<VV> buyer beware tool

[Frank DuVal]

I use these drill taps for thinner metal (steel, aluminum)(electrical 
panel boards, etc), not castings. They can work well, but are prone to 
breaking, just like taps, because they are the same hard metal as taps....

Brands differ in design. Some tap designs become large at the end of the 
taping threads, so you must stop the drill or beak something. Other 
designs allow you to drill, tap and then the tool spins in mid air, as 
the area after the tap is smaller.

Buyer beware and I would use a regular jobber drill and tap on castings 
or thick metal. I use the Greenlee brand [available at local electrical 
supply houses] and various ones purchased through McMaster Carr and MSC.

Don't forget left hand drills! They work well in some cases. Screws back 
out of the holes without the need for tapping in lucky cases. Snap on 
has these for big money, Harbor Freight has them for small money. Also 
McMaster Carr , MSC, etc mill supply houses.

And another item, Boelube is great! Use for tapping and drilling. I like 
the paste form, others like the solid stick . Available through Amazon a 
quick check of Google shows. Why yes, it was developed for Boeing 
aircraft industry.

Frank DuVal

On 6/19/2011 9:34 AM, Grant Young wrote:
> I recently purchased some things known as a combination drill and tap. You can supposedly drill out an offending screw and re-tap the threads without changing tools. Since I deal with a lot of carburetors with screws broken off in the body and spend quite a bit of time drilling and tapping, this seemed like a dream come true. I purchased the Craftsman brand, thinking the quality might be better than a China brand, but the first one I tried to remove and tap a broken bowl cover screw snapped in half. Thinking it might be a fluke, I tried a smaller one to see if the tap portion worked, and it didn't (just stripped threads when the drill tip stopped drilling). So, if you are thinking about buying a set of these, my advise is to think again stick to tried and true methods, at least for carbs.
>
> Grant
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