Help with (screw) hole tapping

[Dario]

I am planning on making my own turnigs tools (with replaceable bits) and need a few help.

I have a bit that have a 0.172" hole (almost exactly 11/64").
What size tap will be ideal for it?

How do I determine the right drill bit to use for any particular tap size?

I noticed that I can have various no of thread...on hand tapping is more thread better or not? Note that in most cases, I will only have 1/4" deep/thick of threading on what I will make and in my mind I am leaning towards more thread (tpi) right or wrong?

I will be using cold rolled steel and some chrome vanadium steel rod (this may be a bit of a challenge but we will see). Again, I am thinking that it is easier to hand tap with more tpi (because it equates to smaller teeth size)...right or wrong?

Any good source for taps? I've been watching a few at eBay but not sure about the size I will go after yet.

If you know of a good site where I can read about this...I will appreciate it a lot. Any additional info before I venture to this will also be appreciated a lot.

Thank you.

 

[guts]

Dario,if you are using standard threads(sae), before you buy any taps shoot me an e mail on the size you need,might be able to help you out.

 

[Ron in Drums PA]

On most taps the right drill bit size is engraved on the side of the tap.

You'll need a minimum of four threads in a hole. (more the better)

 

[Nolan]

If you need # drill size info let me know.
Nolan


INCH TAP DRILL SIZES
Recommended tap drill sizes (for approx. 75% thread)

INCH SIZES - NATIONAL COARSE
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
#1-64 #53
#2-56 #51
#3-48 5/64"
#4-40 #43
#5-40 #39
#6-32 #36
#8-32 #29
#10-24 #25
#12-24 #17
1/4-20 #7
5/16-18 F
3/8-16 5/16
7/16-14 U
1/2-13 27/64
9/16-12 31/64
5/8-11 17/32
3/4-10 21/32
7/8-9 49/64
1"-8 7/8
1-1/8-7 63/64
1-1/4-7 1-7/64
1-1/2-6 1-11/32
1-3/4-5 1-35/64
2"-4-1/2 1-25/32
----------------------------
INCH SIZES - NATIONAL FINE
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
#0-80 3/64"
#1-72 #53
#2-64 #50
#3-56 #46
#4-48 #42
#5-44 #37
#6-40 #33
#8-36 #29
#10-32 #21
#12-28 #15
1/4-28 #3
5/16-24 I
3/8-24 Q
7/16-20 W
1/2-20 29/64
9/16-18 33/64
5/8-18 37/64
3/4-16 11/16
7/8-14 13/16
1"-14 15/16
1-1/8-12 1-3/64
1-1/4-12 1-11/64
1-1/2-12 1-27/64
1-3/4-12 1-43/64
2"-12 1-59/64
----------------------------

TAPER PIPE SIZES - NPT
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
1/8-27 R
1/4-18 7/16
3/8-18 37/64
1/2-14 23/32
3/4-14 59/64
1"-11-1/2 1-5/32
1-1/4-11-1/2 1-1/2
1-1/2-11-1/2 1-47/64
2"-11-1/2 2-7/32
2-1/2-8 2-5/8
3"-8 3-1/4
3-1/2-8 3-3/4
4"-8 4-1/4
----------------------------
STRAIGHT PIPE SIZES - NPS
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
1/8-27 S
1/4-18 29/64
3/8-18 19/32
1/2-14 47/64
3/4-14 15/16
1"-11-1/2 1-3/16
1-1/4-11-1/2 1-33/64
1-1/2-11-1/2 1-3/4
2"-11-1/2 2-7/32
2-1/2-8 2-21/32
3"-8 3-9/32
3-1/2-8 3-25/32
4"-8 4-9/32
----------------------------



METRIC TAP DRILL SIZES
Recommended tap drill sizes (for approx. 75% thread)

