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Dirty-South Blues Harp forum: wail on! > Checking Comb/reedplate flatness
Checking Comb/reedplate flatness
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harpwrench
1082 posts
Apr 18, 2016
8:32 AM
Flat combs aren't a magic bullet, and really don't mean squat if the plates aren't flat as well. They also don't fix problems like the reeds being attached off-center, or bad curves and twists. But if everything else is done right, a comb that isn't flat enough can break up the party.

It's a best practice to always check your custom combs as well. Never take it for granted. Nobody's perfect, and few seconds could save hours of frustration because it was overlooked. And following Murphy's law, if I get in a hurry and don't check one, that'll be the one that causes problems.

One cheap and quite a bit "better than nothing" way to check a comb (and your reed plates) is a utility knife blade. Stand it on edge along each tine (or along the length of the reed, between reeds on a reed plate), and hold it up to a backlight (such as the window in the daytime, with the lights out in the room). It'll be very obvious if your comb/reedplate has big problems. I don't want a leak of course, but another thing I especially don't want is an arc that causes the reed plate to deflect when everything is screwed together.

I use a knife edge machinist edge FWIW, I also fix all the other issues mentioned when you have a $45 super stock service (at minimum) done to your harp. Along with proper profiles and a full strobe tune. That gets a lot of good stuff going on in a harp for not much more (sometimes less) than a custom comb.

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Last Edited by harpwrench on Apr 18, 2016 9:07 AM
harpwrench
1083 posts
Apr 18, 2016
8:42 AM

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www.spiersharmonicas.com
Harp repair and upgrade menu

Last Edited by harpwrench on Apr 18, 2016 8:59 AM
harpwrench
1084 posts
Apr 18, 2016
8:53 AM


This is the blow side of a comb. THINK ABOUT IT. What happens when you tighten the covers down? The blow reed gapping all closes down significantly as the blow reed plate deflects around the arc of the comb, that's what. "WOW, my new Acme dinosaur bone comb instantly transformed a leaky POS into an amazing harp!"
OR, it makes it sticky, and unplayable.
OR, it fills in the gap left from a concaved reed plate, all's good.



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www.spiersharmonicas.com
Harp repair and upgrade menu

Last Edited by harpwrench on Apr 18, 2016 9:50 AM
harpwrench
1085 posts
Apr 18, 2016
9:29 AM
FYI This is what I mean by reeds off center. You can't rotate it to be centered, the reed must be moved over at the attachment point. When sighted from angles used to check profiles, the side closer to the slot will appear down at the base and too tight, the other side will be up, and the result will be a reed that both sticks, leaks, and/or doesn't bend right, depending on the conditions being played under. The technique of closing in the open side with a UST or whatever, just worsens the real problem as it pushes the slot even lower in relation to the reed, creating a larger leak, even though it looks pretty from up top. This has absolutely nothing to do with combs or flatness, it's a very common problem that's only fixed with quality reed work.

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Harp repair and upgrade menu
Todd Parrott
1365 posts
Apr 18, 2016
10:28 PM
Awesome post!
arzajac
1760 posts
Apr 19, 2016
4:41 AM
Those are the natural facts!
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Custom overblow harps. Harmonica Combs and Tools.
ridge
660 posts
Apr 19, 2016
4:47 AM
Thanks, Joe! Your last post confirms what I've been thinking for a year in regards to slot embossing also lowering the slot. I look at old plates that I heavily embossed and shudder now!
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HarpNinja
4227 posts
Apr 19, 2016
5:18 AM
I use a machinist's edge, but also have a flat piece of Corian that I use against a backlight. You can set the whole comb or reed plate on it without having to use any finger pressure.

A few years ago, I started testing the blow plate on a flattened comb, which isn't the best way possibly, but it was pretty effective in looking for leaks. I then moved to using the edge, but the sheer weight of it combined with finger pressure sometimes gave a false positive.

Reeds being misaligned can be tricky to spot if you aren't embossing. They may look good in the slot if you haven't closed the edges. Straightening them without popping the reed off took a long time for me to figure out a solution for.


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Mike
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Lonesome Harpman
198 posts
Apr 19, 2016
5:19 AM
Thanks Joe, another Ah Ha moment!
Slimharp
420 posts
Apr 19, 2016
8:43 AM
Right on. Thanks Joe.
1847
3387 posts
Apr 19, 2016
8:54 AM
that looks like the reed on grey owl's harp.
perhaps its just a bad camera angle:)
MP
3359 posts
Apr 19, 2016
6:24 PM
Great tip! I like to use my Exacto knife w/ the pointed blade for small surface areas and a mini metal pocket ruler edge for larger jobs.
In my book, reeds and reed plates are the heart and soul of a harp. all else follows.
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Have good day. M.A.P.
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Last Edited by MP on Apr 19, 2016 6:27 PM
MP
3360 posts
Apr 19, 2016
6:28 PM
Yeep!
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Have good day. M.A.P.
.
Thievin' Heathen
742 posts
Apr 21, 2016
4:23 PM
@ Harpwrench..,
"The technique of closing in the open side with a UST"

What's a UST?

