Threading math question….

[MrWhoopee]

For a quick calculation of compound infeed, I use the sides of a 30-60-90 triangle, which are 1,2, √3. Divide the single-depth of the thread by 1.732 (√3) then multiply by 2 to get the compound infeed. Keep in mind that this gives a rough value since we don't set the compound to exactly 30º and the tool does not come to a sharp point. Start checking before you reach the calculated value, if you go all the way you have gone too far.

(Someone please check me on this, still waiting for the coffee to kick in.)

 

[Janderso]

For a quick calculation of compound infeed, I use the sides of a 30-60-90 triangle, which are 1,2, √3. Divide the single-depth of the thread by 1.732 (√3) then multiply by 2 to get the compound infeed. Keep in mind that this gives the rough value since we don't set the compound to exactly 30º and the tool does not come to a sharp point. Start checking before you reach the calculated value, if you go all the way you have gone too far.

(Someone please check me on this, still waiting for the coffee to kick in.)

I made a new folder on my desk top with these calculations.
Thanks man!!

 

[Stephen S]

Hmm, haven’t tried the foam method.

From Subject Received Size Categories
SK Stanley 11:01 AM 119 KB

Like I said . A set is under $15 and will cover the gamet of sizes . They're simple to use also .

 

[RJSakowski]

Back in 2015, I set up a spreadsheet to calculate compound travel based on threading tip radius for all the common inch and metric thread pitches. In the intervening eight years, I haven't referred to it once. My usual method is to turn to the major diameter, blue the surface with a Sharpie, and cut threads until the blue is almost gone. From there, I will advance slowly, checking for fit with a nut or other mating part or measuring the pitch diameter.

If you look at the geometry of an ideal thread, the distance along the flank of the thread to the virtual sharp at the root of the thread is equal to the pitch of the thread minus 1/8th of the pitch. The 1/8th is because the top of the thread is truncated. It is fairly simple to calculate 7/8th of the thread pitch and that is the compound travel, neglecting tip radius. The tip radius comes into play because the usual practice it to touch of the threading tool on the diameter and measure travel from there. So for a 1mm pitch thread, the compound travel would be .875mm, neglecting tip radius.Taking tip radius into account, the compound travel will be decreased by slightly more than the tip radius. For a .02mm radius, the approximate compound travel for a 1mm pitch thread would be .875 mm -.02mm = ..855mm. The exact travel is .852mm.

 

[mac1911]

Many of us just go by the major diameter and test the fit with a nut
I do, anyhow

I will do some more threading , Guess im looking for a quick way to get down to “checking for for fit “
Rather than the almost endless stopping and checking I have been doing, lol

 

[Jim F]

A disc mic helps when using wires.

 

[IHinIN]

Maybe try these for holding two of the wires against the mic face. I have a set somewhere in my work toolbox that I have never used so I can’t speak to their effectiveness.

 

[markba633csi]

Usually takes 4-5 passes before the thread even begins to look right- Just have to develop an eye for
when to start checking for fit
But yeah, it can be tedious

 

[toprecyler]

Maybe try these for holding two of the wires against the mic face. I have a set somewhere in my work toolbox that I have never used so I can’t speak to their effectiveness. View attachment 474311

These work fairly well. I use them when I use the wires.

Most of the time, I use the nut or mating part as the guage. But if I do not have the mating part, I will calculate the pitch Diameter from the directions with the thread wires, and go from there. I have not had a job come back with the threads not working.

Couple tricks to remember with thread wires, Clear your chip pan before using. If you drop a wire, will be easier to find without a lot of chips.
You will drop a wire eventually.

Place a board, or piece of paper so wire can fall on that. Or maybe one of the Cheap HF magnet dishes.

Sent from my iPhone using Tapatalk

 

[Nutfarmer]

On most thread sizes I forget the 29.5 degree setting and just feed in with the cross side. I know such sacrilegious actions. The cuter will work like a form tool. When there are threads corser than say 1/2. 13 I will still be proper and feed the tool in at 29.5 degrees. Most of the time for my work if the nut fits it is good. If it is special I will use the three wires or a thread mic. That is only about ten percent of the time. I am working on farm equipment not for NASA.