flat reamers

A forum to discuss the arcane art of making uilleann pipes, reeds, and set maintenance.

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billh
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Post by billh » Sat Dec 15, 2007 4:51 pm

My point is not that flat reamers are 'bad', but of course they have limitations as well as perceived advantages. Since I have tool steel stock and a metal lathe there is, as Sam says, no advantage to me in making flat reamers. If I didn't step-drill, I might give them a try for roughing out.

You're right that D reamers can't really be altered or adjusted once made, I have to make them right the first time. If I screw up, I make another one... as you say it's "not rocket science".

I have a couple of moisture meters of different types. They are OK for green wood and for native timbers and fruitwood, but I find them useless for tropical hardwoods, whose electrical properties are quite different from less dense wood - by the time the timber moisture gets really low, which is of course when you are most interested in the results, the resistivity of the wood goes sky-high and the meters' accuracy plummets to zilch (even with the best available correction tables).

As you say, a chanter's measurements can and usually will change significantly after being initially reamed. Over time, though, it will 'settle in' and if, as is often the case, a spot check with accurate gauges shows that the bore has shrunken slightly below target diameters, a light touch-up with the reamers brings things back in to line. I like to do the final reaming by hand very lightly so that the timber is not significantly warmed.

Bill

ttoberer
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Post by ttoberer » Sat Dec 15, 2007 5:42 pm

well, I guess I didnt mean to create any controversies. it seems like that old cat is tryin to tell us somthin here... in my time with making instruments and just about anything else I have found that what works for me doesnt necessarily work for sombody else. not that my way is better, its just finding somthing that works period. for that I think you all have steered me a little closer. Thanks! it seems alot of the time I make things more complicated than they have to be, its just trying to find the simplest, most effective way that can be a real stickler. I wonder if any of us could make these things with some old broomsticks, a treadle lathe and some hand tools? I think I will have alot more questions once I get things going again. maybe ill try my experiment. Tim

Davy Stephenson

Post by Davy Stephenson » Sat Dec 15, 2007 6:53 pm

It is correct that senitivity of some moisture meters intensifies, but not all, if you cannot afford the better ones, you can always weigh the timber to work out how much moisture is left behind, a guide line of less than 12% is about right, to start working with it, then leave the timber for at least another five years to be sure, letting it dry naturally is the best course of action for the most stable results.

I have bought timber from reputable delalers over the years, who have seasoned the wood in specialised long term kilns, and when drilling the wood, steam has emerged from the hole when it was withdrawn, if this happens, leave it for at least two years before going on to the next stage.

Having worked with many native fruitwoods I have found that Holly is one of the best once it is dry, it resists reabsorbing afterwards, you can always try sealing the timber to stop reabsorbsion, but if there is any moisture left inside it will not be able to release it, and if the timber is heated by mistake, say by leaving it in direct sunlight, you can end up with a banana chanter.

Ebony is one of the worst, if it gets the chance it will readily absorb water and bad results can follow, especially on a finished product, then after the timber has dried out again, I have found that the dimensions are all over the place and re-tuning is most likely needed, if there is any ovality it is then very difficult to get the settings correct, this is why some old sets need careful evaluation before coppying them.

The ovality is sometimes quite bad, and trying to re-tune one brings on many problems as the wall thickness and chimney height can effect the overall tuning more that tiny throat variations, most old set should be where they belong, best left in the museum.

Davy.

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keaaudio
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Re:

Post by keaaudio » Sat May 02, 2009 9:33 pm

billh wrote:...

I clamp the reamer to the milling bed and use shims to "level" the unmilled reamer so that it is not significantly bent and so that its axis is level with the milling bed. For the purposes of "stock removal" which is all that is required here, that gives sufficient accuracy. If/when in doubt you can measure the reamer thickness as you go, to ensure that you have a comfortable margin before the halfway mark.
....

