 The Oboe BBoard
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Author: huboboe
Date: 2011-04-02 05:00
I was talking with cooper off line, asking about double radius gouging, which I have not done, having spent most of my career chasing the perfect 45 - 60 - 45 gouge.
Now that I am making a machine capable of double radius gouging, I think I need to learn lots more than I know now and we decided to put the conversation on the BBoard to get broader input.
Cooper summarized our conversation on the RDG Gouger thread as follows:
1. Most machines have different radius blades available
2. The big difference in feeling from one gouge to another is the grind angle and the curvature that it achieves from the grind angle.
3. These different curvatures cut away different amounts of cane in different areas which produce "different gouges"
4. The rest of the differences between gouging machines are materials, design, etc. But the most important is finding a good combination of radius with grind angle to produce a good curvature.
I agree.
What I am interested in is probably mostly anecdotal, but if enough people agree, we might be approaching (glowing in the sky) Truth.
My first question: If you are going to gouge off the center line (to get the double radius) then you will need a smaller diameter blade than the size-on-size blade of single radius gouging, in order to keep your sidewall thickness.
The smaller the blade, the larger the internal 'spine' produced if you maintain the same sidewall thickness. Is there a 'sweet spot'? What is it?
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: hautbois francais
Date: 2011-04-02 05:08
A question from the last thread, how easy and how long is it to keep consistent the 45-60-45 and the blade centered? I imagine the centering can be a real sob, if one finds it off more often than not.
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Author: huboboe
Date: 2011-04-02 06:34
Hautbois Francais:
Depends entirely on the mounting system. Most gougers index the blade against a stop of some sort suggesting that it will always be in the same place. Many index against screws (like the RDG gouger) and adjusting these screws moves the blade side to side (and tilts it if you move just one). Others mount rigidly to the carriage and you adjust the bed to center the blade. (this is a real pain!). I would expect if the blade is firmly attached it would not move randomly, so if you find the spot that gives you 45-60-45, it should stay there until you move it. If that isn't true, likely something in the machine is sloppy.
How easy is really a function of the mounting design. In my gouger the blade indexes firmly against the back wall of the 'Blade Block', a detachable unit with blade and guides that you can swap out (along with the bed) for, say, EH or d'Amore blade blocks. The blade block mounts to a block on the carriage which moves side to side with micrometer precision, allowing you to gouge either in the center or off to the side, depending on how you adjust it. And you can always return to where you were or go to a different place with a mechanism that moves just .02mm for each full turn of the adjusting screw.
Just to confuse the issue further, if you hold the center at 60 then the sides will vary according to the width of the shape: the wider the shape the thinner the sides.
I really think that variations in cane density introduce greater variability than a couple of hundredths difference in gouge dimensions, but maybe that's just 'adaptive scraping'. Cooper, you'ce gouged more cane than I have. What do you think?
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: JMarzluf
Date: 2011-04-02 07:10
I have been reading all of the gouge-related discussion with great interest. There is far too little information on this subject available to the average do-it-yourself oboist. If you don't have a skilled teacher available, it is nearly impossible to learn the real ins and outs of gouging.
Now, with regard to your newest post, Robert: Also at issue, I believe, is the relationship of the guide and the blade. I see this as a possible fault/oversight with your current design, but I could be wrong. Ideally, I would like to see better close-up pictures of the prototype, or -- better yet -- I would love to have one in my lap! It certainly looks like a very well-crafted machine.
My current understanding is that the guide, which is primarily responsible for holding the cane down in the bed while gouging (thus "feeding" the cane to the blade in a controlled manner), is also very important in ensuring the consistency of the gouge after the blade has been removed for sharpening. If the guide and blade are a match, then you can (through some effort) perfectly align the blade with the guide. This can be checked by measuring the thickness of the shavings produced during gouging, making sure that they are the same thickness at all points from one side to the other (left-to-right). In this way, you can be sure that: 1. your blade is in the same position that it was before you removed it, and 2. you did not change the shape of the blade during the sharpening process.
All adjustments made to the machine in order to change the relative thickness of the center vs. sides must be made to the carriage as a whole (including both the guide and blade as a single unit) in order to maintain consistency.
Also, I am a little lost on the topic of grind angle as it relates to blade curvature. Are you assuming that the blade curvature of a double-radius machine is still "round" (with a measurable, consistent, radius), as it is with a single radius machine? I do not think this is usually the case. I am certainly not a true expert, but I was under the impression that at least most of the successful double radius machines out there incorporate an irregularly-shaped blade, which gives that particular gouge a proprietary "character" all its own. The important effect is on the RATE OF CHANGE from thick (center) to thin (sides), as well as the actual ratio itself.
