MFI protractor project has begun.....

Zeke · 07-25-2006, 06:28 PM

No empty promises from ol' Zeke.

bbthomson · 07-25-2006, 06:49 PM

Very cool Milt.

Please put me on the list of people who will take a set once you are done.

Once again - thanks for taking on another project that will no doubt help others.

Brent
______
70'-911

Zeke · 07:28 PM

Oh, yeah, I forgot.....this is NOT a solicitation for advance orders. That just uses up bandwidth and is clearly against the rules of this forum. So, don't ask. Brent, I'll see that you and all the others that have expressed interest get contacted or otherwise alerted that they are available after clearing it with Wayne. This could take some time to develop. I'm figuring by the end of the year....seriously.

I'm fishing for comments and tips, not orders.

The plastic gizmos you see on the table are far from what I envisoin the final product to be like. But, they are an indestructable plastic, something that I like. Just not rigid enough. I probably will use Lexan if it machines well (think in terms of a router).

Edited for spelling, a more and more common problem with me.

70SATMan · 07-25-2006, 07:21 PM

Looks like a good candidate for molded nylon. Stiff, holds up well. Some guys even use them for leather stamping designs.

Zeke · 07-25-2006, 07:25 PM

No molds. Too expensive. These will be a low volume run and hand made in Gepetto's workshop.

Jandrews · 07-25-2006, 07:29 PM

Creative genius...

Thanks for having guts, Milt!

JA

randywebb · 07-25-2006, 08:42 PM

Looks great!

BTW -- http://www.gepettosworkshop.com/

sballard · 07-26-2006, 05:12 AM

Great project!

In my experience, Lexan doesn't machine well. Delrin would be much better - it's rigid and machines great but it is opaque. I don't know if that's an issue for you. It is also relatively expensive (but very cheap compared to the cost of the original protractors).

Steve B.
Mobile AL

1972 911T

304065 · 07-26-2006, 05:35 AM

Looking good Milt!

Zeke · 07-26-2006, 05:45 AM

Thank you, Steve. That is the kind of information I can use. Most likely I will be using a router in a table with a template guide. I know acrylic is real speed sensitive and can melt and back fill the cut. Translucent or opaque in light colors is fine as I plan on silk screening the scale onto the protractor. If that isn't durable enough after some testing, including oil and gas washing, I will laminate the printing so it is preserved. There is a lot to do here, but I've had a year now to think about my approach.

72doug2,2S · 72doug2,2S's Garage

Milt, please include instructions for dummies (Me) with lots of pics in the final product.

If you want me to print it, I'll be happy to give you an idea on cost. Efficient specs 1,000 copies, 32 pages, 6 x 9 trim, Black and White, self cover saddle-stitch (staples like a magazine). PM me for more.

rvanderpyl · rvanderpyl's Garage

You can actually rout aluminum with a carbide tip bit, I read an article in a woodworking magazine on making jigs this way.

Zeke · 07-26-2006, 08:23 AM

Quote:

Originally posted by rvanderpyl
You can actually rout aluminum with a carbide tip bit, I read an article in a woodworking magazine on making jigs this way.

Yep. Years ago I was in the Swift Race Cars shop and they were using a hand held 3HP router on the honeycomb to lay the keel for a Formula Ford. Talk about some nasty noise!

But, yes, the templates will be aluminum. I'll make those on the new upright metal cutting bandsaw I just built. And then fine tune them with a file plus sanders just like a tool and die maker would do. Not worried about that part.

The big hurdles are: Overall design for functionality and accuracy, consistent and practical duplication, printing/screening of the degree scales and low final cost.

Grady Clay · 07-26-2006, 08:28 AM

Milt,

Anything I can do to help?

Some thoughts:

I have two versions of P228b/c. One has the scale printed (silk screen?) on the aluminum and the other has a substantial decal (black on silver) applied. A decal is easier to produce and far less expensive. It can also be made with finer divisions, 1/2° as example. The spec is ±1/2° deviation and is difficult to interpret with 1° minor divisions.

Brass brazing rod works well for the pointers and is easily available from any welding supplier. All of my original pointers are 2.0 mm brass wire.

The protractor for the MFI pump (KDEP 2975) will be the most difficult because it really does need the formed shape to clear everything. The original from 2.0-2.2 must be modified for a 2.4-2.7-3.0. The protractors for the throttle bodies should be much easier.

It would be worth considering making the throttle body protractors “universal” in the sense they would not be different as P228c.

I can think of several other simple devices we fabricated over the years that made this job simpler. One of the more important is a screw adjust that operates the main linkage at or ahead of the bell-crank at #3 intake. It is important to load all the worn linkage in the direction it normally operates.

Best,
Grady

Early_S_Man · 07-26-2006, 12:18 PM

Milt & Grady,

What about using factory original protractors to make a fiberglass mold of? 'Production' parts could be made of fiberglass/Kevlar/carbon fiber, and a decal could be applied ... seems like 1/2° accuracy would be attainable.

My choice would be a sandwich of fibeglass/Kevlar/fiberglass [at least 0.060" thick] in epoxy resin for best strength and still retain sandability to remove surface defects from the molding process. Flaws molded into Kevlar are a nightmare to deal with ... and attempts to sand result in a fuzzy, wasted item!

Just thinking out loud, here ...

Zeke · 07-26-2006, 04:25 PM

Quote:

Originally posted by Grady Clay

It would be worth considering making the throttle body protractors “universal” in the sense they would not be different as P228c.

No can do. The TB's for the plastic stacks have bent arms; the ones for the mag stacks are straight. So the degrees would be tough to see on one or the other, and the location of the ball is in a different relationship to the scale.

Yes, I have encountered the silver with black vs. the black with silver. In the same radius, there is a 5 degree error out of the total 80 degrees between the two versions. I'm in the process of verifying which is the correct scale. So is RS Dreamer and 356RS. Between us three, we should be able to nail it.

One way that I am doing this "verification" is to use mag stacks on one side while the plastic remain on the other side and calibrated. If the error shows up on one, that is the culprit. Unfortunately, I don't have both 228C versions, 356RS does and I had them for a short time on loan. That's when I found the discrepancy.

This ain't gonna be a walk in the park.

svandamme · svandamme's Garage

tag

sballard · 09-13-2006, 05:55 PM

This idea of constructing affordable MFI protractors is a great one that I can't get off my mind. I was in our school's bookstore today and possibly found a really cheap ($1.10) alternative!

Since I am from the school of coat hanger and duct tape engineering, I couldn't help wondering if these simple devices could be adapted to substitute for the priceless porsche pieces? If the size is wrong, you could always reduce or enlarge them with a photocopier and mount the copies on a piece of hard plastic.

Just a thought

Steve B.

1972 911T (mfi)
1999 328is