Best regards,

Bill
Dear Bill,

your post is a couple of years old, but I am quite interested to know how you made this D reamer. I understand that you first turn the reamer and then mill it. Is that correct. I don't quite understand what you mean by using "shims to level". Could you explain that more?
I could imagine actually that it would be possible to mill the reamer first and then turn it, although it might bend too much then while turning it.
At any rate, I got all the machines but I am not sure about the process. Turning and milling is straight forward, but the clamping is a bit unclear for me.

billh
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Re: Re:

Post by billh » Mon May 04, 2009 6:25 am

keaaudio wrote:t I am quite interested to know how you made this D reamer. I understand that you first turn the reamer and then mill it. Is that correct. I don't quite understand what you mean by using "shims to level". Could you explain that more?
I could imagine actually that it would be possible to mill the reamer first and then turn it, although it might bend too much then while turning it.
At any rate, I got all the machines but I am not sure about the process. Turning and milling is straight forward, but the clamping is a bit unclear for me.
What do you mean by "I got all the machines" ? If you have a milling machine and a metal lathe I would assume you are familiar with turning metal and with milling and workholding/clamping techniques. If so I think it should be clear that turning a piece that is not round in cross-section is not practical for such a long, thin shape. It's impractical at the best of times, being a highly 'interrupted cut', but it would never be feasible for a piece that was not highly rigid. You wouldn't be able to accurately measure your results either.

Shimming is a a fairly standard technique for adjusting distances and tolerances. I use shims and standard clamps with T-bolts to hold the turned workpiece, circular in cross-section with a detailed semi-conical profile, to the milling machine bed; I use the shims to support the thinner parts of the reamer so that the centerline is parallel to the bed. I work out a clamping sequence that allows me to mill around 100 millimeters of length at a time, max, and move the clamps as I go. Since I grind the reamer on its flat face after milling, on a wet grinding wheel, the alignment of these successive milling planes doesn't have to be perfect. Be careful about milling cutter linear velocity since most small milling machines have a speed range that's far too high for milling tool steel - you'll probably be working at the lowest end of the speed range. Shimming doesn't give a terribly secure hold, but it's best not to be too aggressive with the milling cuts anyhow, since heavy cuts are more likely to deform the reamer. If you want a more secure hold, you can make semicircular 'cradles' from brass with different inner diameters and the same centerline height, and support the reamer between the clamped ends that way. Softer brass or copper helps damp vibrations, and it may help to make thicker shims from lead.

For anyone considering such work I would recommend reading up on "model engineering" techniques, which are more suited to the small workshop than most engineering or machining texts (which are oriented towards industrial processes and scales).

regards

Bill

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keaaudio
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Re: flat reamers

Post by keaaudio » Tue May 05, 2009 12:11 am

Dear Bill,
thanks for the advice.
English is not my first language so sometimes I am not quite sure what is actually meant. That is why I asked for more details, and thanks for that.

I appreciate that turning a d shaped rod is not unproblematic, but nevertheless I thought somebody knows a trick. I have tried to do that today actually and if you support the rod in the middle or even twice it is actually possible to turn it. But one has to go very slowly and it is problably not the best way to go. So I did it the other way round and turned it conical first and the put it in the mill. I had sofar not clamped in a conical shaped object in the mill, so I thought it might be tricky to do without the piece slipping of. I have use aluminium spacers now, that I milled to correct size first. That works. I also supported the underside of the reamer.
My collegue actually recommended not to mill a D shape but rather mill out a quarter. This appears to be a better method, but I have not tried out the reamer yet, so I don't know yet. Will let you know in a few days.

cheers
Joe

billh
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Re: flat reamers

Post by billh » Tue May 05, 2009 4:39 am

Hi Joe,

Glad to hear that you're having success. Aluminium sounds fine for the spacers.

I would avoid the "3/4 section" reamers. They are more trouble to sharpen, for one thing. They also tend to rub or burnish rather than cut, unless you raise a burr. Raising a burr affects dimensional accuracy, so that's not ideal. Ideally you want the reamer's maximum cross-section to be at the edge, so that cutting forces are directed there. Since the wood is anisotropic, it tends to go oval even as it is being cut and this can make the 'rubbing' action of the 3/4 section reamer worse, since in this case the widest "point" of the reamer is nearly half the circumference.

I've had a number of conversations with other makers over the years and the ones whose advice I most trust have tried, and rejected, the 3/4 section reamers for various reasons including those above.

C-section reamers can reportedly be good especially for softer woods since the cutting angle/edge is more acute, but they are hard to fabricate and sharpen.

best regards,

Bill

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keaaudio
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Re: flat reamers

Post by keaaudio » Tue May 05, 2009 5:53 am

Hi Bill,

thank you very much for this info. That is very helpful. D reamer it is then. Seems to be the best compromise obviously.

cheers
Joe

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snoogie
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Re: flat reamers

Post by snoogie » Sun May 31, 2009 7:26 am

I use a method suggested to me by Tommy Martin to turn the round milled stock into a D shape reamer. Simply clamp it in a vise and use an angle grinder with a metal working wheel to grind off not-quite-half of the reamer.

