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 Post subject: My reamer-making saga
PostPosted: Sun Aug 30, 2020 1:02 pm 
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If you want to make reamers for cutting flute bores it's going to be a saga. At least for me. In this my first thread here I'm going to post photos documenting my experience, starting with how I made a taper jig and later with resulting tapered rods, milled but warped one-slot reamers, and finally (I hope) with straight multi-slot reamers.

So let's begin. First, I bought some steel plate, cleaned it up, drilled and tapped a few holes, and attached the foundation to a small Chinese lathe.

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Last edited by William Bryant on Sun Aug 30, 2020 5:51 pm, edited 1 time in total.

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PostPosted: Sun Aug 30, 2020 3:51 pm 
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Next came drilling some holes and milling a slot.

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PostPosted: Sun Aug 30, 2020 3:58 pm 
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Then I made a bushing for the taper adjustment rod.

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PostPosted: Sun Aug 30, 2020 4:01 pm 
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Then a way to transfer taper forces and position to the cross slide.

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PostPosted: Sun Aug 30, 2020 4:04 pm 
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Here's the whole contraption before I connected the taper positioning rod to the supports.

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PostPosted: Sun Aug 30, 2020 4:10 pm 
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Then it was time to make some little posts to connect things, one with a slot to make up for the fact that I didn't have the means to mill a slot with a radius in the support. (The post is upside down here.)

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PostPosted: Sun Aug 30, 2020 4:15 pm 
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A nut to hold things in place and a holder for a dial indicator to measure the distance from parallel.

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PostPosted: Sun Aug 30, 2020 4:21 pm 
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I am thoroughly enjoying this, William. :thumbsup:

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PostPosted: Sun Aug 30, 2020 4:30 pm 
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A fixed stop block to make it easy to find parallel.

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PostPosted: Sun Aug 30, 2020 4:37 pm 
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A dial indicator to keep track of the degree of taper. Distance from point of pivot to point of movement is 18.75" but it can easily be converted to taper-per-foot with 8th grade math.

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PostPosted: Sun Aug 30, 2020 4:51 pm 
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I'll post more pictures of the taper jig if something isn't clear.

Next it was time to measure the bore of a prototype and taper a rod to fit.

Here's my measuring device, basically a telescoping gauge with a stop so that I can tell exactly how far down a bore I'm taking the diameter.

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PostPosted: Sun Aug 30, 2020 5:00 pm 
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I was worried that my taper attachment would be too weak and flex too much, so I made many light passes and everything turned out fine. The taper was inside .001" of my intentions.

WARNING!! If you try this yourself please design a safety protocol to prevent yourself from ever bolting on your taper jig before disengaging your cross slide screw. Engaging both at once will crash your lathe. Treat this like you treat firearms safety rules or helicopter pre-flight check lists. Double check. Triple check. Every time!

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PostPosted: Sun Aug 30, 2020 5:22 pm 
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Trying to cut a tapered rod to match the bore of a flute I own worked out better than I had hoped.

Here's the tapered rod with a dry eraser mark.

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Here's the tapered rod after carefully sliding the flute joint on so as to keep it off the mark as long as possible.

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And here's the rod with the mark rubbed off with a little twist. Success!

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PostPosted: Sun Aug 30, 2020 5:26 pm 
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William, this is hugely impressive--you clearly have advanced machining skills and excellent problem-solving techniques! I think your solution is elegant, though it does seem to be confined to making straight tapers, is that correct?

The only thing that struck me as a potential down-side (and I really had to stop drooling over the lovely machining you did to even evaluate any possible limits) is if you wish to create a taper that has perturbations in it.

When I made my first "Irish" flute (and this might be repetitive if you've read through the older threads on reamer making) I tried to make my life easier by doing a straight taper, which was a clear departure from the data I had gotten from Terry that came from his original Pratten flute. The straight taper made a really nice flute, but my flutes did not attain that next plateau until I returned to the original data, which indicated a bore with a fair number of "bumps" and "dips" along it's length. Past flute makers definitely used a "wiggly" bore to enhance tuning/harmonics, and even though many of the perturbations are quite small, the cumulative effect is profound.

The only way in which I was able to create a taper with the proper pertubations was to turn it incrementally. I took my steel stock and marked my data points along it's length (I made very shallow grooves at 10mm intervals for visibility) and then I marked (with an engraver) the target diameter of each data point. Then I hung a few inches of it outside the headstock spindle (I'm using a collet chuck) and supported it with the tailstock as well. I work each individual data point down until it is at the target diameter (actually .003" over the target because I sand it smooth afterwards). Once my data point is correct, I move along and do the next one. Once I'm up against the headstock/collet, I pull out a few inches more of stock and start again. This means that the stock that I'm working is never more than 4" away from the spindle head, so there is no chatter or flex. You can see a photo below of what the in-progress taper looks like.

This method is slow and requires me to take a LOT of measurements with my micrometer along the way, doing delicate finish cuts to maintain accuracy. I can actually blend the steps as I go with some "freehand" control of the tool (riding the x and y axis controls) and then finish with sandpaper. This method consistently gets me within about .001" of my target, which is plenty accurate for a reamer.

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Last edited by Geoffrey Ellis on Mon Aug 31, 2020 2:02 pm, edited 1 time in total.

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PostPosted: Sun Aug 30, 2020 7:57 pm 
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Geoffrey,

Thanks so much for your thoughtful and very kind reply. I've got a million questions and maybe a few observations, but alas! other duties to attend to before I can jot them down.

Stay tuned!

Bill


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