Tool Advice for 80/20 5/16" tap bit (DIY)

[Cut Once]

I am looking to put some end taps on my 80/20 15 series extrusion and want to know what bit I should use.  I know I need a 5/16" but I would appreciate any recommendations from those who have experience.  Should I buy a bit that goes in a drill or am I better off hand tapping either way I would appreciate the advice and maybe a link to the bit I should use.

Thanks

 

[rst]

The holes in the 15 series are the correct size for tapping 5/16

 

[Michael Kellough]

Use this kind of All in one combination drill and tap. The drill section will keep the tap oriented along the axis of the hole.

Clamp the stock down hard with two clamps. Any movement and the tap will snap.

Use a cordless drill that allows easy switching between forward and reverse. Cordless so it will stop instantly. Use a medium high clutch setting until you get a feel for how much torque the tap can stand. Going slow is better than snapping the tap but it’s stronger than you’d expect.

Use lubrication on the tap. Can be almost anything from alcohol to wax. Use a nylon bristle brush to clean swarf from the tap.

You can also use an M8 tap on 15 series and 40 series stock.

 

[Cheese]

An alternative to Michael's solution is to use a spiral tap as you may already own one.  [smile]

The spiral tap shoots the chips ahead of the tap so that you don't have to keep swapping from forward to reverse. Otherwise just follow Michael's suggestions.

If you're tapping a lot of extrusions, consider a TiN or TiCN coated spiral tap. It has a harder surface, lasts longer and will not gall as easily in aluminum.
https://www.mscdirect.com/product/details/41113671

[attachimg=1]

 

[rmwarren]

I use the 15 series ULS which have the hole that has the X pattern and they tap with a a standard 5/16" tap in a drill no problem. The heavier 15 series have holes without the relief slots and they can be harder to tap. For all my uses the ULS has been plenty strong and it’s cheaper than the other series.


That tap isn’t even particularly sharp.

RMW

 

[RightAngleDesign]

I do a LOT of machining of aluminum, and in case you have a bunch of holes to tap I'd recommend a product called Tap Magic Aluminum to use as your lubricant. It works extremely well, is relatively benign, and cleans up easily with acetone.