RGB progress - slow & painful...

[Hemlock Mike]

Aluminum is a gummy metal -- It loves to grab taps.
I use Kerosene as a lube and drill for only a 50% thread as high strength isn't needed.

Mike

[Dr Laser]

I use Lithium lube and it taps in like in butter.

[Insanity]

Tufcut cutting compound is the best, it keeps the tap sharp as well..

Another good way to ease the pain, is to drill the pilot hole a 10th oversize, although this is not strictly correct engineering wise, the pressure is downward and the thread is not holding any load. So a very slightly loose thread is not a problem. Plus, it's easier to tap the hole and less chance of breaking the tap.

For threads holding a load such as hanging brackets, drill a 10th smaller and use a taper, second and plug tap set drenched in compound. It's a longer process and you must follow the one turn in, half turn back process. But you will get the strongest possible thread, short of using a helicoil.

By the way, this is only any good if you are using a pillar drill/drillpress. A pistol drill won't really drill within a 10th. In this case, you are better off drilling smaller, as the drill is not stable and will cut oversize..

Hmmm, I have a lot to say about the job I hate most..

By the way, Loving the projector Stuka.. Looks really high quality and expensive.. Very nice.... Hopefully we will get the wheel issues sorted soon...

Cheers
Mark

[Jem]

I've just bought a set of HSS metric taps from M3 up to err... whatever (can't remember and they're not in front of me , but the largest is probably somewhere near 10mm)

What drill sizes should I ideally be using for them, I'll probably use M3 and M5 most.

Cheers

Jem

[Insanity]

There is an easy calculation for Metric Coarse which you have. Take the thread pitch away from the diameter and you have your tapping drill. So for M10x1.5 you drill 8.5. 10 - 1.5 = 8.5..

Here you go:
----------------------------TAP DRILLSIZE SIZE----------------------------1mm x .25 .75mm1.1 x .25 .851.2 x .25 .951.4 x .3 1.11.6 x .35 1.251.7 x .35 1.31.8 x .35 1.452 x .4 1.62.2 x .45 1.752.5 x .45 2.053 x .5 2.53.5 x .6 2.94 x .7 3.34.5 x .75 3.75 x .8 4.26 x 1 57 x 1 68 x 1.25 6.89 x 1.25 7.810 x 1.5 8.511 x 1.5 9.512 x 1.75 10.214 x 2 1216 x 2 1418 x 2.5 15.520 x 2.5 17.522 x 2.5 19.524 x 3 2127 x 3 2430 x 3.5 26.533 x 3.5 29.536 x 4 3239 x 4 35----------------------------

[Insanity]

Hmm, that didnt turn out too well, but you get the idea

[Stuka]

....
By the way, Loving the projector Stuka.. Looks really high quality and expensive.. Very nice.... Hopefully we will get the wheel issues sorted soon...

Cheers
Mark

You've got the expensive part right, that's for sure !

Worth it, though...I think...

[Jem]

Thanks Mark that's really helpful. I've printed it out and stuck it inside the tap box

Jem

[Hemlock Mike]

Through holes in 1/4" aluminum plate usually aren't too much problem with lube. I don't need 75% threads so i usually go one drill size larger after the pilot hole. This also gives me a more round hole.

Mike