What is this?

woodchucker

woodchucker

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It's marked BTC No. 4 HS
HS high speed steel probably but usually HSS.
  • It's tapered,
  • its got a down cut, not an upcut.
It reminds me of a spiral bit for a rotozip, but I don't think so, it had cosmoline on the bit, and was in the machinist lot I bought a couple of weeks ago.

BTW that's sitting on a drawer front of a cabinet I am refinishing for myself. It was painted. People paint the most beautiful wood. That's after a dark stain to pop the grain and shellac. Nice right?
SDC12006.JPG
 
It is a #4 taper pin reamer, for making holes for tapered pins that hold handles to shafts and other assembly fit ups. They are sold in sizes from 7/0 to 14, 21 sizes that I know of, from tiny to huge. The taper is the same on all of them and there is no official pin sizing, you cut whatever length you want out of a longer pin that contains what you need, install with a hammer, then dress the ends. The spiral flutes are needed when a keyway or some other notch is in the hole, and leaves a better finish, but they cost more than straight flute versions. I probably have at least 50 taper pin reamers, and lots of pin stock. I prefer them to any other type of pin for mounting handles to shafts. Roll pins are #2 on my list. I have not seen any on modern equipment, because they take longer to install than straight pins or roll pins.
 
Ok, so this would be chucked, since it doesn't have a square for a tap handle. I have a bunch of taper reamers smaller than this one, none that are spiraled like this. One that gently twists. So the wierd thing is that it's a down cut , sending the chips to the narrow end. But that makes sense, in that it avoids digging itself in, avoiding making it difficult to remove, since you don't want to reverse a reamer .

Thanks Bob, I like taper pins too.
 
woodchucker said:
Ok, so this would be chucked, since it doesn't have a square for a tap handle.
Click to expand...
They make both hand and chucking style taper pin reamers. The hand ones have a square shank, and the chucking style is a plain round shank. Just like other reamers...

They can often be purchased used for cheap, because people do not know what they are for. I have bought tool lots of nice ones, maybe 25 cents per reamer, or less.
 
I have a blue print for the cam shaft assy on a 19-aught-something marine gas engine. The cams are to be installed onto the shaft.

1. Cams are pre-drilled;
2. Install them loose onto cam shaft, install shaft on engine, position everything for correct timing;
3. Drill through the cams into shaft, then ream for taper pins;
4. Remove cams and case harden;
5. Reinstall everything, then secure with taper pins.

E-693_CamShaftAsy_8HP_1200.jpg
 
I always thought the cams on a camshaft were integral, never knew they were separate.
 
I had the opportunity to see the Grand Prix Museum in Castle Donington, Leicestershire, UK a few years back. Amongst the large collection Grand Prix racers from virtually every year that races were held, were some exhibits of early engines. Of note were the crankshafts from some early racing engines that were assemblies of multiple parts rather than the single piece crankshafts found in modern engines. https://www.donington-collections.co.uk/grand-prix
 
Tapered pins are getting harder to find too. Not to many years ago assortment of sizes could be had at fair prices. There going up now and tuffer to get in an assortment.
 
I know some motor cycles also used multi part cranks, and were expensive it you messed them up. ON the cam, can you imagine trying to hold the cam lobs in place and drill them. Would not take much to have the timing off on it. I wander if that is why some of the old boat motors sounded a little funny compared to others.
 
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