I've recently been running many jobs with bastard sized threads that are not found on most Tap Drill Charts. As you may know, finding the tap drill size for a #10-64 tap may be a bit of a challenge.

My solution? Create a 'chart independant' application that will calculate the required tap drill size given the tap's major dia, the desired percentage of thread, and the TPI or Pitch of the tap.

It will calculate for Inch Cut and Inch Form, as well as Metric Cut and Metric Form taps.

There are 2 different downloads; The small one is just the executable, for those that already have the VB6 Runtime libraries, and the larger one has an install program. They can be found at cadcam's FTP site under Unspecified Uploads as Tap Drill Calculator.zip and Tap Drill Calc Setup.zip.

Enjoy it and please post a comment if you try it out.

'Rekd

directly, note that you MUST have the VB6 Runtime libraries to run this. Otherwise, download the setup package from the FTP site.

Matt,

I think it's a neat little program. As you may remember, I also wrote a thread data program (inside ME Consultant), so I find such things to be interesting.

A couple of comments:

There's room for a little "Calc" button to be a mouse-driven equivalent of the Enter key, which would feel better to me. Not a big deal, though.

Even though you don't need a tap drill chart to calculate the drill diameter for any size thread (good), your program outputs diameter data. Won't you still need a drill chart to figure out what drill to use (example M12-1.75 tap, 80% thread, requires a 10.18mm drill - off the top of your head, what available drill is nearest to that?)

Thanks for writing it and sharing it with us.


Mike

Originally posted by mrainey
Matt,

I think it's a neat little program. As you may remember, I also wrote a thread data program (inside ME Consultant), so I find such things to be interesting.

A couple of comments:

There's room for a little "Calc" button to be a mouse-driven equivalent of the Enter key, which would feel better to me. Not a big deal, though.

Even though you don't need a tap drill chart to calculate the drill diameter for any size thread (good), your program outputs diameter data. Won't you still need a drill chart to figure out what drill to use (example M12-1.75 tap, 80% thread, requires a 10.18mm drill - off the top of your head, what available drill is nearest to that?)

Thanks for writing it and sharing it with us.


Mike

Thanks, Mike.

While a change in focus on any control will fire a calculation event, a command button for it is a good idea as well.

Also, the main reason behind this program was to eliminate having to call a rep/manufacturer or 'look it up in the bible' to find the drill size for the bastard taps. Having a reference chart for the 'closest match' is a great idea, but in many, (most?) cases it won't produce results that match a drill chart exactally, as the end result is calculated with nearly an infinate number of possible solutions for which drill sizes do not exist.

Mayhaps I'll fix myself a Rum & Coke and see if I can come up with some kind of logic or dig up a function somewhere to find the closest match, 'cuz it really would elimate another annoying step in my job... ;)

Thanks for the tips. Great ideas!

'Rekd

While a change in focus on any control will fire a calculation event

A change in focus (via mouse click or Tab key) doesn't display the recalculated tap drill diameter on my system (XP Home)

Originally posted by mrainey
A change in focus (via mouse click or Tab key) doesn't display the recalculated tap drill diameter on my system (XP Home)

Oopsie.. my bad. :D

Try this one. I added the Calc button and saved settings for the type of tap selected.

'Rekd

Someone asked if it was possible to launch this from the MasterCAM toolbar.

The answer is yes. You'll need to create a new VBScript, with this..

Const THE_FILE = "C:\TapDrillCalculator.exe"

ShellAndWait THE_FILE, False


Then save it, and modify the toolbar via Screen/Config, and point to that VB script. If you don't have 9.1, you can't do it.

'Rekd

p.s., replace the path with yours.. ;)

Looks like a winner to me.

Where is the FTP site found?

Originally posted by motomitch1
Where is the FTP site found?

HERE (http://cnczone.com/forumdisplay.php?s=&forumid=99)

I just tried the calcualtor and I have a recommendation which I think makes a software OK or awsome in my book. Make the tap diameter field able to take decimals or fractions such as 3/8 or 1/4.

Other than that I think you did a great job on the GUI and the function is good.

Originally posted by TAB
I just tried the calcualtor and I have a recommendation which I think makes a software OK or awsome in my book. Make the tap diameter field able to take decimals or fractions such as 3/8 or 1/4.

Other than that I think you did a great job on the GUI and the function is good.

Great idea!

I've added it. I've also added a command line arg that you can use to display the metric hole size in inches instead of milimeters. Use "/in" in the shortcut to do this.

I've also shortened the time the about window stays up, and some other cosmetic changes/debugging.

I'm contemplating on some of the other suggestions, so keep an eye out.

Enjoy!

'Rekd

Excellent! I'm a brand new to this forum, and came at just the right time to find this. I recently "discovered" roll taps and I'm glad to see that you have them covered with this program.

