Besides, it's a screw with rolled threads, and that would explain it being a bit undersize.
So, my first guess, UNC #6 seems correct. (UNC is the same as UTS Coarse)
Besides, it's a screw with rolled threads, and that would explain it being a bit undersize.
So, my first guess, UNC #6 seems correct. (UNC is the same as UTS Coarse)
Thanks for all your help, BOTH of you guys! I will try if possible tomorrow to drill and tap a few test holes... my health has been getting worse and I don't sleep anymore due to the pain, stress and anxiety from it all... hence being awake all night and chatting with the wrong (or right?) time zone on this forum!
If you can get to a hardware store they generally have small display with the hardware with small sections of threaded tubing and threaded rod to check threading.
As for what size pilot holes to drill it somewhat depends on what material you're tapping. Sometimes it's better to drill slightly smaller or larger depending on the material.
Here's a tap drill chart...
http://www.physics.ncsu.edu/pearl/Tap_Drill_Chart.html
Thanks! Quite a helpful chart!Originally Posted by TiE_Shepherd
Ugh! It's NOT a UNC #6 after all... they fit/grip but WAY to loose... Oh and my poor tap! Good thing it has lifetime warranty! Back to the store for a replacement... then try to find a 5/32 BSW in Canada... probably NEVER happen!
Did you try those red screws in the back of any other computer case you have?
And, err, it's NOT an 5/32" BSW either, because that requires a drill size of 3.2mm, and your outside diameter is [supposedly] 3.1mm....it wouldn't even engage!
At this point you may have to assume that the red screws are crap!
Yup! Fit OK... a little loose but they grip towards the end when there's tension.
Hmmm... The UNC #6 (Major Dia .1380/Minor Dia .0997, 32 Threads Per Inch) was a #36 drill (.1065/2.7mm) into Aluminum, Brass & Plastics = 75% Thread while the 5/32" BSW (Core diameter 0.1162, 32 Threads Per Inch) is a #30 drill (.1259/3.2 mm)... hmmm it's bigger? Now I'm confused... I thought the 5/32 was a hair smaller? Guess not! It wouldn't even touch it... so what size DO I need?
Tempting, but I bought 20 of them for this project, at 2 different times so I payed shipping twice (after I decided to build 2 units simultaneously) and cost me a buck a piece after shipping in the end ($20 for 20) I really need to make these work somehow... it's just a matter of finding the right tap! (impossible?)
Thus, I still guess they are undersize... and maybe your tapped hole become oversize in that alu, with such a screwy tap?
Yeah! Screw that tap! I'm not giving up yet... the quest continues...
I agree... now what?
First of all are you tapping dry? You should be using cutting/tapping fluid of some kind. Even WD40 is better than nothing.
Second how hard are you going at those threads? You know to turn it only so far and then back it out to clear the chips right?
A good tapping fluid for aluminum is alcohol (methylated spirit, or equivalent). Use liberally.
Looks like your tap wasn't properly hardened. I usually break my taps (HSS steel), I don't tie them into knots...
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