CAD files for metal parts

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Ozzietx
Posts: 3
Joined: Thu Jun 29, 2017 10:11 am
Location: San Antonio, Texas

CAD files for metal parts

Post by Ozzietx »

I tried searching, but couldn't find this.

Has anyone converted the flat metal templates to CAD, and had them cut to test?

This seems like an inexpensive way to cut down on some of the build time.

I realize that there are not too many metal parts to fabricate, and even fewer would qualify to be water jet, or laser cut.

I'd love to hear from anyone that has attempted this.
rmueller23
Posts: 2
Joined: Thu Mar 09, 2017 2:34 pm

Re: CAD files for metal parts

Post by rmueller23 »

Searching the Matronics archive (http://www.matronics.com/search/) reveals the following post re Chris Tracy's experience using CAD to facilitate fitting fabrication:

-----Original Message-----
From: owner-pietenpol-list-server(at)matronics.com
[mailto:owner-pietenpol-list-server(at)matronics.com] On Behalf Of
Catdesign
Sent: Wednesday, February 08, 2006 1:10 AM
Subject: Pietenpol-List: Making Metal Fittings


All this discussion about CAD has prompted me to speak up and relate my
experience with making fitting per the drawings. I drew up all the
fittings using TurboCAD. I like TurboCAD and will likely upgrade to
their 3D version when the price comes down.


I knew from Mike Cuy's posts on this list that many of the fittings need
to be a bit longer. On some fittings I think this is due to not
allowing for the bend allowance when they were drawn. On others, I just
don't know why. So when drawing each fitting I included the bend
allowance (even put in bend lines) as shown in "Making Fittings" by Tony
Bingelis ( The Sport Plane Builder Book from the EAA [catch that
reference Mike?]).


It worked well to glue on the printed fitting templates and cut them
out. After cutting, grinding then sanding you end up with a fitting
that is very close to the drawing. The crosshair in the bolt hole is
very helpful in placing a dimple exactly where the plans show the center
of the hole. But there is the problem, not all the fittings I've made
seem to fit my fuselage and tail like I think they should. Fortunately,
a much wiser builder then I told me not to make the fitting until I need
them, just for this reason. I think the problem lies in the way the
plans were drawn and the inaccuracies of building. Now, I am not saying
the plans are wrong. All I am saying is that in places the fitting
could fit the location better.


So here is what I now do. I make a template using cardboard, paper,
light aluminum or whatever is handy, right on the completed structural
element. I make my template large enough to layout the holes where the
plans say to do it. Then I adjust the center of these holes to the best
spot on the structure. Usually this is to the centerline of the wood
member or away from a glue joint. I then adjust the outside dimension
of the fitting to maintain the setback away from the edge. Holes
hanging out in space I located per the drawing but a bit farther away
(ie longer tabs, as Mike suggests). I mostly follow the plans but the
CAD drawings were, for me, a waste of time. The thing about fittings is
you need to look at what they are supposed to do and make them fit your
plane not the plans.


If I can, I do all the bending before drilling any holes. As for holes,
leave them undersize clamp them in place and drill the matching holes on
the wood member. Then I do the final trimming down to the correct shape
and size. On doubled up fittings (you know where there is one on the
inside and one on the outside) only drill holes on one then clamp both
on the fuselage drill an undersize hole all the way through the other
fitting. Then enlarge the hole to the proper size and then finish to
the shape and size.


That's the way I see it. Now I haven't made that many fittings yet so
this might be my problem and more experienced builders may not encounter
this. I'm new to metal work but I'm finding the learning curve to be
fun. My wood construction is as close as I can come but trust me I know
it's not perfect.


Oh, one more thing, because I feel that this advice, to not build the
fittings first, has saved me a bunch of money, I have chosen to not give
out the CAD files because I would feel terrible if someone used them to
make the fittings and they did not fit.


Sorry about the long post


Chris Tracy
Sacramento, Ca
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