Alex

I just started playing with this program and noticed a problem with Inch Roll form taps. The hole size calculated with the program is quite a bit larger than in the charts I found.

For example, wanting a 1/4" threaded hole, I loaded this data: tap dia. = .2500, % of thread = .65, TPI = 20, checked Roll, giving a hole size result of 0.2498. My charts give a 0.2280 drill size. Might the formula for roll taps be wrong?

The charts I'm looking at are here:
http://www.rose-training.com/rolltapch.pdf and here: http://www.championscrew.com/form_tap_drill.htm.

Alex

I hope the author is still around. I just started playing with this program and noticed a problem with Inch Roll form taps.

The hole size calculated with the program is quite a bit larger than in the charts I found. For example, wanting a 1/4" threaded hole, I loaded this data: tap dia. = .2500, % of thread = .65, TPI = 20, checked Roll, giving a hole size result of 0.2498. My charts give a 0.2280 drill size.

Might the formula for roll taps be wrong?

The charts I'm looking at are here:
http://www.rose-training.com/rolltapch.pdf and here: http://www.championscrew.com/form_tap_drill.htm.

Alex

% of thread = .65

Might the formula for roll taps be wrong?


You entered a decimal point in the percentage (.65 instead of just 65). Remove it and you should get the results you're looking for. :)

Does this cover STI taps as well (cut and formed)?

JP

Does this cover STI taps as well (cut and formed)?

JP

No, but only because I don't know the formula. If you do, let me know. :D

I have no clue at all.

I know Balax has some drill sizes in the back of their catalog, but know of no formula.

JP

I have no clue at all.

I know Balax has some drill sizes in the back of their catalog, but know of no formula.

JP

I'm thinking about adding it as a database function instead of a formula. It will surely make the app slower.

Meh.

Hi friends,

I have to machine M50x1.5-6e thread on the OD. I can't understand the "6e". What it is mentioning? Is it a standard? If it is a standard of threading, then what tolerance i have to maintain for the major diameter? Is there any standard chart? I came to understand that we have to do EN plating after threading and the "GO" gauge must be able to pass freely. Unfortunately we don't have any idea how to manufacture a "GO" gauge without knowing the major diameter tolerance.

Please help,
Thanks,
Selvaraj,
Chennai.

The 6e is a class of thread. In other words, it more closely defines the thread's shape and size. A quick search in the machinist bible should tell you the specs.

hello all,
thanks for any help as i'm new to CNC.
i would like to know how to write g-code to tap a 2-56 thread.
speed and feed? 75% thd. i can't for the life of me find the calculation
for the speed and feed.
again, thanks for any help.

Kenneth

I ired the link for the FTP site b ut it failed. Could someone redirect me or just provide the link to the latest version with the full installer?

Evan

I love it especially with the calculate button, I was wondering would you let me recompile in with NS basic and make it work on PDA, PalmOS and WIN CE? if so let me know and I will get together with you.

Evan, the link in post 12 is the most recent.

http://www.cnczone.com/forums/showpost.php?p=20458&postcount=12

I don't think I made an installer for it. You'll need the VB6 Runtime Library to use it.

http://www.microsoft.com/downloads/details.aspx?FamilyId=7B9BA261-7A9C-43E7-9117-F673077FFB3C&displaylang=en

You should download the exe and try to run it before you install the library. Meantime, I'll dig up the source and build an installer when I get time.

frog, PM me with contact info.

I have been busy with school I will have a break soon, just finishing up my masters and am tired of the keyboard, if you email me the formulas that you are using I will use that or the source code what ever you are comfortable with should only take me a couple of hours, but would be sweet for everyone including myself to have in your pocket, I was also thinking about adding a speed chart for the lathe and mill to it, just an idea. if that is ok with you.

hello:

All tap drill sizes can be found in normal calculator as follows:

Divide 1/ pitch of the tap & subtract the answer from the major diameter of the tap and go to the nearest nominal drill size.

Example: 3/8 16 tap 1/16 = .062

.375 - .062 = .312 = Tap drill size

Works for all taps English & Metric

tinkertoy 41

How about the pilot dia for roll taps:

I use:
Major dia - .0068 * % of thd * pitch = pilot dia
or for 65% thd:
Major dia - (.442*pitch) = pilot dia

Adjust for "H" level if needed for plating:
Add to Major dia
Imperial-
H3=+.0005
H4=+.001
H5=+.0015
H6=+.002
H7=+.0025
Metric-
D3=+.0005
D4=+.001
D5=+.0015
D6=+.002
D7=+.0025
Note that minor dia will increase for plating allowance this way(nuts)

I forgot about this thread, I will put something together for palm OS if anyone is still interested, I have been busy teaching engineering and IT, as well as upgrading a Boss 5, I however will make some time, I will hopefully get a beta version up soon.