STME58
40 posts
Dec 07, 2011
8:18 PM
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I have access to a 84X microscope and digital camera setup so I used it to take a close look at my LoD Seydel Session Steel. I was hoping to see a crack or other evidence as to why a reed went flat but I did not. What I did get was some insight into how this harp was made. I have arranged the photos into a powerpoint presentation that I would like to share if possible. I have added my comments from a sheet metal part design engineers perspective and I would love to get comments from those of you with customising or manuufacturing experince on what is going on in the details of the harp.
Does anyone know of a way to post a powerpoint presentation so forum members can see it? A better first question might be, is anyone interested in seeing this?
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WinslowYerxa
128 posts
Dec 07, 2011
9:58 PM
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Posting content other than text is explained here:
http://www.itriser.com/harmonica/mbh_how-to.htm
I'd be interested.
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STME58
42 posts
Dec 08, 2011
12:54 AM
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I tried the link and it did not work ,
I will have to find another way to get these images up.
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jim
1068 posts
Dec 08, 2011
1:42 AM
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register a dropbox account:
www.dropbox.com
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MrVerylongusername
2103 posts
Dec 08, 2011
2:10 AM
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I downloaded it fine, but I agree that dropbox is far simpler.
Those filesharing sites deliberately make the links confusing so you click on their adverts and not the real download button. PLUS their captcha was a real bitch. Anyone who thinks the MBH one is bad needs to try this - I had to generate 7 different codes before I could even try typing one.
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jim
1069 posts
Dec 08, 2011
2:27 AM
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bend it in the slot. If there's a minor crack - it will break.
shit happens.
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HarpNinja
1968 posts
Dec 08, 2011
6:32 AM
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Totally ignorant question - what magnification is this? I actually want a new microscope, but am unsure of how much power I want.
I like Jim's suggestion. I was sent a couple of 1847's that had reeds that were totally cracked off...so I would imagine just playing with it would snap off.
Regardless, a drop that far in tuning warrants a fix. The 1847 stuff is easy to fix using a new (sometimes the old) rivet. They are large enough to work with.
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Mike
Quicksilver Custom Harmonicas
VHT Special 6 Mods
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STME58
44 posts
Dec 08, 2011
9:11 AM
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Jim,
Thanks for the dropbox info. It was much easier than what I found.
http://dl.dropbox.com/u/52636345/Sydel%20Session%20Steel%20Migrographs.pdf
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STME58
45 posts
Dec 08, 2011
11:38 AM
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HarpNinja,
Your question is not ignorant, but a basic and reasonable one when presented with a magnified image. It is also hard to answer because of the scaling to the image done in the computer and the manual soom on the microscope. The reeds are about 2mm across so that gives and idea of scale.
I was using a Lumenera Infinity-2 2 meapixel image capture device with a Navitar 12X lens. There is a multiplier of unknown power (looks to be about 3x) on the end of the Navitar. The Navitar itself zooms from .58x to 7X (I don't know why it is called a 12X).I expect the power was around 15-30x to the capture device but the resolution of the capture device makes a big impact on the details captured.
I was using 2 fiber optic light power supplies, one driving a ring source around the lens and the other driving two flexible stalk lights that could be easily positioned to cast or eliminate shadows.
This setup is right down the hall from my desk. I think the cost of this system is in the low thousands of dollars,not hundreds and not tens of thousands. It also has simple rack and pinion stage that allows moving the target in a controlled manner.
If people find this interesting I will get images of other harps as I take them apart.
Last Edited by on Dec 08, 2011 11:41 AM
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STME58
46 posts
Dec 08, 2011
1:17 PM
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There are two questions I am vary curious about from these photos.
One is from the detail of the tip on page 2. It looks like an attempt was made to round the tips of the reed to match the round corners of the slot. The end of the reed curve in but is cut short. It is as if the corners were rounded but the tip was cut off square. Would a customiser either file the slot closer to square and use a square tipped reed or curve the tip of the reed to match the slot and make the reed a bit longer to keep a consistant gap all the way around the reed?
My other question concerns the root. On page 4,9 and 11, the reed seems to contact the plate on the rounded corners of the slot so that the bottom of the reed contacts the reed plate only on the sides and not all the way across the reed. Is this intentional for some reason? It seems like a good line contact between the reed and the reed plate would give mre consistant performance.
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walterharp
776 posts
Dec 08, 2011
7:46 PM
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First, really cool images...
Second, it probably went flat because you blow and draw too hard,but i have had steel reeds on sydels go out pretty fast.. occasionally just bad luck with a flawed reed.
basically the microsope won't help, you need a reed replacement or a new reed plate.
this really makes me think about what customizers do. the embossing process will round the reed side down into the reed plate, it kind of looks like what this harp has from the manufacturing process.
it also brings up something that i have thought about. i suspect that the fulcrum of where a reed vibrates is based on the lowest point in the slot it contacts.. so probably does not matter much where that point is, but anything below that is wasted air. your images suggest that is correct.
it is really nice to see real data here.. appreciate it, though may not give you the specific answers you are after
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STME58
47 posts
Dec 08, 2011
9:11 PM
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Walterharp,
Thanks for the input. I know the microscope won't help my reed problem. I have had enough 7 blows fail to know it is my technique (just what it is about my technique I have yet to discover but harps are lasting longer as my skill improves). I was just curious to see what a failed reed looked like and to discover a bit more about how a harp is made.
I was also thinking about the fulcrum. Is seems that as the reed bends into the slot the fulcrum is wherever the reed contacts the edge of the slot as you state. As the reed oscillates up, the fulrcum is either the rivet, the step where the reed gets wider, or someting in between. I would love to get a high speed camera in there and see what is going on.
I will do a literature search and see if anyone has done such work. Or perhaps someone here is aware of it.
Last Edited by on Dec 08, 2011 9:11 PM
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STME58
49 posts
Dec 09, 2011
2:10 PM
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I had a set of Manji plates on my desk so I captured some images for comparison.
http://dl.dropbox.com/u/52636345/Manji%20D%207%20outer%20reed%20micrographs.pdf
I don't know which is "better" but there are some clear differences.
This harp was used quite a bit. Some of the images would be good to show anyone who wants to "try" your harp.
After looking at this I am not sure I want to put this back in my mouth!
Last Edited by on Dec 09, 2011 2:14 PM
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jim
1071 posts
Dec 09, 2011
4:41 PM
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great pictures.
I think Suzuki fine-tunes everything by hand after initial tuning.
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