Metrology - nearly metal

Have the need for a low cost CMM or equivalent. The requirement is to measure bagpipe chanter reed blades (made with metal machinery!). Reeds are of shaped bamboo slips one and one half inches long by three quarter inches wide and sixty thou thick (that is the envelope dimensions). Accuracy plus/minus half a thou. Blades are tapered in length and width, variably. Have considered a micrometer stage microscope, my eyes are getting weaker but could probably manage with average of several readings. This method would be OK for X & Y axes but what about Z? Could the focussing mechanism provide accurate measurement? Ideal would be a computerized laser measuring machine but definitely far too costly. Micrometers although very accurate are difficult to apply to the varying thickness of the blades and angular geometry. Anyone with experience measuring small parts in a quality control environment. Any suggestions on suitable and available tools? (A hammer to smash the reed and render the pipes inoperable is not an acceptable reply!) Has anyone homebuilt a CMM equivalent? Any leads on cheap components and plans for building one? All help appreciated, and I promise that the reeds produced will make 'pipe music better. Ray

Reply to
Ray Field
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A toolmaker's microscope would work. The limit on resolution would be the surface finish on the bamboo, especially when using the focus to take Z dimensions. Presumably you could avoid taking depth measurements with the focus by using the fat end as the X dimension zero and rotating the reed on edge in a fixture to take Z dimensions.

An optical comparator might also work and give you a larger working field, but would require using surface illumination in the Z direction, but I don't think would be as sensitive as a microscope in that axis.

If you send me a reject reed and a table of the dimensions you're interested in, I'll measure it for you and take a few photos thru my toolmaker's 'scope.

Reply to
Ned Simmons

Might be an application for some sort of comparator, blow the silhouette up on a screen and compare it with the outline of a good one. Has been some old posts here on making one from an old fiche projector. There are also knife-edge micrometers around, should you prefer the direct method.

Bamboo, like wood, isn't a uniform material, I can remember reed players in school always messing around with various jigs that the band director had to improve their reeds. So you'll probably still end up sanding and scraping to get the sound you want.

Stan

Reply to
stans4

"The ill wind that no one blows good."

Ahh... my son and I have been working on that issue for a couple of years. He plays both highland and Illian (dry wind) pipes.

The problem is that a good reed that can switch octaves is ultimately a VERY complex shape -- not merely a single-plane profile, but contoured in all three axes.

He's become very good at carving his own slips and tailoring them to a particular chanter or drone, but hasn't yet quantified much of anything. He's made reeds from everything from beer cans to credit cards to graphite composites, and they all work (some only passibly).

You have quite an analysis project ahead of you. Even the real "masters" still carve pipe reeds by hand. (although the Japanese seem to be successfully making cast composite reeds for orchestral woodwinds)

LLoyd

Reply to
Lloyd E. Sponenburgh

Cutting it into sections and laying them on end to get your Z-axis measure is a good second best to smashing them. You'll still save the neighbor's ears, but you won't have the satisfaction of generating shards with each hammer blow.

Reply to
Tim Wescott

What if you put a dial indicator in a stand and laid the reed flat on a surface plate?

Seems to me that you could measure the Z profile with little problem that way.

Reply to
Roger Shoaf

Probably the Z axis is not gonna work with an optical system; even if you could identify the focus, how do you make the reference surface (the back side of the reed) known to that half-a-thousandth tolerance?

Lever/anvil/dial gage meters are what some reed-makers use, is that unacceptable for some reason? Look for 'dial thickness gage'.

I've heard of measurement systems based on air pressure that would allow you to make a no-contact measurement; instead of anvils in contact, it's orifice in near proximity (and when the air flow gets partly blocked, the pressure rise says you're exactly THIS close).

Reply to
whit3rd

Gear tooth caliper:

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jsw

Reply to
Jim Wilkins

Reply to
Ray Field

Wonderful old Nikon Measurescopes, original model with fat 1-inch micrometers on X and Y, are often around for a few $100s. You can mount a dial indicator on the focuser for Z. This will get you 0.0001" precision in all three axes, and theta in a rotary stage if so equipped, subject to your technique.

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Reply to
Richard J Kinch

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