reaming

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chas
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reaming

Post by chas »

Hi, all,

I'm up to about six flutes made (five completed). Everything is going really well except for reaming the left-hand piece. The reamer vibrates, and this causes things to loosen. If I crank down hard enough on the wood in the lathe chuck, it's fine. I've put some flats on the reamer in the drill chuck. So the drill chuck comes loose in the taper of the tailstock ram and the reamer seizes in the wood. Both the male and female tapers (on the drill chuck and tailstock ram) are now scored, so new ones of those will be ordered soon.

I'm reaming at 130 rpm. I've had three different types of reamers, one homemade and two commercially made. The 3/4 round one I made didn't chatter the way the commercial ones do, but it sure seized a lot.

This only happens with the left-hand piece, which is the biggest both in length and diameter. I step-drill it, and the seizing only happens once the piece is almost finished. The inside is burnished and just about glassy, and almost no sawdust is being created at this point.

Any suggestions? Hand reaming isn't an option with my arthritic hands.

Thanks in advance for any advice. Once I've gotten the flutes made, I've been really pleased with them.
Charlie
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Re: reaming

Post by Loren »

Hi Charlie, did you see my description in a recent thread of the process we used? Might be something useful there for you.

130 rpm sounds kinda fast. I don’t remember the exact speed I reamed at, but I’m fairly certain it was about half the rpm you’re using, maybe even less.
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Re: reaming

Post by kkrell »

Lubricant?
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Re: reaming

Post by Loren »

kkrell wrote: Tue Jan 18, 2022 7:47 pmLubricant?
No thanks, I’m trying to cut down.
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Re: reaming

Post by Terry McGee »

Hi Charlie

Can you tell us about your reamers? Am I right in thinking that the "three-quarters round" one is a cone with a 90 degree segment cut out? And are the others straight D-bits (ie half round), or something else?

I'm guessing from "and the reamer seizes in the wood" that your reamers are not sharp enough. But it's easy to say that from the safety of a small coastal village at the bottom of the world....

You might find this interesting. https://www.youtube.com/watch?v=VtgDccI93eo

Coincidentally, I'm engaged in a project to try to map out the early days of Irish flute making. My co-conspirator brought this video to my attention. About 4 mins in you'll see Hammy Hamilton, way back around 1980, with reamer in hand. Note the cross sectional shape. Such reamers - sometimes made by grinding flat files - removed a lot of wood pretty quickly, but didn't leave a fine finish. Never tried one myself, but could be of interest. You can always clean up the bore later....
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Re: reaming

Post by Loren »

Thanks for sharing that wonderful slice of history Terry, somehow I’ve managed to miss it all these years.

And the wrenches :lol:
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Re: reaming

Post by ChrisCracknell »

Thank you for that video link too - seeing Hammy at that age and making flutes is lovely.
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Re: reaming

Post by Loren »

Charlie,

Re-reading your post and thinking about it some more:

Surely check the sharpness of your reamers as Terry suggests, but assuming that’s not the issue, it sounds to me like you may have too many twisting and flexing forces acting on a relatively unstable reamer end of the system. If I’m understanding correctly, you’ve got the reamer chucked in an MT drill chuck, going into your lathe’s tail stock MT. Is that correct? Is it a #2 MT? That set-up seems problematic to me, if I’m envisioning it properly. Far too much opportunity for movement/flex between the far end of the reamer and where the tailstock and ways meet, and it sounds like you’re putting more rotational forces on the MT connection than it can handle, and possibly you’ve got some flex or other movement happening along that chain. Things you can do to help:

Cut the RPM’s way back to somewhere in the range of 30 to 70 RPM. Experiment within that range.

Use less forward pressure on the reamer - advance more slowly.

(Note: Heat build-up could also be a contributing factor so lowering speed and feed rates would also help in that regard.)

Lubricate the ways well prior to reaming so that you can make the tailstock as tight to the ways as possible while still being able to smoothly advance the reamer.

If the reamers are sharp, and rigid enough to avoid flexing, and the above suggestions don’t solve your problems, then you should consider chucking the reamers in the HS and feeding the pieces over the reamer, using the chain whip method to deal with the rotational forces.

I’m sure there must be other other options, but I do know that solution works extremely well, having reamed thousands of sections that way.

Certainly there could be other things contributing to the problems you’re having, a bit difficult to know without actually seeing your lathe, reamers, technique, what coffee you drink….. could be anything :lol:

Honestly, Mad Props to the guys who had to work this stuff out mostly on their own through trial and error. It’s become much easier to get some helpful advice in the last 20+ years or so.

Will be interested to hear how it all works out Charlie, hope you’re having fun with it, despite the challenges!

P.S. Serious answer to Kevin’s question: It would seem counter productive to the process of scraping off wood from the bore, but hey, it might be worth a try. I imagine the trick would be finding a lubricant that could be applied to the non-cutting surface of the reamer, one that would dry prior to reaming and stay put.

