Build a new diaphragm for M horn

So at the beginning of 2020 I picked up this M5 off ebay. It was sold at a pretty decent price, but when I got it I discovered that it was missing one of three diaphragms in the #1 bell. I looked all over but wasn't able to find a replacement, so I got the material and made my own.
This is a 6" X 25" sheet. McMaster-Carr part # 9014K315 (accurate as of May 2020)
This video is part one of three.
Part two, parts and anatomy:
• M Horn Anatomy and Parts
Part three, voicing.
• M5 Horn Voicing (M5 Tu...
Part four, full air tank runby:
• M5 Chip Tooth Full Air...

[@EPWI92]

Nice video. I’m looking forward to the information in the next videos.

[@AlexTrain5249]

Thanks to you, I now know exactly what to do to restore WSOR 101’s M3. Brilliant!

[@mafarnz]

You should be able to reuse whatever diaphragms are in the horn. Hopefully, all that you need to do is clean it out and voice it. Check out my video I did on voicing M horns.

[@coasternamegenerator5611]

That was a nice m3. Sucks that it was replaced by a Leslie S2M tho.

[@midwestmodelrailroadworkshop]

Nice job! I can definitely appreciate some at home horn experiments!

[@wwrr98]

Looking forward to the next video, and hearing the results of the repairs. Also, very jealous you got that! I never saw it on eBay, been watching for an M5 for a while now

[@StripeyType]

Step drills (all drills, really, but step drills exhibit this problem to a greater degree) behave a bit like a rotor in a rotary engine, due to the room afforded by the relief behind the cutting edges and the flutes themselves. As a result, they tend to cut oversize, and not particularly precisely-round holes. This problem is typically solved in the machine shop with reamers, or with single-point boring. Anyhow, thanks very much for this! If ever you find that you need replacement diaphragms again, give me a shout. I would be happy to make some for you in my own shop so you don't have to abuse your dremel. ;)

[@mafarnz]

That's good to know! I was trying to do this on the cheap, with the tools that I already had. I did pretty well. If this horn were ever to go on a locomotive I would first pay to get a proper machine shop set of diaphragms made.

[@flattrain5834]

Nice! Hope they sound good after. Also, according to Nathan, a k5la eats 71 liters of air a second at 120psi, but in your 20 gal tank dump video, you can get over 10 seconds of honk time?

[@mafarnz]

That's what I got. Keep in mind the pressure is dropping that whole time.

[@flattrain5834]

The 20 gal tank that you used was 120 psi. 20 gallons is 75 liters, so wouldn’t you only have 1 or 2 seconds?

[@mafarnz]

In theory yes. The proof is right there in my video though. Does the Nathan documentation say anything about the size of the air line they were using? I’d imagine that a 3/4” or 1” could force a lot more air quicker through the horn. Or maybe they went with a worse case scenario for a horn that’s heavily worn? I’d like to see this source you quoted. I’m not arguing the numbers with you, but again, with 20 gallons starting at 120 PSI, all 1/2” lines, I got over 10 seconds.

[@mafarnz]

P.S. if you have questions about the air consumption video, it would be best to post them to that video, rather than an unrelated one.

[@flattrain5834]

Alright, thanks! Here is my source for horn info. microprecisiongroup.com/nathan-airchime/technical-info

[@theark-la-missrailfan]

Neat Vid! But what does the term “Scallop Base” M5 means?

[@mafarnz]

I’ll go over that in the next video I post.

[@theark-la-missrailfan]

Very well!