Subject: Re: [Spridgets] Rearden metal

From: "Dean Hedin" <[email-masked]>
Date: Sun, 16 Dec 2012 01:03:18 -0500

I'm making two rotors for the Sprite Judson supercharger.

Pictures to follow.

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From: [email-masked] [mailto:[email-masked]] 
Sent: Saturday, December 15, 2012 7:04 AM
To: [email-masked]; [email-masked]
Subject: Re: [Spridgets] Rearden metal

Aren't you going to tell us what you're making?

In a message dated 15/12/2012 05:34:27 Coordinated Universal Time,
[email-masked] writes:

I find myself for the first time machining some 7075 Aluminum alloy on the
lathe the other evening.

This is my new favorite metal.  It is as strong and hard as many steels yet
it machines very easily.

The presence of chromium in this alloy does not go unnoticed.  The surface
finish is spectacular.  When cut with a fine tool you get that prismatic
effect, like looking at a CD. This happens with other aluminum alloys to
some extent, but they soon dull over after short time.  7075 stays bright.

I can't believe I've wasted my whole life messing around with 6061.

I'll have to get some more of this stuff.  It's expensive from the big
online vendors like McMaster or MSC, but there are a couple guys on ebay
with very reasonable prices.

In fact I've discovered ebay is the way to go for metal stock.  You can
often find oddball stuff that people have left over from big projects that
they just want to get rid of. I was able to get four foot of bearing grade
stainless steel rod like this.  The shipping cost more than the rod!  The
same stuff from McMaster would have cost over $150.
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[email-masked]

Archive: http://www.team.net/archive

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From: WFO Herb <[email-masked]>
Date: Sat, 15 Dec 2012 22:08:43 -0800

Dean,
What clearance between rotor & vanes?
Herb

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[email-masked]

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From: <[email-masked]>
Date: Sun, 16 Dec 2012 00:10:39 -0600 cv=PiaW17gLAxKjLTbcG5GoCO+ImFdQV78k7hXPOC0VLJA= c=1 sm=0 a=X6EWi9_stYMA:10 a=pVMl2t813bUA:10 a=8nJEP1OIZ-IA:10 a=JAralIE_AAAA:8 a=SuaT7PSqOx1rtCylsrEA:9 a=wPNLvfGTeEIA:10 a=Tmb4VmKG5BwA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117

Just in case anyone wants any reference pictures for locations of stuff here 
are pics of Iris right before I sold her.

http://www.flickr.com/photos/speichinger

Leo 
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[email-masked]

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From: "Dean Hedin" <[email-masked]>
Date: Sun, 16 Dec 2012 17:42:40 -0500

It depends on the vane material used.

You have to calculate the thermal expansion of the iron housing through the
temperature

range you expect.  20 to 200F is reasonable in this case.

You then calculate the vane growth in similar fashion.

You then subtract the two and that is the cold clearance.

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From: WFO Herb [mailto:[email-masked]] 
Sent: Sunday, December 16, 2012 1:09 AM
To: Dean Hedin
Cc: [email-masked]; [email-masked]
Subject: Re: [Spridgets] Rearden metal

Dean,

Herb

Pictures to follow.
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[email-masked]

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From: "Dean Hedin" <[email-masked]>
Date: Sun, 16 Dec 2012 18:01:35 -0500

http://tinyurl.com/c82zcfw

Almost there...  

Just need to cut those troublesome slots and I'll be home free.

The extra length shaft is sacrificial. It's needed for fixturing
while I cut the slots.  You wouldn't believe the contraption that
is needed to cut those dang slots!

I sure hope I can cut those slots.  Otherwise all the efforts up to 
this point will be for naught.

You can see in the picture the old rotor slots start to wear in "v"
shape.  That's why I'm doing this.  The believe is that the harder
7075 will be more robust with regard to wear.

BTW, the link I posted the other night about all the how-to machining
stuff was no coincidence.  I've had to study up on techniques!

Look at the shine on that 7075.  Isn't it something?  That's right off
the lathe, no polishing or anything.

The original Judson rotor was cast aluminum onto an interlocking shaft. 
I've had to come up with a more modern approach to mounting the rotor
onto the shaft.  

I've cut a 3/4" long machine key on the back side and the two are
interlocked with 1/4" square key.
 
The shaft hole was reamed to a tight slip fit and I used Locktite 680 shaft
mounting compound.  The machinist at work assures me this will never come
off. 680 is a really strong version of thread locker, designed for things
that are never intended to be disassembled.

Even if it did I'm still covered because the way things are designed the
rotor is pushed against the key as a result of tightening the nut on the
front of the shaft.
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[email-masked]

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From: Linda Grunthaner <[email-masked]>
Date: Wed, 19 Dec 2012 06:54:39 -0500

Awesome!
Lin

On Sun, Dec 16, 2012 at 1:10 AM, <[email-masked]> wrote:

> Just in case anyone wants any reference pictures for locations of stuff
> here are pics of Iris right before I sold her.
>
> http://www.flickr.com/photos/**speichinger<http://www.flickr.com/photos/speichinger>
>
>
> Leo ------------------------
>
> [email-masked]
>
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