I suppose if you reamed slowly enough, then a light rubbing of the right sort of hard wax on the back of the reamer might work without melting into the wood……possibly? Once hot wax melts into wood it’s a problem.
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Re: reaming

Post by paddler »

Am I right in assuming that you are holding the wood in the lathe chuck and have the reamer held firm in a drill chuck mounted in the tailstock?
In other words, the wood is rotating and the reamer is stationary?

If so, then you have the problem that the reamer will be acting more like a boring bar than a reamer, and will generally not cut a bore the same
shape as the reamer itself. The issue is that neither the wood nor the reamer can move to ensure that the reamer is in the center of the bore,
so the hole cut by the reamer can be arbitrarily larger than the diameter of the reamer, just as the hole cut by a boring bar does not end up the
same size as the boring bar. The size depends on the degree to which the cutting edge is off-center.

I think the chatter you experience may stem from this problem. Basically, the cutting edge cuts for a while, then the reamer, drill chuck and
tail-stock flex enough to allow the reamer to move slightly away from the cutting edge. This movement would not be possible if the reamer
was self-centering, because the back of the reamer would be pressed against the opposite side of the bore.

A better approach is to mount the reamer in the headstock (so the reamer is rotating) and to hold the wood in such a way that it can be freely
fed onto the rotating reamer and retain the ability to move and self-center. Most people do this "by hand" but rather than directly holding the
wooden piece in their hand they use some kind of handle that improves leverage and saves straining the hands. I use a strap wrench. Loren's
post in another thread described using a chain whip. In both cases the handle rests against the lathe ways to prevent it from rotating.
Geoffrey Ellis clamps a device (T-bar?) onto the wood so he can hold it by hand.
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Re: reaming

Post by waltsweet »

Charlie,
Recent learning for me: The initial bore can be off center. For best results, I must do the initial drilling (and drying), then hold the workpiece between centers. Skim a little off the OD so it's concentric with the ID*. Making the workpiece co-axial with the tool reduces chatter and the bell-ends described by Loren. Maybe this step would have to be done a 2nd time if the reaming removes a lot of material (and introduces irregularities).
Are you using a machine lathe? Get a quick-change tool post (Phase ii) for the carriage. Get the wedge-block to hold your 2MT. Does your drill-chuck have a shank with a flat tang? This arrangement will prevent slippage.

*or skim a little off one end, where the chuck will get a new grip.
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Re: reaming

Post by Loren »

waltsweet wrote: Wed Jan 19, 2022 12:47 pm Charlie,
Recent learning for me: The initial bore can be off center. For best results, I must do the initial drilling (and drying), then hold the workpiece between centers. Skim a little off the OD so it's concentric with the ID*. Making the workpiece co-axial with the tool reduces chatter and the bell-ends described by Loren. Maybe this step would have to be done a 2nd time if the reaming removes a lot of material (and introduces irregularities).
Yes Walt, good points. FWIW our process also involved turning sections round (again) just prior to reaming. I’d certainly reface at least the headstock end of the piece as well if I were chucking the wood, rather than the reamer. In our case we had specialized final reamers that had either a either a length stop which also faced the end, or a built in socket cutter which faced as it finished the socket.
Are you using a machine lathe? Get a quick-change tool post (Phase ii) for the carriage. Get the wedge-block to hold your 2MT. Does your drill-chuck have a shank with a flat tang? This arrangement will prevent slippage.

*or skim a little off one end, where the chuck will get a new grip.
Interesting idea Walt, if I were a real machinist I might have actually thought of that! Maybe.
I always enjoy seeing/hearing other maker’s solutions to these problems, and I envy those with more extensive manual machine tool skills and experience.

Looking forward to hearing what ends up solving Charlie’s current problems.

And yeah, if you don’t have one already Charlie, get a QC tool post. Better yet, get a dozen. Well, maybe get a dozen after you sell a few flutes, those things are pricey.

Paddler, looks like maybe we were both composing our replies at the same time. :lol:
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Re: reaming

Post by GreenWood »

What comes to mind is that the cutting edge is not sharp enough and is distorting the whole work. If you imagine a 20cm wide plane (or scraper) for example and expecting it to cut smoothly/evenly without great outward (downward) pressure, it would have to be very sharp. So the moment part of the reamer blade stops cutting but pushes outwards, or the combined pressure along the whole blade ends up doing the same, then the work will get distorted around the length of the edge, and that change of shape will eventually jam the reamer. I don't know if the number of edges would help or not, it would be balancing of the work having more support to stay round (say with four edges) vs the effect of all the cutting pressure being given to just one edge if it were a single cutting edge (which therefore might manage to cut better) ? So from that perspective keeping the blades very sharp and introducing the reamer more slowly would be my answer.... after listening to what all the other commentators have to say first because I am sure they are vastly more experienced at lathe work and power reaming than myself.


Thanks for that video Terry :thumbsup:
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Re: reaming

Post by chas »

Well, folks, this is why I so often turn to the Chiffboard with important (and not-so-important, and even trivial) questions.

I'll address questions and comments in the order they were posted.

