X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 30 [X] Return-Path: Received: from fed1rmmtao101.cox.net ([68.230.241.45] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1874181 for flyrotary@lancaironline.net; Wed, 28 Feb 2007 12:10:27 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.45; envelope-from=dale.r@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao101.cox.net (InterMail vM.7.05.02.00 201-2174-114-20060621) with ESMTP id <20070228170935.MTGD6078.fed1rmmtao101.cox.net@fed1rmimpo02.cox.net> for ; Wed, 28 Feb 2007 12:09:35 -0500 Received: from [192.168.1.100] ([68.2.134.48]) by fed1rmimpo02.cox.net with bizsmtp id V59b1W00J12ovmC0000000; Wed, 28 Feb 2007 12:09:35 -0500 Message-ID: <45E5B73F.8000106@cox.net> Date: Wed, 28 Feb 2007 10:09:19 -0700 From: Dale Rogers Reply-To: dale.r@cox.net User-Agent: Thunderbird 1.5.0.9 (Windows/20061207) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: engine mount 4130 vs 304 SS References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Russell Duffy wrote:

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The 4130 can be gas welded. It will last longer than you will, if it is dry inside when welded.

It is stronger than stainless in the same section.

You can wash the inside with Linseed oil and weld the hole shut when finished. Then it will outlast all of us. You can use scrap 4130 from aircraft salvage.

You can fix it anywhere there is a gas torch. Not just a TIG set. Rare at little airports.

Check the Dillsburg aeroplane co. In Dillsburg Pa. for best new prices.

Thanks for the comments Lynn. I only have TIG to weld with, and the gyro won't be traveling unless it's on a trailer, so weldability isn't an issue. I did figure that 4130 was stronger, but don't know if it's enough to matter, particularly since I'll be probably using 2-3 times the size I really need. Fortunately, the quantity I need is so small that I won't be shopping around for price. I'll just order from McMaster Carr, and have it next day via UPS ground. Gotta love the way that works :-)

Cheers,

Rusty

Rusty, The main strength difference between 4130 and SS304 (aka 30304) is that 4130 can be heat-treated, 304 cannot. Then again, 4130 used in airframe constrution is almost always in "normal" state, so the UTS values aren't terribly far apart: ~75K psi for 304 and ~100K psi for 4130. Yield strength is a different matter. 304 is ~29K psi vs 50K psi for 304. If 29K is enough to do the job, then there are a lot of good reasons to use SS. If you are going to do a lot of drilling on 304 (or 316, which is nearly the same, except slightly better salt corrosion resistance) get some M42 (cobalt) bits. 304 is hard on tooling. (Go ahead, ask me how I know ...) Dale R. COZY MkIV #1254