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JF36

JF36

Member
Joined
Sep 25, 2011
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147
Location
Pen Argyl, PA
When using a die how do you tell what diameter you need to turn the stock down to? Mine always end up to small or to big.
 
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Usually the die size is the shaft/rod diameter you want to use. You can turn it undersize a little if the material is a little more difficult to thread. .004" to .010" under. Try slightly smaller each time until happy with the results. Each material is a little different. Lubricate when threading.
 
Curly said:
Usually the die size is the shaft/rod diameter you want to use. You can turn it undersize a little if the material is a little more difficult to thread. .004" to .010" under. Try slightly smaller each time until happy with the results. Each material is a little different. Lubricate when threading.
Click to expand...

Thanks I guess I just have to be a little more careful in my turning
 
Littlemachineshop.com has a printable chart you can print. It shows what diameter to turn to for different materials. Kind of handy to have around. On the home page, in the column on the left, click on Charts(I believe)
 
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dalecamino said:
Littlemachineshop.com has a printable chart you can print. It shows what diameter to turn to for different materials. Kind of handy to have around. On the home page, in the column on the left, click on Charts(I believe)
Click to expand...

Thanks I will look for it
 
you can use your calipers too. Measure the tap on the cutting sections, depending on your calipers increase it a half increment for the die. Turn a tenon to that size and your die should have no problem. If you measure the die with your calipers you may have to decrease a half increment or so depending on where you measure. Also if you are turning acrylics you can match the tenon to the die size if your die is say a 12mm your tenon should be 12mm.
 
Problem is there isn't any thing for metric, I'll look in my Machenriy and I'm sure there is a similar chart in there for Metric threading and drill/ tenon sizes for metric. But the same rules will apply, you may want to expand the Die size a tiny bit, then back off the screw until you get a fit that is in line with what you want. My guess is you would want a thread fit of about 75% , but that may also wind up with a 70% 0r so thread depth.
 
When I started doing these, I did a LOT of searching and read somewhere that for METRIC threads there are two rules of thumb and I have found them extremely helpful and very easy to remember, no complicated formulas to memorize and you don't have to have a chart hung up on the wall.

1. To find the approximate drill size for drilling a hole to tap threads into, subtract the thread pitch from the thread diameter, an example would be using a 9mm x .75mm tap.

Subtract .75 from 9 giving you 8.25mm or .324". Notice I said approximate, these rules were written without regard to specific material and thread clamping engagement ranges from 50% to 75% DEPENDING ON THE APPLICATION AND MATERIAL USED. For this particular thread size I settled on the "Q" (.332") drill bit because I like the results, you may find another size to suit you better.

2. To find the approximate tenon diameter for the die to cut threads on, just use the major diameter of the thread, an example would be using a 9mm x .75mm die.

9mm is .354" so a tenon of that diameter would be approximate. For this particular thread I settled on .360" as a tenon size and am happy with the results.

My advice would be to use these rules to find the approximate sizes then fine tune from there until you find the thread engagement feel that you think is right for your pens. There is NO 100% absolute correct answer for a proper hole or tenon size for metric threads in acrylic or ebonite!
 
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For metric I cut the tenon .2mm smaller than the called for diameter. using a m10 x .75 as an example
For A 10mm thread would it be 10mm-.2mm =9.8mm
To determine the hole I subtract the pitch from the diameter and then add .15mm.
10mm - .75 =9.25 then add the .15mm = 9.4 hole

Most tap and dies sets dont cut 100 % of the depth thats listed. this gives me a smooth fit in almost all my applications so far.
 
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