First, Loren, thanks for pointing to your post. It hadn't occurred to me that the Delrin Pratten thread would drift into reaming. Silly me. It never would have occurred to me either to use a chain whip for reaming a flute. But the idea is brilliant. It's something that would grip REALLY well as long as the wood has a large enough diameter (as you alluded).

Terry, the reamer set I'm using now has multiple spiral flutes. The two smaller ones work great, it's just the biggest one that seizes. These were from a company that, I think Walt had mentioned awhile back. It took me two solid weeks of turning and milling a few hours a day to make my own reamers; that's not gonna happen again till I'm retired, and I haven't found vendors who make D-type reamers. This one shouldn't be dull, since I'm only on about my fourth or fifth pass with it, and the first four were with castello, which isn't hard nor abrasive.

I think everybody has identified the problem(s), and thank you all. I am putting the wood in the headstock and fixing the reamer in the tailstock. I have a 9x20 lathe, so not much room at all, and I'll have to think carefully about fixturing the wood so that it's stationary. I will think about the chain whip. I do see the reamer precess. I have trued up the wood to the holes in both ends, but the reamer doesn't stick out the pilot at the beginning of reaming, so no way to true that up. I hadn't appreciated that fixing the work piece and fixing the reamer were not equivalent. Too much physics, just thought it was changing the reference frame. :oops: (My undergraduate thesis was literally about rotating reference frames) I agree that is the origin of the chattering. At this point, if I just turn the reamer in the work by hand, it screams, and while I can't see where the flutes have grabbed, I can feel it.

Walt, can I ask you what sort of design reamers you've gotten from the Connecticut company? The guy I talked to was very helpful, said he's supplied wind makers, they could sharpen them for wood, and suggested the spiral flutes.

Again, thanks everybody, and if anything else occurs to y'all, keep the suggestions coming. I love this community of knowledgable and helpful folks.

Cheers, Charlie
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Re: reaming

Post by Loren »

Hmmm, spiral fluted reamers you say? Interesting, I thought that type design was primarily intended for enlarging holes, not long bores, but again, unfortunately not my area of expertise. That said, all our custom made multi flute reamers had straight, relatively wide flutes. IIRC, it was 2-3 flutes together, spaced over 1/3-1/2 of the reamer, while the rest of the reamer body was solid and smooth. So essentially a scraping side and a burnishing/stabilizing side. Not that a conical fluted piece of steel has sides, but you see what I mean. Hopefully.

I’m trying to imagine how longish multi-fluted spiral reamer would work compared with a straight fluted reamer. Am I wrong in thinking that anything spiral fluted is going to have a cutting action in this sort of application, rather than the scraping accomplished by a straight fluted reamer? I miss Glenn Schultz right about now…
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Re: reaming

Post by paddler »

As far as I know, the main purpose of spiral fluted reamers is to help with chip clearing.
Depending on the relative direction of the spiral vs the rotation they either push the chips
forward (through the pilot hole) or evacuate them back up the reamer. Straight fluted
reamers don't encourage the chips to move along the reamer in either direction. But
no matter what configuration you have, the flutes are going to clog with chips quite frequently
when reaming flute sections .... especially long sections.

In my experience, chip clearance is one of the key challenges when reaming flute bores.
The more cutting edges you have, the smaller the flutes tend to be, and they tend to clog
more easily. In part this is also because more cutting edges remove material faster.

I have found that the reamer needs to be removed from the billet and the chips hand-cleared
from the flutes many times during the reaming of a single flute section. If you don't do this the
reamer quickly clogs, screams at you, and ultimately binds in the hole. The high frequency
of reamer removal and chip clearance is one reason why I don't like to clamp the reamer
in the tailstock. That really complicates the process of removing the reamer from the hole
entirely. If either reamer or wood billet is held by hand it is easy to quickly
extract the reamer from the hole (or take the hole off the reamer), clear chips, reinsert
and continue reaming.

The other reason I like one or other to be free floating is for accuracy. If both reamer and
wood are clamped in place, then you require perfect concentricity and alignment of both to get
a bore that accurately replicates the dimensions of the reamer. The OP mentioned filing
flats on the reamer so that it can be held in the drill chuck. This raises the question of how
accurate those flats are relative to the axis of the reamer. Even if the axis of the M2 taper
in the tail stock is perfectly centered and aligned with the axis of rotation of the lathe head,
even a slight variation in distance between the filed flat surfaces and the axis of the reamer will
lead to the reamer being positioned off-center, and likely also pointing in a direction that
is misaligned with the axis of rotation. This will produce a bore that is larger, and a different
shape than that of the reamer.

The main point of a reamer is that the non-cutting parts of the reamer hold it centered and aligned
with the axis of the hole being cut, simply by resting against the wall. A reamer only really needs
external stabilization to prevent it from rotating with the material being cut.
It does not need external stabilization for centering or alignment. In fact, trying to achieve
this externally tends to introduce inaccuracies that kind of defeat the purpose of reaming
in the first place, assuming you are reaming primarily for accuracy in the final bore dimensions.
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