A few minor problems for the 13B. One hole was ten thou
 off or so but it could be drilled out with no problems.
 One cup tab was a bit too long so that could be hacksawed off.
 We had a few typical bolt circle problems but easily fixed by
 drilling the holes out to 27/64th instead of 10 MM.

 Other than that the 13B was usable. The starter hole
 was a bit on the small side but I can set it up in my
 cheap Chinese mill and bore it out about .020.
 The starter hole should be 2.640.

 I was working from Tracy's dwg and I should have
 checked the dwg against Tracy motor plate which I also have.
 The drawings had a few errors and I probably made one or
 two my self. The dwg does not match Tracy's plate :)

 The RX8 extra bell house bolt was way off by about a half inch so
 that is going to require a whole new dwg which I have about done.
 I want to make the plates fit both the 13B and the RX8 motor.

 Jeff I'll get the  fixed dwg to you in a day or so.


 Paul Lamar

 Paul

 So this is usable. If  you want I can open up the starter hole here. It
 measures 2.620 on the solid model. I depend on the solid model for
 geometry for expediency. If you need to digitize the bolt pattern on the
 housing we can do that. We need absolute numbers. I do not know the
 difference between the RX7 and 8.  the half inch hole problem, does that
 make it unusable??? No worries, we just get it right for the folks that
 need them...

 jeff

 I'll ship it back if you want it. I only have one RX8 end housing
 and it is on my RX8 P-port test engine which I don't want to take apart.
 I think I got it measured fairly accurately.

 If you have a 13B end housing that would be a good one to digitize.

 The solid model is now fine. I fixed it. Jarrett has it now and
 he is converting it to a Solid Works file for you. I made a couple of
 other changes while I was at it. After you do it three or four times
 you get better and faster. The new version is much more accurate as
 I had been there and done that :) All ribs are now the same width and
 parallel. We need to drill all the 10 mm holes out to 27/64th as that
 will ease the bolt circle problem.

 No change in the back pattern.

 We should look into a spun or pressed bell housing and use the two hollow
 dowel pins on the end housing to locate the unit more accurately. Along
 with a lighter weight gear box of course :) The bolt and spacer idea is
 less than ideal.

 Paul Lamar

 Paul

 I think when you send me the new geometry I will make a template, send
 it to yo then you can check for fit. I am not in favor of making the
 holes larger. I can use my machine as a CMM and get the number exact.  I
 did that with the rotor housing and it is perfect.... We save these
 master coordinates for all future parts. This should be done all around
 the block.
 I have machined bell housings before. Lots of aluminum chips but can be
 done fairly quick as opposed to finding and getting someone quote,
 setup, bid,etc. Lots of time and money..
 My guess a billet block of 6061 for a bell housing would be at least 60
 lbs..Al plate is a little over $3.00/lb.  Figure $200 for material.  It
 will machine down to about close to 8  lbs or less. If the housing is
 not too complicated with lots of ribs, this could be machine in 1 day.
 More,  obviously for the first article sample, but for any production
 at  all,  $600 to $700 is doable. Eventually get a cast part , but this
 way we could get something out cheaper and sooner...
 I agree the bolt and spacer arrangement needs to be fixed....

 jeff

 No doubt about it that is the ultimate solution. I rejected it in
 the past because of the cost. Prices have come way down on NC mill
 stuff as a lot of people have the machines payed off.

 The problem with sand casting is weight. The foundry has problems with
 anything thinner than .2 inches. Also the cost of sand castings has
 gone way up. NC milling is now more competitive.

 Try these until Jarrett gets the SW version out.

 Paul Lamar
 --



How about a composite bell housing?  I know you aren't a fan of
composites for some applications, but the bell housing might be a
relatively good one..


Matt-

Labor intensive.
Might be OK if we had a mold.
One could NC mill a 3D female mold.

The thing about an NC mill it works while you sleep :)

Paul Lamar



How many of these things are people going to need?  One per airplane,
right?   Max, two.  So what if the layup takes four hours and baking
it in the autoclave takes eight hours tying up the tool (mold).  The
autoclave operates while you sleep..  If there are high production
numbers, pressure cast the part..  For low production numbers, a
process which is a bit more labor intensive, but which results in a
superior part can be acceptable/preferable.

I don't want my tone to be misconstrued because of email..  I'm
impressed by the NC mill work that's been going on, and if someone
comes up with a slick bell housing design that is milled, or which
uses the automotive part as a base, I'm all for it.  Just pushing the
idea envelope around a bit.


Matt-