drill size for thread tap?
#1
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i have a few 8mm threads to tap on the rs200 chassis,i have the taps but am unsure what drill size to use.
is there a drill/tap size guide out there?,i have googled but kept coming up with bath taps
cheers
dave
is there a drill/tap size guide out there?,i have googled but kept coming up with bath taps
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cheers
dave
#5
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I usually use 7.2mm
You want the hole to be big enough that the tap then goes in easy, but not so big that there is no thread left. It will vary on the type and thickness of the material.
Drill a smaller hole and try the tap - if it's too hard, go for a bigger hole
You want the hole to be big enough that the tap then goes in easy, but not so big that there is no thread left. It will vary on the type and thickness of the material.
Drill a smaller hole and try the tap - if it's too hard, go for a bigger hole
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#7
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Originally Posted by focusv8
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has all the sizes i need now
dave
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#9
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If you're ever REALLY unsure - just go 1mm under the size of the M
That's not a particularly professional thing to do - just gets you out of a tight spot
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
That's not a particularly professional thing to do - just gets you out of a tight spot
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
#11
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Originally Posted by martin-reyland
Originally Posted by Big Will 85
If you're ever REALLY unsure - just go 1mm under the size of the M
That's not a particularly professional thing to do - just gets you out of a tight spot![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
That's not a particularly professional thing to do - just gets you out of a tight spot
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
#12
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This will help you for future referance
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
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
need anymore?
![Big Grin](https://passionford.com/forum/images/smilies/icon_mrgreen.gif)
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
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
need anymore?
#13
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Originally Posted by Big Will 85
If you're ever REALLY unsure - just go 1mm under the size of the M
That's not a particularly professional thing to do - just gets you out of a tight spot![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
That's not a particularly professional thing to do - just gets you out of a tight spot
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
easy way to remember, if your tap says M12 x 1.75 for example subtract the 1.75 from the 12 to give the tap drill size, in this case it'd be 10.2mm
#17
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Originally Posted by crash_ash
easy way to remember, if your tap says M12 x 1.75 for example subtract the 1.75 from the 12 to give the tap drill size, in this case it'd be 10.2mm
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
ps,
Working as cnc operator in sweden, drills a lot of holes and thread´s them
ds.
#18
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Originally Posted by PatrickSwe
Originally Posted by crash_ash
easy way to remember, if your tap says M12 x 1.75 for example subtract the 1.75 from the 12 to give the tap drill size, in this case it'd be 10.2mm
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
ps,
Working as cnc operator in sweden, drills a lot of holes and thread´s them
ds.
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
#19
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Originally Posted by GARETH T
buy one of those, and stick it in your garage toolbox
![](https://i17.ebayimg.com/05/i/08/f1/ee/ag_1.JPG)
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
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#20
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Originally Posted by wirralphil
K5SSY it's actually 6.8mm for a 8mm thread ![Pthbbbb](https://passionford.com/forum/images/smilies/smile045.gif)
![Pthbbbb](https://passionford.com/forum/images/smilies/smile045.gif)
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#21
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sigh...you take the addendum and dedendum of the thread and adding them up thus giving the thread depth or .86603xp to give the fundimental triangle minus the basic crest radius,minus the basic root radius.
Take 60% of this depthx2 then take this figure away from the tap diameter, that should be about right for the hole size to be drilled.
Take 60% of this depthx2 then take this figure away from the tap diameter, that should be about right for the hole size to be drilled.
#22
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Originally Posted by st3v3
Originally Posted by PatrickSwe
Originally Posted by crash_ash
easy way to remember, if your tap says M12 x 1.75 for example subtract the 1.75 from the 12 to give the tap drill size, in this case it'd be 10.2mm
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
ps,
Working as cnc operator in sweden, drills a lot of holes and thread´s them
ds.
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
#23
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Originally Posted by GARETH T
Originally Posted by st3v3
Originally Posted by PatrickSwe
Originally Posted by crash_ash
easy way to remember, if your tap says M12 x 1.75 for example subtract the 1.75 from the 12 to give the tap drill size, in this case it'd be 10.2mm
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
ps,
Working as cnc operator in sweden, drills a lot of holes and thread´s them
ds.
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Wink](https://passionford.com/forum/images/smilies/icon_wink.gif)
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
![Pthbbbb](https://passionford.com/forum/images/smilies/smile045.gif)
#25
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Originally Posted by philram
Originally Posted by GARETH T
buy one of those, and stick it in your garage toolbox
![](https://i17.ebayimg.com/05/i/08/f1/ee/ag_1.JPG)
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
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#26
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Originally Posted by crash_ash
Originally Posted by philram
Originally Posted by GARETH T
buy one of those, and stick it in your garage toolbox
![](https://i17.ebayimg.com/05/i/08/f1/ee/ag_1.JPG)
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
http://cgi.ebay.co.uk/BRAND-NEW-PREC...QQcmdZViewItem
![Top](https://passionford.com/forum/images/smilies/smile011.gif)
![Big Grin](https://passionford.com/forum/images/smilies/icon_mrgreen.gif)
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which i have in my locker at work
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