYS be a bit bigger than the drill size.

Aim for perfect sizes and the polishing will make for a nice fit without being sloppy. :wink:
Click to expand...

I understood all this before i cut my first thread. The only problem was that is i, like many others on here im sure, dont have a 11.2mm drill readily available without online purchase, but what i do have is a 7/16, which im sure everyone on here has, which is really really close to an 11.2mm. Is it perfect no, but it is so close that it work until i get anal enough to order me an 11.2.

With the die, i tried a 12mm at first but kept cracking threads, even if i had the die all the way open.A t least in my test subject, which happened to be PR, which might not have been the best to experiment with, but i knew that it was brittle and thought that this would be a good material to get things dialed in. Now im not saying that wasnt user error, but because of that, i made a few adjustments and right now i actually turn my tenon to 11.6 and im finding that so far i am happy with the threads. This might be the reason why some use a smaller tenon. Gives a little wiggle room. I might go up in size on the tenon later, but for now this has worked for me. Im sure when i get a little more experience with it i might even buy the right drill bit:biggrin:
 
KenV

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One point -- "theoretical perfect" is seldom the "practical perfect" unless you are really good and using a CNC thread mill.

Unless critical, I was taught to leave the tips of the threads flat if tear out and breakage was a problem -- strength was not an issue, and even flat top threads look better than chipped, torn out threads.



Looks like the 7/16 will give a bit of "grace" for avoidance of chip and tearout.
 
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I can confirm these numbers based on my own trial and error. I independenty arrived at 11.8mm for the male threads (Wish I would have had this info up front :). Any larger and the threads dont cut smooth. I even have been as small as 11.7mm (oops) and they work fine. 7/16 drill for female threads works great for me. - I dont really see the need to purchase the 11.2mm bit.

My experience is with cast alumilite.
 
skiprat

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Don't get me wrong folks. I agree totally about the 'theoretical and practical' issues. I said exactly the same thing in this thread ages ago :wink:
Post 21 to be precise.

My point was that you should aim for the largest diameter that works and the smallest drill that works. This was because of the thread recently that said they were worried about polishing the threads as that would make the fit even sloppier than it was.
There are several tricks to prevent pr cracking when threading and still leaving it at the 'correct' size.

Try warming the pr and tooling in hot water for a few minutes before starting the threading. Everyone knows that cold plastic is FAR more brittle than warm plastic:wink:
 
mredburn

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I find that the 7/16 drill measures less than 11.2 and the next size up is 29/64 which measure 11.4. With the inherent slop of a drill bit the 7/16 should work well for most members.
 
KenV

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No rocks were thown Stephen - You were most clear on the "theoretical" and I wanted to assure that we were also discussing practical. That opens the discussion on tolerances and precision needed for function and appearance.

Good process suggestions - and I will add lubricant may be useful.
 
PenMan1

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KenV said:
No rocks were thown Stephen - You were most clear on the "theoretical" and I wanted to assure that we were also discussing practical. That opens the discussion on tolerances and precision needed for function and appearance.

Good process suggestions - and I will add lubricant may be useful.
Click to expand...

I didn't notice any rocks being thrown in either direction and I really like and find all the post here very useful!
FWIW, I find that PAM cooking spay works very nicely as a lube for cutting threads in PR. It is really slick and less expensive that most "cutting" oils.
 
S

soligen

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My post wasnt intended to be rocks either. Just stating where I landed through trial and error, which works very well for me.

PR I havent been brave enough to try after the intial failures, and feedback from members that is doesnt thread well. May be time to try PR agian. Thanks for the "Warm it up" tip. I'll probably try a hair dryer so I dont have to dis-mount the blank.

Next thing I'm also going to try is a M10 x .75 tap (instead of M10 x 1) for the section. I think the finer threads will put less stress on the blank while cutting, but still be course enough to be strong - just a theory right now. Unfortuately my tool supply place was closed yesterday for the holiday weekend, so that experiment will have to wait.

PenMan1 said:
KenV said:
No rocks were thown Stephen - You were most clear on the "theoretical" and I wanted to assure that we were also discussing practical. That opens the discussion on tolerances and precision needed for function and appearance.

Good process suggestions - and I will add lubricant may be useful.
Click to expand...

I didn't notice any rocks being thrown in either direction and I really like and find all the post here very useful!
FWIW, I find that PAM cooking spay works very nicely as a lube for cutting threads in PR. It is really slick and less expensive that most "cutting" oils.
Click to expand...
 
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