PLEASE correct me if my concerns are unfounded, or if my impressions are based solely on the alternate reality I tend to fabricate in my own mind as I stare at cane for so many hours at a time!
Best regards,
Jonathan
http://www.marzlufreeds.com/
Post Edited (2011-04-02 07:13)
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Author: RobinDesHautbois
Date: 2011-04-02 11:48
Now, my machine is definitely not a "successful" double-radius machine, but the blade does not necessarily have to bee of irregular shape to get it.
I can only speak in engineering terms of vector mechanics here, but you can see the principles of double-radius are shown half-way down my blog post:
http://robindeshautbois.blogspot.com/2011/03/gouging-oboe-cane-part-1.html
=> any irregularity in the curve will mostly serve to achieve your personal preferences.
The guide (plane bottom--- in my blog I use the word for the roller stop-bar) CAN be used to press the cane against the bed, but I'm not convinced that is so necessary. In terms of vector mechanics (force distribution) it doesn't matter if parts of the blade stick out more (compared to the guide) than others, as long as there is symmetry from side to side. Thus, the blade can have an oblong shape whereas the guide can be a perfect cylindre and no harm will be done. Without that symmetry, the call will be yanked to the side where the blade extrudes the most.
Now, Robert, Jonathan, Cooper, Craig and others, you have a truckload more experience than I do, and so you can formulate a better design on what is preferable in such conditions and for such type of reed preference.
Robert:
the "grind angle" do you mean the angle of the bevel relative to the flat top of the blade? If so, the bigger, the more solid, but the smaller, the easier the cut. Smaller means easier, but also less stable..... its with a rather small bevel angle that I manage to change my blade shape: I manually add a 2nd bevel.
Robin Tropper
M.A.Sc., B.Mus., B.Ed.
http://RobinDesHautbois.blogspot.ca/music
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Author: RobinDesHautbois
Date: 2011-04-02 11:53
A simple answer to a simple question:
The blade's curve will not change. So the ratio will not change. Once you find a blade you like, have it sharpened every few years and you're set.
The only thing that can change the ratio is if the blade gets tilted, somehow. On my beaten up old junk, all I have to do is sneeze! But on the machines we've discussed here (all of them) there should be no trouble with that.
Centering is not that hard. If you take the blade off for manual sharpening, you will need to verify the thickness of the shavings and you will see to the centering at the same time.
Robin Tropper
M.A.Sc., B.Mus., B.Ed.
http://RobinDesHautbois.blogspot.ca/music
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Author: jeremyreeds
Date: 2011-04-02 12:24
Hello, I find this (and previous) thread interesting.
I have a Howarth oboe gouging machine which have served me very well, and 2 "copies" that I got made with different diameter beds and angles of the tool (blade) carriage, etc. -variations-
I make a lot of reeds, and I am not very particular about the gouging dimensions of the gouged piece of cane that I make my reeds from. I have come to the conclusion that the most important aspect of reed making is the cane, the older the better. Right now I am making reeds with cane 15 years old, I am getting great results and I am sure this results would be as good as if I was gouging the same cane by hand. I understand the advantages of mechanising the process, speed, concistency, etc., etc. In this machanisation and innovative process it would be very nice if by gouging cane we could come up with an already sounding reed, first step would be to create a 'spine' in the gouge, so that we would only have to scrape the windows and tip. Isn't this what the 'double radius' is about?
For what I have read so far, in these 2 threads, and here: http://www.patentstorm.us/patents/6683238/description.html, particularly in the line that reads:
"One example of a gouging machine is a double-radius gouge having a blade that cuts slightly off-center so that only one side of the cutter blade contour is cutting out cane. The cane is flipped repeatedly in its holder and re-gouged until the final dimensions are met."
the only thing we need to have double radius gouge is to set the blade (tool) off-center (off-set), and that could probably be done with most machines. Am I wrong?
Regards
Jeremias
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Author: RobinDesHautbois
Date: 2011-04-02 21:13
SUPER COOL that you found the patent information!
The users of actual double radius machines will have to answer. As far as I can surmize, the machine would need some means of compensation for the "swing" procuded by the blade being offset with respect to the bottom of the plane (the "guide" or undercarriage).
