what are these drills for

[isambard]

I bought a box of mixed taps dies and drills off e-bay and in it were two types of drill bits that I have no idea what they are used for so I hope forum members can help. The first photo gold coloured drills marked Mohawk and have smaller drill ends like a pilot drill the other has a spiral cutting edge but has point where the cutting edge should be

 

[Woodster]

The 1st 3 are what look like step drills are are normally specially ground for a particular application. you should be able to simply regrind the cutting edges for normal drilling.
The other drill is a taper drill. Notice how the flutes are opposite? This is to stop the drill driving itself in. This drill is for tapering existing holes and should be used prior to taper pin reaming.

 

[AussieJimG]

The first two look a bit like wood bits used with a brace. But the wood bits had a tapered square section to go in the brace.

Jim

 

[Mike1]

The first two in the top picture and the drill in the bottom picture look like the bits that go in a hollow mortise chisel, as used for woodworking.

 

[isambard]

Hi Guys thanks for the info all I know about them is they were from a closed down engineering works and were with a load of reamers, taps and dies I bought

Tom

 

[rodw]

I am not sure if the first two are wood bits (or augers) as the flutes seem very thick, more like a normal twist drill. However, the pilot drill seems to indicate this is what they are. All the wood bits I ever used had flutes that looked more like the thinner ones on the second photo.

 

[isambard]

Hi rodw I have tried the Mohawk drills on steel and they go through very quickly and I've been told they could be for stack drilling several jobs at once the pilot bit on the end stops them going off course but I don't know for sure.

Tom ,

 

[MachineTom]

The first three are for a mortising chisel drill (square holes in wood). the last a is a tapered machine reamer.

 

[isambard]

Hi Tom thanks for the reply I just had not seen any before but I have seen the mortise cutter on a drill it's a square chisel with a drill in the middle but the drill in that was the old type like in a brace and bit.

Tom

 

[steamboat willie]

The things you learn! Another thread woven into my threadbare tapestry of knowledge! Thanks MachineTom!
Bill.

 

[portlandron]

Not sure what they are but I don't think they are mortising bits.

Mortising bits don't have or need that kind of point on the end to guide as they are held inside the mortising chisel. The spiral part of mortising bits are more open to move the cut wood up and out of the hollow chisel. Also the sides of the bit that rub against the inside of the hollow chisel are not as wide as the ones you have. Being that wide it would create more friction and heat rubbing against the inside of the hollow chisel which is a problem with mortising chisels.