# Toolmakers Reamer



## Xyzzz (May 24, 2022)

I was looking into details of How to grind D-bits (single lip cutters) and part of that led me to a statement that was something like “…similar to a Toolmakers reamer where a single 20 degree cutting edge is ground and stoned…” 

Does anyone know what this reamer might look like? It proports to make an exceptionally accurate and smooth reamed hole with a home made reamer. 

Is it just grinding a solid blank on a 20 degree angle and then pushing that into an underside drilled hole? 

I got the feeling this is an old school technique, but one that might be a nice option when u don’t want to buy an expensive reamer maybe for an odd sized hole. 

Anyone heard of this? I especially would like to see a picture.


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## jwmelvin (May 24, 2022)

I’m interested to follow this discussion. I recently made a d-bit reamer of sorts, for a taper pin. I just ground the taper, then split on a diameter, and added a relief right behind the cutting edge of a few degrees.


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## benmychree (May 24, 2022)

Real taper pin reamers are not expensive ----


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## matthewsx (May 24, 2022)

benmychree said:


> Real taper pin reamers are not expensive ----


But not nearly as satisfying as making one yourself, or when you can't wait a day for McMaster to deliver....

JOhn


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## benmychree (May 24, 2022)

matthewsx said:


> But not nearly as satisfying as making one yourself, or when you can't wait a day for McMaster to deliver....
> 
> JOhn


Hopefully, the tool's performance was up to expectations.  Personally I prefer the high spiral type, as they are able to clear the chips without backing out frequently.


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## matthewsx (May 24, 2022)

benmychree said:


> Hopefully, the tool's performance was up to expectations.  Personally I prefer the high spiral type, as they are able to clear the chips without backing out frequently.


Definitely nice to have the right tool for the job, wonder if it was for a real taper pin or just a split pin? All my reamers are straight flute but I have some spiral taps that work wonders. I was gifted a bunch of tooling from a local grinding specialist many years ago and the difference between that and anything you find at the hardware store is night and day. It would be good for anyone getting into the hobby to visit their local industrial tool supply and talk with the guys behind the counter....

You've forgotten way more than I've ever learned so I definitely defer to experience. But, it is nice if you can make tools yourself to do the job. I'm looking forward to making some of those and using my new/old furnace to bring them to hardness. Just because....

John


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## jwmelvin (May 25, 2022)

benmychree said:


> Hopefully, the tool's performance was up to expectations. Personally I prefer the high spiral type, as they are able to clear the chips without backing out frequently.



That taper tool worked perfectly. I set the angle by referencing a sine bar, and that worked out well. Since I needed one hole, the $40 reamer from McMaster seemed unnecessary. And I have a tool grinder I’d like to become familiar with. So it was a win-win. It did require a pecking approach, after drilling to close to the small-end diameter.

Yes, it was for a real taper pin, #2 size.


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## ub27Rocks (May 25, 2022)

a useful article on the topic: http://www.stubmandrel.co.uk/workshop/29-d-bits

I often make d-bits from drill rod and then harden with blow torch/oil For most uses I don't bother with tempering.

gerrit


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## Xyzzz (May 25, 2022)

Ok! Thanks for the responses. AND I’m making progress. That link you provided, discusses exactly what I’m hoping to find a picture or drawing—-

“One final thought – the so-called toolmaker’s reamer is an even simpler tool. In this case the blank is cut across at about 20°, hardened, tempered and stoned to a good finish. Less robust than a d-bit, such reamers will take a very accurate final skim from an undersize hole”

Anyone have a picture of one of these 20 degree cut reamers?


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## francist (May 25, 2022)

Yeah me too, the description was a little vague for me. I found this though, wonder if it's generally the same thing and is illustrating the 20-degree cut? I can imagine how this would track exceptionally well.

-frank


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## jwmelvin (May 25, 2022)

There’s some discussion https://www.practicalmachinist.com/forum/threads/how-do-you-make-a-d-bit.225698/#post1576353

And here: https://www.homemodelenginemachinist.com/threads/diy-reamers.4142/


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## ErichKeane (May 26, 2022)

I wish I had known about how to do this a while ago! I ended up having an oddball taper that I ended up having to buy an expensive reamer for.  Good to know I could have just made one cheap enough :/


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## Xyzzz (May 26, 2022)

Pay dirt! Thank you! I was assuming something like this. I’m interested in making one and seeing how well it works.


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