William Bryant wrote:
I'm not sure where to go next with this.
Also, a related issue for those of you using your lathe to do your reaming. Holding on to a piece of wood while pushing/pulling it up the spinning reamer poses a serious injury risk if a hand slips off the wood onto the reamer. Is this a necessary risk of flute making, or do some of you put a handle on your reamers and hold your wood in a vise? I'm 63, don't have a very firm grip anymore (I have a slight tremor in fact), and lost part of a finger to a machine years ago so don't find this question purely theoretical.
My own experience with that reamer design was also disappointing. I made two such reamers, with that same style of blade, and I can't get them to work at all. They barely feed into the work and it takes tremendous effort. I'm still puzzled by that. I based mine on a drawing done by Rod Cameron, who presumably used this same design, and who presumably got a better result!
I've made two and four blade versions as well, but to date my favorite for cutting efficiency is a modified D-profile. With these, you do risk warping, and because of that I switched from 41L40 (which is cold roll) to 01 tool steel for this reamer that I just finished last week. It was a very slow process, the tool steel being way harder than the leaded stuff I'd been using. So my results were definitely not as pretty (in terms of the finish) but in terms of function I've never made a better one.
This is a short reamer with a very long shaft that use for my Essential Flutes, which have a Boehm taper in the head of a single piece body. This requires the reamer to reach well up the bore to do it's cutting, so the reamer and shaft is 3' long. You'll see that I did a D-profile cut, then I turned it face up and used a 1/4" ball endmill to create that scoop right at the cutting edge. This was very tricky. I had to put bluing on the surface so that could see better, and then slowly cut along the very edge of the reamer. Took a couple of hours maybe to do this without ruining the edge, because the idea is to get so close that the blade of the scoop is just a few thousandths of an inch thick. The result is a crazy sharp cutting edge.
These photos look a bit disreputable because I took the finished reamer shots right after cutting some ebonite with it. You'll also see the result of the ebonite cut! When ebonite shaves like that, you are dealing with a very sharp blade, because otherwise it turns to powder.
The other advantage of this style is that you minimize torque. Four blade reamers create a lot of torque, so you have a harder time controlling the piece of stock you are holding. I don't use my lathe for reaming, having instead a dedicated work station with a gear motor set up that holds my reamers. Then I hold my work by clamping it into a v-block. If it is round stock, then I wrap it in hose clamps to stabilize it and allow it to be grabbed by the v-block. I clamp the block with simple large c-clamps, which hold the block together and give me handles with a lot of leverage. This is still a very physical approach, and I'm looking to improve on it. It has an element of danger if one is careless, because that gear motor is so powerful that if you get tangled up with the handles of the clamps, things can go wrong very quickly. Happened to me yesterday and nearly broke my arm, motivating me to make some changes to the procedure. You can see this in action if you are willing to sit through a short micro-documentary about me

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https://vimeo.com/321618537


