Let's see if C&F can handle a VERY LONG POST:
Quotes pulled from the WOODENFLUTE list of long ago, regarding steel & reaming.
CASEY BURNS - 2000 In a D section reamer (basically turn the taper then cut it in 1/2) this is a problem but not so much in the 3/4 round reamer. The edge is kept sharp this way: on the flat cutting surface, I first file off the old edge, then stone the surface smooth. Then the cutting edge is generated using a hard steel burnisher held at about 5 degrees from the cutting surface and burnish the edge. If the reamer is cutting in one spot a little narrower, I can burnish more in that spot to bring the edge out further. In extreme cases the metal can be upset by punching it just inside the edge with a center punch.
Using this method, one gets years of surface out of a 3/4 section reamer. I usually need to resharpen it after every 10-15 bores - but I change my reamers faster than they wear out to a D cross section!
There is no "relief" on the diameter of the reamer. It's not necessary. The burnished edge seems to be all that is necessary to plane the wood.
On flutes, I bore out the joints in one diameter - that being the minimum required for the reamer to pass through (1/2" is a good size for larger bored Pratten style middle joints). The reamers I have been making lately are not piloted, but instead have a cutting edge similar to that of the gun drills on the end - this makes them more aggressive - important in a production shop.
In bagpipe chanter bores, however, I will step bore as much as I can - usually dependent upon what drills are lying around, since these reamers are a bit more delicate and much more difficult to make.
Just another note on reaming: My method of reaming is to usually set the lathe belts at the slowest nongeared speed (about 180-240 rpm) and chuck the reamer in the 3 jawed chuck. I stick a couple of hose clamps in the middle of the joint to be secured, then attach a Carpenters Woodscrew clamp over this to have something to hold onto while reaming. Easy on the hands!
For bagpipes I recenter the bore by turning between centers on the lathe, then chuck up the blank using a steady rest as well, then ream from the tailstock end with a reamer held in the toolpost - on the Myford there is quick change tooling that makes this easy and convenient.
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TERRY McGEE – 2000 [reamer profiles and heat treat issues]
How many uses do you all get out of a reamer before it wears down to the point that it either cuts undersize or simply won't cut at all (IE the edge wears in far enough on a 3/4 section that there's no longer sufficient relief for it to touch the bore)?
Don't know yet!
And on a related note, how many "steps," in addition to the pilot hole, do you drill in the bore before using the reamer?
I step drill at 1mm increments.
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MARK HOZA – 2000 And on a related note, how many "steps," in addition to the pilot hole, do you drill in the bore before using the reamer?
I drill a 1/2" pilot hole and then ream out the billets. I don't step drill them. If my reamer is sharp I can ream the billets quite quickly and I can't see that step drilling would save any time.
I also use hose clamps on the outside, but I hold the billet with gloved hands while the reamer spins in the chuck. I'm using a metal (Myford) lathe, by the way.
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MARK HOZA – 2000 I have had this same problem, EXACTLY, so will share what I found. It's terribly frustrating business when your reamer won't cut.
12+ inches is no problem. I use one that is about 17" and it works fine, as long as I have it sharpened properly.
I find that it doesn't take much to get a reamer to work in smaller diameters, such as you find at the beginning of your reamer. I rarely have trouble there. It's about 1/3 up and beyond that which gives me troubles as the reamer gets dull, or if it is not milled properly to begin with. (I use the third slowest speed, by the way, as I find that it cuts slightly better, for me. There might be a good reason for me to use the slowest speed, but this is what I've been doing.)
I find that it is infinitely better to undercut the cutting edge of the reamer so that the cutting edge is slightly acute. I only use an angle grinder to mill out my reamers, so you are ahead of me with a milling maching, if that is how you mill them out. So, 100% dead straight isn't the concern, it's that the edge is slightly undercut along the length. I then file the undercut face to clean up the edge, followed by a fine diamond lap and then a stone.
When the edge is sharp enough to slice and dice my finger when I slip (as he says with a band-aid on his finger from finishing up a new reamer today), I then burnish it up so that there is a slight raise on the cutting edge. If the face is not undercut I find that I can't get enough of a lip. I think that the undercut helps you burnish up just a tad more metal. It also works better even when the reamer is dull, so this isn't the only reason.
Anyway, I'm confident that this will help you. I've spent a number of hours learning the hard way and I know how frustrating this particular problem can be.
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PAUL JACOBS – 2000 You can make a reamer by turning steel to the shape of the bore and then cutting away a half or a quarter (as suggested in recent postings)but this involves removing much metal. All one needs to do is create an edge by milling a groove and take away some metal to one side of the edge so that the edge can engage the wood being cut. If you take away some metal through 90 degrees or 180 degrees the effect on the wood being cut is the same whether the metal removed extends to the centre or is just one or two millimetres deep to the original circumference. The only disadvantage of this type of reamer is that there is less space for shavings compared with a fully quartered or halved reamer so it has to be cleared frequently. The big advantage is that it balances well if used as a mandrel and rotated at high speed as relatively little metal has been removed from one side
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TERRY McGEE – 2000 I step drill every 1mm on diameter to minimise the work the reamer has to do. This extends time between sharpenings. I use normal spade bits with their tits ground off (ouch!) and the flat part ground to a 90 degree included angle (with appropriate relief). They cut like mad, so it doesn't take long. I attach the dust collector to the end of the hollow lathe spindle, so all the swarf and dust goes up the tube.
I also use two reamers for long parts like Prattens body's.
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CASEY BURNS – 2000 Steel for Reamer: I personally find W1 and O1 too hard for reamers most of the time - and these are a bit more expensive. I recommend something called Stressproof, which is a .45% carbon steel - this can be found at almost any steel distrbutor in the yellow pages and comes in a wide variety of diameters. I do not harden my reamers - to do so would invite warpage.
Instead, the cutting edge is burnished out using a piece of hardened steel set at about 4-5 degrees to the edge. The act of burnishing actually hardens the cutting edge just enough to work.
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HAMMY HAMILTON – 2000 I have always used silver steel for reamers. It's available, in Ireland at any rate, in metre long round bars which come in every size from 1mm up to about 25mm. Its a bit 'sticky' to turn and mill, but I've recently discovered that a carbide tool, and using good old tallow as a lubricant works fairly well.
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