If the whole blade assembly is left intact, but the bed is off-center with respect to the undercarriage, then the swing is minimized. Some might argue that in that case, the cane is not held in place correctly, but I think more geometric analysis is required to confirm or deny such a hypothesis.
Robin Tropper
M.A.Sc., B.Mus., B.Ed.
http://RobinDesHautbois.blogspot.ca/music
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Author: huboboe
Date: 2011-04-04 05:08
Whoah! Been away for a day and a half and look at the response!
Jonathan: I assume your observations and questions refer to the Westwind gouger...
The blade is mounted exactly centered in the guides, which are machined at the same radius as the blade. The 'sidewall adjustment' mechanism carries the blade & guide assembly horizontally from the centerline of the bed to either side of it, so you can single radius gouge on the centerline or double radius gouge off of the centerline.
My earlier question is 'what is a good profile diameter for double radius gouging'?
The accuracy between the guides of the remounted blade is assured by mounting it against the back wall of the blade/guide assembly. You will not change the profile of the blade if you sharpen by honing the flat top of the blade.
The 'carriage-as-a-whole' really isn't. Instead the 'bearing block contains the bearings which move the carriage on the shaft. (On the X axis.)
The blade block carries a secondary block which is adjusted in the Y axis, the 'sidewall thickness adjustment. Adjustments to change the relationship of the center/sidewall dimensions are made with the 'sidewall adjustment' independent of the gouge thickness adjustment.
The secondary block carries a mounting block for the detachable blade/guide assembly. The 'gouge thickness' adjustment moves the blade/guide assembly up or down (in the Z axis) with respect to the bed when the gouge is complete. This will, of course, result in a small change in the sidewall thickness as the curved blade plunges further into the cane, but this can be brought to the desired dimension with the sidewall thickness adjustment.
Each adjustment on the gouger is independent of all others.
As I said earlier, I am new to double radius gouging so I can't speak for common practice, but as Cooper says above, they are usually smaller and asymmetrical. In my case they are smaller (but by how much??) and symmetrical on the guides.
I'll post some pictures tomorrow...
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: huboboe
Date: 2011-04-04 05:35
Robin:
I like the description of single/double radius gouging linked above to your blog. The graphic illustrations are just what I had in mind but hadn't yet done for my own site...
I agree with you that symmetry is critical for balanced cutting forces, but I think the guides have a real job to do in resisting the lifting tendency of those cutting forces.
As to the 'grind angle'. yes, I mean with respect to the top of the blade. Yes, the smaller angle results in an 'easier' cut because less blade is in the work. As the angle becomes smaller the cane 'sees' not a circular cross section but an increasingly more elliptical cross section, resulting in thicker sides with respect to the back. On a double radius gouge I think this would result in a more pronounced 'spine' in the gouge.
Question #2: Is that useful?
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: huboboe
Date: 2011-04-04 06:00
Jeremias: Most machines will allow you to move the blade off of the centerline, but that creates the problem of unbalanced cutting forces skewing the cane in the bed. And if your blade gives you a 45 - 60 - 45 gouge single radius gouging, your side walls will now be thinner, so you will need a smaller radius blade...
In my earlier post to Jonathan I said, "The blade block carries a secondary block which is adjusted in the Y axis, the 'sidewall thickness adjustment." I meant to say, "The BEARING block carries a secondary block..."
The blade block is my name for the detachable blade/guide assembly block onto which the blade mounts. Sorry for the confusion.
Cooper, or any experienced double radius gouge person: Would you say .5mm smaller than the cane/bed size, or .75mm or even 1mm smaller is most typical or common in your experience?
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: JMarzluf
Date: 2011-04-04 06:55
Thank you for the clarification with regard to the details of your design. This sounds intriguing indeed. Isolating the adjustments for each axis in this way sounds like an ideal situation. Also, I am particularly impressed with the simple notion of mounting the blade flush with the wall of the "blade/guide block/assembly," to ensure proper alignment with the guide. This should eliminate the most frustrating (for me) aspect of maintaining a gouging machine.
In answer (or not) to your question, I do not know what the proper symmetrical radius should be for a double radius set-up. Nor do I know if a symmetrical approach to double radius gouging will work at all. It still seems to me that the rate of change (of thickness) from the center to the sides of the gouged piece will not be ideal if done with a symmetrical blade. This is based solely on the fact that my machines (an Opus 1, by Robin Driscoll, and a Graff, set up by David Weber) do not have symmetrical blades. I can only assume that the concept of using a symmetrical blade has previously been tested and rejected.
