Originally posted by mklotz
View Post
Announcement
Collapse
No announcement yet.
15MM Tap......Drill Size
Collapse
X


Originally posted by mklotz View PostDan,
Some of us are comfortable with math, some aren't. If you like your shop papered with cheat sheets, go for it.
In this day and age, if you have to double check the formula, then you might as well look up the answer too.
"Siri what is the drill bit for 75% engagement of a 15mm thread?"
DanAt the end of the project, there is a profound difference between spare parts and left over parts.
Location: SF East Bay.
Comment

Originally posted by j.bain87 View Post
How much simpler could it be for METRIC ?
Much simpler than that archaic "MONGREL" you dumb yanks want to hang on too.
K.I.S.S.  Keep It Simple STUPID.
...lew...
Comment

Here's an online calculator that I like:
http://theoreticalmachinist.com/TapDrillSizeCalculators
Good for forming taps, too. BTW it appears, from looking at a few examples, that D  .5 X pitch works for form taps at 75%. Has anyone found that to be a generally applicable rule?
Interesting that the calculator defaults to 77%. I've never seen that before.
Comment

Originally posted by danlb View PostMath's not a problem (much). The problem is faithfully remembering the hundreds and hundreds of formulas that one has to use from time to time. Cooking, welding, gardening, painting, machining, electronics, graphics... they all have formulas. And they often have derivative formulas too.
In this day and age, if you have to double check the formula, then you might as well look up the answer too.
"Siri what is the drill bit for 75% engagement of a 15mm thread?"
Dan
Comment

Originally posted by j.bain87 View PostKeep it Simple, eh.
How much simpler could it be for METRIC ?
Much simpler than that archaic "MONGREL" you dumb yanks want to hang on too.
K.I.S.S.  Keep It Simple STUPID.
Comment

If you cant access tap charts online, or beg steal or borrow old ones, you may not want to play with macbine tools.. The info cor 95 percent of taps is very accessible.
Besides tap size formula is a 1.5 out of ten ...simple stuff compared to say gear cutting or hobbing.
Comment

Originally posted by Lew Hartswick View PostWhat is the tap drill for a 3/8  16 thread? Well a 16 tpi is 1/16 of an inch pitch and 3/8"  1/16" is 5/16 Well how about that . If you can't do that you probably shouldn't be trusted with any power tools.
...lew...
Stated perfectly.
Why do all you nutpicks insist on complicating things??
All math is easy. I just needs to be explained the right way.
That is the huge problem with our schools.
Subjects are taught with an agenda of some sort,
and learning is not considered.
DoozerDZER
Comment

Marv,
I know you are well versed in math and did not mean to imply that you do not know how to use a four banger.
I wasn't trying to make your formula more accurate, I was trying to make it easier to remember when you are out in the shop and have grease and chips on your hands and under the nails. For myself, I do find the whole number 75 easier to remember than the decimal number 0.013. Memorization was never my strong suit.
When I started the post, I was going to say that the 75 factor in the denominator was more accurate than the 0.013 in the numerator, but I did a quick, back of the envelope (literally) calculation and it seemed to indicate that the 0.013 factor was actually a tiny bit more accurate. But given the facts that you can almost never get an actual drill that is the calculated size and the other known fact that drills will make holes that are somewhat larger than the drill size (but there is no accurate way to know how much larger), the small amount of difference between them does not amount to a tinker's damn. I did not bother to confirm that quick calculation because either one is definitely close enough. 1/75 = 0.0133333... so the difference is really small. I believe I erased all reference to the 75 factor being more accurate from my post.
Originally posted by mklotz View PostDan,
Some of us are comfortable with math, some aren't. If you like your shop papered with cheat sheets, go for it.
A chart will never be complete or, alternatively, if it is it will be too big and unwieldy. An equation covers all cases including "tap drill" sizes for which there are no taps. See if your chart will tell you the size hole to bore for a 2.5  8 thread with 85% DOT.
Paul,
I know how to do the calculation on a 4 banger, thanks very much. I use an RPN which makes it much simpler yet.
The difference between 1/75 and 0.013 isn't going to be enough to matter. Drills don't come in sizes that closely spaced and, besides, they don't drill on size, not to mention that the percentage engagement is going to be a guess at best.Paul A.
SE Texas
And if you look REAL close at an analog signal,
You will find that it has discrete steps.
Comment

Originally posted by tom_d View PostHas anyone other than the "dumb yanks" walked on the moon using a better system?Regards, Marv
Home Shop Freeware  Tools for People Who Build Things
http://www.myvirtualnetwork.com/mklotz
Location: LA, CA, USA
Comment

I like a chart because I haven't yet seen a formula the tells me the right letter number or fraction drill bit to reach for. Anybody can do the math for a 5/16 24 and get that the TD should be .271......then what? Faster imo to look at chart for and then reach for an "I" drill....keep the formula for custom sizesin Toronto Ontario  where are you?
Comment

Originally posted by Forrest Addy View PostPick a system of calculation and stick with it. Mix them up and you'll either confuse yourself or screw up the job.
https://www.wired.com/2010/11/1110ma...serverreport/
Comment
Comment