Looking for a good reliable Acme thread drill/tap chart

[WobblyHand]

I just found this: https://www.engineersedge.com/hardware/acme-threads-calculator.htm

It calculates the major, minor and pitch diameters of any (nearly any) standard acme thread, both internal and external. Just enter 0.625" and 10 TPI and out come the answers. Unfortunately I can't just cut and paste the answers. It has values for the different thread classes. Hope this helps.

It comes up with 0.5250" for minor diameter min (internal) for all classes. Minor diameter max (internal) is 0.5300". Closest fit standard drill is 17/32" (0.5312"), whereas 13.2mm (0.5197") is just under.

 

[ltlvt]

Wires are for if you are measuring the pitch diameter of a V type thread. Acme threads have a flat top, flat bottom. In your case the major diameter is 0.625”. Use a narrow measuring tool (blade mike, or probably the narrow jaws of most any calipers) measure from the crest to a valley, subtract that from the major diameter = thread depth relative to the center line. Then take major diameter - 2x the thread depth, there is your minor diameter. The tap drill is a “scosh” larger than the minor diameter.

Thanks for mentioning the difference between Acme and V thread. I will try your method. Does my scosh-ometer need to be in metric or imperial ? LOL just kidding.

 

[ltlvt]

See Woodchucker above... That's the most complete...

I don't have the book.

 

[SeattleJack]

Well so far I have downloaded about a Gazillion charts and none of them give me the drill size for a 5/8" -10 TPI Acme thread. All of them want me to use a 5/8 x 8 tpi.
I am at the point of drilling and tapping the cross hole for the cross-slide nut. Thanks in advance. I'm thinking I saw somewhere that the drill size was .531 to .535. I just don't want to trash all the hard work and head scratching I have done to get me this far.

The proper minor diameter for the 5/8-10 ACME thread is .525-.530. The best available standard drill would be 17/32 or .531 so you are safe to proceed.

 

[WobblyHand]

The proper minor diameter for the 5/8-10 ACME thread is .525-.530. The best available standard drill would be 17/32 or .531 so you are safe to proceed.

Yes, same as what I wrote in post #11. Thanks for confirming.

 

[verbotenwhisky]

ltlvt, See if this is what you are looking for.​

This information came from the following which manuscript which was recommended on one of Stefan Gotteswinter's videos. I use this book more than I use the "Machinery's Hand Book".




5/8" x 10TPI is likely a single point thread but the you might be able to bastardize the math in the chart above to get what you need.

 

[ltlvt]

ltlvt, See if this is what you are looking for.​

View attachment 499574

This information came from the following which manuscript which was recommended on one of Stefan Gotteswinter's videos. I use this book more than I use the "Machinery's Hand Book".


View attachment 499575

5/8" x 10TPI is likely a single point thread but you might be able to bastardize the math in the chart above to get what you need.

Great info Whiskey. I guess I will just use 5/8-8 tpi as my reference. Maybe charts do not specify 5/8-10 tpi because they are the same as 5/8-8 tpi. I downloaded a pretty good book from Kindle last night. Paper books are so hard for me to read without a magnifier so most of my reading is now done electronically. Pluss I have a laptop and wifi in my shop so I can usually email myself any links and save them to my Shop File in Yahoo mail. Saving the links to my email makes them available anywhere I am via my phone. This way if any of my devices crash I still have access to the information without renting space in the Cloud.

 

[verbotenwhisky]

Great info Whiskey. I guess I will just use 5/8-8 tpi as my reference. Maybe charts do not specify 5/8-10 tpi because they are the same as 5/8-8 tpi. I downloaded a pretty good book from Kindle last night. Paper books are so hard for me to read without a magnifier so most of my reading is now done electronically. Pluss I have a laptop and wifi in my shop so I can usually email myself any links and save them to my Shop File in Yahoo mail. Saving the links to my email makes them available anywhere I am via my phone. This way if any of my devices crash I still have access to the information without renting space in the Cloud.

I use my phone as a computer that can make phone calls so I understand your point.

 

[WobblyHand]

Great info Whiskey. I guess I will just use 5/8-8 tpi as my reference. Maybe charts do not specify 5/8-10 tpi because they are the same as 5/8-8 tpi. I downloaded a pretty good book from Kindle last night. Paper books are so hard for me to read without a magnifier so most of my reading is now done electronically. Pluss I have a laptop and wifi in my shop so I can usually email myself any links and save them to my Shop File in Yahoo mail. Saving the links to my email makes them available anywhere I am via my phone. This way if any of my devices crash I still have access to the information without renting space in the Cloud.

The dimensions are not the same between 5/8-8 and 5/8-10. For one the thread depth is different on 8 TPI vs 10 TPI.

The proper minor diameter for the 5/8-10 ACME thread is .525-.530. The best available standard drill would be 17/32 or .531 so you are safe to proceed.

The formulas that @verbotenwhisky used in post #16 are correct. You need to use the formulas, not the table, if you expect to have your parts come out correct for 5/8-10.

 

[WobblyHand]

@ltlvt here is a picture of a spreadsheet I made for you, using the formulas.

This spreadsheet should work for all sizes. (Full disclosure, I only tested it on 5/8-8 and 5/8-10!) If you want a copy of the spreadsheet I can attach that. (I hope so!) This does not give tolerances, but that is what I have so far.