Hi Mark;
    I did something similar. I wanted to use fittings that were common to me in my line of work as due to the very low cost to me (free) for a high quality product, I would be more inclined to simply change out all hoses during each annual. This meant installing an NPTxTube Swagelok fitting into each port.
    On several of the ports I had the same issue where there wasn't enough material to drill & tap out to the next size up and the closest size was just too close to the existing size to cut a decent thread. I tried cutting the thread anyways, then I used Devcon plastic steel (same as JB Weld) as a thread sealant and installed the desired fitting. Next day I put a large wrench on it and could not budge it. I added a snipe to the wrench and still could not budge it. So I did several other similar fittings the same way. None ever leaked during 50 flight hours and many more on the ground.
    If removal is ever required an oxy/acetylene torch used to heat the center of the fitting (not the housing) to red hot (or close) will break down the plastic weld and fitting will thread right out and plastic weld residue will just be an easily removable crumbly powder. This won't damage the housing if done with care and the operating temp of the engine will never come close to breaking down the plastic steel.
    In your case you can just use a commonly available bolt that is close enough and use that to plug your port.

Todd
RV9 Turbo13B




On Thu, 2010-12-09 at 18:48 -0600, Mark Steitle wrote:

Yes, but welding on the housing could warp it rendering it junk.  We don't want to risk it.  We're moving forward on having a bolt made.  

Mark

On Thu, Dec 9, 2010 at 5:15 PM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Can it be welded up, redrilled, and retapped?

 

Bill B

 

---

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Thursday, December 09, 2010 10:29 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Source for 18mm x 2.0 Bolt

 

Ah, I had missed the part about already tapping the hole with the 18x2.0.  Yes, that sort of puts you needing a 18x2.0 bolt.

 

Ed

 

From: Mark Steitle

Sent: Thursday, December 09, 2010 7:37 AM

To: Rotary motors in aircraft

Subject:[FlyRotary] Re: Source for 18mm x 2.0 Bolt

 

Ed, 

 

I totally agree, except were you don't have much other choice, like when plugging the heater port.  There isn't enough material to drill & tap to a common size.  The 18mm was a good fit, and would have worked out great if we had used a more common pitch, like 1.5.  Who would have known that they make taps for non-existent bolt sizes.

 

Mark

On Thu, Dec 9, 2010 at 6:15 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

I would avoid the "have it made route" if possible.  If for some reason you ever needed a replacement, you'd have to have it made again.  Although, I must admit, I can't imagine what would ruin an 18x2.0 bolt that wouldn't trash the engine - but you never know {:>).

 

I try to stick with easily available standard sizes if at all possible for just about anything on the aircraft - so I can run down to local Auto store when away from home and get the part if needed.

 

Ed

 

From: Mark Steitle

Sent: Thursday, December 09, 2010 6:35 AM

To: Rotary motors in aircraft

Subject:[FlyRotary] Re: Source for 18mm x 2.0 Bolt

 

From the responses received on this it looks like the best route is to go see the machinist and have one made.  Oh, and throw the 18mm x 2.0 tap in the trash.  

 

Mark

On Wed, Dec 8, 2010 at 9:26 PM, Dave <david.staten@gmail.com> wrote:

Bought something bigger, cut it down... filed the threads into a taper at the tip and played with it carefully so it didnt cross thread. Thats what I did with our first attempt at a block, when we put an aluminum adapter on the oil pump pad for oil return and PSRU feed.

Later gen used the stock oil return fitting with an AN adapter on it.

On 12/8/2010 3:40 PM, Mark Steitle wrote:

Kelly, 

 

Short story is that this is the tap size I had handy that fit the hole.  We're trying to plug the heater port on the rear housing.  Who would have thought that an 18mm x 2.0 would be an oddball size!  We found a place that sells 18mm x 2.0 nuts, but they tell us that nobody makes an 18 x 2.0 bolt.  That seems hard to believe.    

 

Mark 

On Wed, Dec 8, 2010 at 3:26 PM, Kelly Troyer <keltro@att.net> wrote:

Mark,

   Try the link below.............What in the world is it for !!.................There may be other sources but

 

this is the first one I found.................

     http://www.fullermetric.com/products/hex/din933_931-8.8hex_head_cap_screw.html#14-20

 

Kelly Troyer
"DYKE DELTA JD2" (Eventually)

"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold

"TURBONETICS"_TO4E50 Turbo

 

 

---

From: Richard Sohn <res12@fairpoint.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wed, December 8, 2010 2:57:49 PM
Subject: [FlyRotary] Re: Source for 18mm x 2.0 Bolt

You will have a hard time for that. M18 x 2.5 is standard and first choice fine is 18 x 1.5 . You may have to get it made.

 

Richard Sohn
N2071U

----- Original Message -----

From: Mark Steitle

To: Rotary motors in aircraft

Sent: Wednesday, December 08, 2010 1:49 PM

Subject: [FlyRotary] Source for 18mm x 2.0 Bolt

 

Anyone know where I can purchase an 18mm x 2.0 bolt?