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Diameter MAW valves?

Postby hubert » Sat Nov 11, 2017 11:03 am

Would be grateful to be informed about the exact diameter of the standard MAW valves for the big valve instruments of B&S/MeinlWeston.
Thanks a lot, if someone would be so kind to take measurements or could indicate, where to look for it.
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Re: Diameter MAW valves?

Postby kmorgancraw » Sat Nov 11, 2017 1:28 pm

His PT6P valves are 1.13 inches.
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Re: Diameter MAW valves?

Postby hubert » Sat Nov 11, 2017 2:15 pm

Thanks a lot for your help.
Best,
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Re: Diameter MAW valves?

Postby bloke » Sat Nov 11, 2017 2:32 pm

makes sense...comes out to an even 1/10 of a mm
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Re: Diameter MAW valves?

Postby kmorgancraw » Sat Nov 11, 2017 3:08 pm

bloke wrote:makes sense...comes out to an even 1/10 of a mm


Or .142796 links...
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Re: Diameter MAW valves?

Postby hubert » Wed Nov 15, 2017 1:42 pm

FYI: today my repairman informed me, that Meinlschmidt can supply MAW-valves with somewhat oversized diameter. For my Wisemann I would need 28,89 mm instead of the standard 28.7 mm (=1.13 inches).
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Re: Diameter MAW valves?

Postby kmorgancraw » Wed Nov 15, 2017 4:48 pm

hubert wrote:FYI: today my repairman informed me, that Meinlschmidt can supply MAW-valves with somewhat oversized diameter. For my Wisemann I would need 28,89 mm instead of the standard 28.7 mm (=1.13 inches).
Hubert


My Wisemann valves measure precisely 1.13 inches.
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Re: Diameter MAW valves?

Postby The Big Ben » Wed Nov 15, 2017 6:55 pm

I've wondered how the MAW valves are fit to a particular horn. Do the pistons need to have the final fitting made by a tech? "Proper fitting" is with a clearance of .0005-.00075 in. Can pistons come in the mail and be within that tolerance in a casing the manufacturer hasn't seen and measured?
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Re: Diameter MAW valves?

Postby kmorgancraw » Wed Nov 15, 2017 7:55 pm

The Big Ben wrote:I've wondered how the MAW valves are fit to a particular horn. Do the pistons need to have the final fitting made by a tech? "Proper fitting" is with a clearance of .0005-.00075 in. Can pistons come in the mail and be within that tolerance in a casing the manufacturer hasn't seen and measured?


Ideally they should come in the mail and be over-sized so that they require fitting. The MAW valves I received for a King 1241 were this way. If they showed up and fell right in with no resistance, I'd be concerned.
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Re: Diameter MAW valves?

Postby hubert » Thu Nov 16, 2017 4:14 am

Kmorgancraw is right, that is also the information I have got from other sources: delivered oversized, then handlapped to exact fit.
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Re: Diameter MAW valves?

Postby the elephant » Thu Nov 16, 2017 11:15 am

This is the case with pretty much all replacement pistons. They have to be hand lapped so that they mate up properly with their new home. If you purchase a replacement casing set it is the same thing: the old pistons and new casings have to be lapped to one another.
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Re: Diameter MAW valves?

Postby The Big Ben » Thu Nov 16, 2017 11:19 am

Thank you! I've read posts that say "they drop right in". I have had valves refit to the .0005 standard in my tuba and I couldn't see how the MAW valves would work without final hand fitting. Martin can make magic but I don't think *that* much magic.
Last edited by The Big Ben on Thu Nov 16, 2017 11:21 am, edited 1 time in total.
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Re: Diameter MAW valves?

Postby the elephant » Thu Nov 16, 2017 11:21 am

I think that many who have stated that they "drop right in" probably have pretty mediocre valve action but do not know enough to realize this. All new pistons "drop right in" but they do not yet have the FINISH they need to have to run really well. The oversized bit is what lapping polishes off.

Keep in mind that pistons have a much looser tolerance than slides. Slide work well with a .002" or so gap. Pistons are more like five to eight thousandths.
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Re: Diameter MAW valves?

Postby hubert » Thu Nov 16, 2017 12:49 pm

For me as a Wisemann owner it was important to discover that the diameter of the Wisemann valves is not as consistent as that of the B&S/MW-valves (see earlier posts about this subject and e.g. the experience of Bloke with Wisemann tubas). Sometimes standard MWA valves ar OK for the Wisemann, but rather often the Wisemann valves seem to be so much wider than the B&S/MW/standard MAW valves, that standard MAWvalves (even with a bit oversize) wobble in the cases and thus in fact do not fit. As far as I was informed, MAW valves are normally being made at B&S/MW diameter of 1.13 inches or 28.7 mm or very, very close to that (because of reasons explained elsewhere in this post). Now I was informed, that Meinlschmidt accepts orders for valves with considerably more than normal "oversize", which is the case with my Wisemann. This tuba has a valve diameter of 28,89 mm, which is almost 0,2 mm more than the standard B&S valve and thus is a huge difference. That is what I wanted to share, because it perhaps can be useful for some owners of Wisemann tubas (and some others?).
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Re: Diameter MAW valves?

Postby the elephant » Thu Nov 16, 2017 12:57 pm

Cool! Thanks!
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