My geometry chops haven't been exercised since high school, but shouldn't it be possible to graph this out somehow? My suggestion would be to aim for a thickness of .60 mm at center, and .40 on the very edge of a piece of 10.25 mm radius cane, pregouged to a width of 8 mm. This is the current result I get with my favorite machine. The side thickness I end up with, measured at the widest point of the shape I use, is right around .47 mm. Of course, the added variable of different shapes is the whole reason why the adjust-ability of the double radius gouge is, in my opinion, beneficial.
With much love and encouragement from your most dedicated would-be beta tester  ,
Jonathan
http://www.marzlufreeds.com/
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Author: hautbois francais
Date: 2011-04-05 00:25
huboboe:
Now, I see from your comments earlier and Cooper's, using a smaller blade than the bed, will yield a thicker sidewall. If u have a gouger, at 11 bed and 11 blade, it could potentially give you a thinner sides and not the 45-60-45 ideal dimensions.
Sometime, it takes careful reading and re-reading to take in the vast pool of information here. The last thread has already 94 posts. I am glad you have started this one which is more specific in the technical details.
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Author: huboboe
Date: 2011-04-05 05:36
Hi, Cooper: In my naivety, I'm assuming a 45º angle grind on the blade and the blade mounted at 45º on the gouger, yielding a circular profile on the cane. I understand, though, as the grind angle becomes shallower, the blade becomes more elliptical; the nose elongates and narrows and the cut becomes increasingly u shaped.
If this is what your gouge looks like, then, for an offset 'center' thickness of .60, how wide is the final cut if you don't turn the cane but gouge just one of the two radii to completion? (And what IS the angle of your grind?)
There may not be an obvious magic number, but if we can measure what works for you, maybe we can back engineer a starting place from which to make small changes by way of experimenting.
As you said in your summary, the important thing is finding the ideal combination of grind angle and radius. What's a middle of the road, ballpark combo in your experience?
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: JMarzluf
Date: 2011-04-05 13:53
I know this was aimed at Cooper, but I will chime in. My experience has shown that, when using a double radius machine, it is impossible to gouge in only one direction (i.e. only one side of the cane) to "completion." The guide will bottom out against the now-thicker side of the cane long before the roller will come down against its stop-rail. One MUST flip the cane in order to complete the gouge. This is not a practice strictly designed for gouge symmetry.
Jonathan
http://www.marzlufreeds.com/
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Author: huboboe
Date: 2011-04-05 23:36
Jonathan: A response to Cooper, but aimed at the BB. I'm trying to see what kind, if any, of a consensus exists among those who double radius gouge.
I expected that answer, since Cooper had described the process as asymmetrical, BUT, if the gouger were set up with the blade and guides symmetrical at the same diameter (like a single radius gouge only smaller), then you could cut to completion, since the guides would not impede the carriage travel. You probably wouldn't want to, though...
It sounds like this has not been tried, but the question now becomes: how important is it that the blade profile presented to the cane be elliptical and not circular? It seems to me that unless the grind angle were quite a lot shallower than the 45º that provides a circular profile, the amount of ellipticality would be very small and MIGHT not matter. Cooper's Principal of the ideal blade angle/diameter combo suggests that it does matter, but this is subject to actual test...
I don't see any good way to profile elliptical guides short of having an infinite assortment of dedicated form cutters (hand filing does not cut it in my book) so I see myself as confined to circular guides.
I had hoped someone might say, 'Hey, Bob, try a 9.5 blade, offset 1.5 mm on 11mm cane.' or something of the sort, but I guess I'm gonna have to just try a variety.
And a standard disclaimer, just so no one thinks I forgot: Cane is a Natural Substance and not Uniform, so there really are no hard numbers, just close approximations.
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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Author: hautbois francais
Date: 2011-04-06 04:18
It helps that you have the gouge cane per your specs, dimensions, cane density and hardness etc. In the end, as Hubobe has said, cane is an organic and natural and in itself will have a lot of variability.........even if u get the perfect 45-60-45, and every other step, u dont make a mistake, and sometimes still u dont get a good sounding reed. The thing also is to try to achieve consistency, from gouge to finish reed, and then try best to adjust for best sound if possible. That is the hard part.
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Author: huboboe
Date: 2011-04-06 05:20
Thanks, Jonathan. All my dreams have now come true...
Robert Hubbard
WestwindDoubleReed.com
1-888-579-6020
bob@westwinddoublereed.com
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