Thanks for giving up a little of the dark art of reed work.
1847
3394 posts
Apr 21, 2016
5:00 PM
a useless sjoberg tool. i am only half kidding dont get bent out of shape.
arnenym
388 posts
Apr 23, 2016
11:35 AM
If you try to fix that problem with a UST you don't know how to use that tool.
If you use a UST to "Embossing" or "Sizing" it's a great tool.
Killa_Hertz
1156 posts
Apr 23, 2016
3:49 PM
I ve been looking for an appropriate sized machinist straight edge for a while. At a reasonable price.

Anybody have any sources?
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harpwrench
1086 posts
Apr 28, 2016
7:43 AM
A pack of utility knife blades from Ace hardware will show you all you need to know as a hobbyist. If you see a problem flip the blade the other way, if the problem moved it's the blade but if it looks the same you probably have a not-flat part.
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www.spiersharmonicas.com
Harp repair and upgrade menu
Killa_Hertz
1193 posts
Apr 28, 2016
8:14 AM
Really? Thats flat enough? Seems like they would be too imperfect. But I suppose your right. If I use more than one reference and they all tell me the same thing, more likely than not, its correct.

Im not sure what type of blade your referring to exactly. Not that it probably matters. I get the point, but just out of curiosity.
















Well in my experience all plates are Effed Up somewhere.

I finally got my manjis playing alot better. I had three new ones that I hadnt really touched. except a quick gapping. I opened em up and the reed plates were all high at the 3 hole area and slightly twisted. And the stock combs are atrocious. So I flattened them and the plates But I think the biggest Improvement was in the reed shaping. Manjis seem to be more sensitive to a reed being a little off. But once I got them shaped right, it was night and day. I kept blaming it on other parts of the harp, but I think it was the reed shape all along. But luckily the manjis are so close to perfect OOTB that it doesnt take long to get em right.

IDK ... I could be way of base, but thats what it seems like to me.
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Last Edited by Killa_Hertz on Apr 28, 2016 8:17 AM
harpwrench
1087 posts
Apr 28, 2016
10:03 AM
Top one is what I meant. Yes reed shape and gapping more or less trumps everything (except tuning), especially on the 2-3-10 hole bends, the better it is the less everything else matters.


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Harp repair and upgrade menu
Killa_Hertz
1196 posts
Apr 28, 2016
10:19 AM
Yea idk about 10 because i don't really play that high. I haven't really been able to get those bends going.

But yea for sure 2&3 ive found to be the big ones. 3 especially is touchy.

I just need to hone my shaping skills, But it's alot to do with repitition i think too. I haven't done that many harps. Probably 20 or so. But im getting there. I dont play Overblows, but some of my harps i can get OBs on most of the holes. Because they're just set up tight like that.

Im glad you said that though. Maybe i should pay more attention to reed shape and less to flat sanding and trying to get everything straight.

I know on the manjis it made a world of difference.
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harpwrench
1088 posts
Apr 28, 2016
10:31 AM
The point is that proper reed shapes are calibrated against the horizon of the slot. So if the plates deflect when you assemble it, then our calibration loses its integrity. Air tightness still matters but leakage through the reeds has more to do with how well it plays overall.
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www.spiersharmonicas.com
Harp repair and upgrade menu
isaacullah
3193 posts
Apr 28, 2016
11:14 AM
" The technique of closing in the open side with a UST or whatever, just worsens the real problem as it pushes the slot even lower in relation to the reed, creating a larger leak, even though it looks pretty from up top. "

This makes perfect sense! But what if you emboss or what you emboss or whatever from the bottom> of the reedplate? Just curious...
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Killa_Hertz
1197 posts
Apr 28, 2016
11:20 AM
True. I never really thought about the deflection effecting the gap and shape until you brought it up recently. But even still it didn't really fully register I don't think. Hah.

So they all sort of go together. That really helps alot to think of it that way. The deflection is killing all the work if it isn't straight.

Thanks for all the pointers.
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Killa_Hertz
1198 posts
Apr 28, 2016
11:25 AM
isaac ... I could be wrong, but I read that as only applicable to off center reeds. Hes saying that an off center reed is also crooked on an angle. the tight side being low and the open side being up. So to try to close the open side by embossing will only increase the gap size. The gap size along the long edge of the reed that is.
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Last Edited by Killa_Hertz on Apr 28, 2016 11:32 AM
harpwrench
1089 posts
Apr 28, 2016
1:17 PM
Right, if it's not centered you're looking at an uphill battle the whole length of the reed
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www.spiersharmonicas.com
Harp repair and upgrade menu
ridge
664 posts
Apr 28, 2016
2:39 PM
I had posted this in a thread some time back in 2014 about how I picture the effect of embossing too much. You achieve narrowing the slot at the cost of simultaneously lowering the height of the slot relative to the reed.



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Last Edited by ridge on Apr 28, 2016 2:40 PM


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