YHM QD mount question

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maddyn
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YHM QD mount question

Post by maddyn »

Hello,

I was wondering if anyone knew the size/pitch of the acme thread on the YHM QD flash hiders, for .30 cal? I suppose if I'm planning on doing my own form 1 it really doesn't matter, but I'd like to have something fairly standard and it would give me a better idea of scale.

Thanks for the help
AMProducts
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Re: YHM QD mount question

Post by AMProducts »

Acme threads are quite standard (if it is infact an acme thread) Measure the OD of the thread section (you may have to use a ring gauge for this) and then look it up.

http://en.wikipedia.org/wiki/Trapezoida ... cteristics

If you're feeling more adventurous, here's a suppressor mount I've been working on. The threads are ACME (on the outside) with a 1" 1/5 pitch. The front of the suppressor uses a #3 jacobs taper to both index and seal the suppressor to the gun, the threads are merely there to apply force for taking it on and off. It's intended to fit on standard 1/2"-28 (AR) threads using a crush washer for indexing.

http://www.ammomfg.com/freestuff/STANAG ... 0Mount.pdf

I'm probably going to cut a few later this week from pre-threaded acme stock. I just GPL'ed the design, so share and share alike.
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maddyn
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Re: YHM QD mount question

Post by maddyn »

I never thought about using an actual piece of acme thread stock and just turning it down for the mount, would be way easier plus you could also purchase a nut that would match... I'm still learning/practicing on the thread cutting which is kinda hit or miss at this point. looks like a good design though, gave me some good ideas.
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jus2311
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Re: YHM QD mount question

Post by jus2311 »

How are you going to fit the #3 taper and the threads for proper seating of the taper? I assume you are going to give enough clearence so it doesn't "lock" the taper area and threads with too much pressure.
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mhidpa
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Re: YHM QD mount question

Post by mhidpa »

I would be interested in the info on the yhm also. I know someone on here has made a form 1 can that mounted on a yhm qd mount.
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JohnnyO
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Re: YHM QD mount question

Post by JohnnyO »

That would probably be mine.
ACME 8 TPI
Major dia.=1.030
Minor dia.=.940

Still going strong after many thousands of 9mm and .22lr

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mhidpa
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Re: YHM QD mount question

Post by mhidpa »

Thanks for the info. My form 1 was sent off last week. Hopefully it will turn out as well as yours.
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Re: YHM QD mount question

Post by AMProducts »

Johnny,

1.03 x 8 TPI is not a standard acme pitch, which is kinda've a bummer.

As for the one who asked about the #3 taper... the idea is the thread just pulls the suppressor on and off the taper, so the taper is what does all the sealing and indexing. I don't know if you've ever used machine tools with tapered shanks, but it is a very repeatable and accurate way to index tools, usually within a few thousands. Which using a single start thread (acme) will mean the suppressor will reseat itself in exactly the same place every time, giving a very repeatable POI shift.
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jus2311
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Re: YHM QD mount question

Post by jus2311 »

Being a tool maker I have used machine tools and yes I understand your theory...my question is once the threads lock the taper how are you going to get the release? I think it would take a considerable amount of pressure to release the taper lock once the threads have it locked in
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AlohaRover
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Re: YHM QD mount question

Post by AlohaRover »

I was just curious, does anyone know, is the YHM thread/mount patented?

I see a couple folks here have made their F1 cans to mount this way.
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Capt. Link.
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Re: YHM QD mount question

Post by Capt. Link. »

The taper and thread mount is better than the quick mounts of today based on accuracy. Sako has used them in the past with great success they used a jam nut for adjustable timing back then.
The QD mount was made for CQB where ultimate accuracy is not as important as fast deployment it is also the reason many feature adjustable timing to get acceptable accuracy.
If you don't mind a offbeat mount a tapered pipe thread is self alining,self sealing and compensates for wear.With a retention device that would make a good QD mount.
I'm sure someone can answer the patient question posed on the YHM mount.

Be sure you are aware of the tradeoff with QD mounts.
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delta9mda
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Re: YHM QD mount question

Post by delta9mda »

AlohaRover wrote:I was just curious, does anyone know, is the YHM thread/mount patented?

I see a couple folks here have made their F1 cans to mount this way.
yes patented. it is understood that if you are form1'ing you can make something like this as you are not producing and making a profit.
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Re: YHM QD mount question

Post by AlohaRover »

Capt. Link. wrote:The taper and thread mount is better than the quick mounts of today based on accuracy. Sako has used them in the past with great success they used a jam nut for adjustable timing back then.
The QD mount was made for CQB where ultimate accuracy is not as important as fast deployment it is also the reason many feature adjustable timing to get acceptable accuracy.
Thank you and Delta.
Very good points to keep in mind.
I am still building stuff for my own use and R&D. But I have had a couple of folks ask about purchasing.
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Bendersquint
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Re: YHM QD mount question

Post by Bendersquint »

delta9mda wrote:
AlohaRover wrote:I was just curious, does anyone know, is the YHM thread/mount patented?

I see a couple folks here have made their F1 cans to mount this way.
yes patented. it is understood that if you are form1'ing you can make something like this as you are not producing and making a profit.
Patented is patented, doesn't matter if its for profit or for fun. A patent protects the owner of the patent from ANYONE making it. DELTA, you know this as we have specifically spoken about this. :?

Why do you think people ask SWR to use the Omega baffle in a Form1 22lr can?

Talk to any patent attorney about that and they will tell you if you have permission then thats fine but no explicit permission from patent owner and you are looking at a lawsuit. Will that happen against a Form1'r? Probably not but who wants to be a test case for patent violation?

In regards to the YHM mount I believe the mount itself is patented but not the mount on the suppressor, therefore just buy a YHM mount and you aren't violating anything because you aren't building anything patented.
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Re: YHM QD mount question

Post by hellreaver »

maddyn wrote: Sat Jul 30, 2011 9:45 am Hello,

I was wondering if anyone knew the size/pitch of the acme thread on the YHM QD flash hiders, for .30 cal? I suppose if I'm planning on doing my own form 1 it really doesn't matter, but I'd like to have something fairly standard and it would give me a better idea of scale.

Thanks for the help
Can you take a basic measurement of the 30 cal? I have a 556 and a model of threads that have been working for me. Here's a basic coil pattern.

https://imgur.com/a/jhH3SLF
hellreaver
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Re: YHM QD mount question

Post by hellreaver »

Whoops, imgur completely screwed the compression on that image.
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