METRIC COARSE SIZES
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
1mm x .25 .75mm
1.1 x .25 .85
1.2 x .25 .95
1.4 x .3 1.1
1.6 x .35 1.25
1.7 x .35 1.3
1.8 x .35 1.45
2 x .4 1.6
2.2 x .45 1.75
2.5 x .45 2.05
3 x .5 2.5
3.5 x .6 2.9
4 x .7 3.3
4.5 x .75 3.7
5 x .8 4.2
6 x 1 5
7 x 1 6
8 x 1.25 6.8
9 x 1.25 7.8
10 x 1.5 8.5
11 x 1.5 9.5
12 x 1.75 10.2
14 x 2 12
16 x 2 14
18 x 2.5 15.5
20 x 2.5 17.5
22 x 2.5 19.5
24 x 3 21
27 x 3 24
30 x 3.5 26.5
33 x 3.5 29.5
36 x 4 32
39 x 4 35
----------------------------
METRIC FINE SIZES
----------------------------
TAP DRILL
SIZE SIZE
----------------------------
4 mm x .35 3.6mm
4 x .5 3.5
5 x .5 4.5
6 x .5 5.5
6 x .75 5.25
7 x .75 6.25
8 x .5 7.5
8 x .75 7.25
8 x 1 7
9 x 1 8
10 x .75 9.25
10 x 1 9
10 x 1.25 8.8
11 x 1 10
12 x .75 11.25
12 x 1 11
12 x 1.5 10.5
14 x 1 13
14 x 1.25 12.8
14 x 1.5 12.5
16 x 1 15
16 x 1.5 14.5
18 x 1 17
18 x 2 16
20 x 1 19
20 x 1.5 18.5
20 x 2 18
22 x 1 21
22 x 1.5 20.5
22 x 2 20
24 x 1.5 22.5
24 x 2 22
26 x 1.5 24.5
27 x 1.5 25.5
27 x 2 25
28 x 1.5 26.5
30 x 1.5 28.5
30 x 2 28
33 x 2 31
36 x 3 33
39 x 3 36

 

[Dario]

Thanks guys!

Looks like I may go with #10-24 or #10-32

I will check out what size machine grade screws I can get locally/easily then find the taps.

I appreciate all the help...THANKS!!!! []

 

[Paul in OKC]

Dario, a 10-24 is basically a 3/16 diameter. You might need to go to an 8 size. Take a 10 size screw and see if it fits in the hole.

 

[Monty]

Too bad you can't make it to Houston this weekend, I'd load you up with everything you need.

 

[Dario]

Originally posted by Monty
<br />Too bad you can't make it to Houston this weekend, I'd load you up with everything you need.

[B)][][xx(]

...BUT!...I'm sure those can be shipped [] Let me know, we surely can get some trade going. [][]

 

[Dario]

Originally posted by Paul in OKC
<br />Dario, a 10-24 is basically a 3/16 diameter. You might need to go to an 8 size. Take a 10 size screw and see if it fits in the hole.

Thanks Paul,

I will check this tomorrow...bring my bit to HomeDepot. Don't have a 10 size screw here (I might but I just don't know).

 

[Monty]

Originally posted by Dario
<br />

Originally posted by Monty
<br />Too bad you can't make it to Houston this weekend, I'd load you up with everything you need.

[B)][][xx(]

...BUT!...I'm sure those can be shipped [] Let me know, we surely can get some trade going. [][]

email sent

 

[guts]

Dario,they should be there friday.

 

[Dario]

Thanks Bill and Monty!

I will be posting my "creation" (probably a mangled piece of steel that somewhat resembles a turining tool) when I have one fabricated. [][}]

 

[Ron in Drums PA]

I was just thinking

Davis Ellsworth's tool bits are just CA glued into a hole, no set screw. When he needs to remove a bit he uses a torch to heat the tip and with a pair of pliers just yanks the bit out.

 

[Dario]

Originally posted by Ron in Drums PA
<br />I was just thinking

Davis Ellsworth's tool bits are just CA glued into a hole, no set screw. When he needs to remove a bit he uses a torch to heat the tip and with a pair of pliers just yanks the bit out.

Ron,

I know about this but I want to make some that uses round discs and teardrop scraper anyway so decided on making them all with screws.

Checked some local auto store here, can't find the small (#8 and #10) allen wrench driven set screws [B)] They do carry the 1/4-20. Time to hunt online!

 

[Monty]

Originally posted by Dario
Checked some local auto store here, can't find the small (#8 and #10) allen wrench driven set screws [B)] They do carry the 1/4-20. Time to hunt online!

I'll check my stash of allen screws tonight. I have zillions of them in various sizes.

 

[Ron in Drums PA]

Originally posted by Dario
<br />Checked some local auto store here, can't find the small (#8 and #10) allen wrench driven set screws [B)] They do carry the 1/4-20. Time to hunt online!

Check Lowes Dario

 

[Dario]

Monty, Thanks do check and see if you can sneak a few with my package.

Ron, Thanks, I will check Lowes and HomeDepot too. I always thought machine grade screws will be better found in auto stores [B)]

Paul, You were right I tried #10 (at the store) and it won't fit the hole. I might still go with #10 though since it is a bit bigger. I will just tap (or drill) the cutter's hole also []