From there I use my stationary grinder to sharpen it and get a consistent edge. Then hone it with a sharpening stone. You have to remove the ridge that builds up on the outside of the reamer, otherwise it'll affect the finished dimensions of the bore.

Simple and inexpensive. I couldn't justify the expense of a milling machine (as much as I'd love to have one!).

-gary
There is no try, only do or not do - Yoda

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bobble991
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Re: flat reamers

Post by bobble991 » Sat Jun 20, 2009 3:01 pm

snoogie wrote:Simply clamp it in a vise and use an angle grinder with a metal working wheel to grind off not-quite-half of the reamer.

-gary

Do you keep cooling the reamer during angle grinding? I guess air cooling will allow it to harden? I guess Ill have to do it this way for a while until I have the cash for a milling machine :cry:

Bob

billh
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Re: flat reamers

Post by billh » Mon Jun 22, 2009 3:15 pm

Hi Gary and Bob,

I use the (tiny) Sieg X1 mill. Though they've added some features and raised the price lately :-(, it's about the lowest price for a halfway decent mill that I've come across. Axminster in the UK has them, in the US Harbor Freight should have the cheaply, and perhaps they'll have the less expensive X-1 (Axminster only carries the "'Super' X-1 Mark II" now). It's not an impressive mill but it seems to do the job, if you're patient with it. Watch the tool speed, you'll want to be at the very bottom of the RPM range for milling tool steel, even with a small diameter mill.

LiamO'Flynn
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Re: flat reamers

Post by LiamO'Flynn » Mon Jun 22, 2009 4:58 pm

I find this stuff very interesting so I asked a toolmaker friend what would be the best way to make a reamer and he suggested that after you turn your tapered round steel you then take it to an engineering shop that has a surface grinder.You get them to grind exactly one quarter way down the reamer,but have the grinding wheel at 90 degrees to the reamer so that the surface is hollow ground,then you turn over the reamer and grind down a quarter on the other side.This gives you four cutting edges,two cuts turning one way and two the other way.Professional grinders have a coolant liquid that keeps the reamer cool as its being ground. You also have to be careful to remove any buff that is raised by the grinder.

Liam
Liam O'Flynn the plumber not the piper .

billh
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Re: flat reamers

Post by billh » Mon Jun 22, 2009 5:50 pm

The surface grinder is a great idea and would avoid the whole milling issue. Would need for it to be a sympathetic shop to avoid messing the thing up, it could be tricky to hold a round reamer to the grinding table.

I don't quite get the geometry you're suggesting, Liam. I'd go for the D section - easier to sharpen. If I understand your friend's suggestion you'd end up with four negative rake edges which were not easy to sharpen, which seems not so good. I think the double-hollow flute version would have some of the drawbacks of the "3/4 section", perhaps more.

Hollow ground is good though, so if the surface grinder were set up to hollow grind the reamer to an approximate D, it would make resharpening a breeze. The burr could be taken off easily by honing in that case.

Bill

LiamO'Flynn
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Re: flat reamers

Post by LiamO'Flynn » Mon Jun 22, 2009 6:17 pm

The table on a surface grinder is magnetic,when the power is on you couldn't move the reamer even if you wanted to,metal shims are placed under the reamer to bring it level .The idea of hollow grinding gives you a slightly positive rake, in fact the smaller the diameter of the grinding wheel the more positive the rake.

Liam
Liam O'Flynn the plumber not the piper .

billh
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Re: flat reamers

Post by billh » Tue Jun 23, 2009 4:46 am

You rake angle will depend on the diameter of grinding wheel and depth of the groove. With a shallow groove (you said 'one quarter') you still get negative rake; with a reasonably big grinder diameter you need to go nearly to the center of the reamer for the rake to go positive. Since the reamer is tapered I don't see how you'd be able to use a constant _small_ grinder diameter to correct for this without the groove profile being too narrow at the reamer's large end or too large at the small end. I think the loss of rigidity would outweigh any advantage to having double the number of cutting edges.

It would be nice if grinding eliminated some of the bowing of the reamer that tends to happen after machining.

The magna-clamp thing sounds pretty interesting...

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