Spring Gear: Bolt Hole Placement

[Mike Davis]

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Date: Tue, 07 Sep 1999 16:26:17 +0000
From: Dan Morehouse <danmorehouse@webcombo.net>
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Hi!

I measured the distance from the center of the forward outside bolt
hole in SG13 to the edge of my tapered front carrythrough, where the
hole would be drilled. This was ~7/16". Normally, shouldn't the bolt to
edge distance be 2D, like with rivets? Assuming this that would give me
5/8" for the 5/16" bolt or 3/4" for Alister's upgraded 3/8" bolts.

Do I not worry since the edge is not in a direct stress plane or do I
move the bolt holes away from the edge? If I have to move, I've got few
options. Moving them perpendicular to the carrythrough toward the
upright gets more edge distance since less of the carrythrough has been
shaved off. But that would mean drilling through the spring gear SG1
itself. Not good.

Moving the bolt toward the center along the radius of the carrythrough
gives more edge distance but runs closer to the bolts connecting the two

carrythroughs, running 90 degrees to them. This brings about another
question.

Even if I don't move the bolts toward the center along the carrythrough
they would pass ~1/4" away from these carrythrough connecting bolts.
Would this bother anyone, especially those that would fly with me?

And as long as I am talking about edge distances with bolts I've notice
that SG5, the spacer block, 1 1/2 x 1 3/8. Murphy's 3/8" bolt would
require 3/4", so the 11/2" direction would just barely fit ane the 1
3/8" direction would be a bit short. Again, stress direction might void
these requirements. Upgrading to New Zealand's 7/16" bolt would make
things even tighter. What did you do Alister?

Thanks for your guidance,
Dan
R280

[Mike Davis]

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From: "Alister Yeoman" <yeoman@voyager.co.nz>
To: "Murphy Rebel Builders List" <murphy-rebel@dcsol.com>
Subject: Re: Spring Gear: Bolt Hole Placement
Date: Wed, 8 Sep 1999 13:24:58 +1200
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Hi Dan,

I think you have summed it up when you said 'stress direction might void
these requirements'.

We basically are dealing with a spacer here, so as long as it has an
acceptable 'wall thickness' it will be OK.

Part of the problem is that most of us trim the angle off the end of the
front carrythrough as per the Murphy manual. That measurement is too large
and it does cut our options down for maintaining suitable edge clearances in
that area.

I guess the best thing to do is to 'balance' the 'wall thickness' between
the edge of the carrythrough and the 1/4" bolt. When you mill your solid
block inserts ( I assume you will be doing this) allow more edge clearance
on that i.e. it may stick a little bit further out than the carrythrough end
at the front where it has been cut on an angle.

If you think we are compromising things here, go back and compare this
design to Murphy's original plan!!
We do have to deal with the basic dimensions that have been dealt to us.

The inner bolt and spacer would operate on the same theory of 'wall
thickness' of a spacer, I would be comfortable putting a 1/2' bolt in this
location! I almost did but the bolt was quite expensive!!

Hope this helps.

Cheers

Alister






-----Original Message-----
From: Dan Morehouse <danmorehouse@webcombo.net>
To: murphy-rebel@dcsol.com <murphy-rebel@dcsol.com>
Date: Wednesday, September 08, 1999 11:28 AM
Subject: Spring Gear: Bolt Hole Placement

Hi!

I measured the distance from the center of the forward outside bolt
hole in SG13 to the edge of my tapered front carrythrough, where the
hole would be drilled. This was ~7/16". Normally, shouldn't the bolt to
edge distance be 2D, like with rivets? Assuming this that would give me
5/8" for the 5/16" bolt or 3/4" for Alister's upgraded 3/8" bolts.

Do I not worry since the edge is not in a direct stress plane or do I
move the bolt holes away from the edge? If I have to move, I've got few
options. Moving them perpendicular to the carrythrough toward the
upright gets more edge distance since less of the carrythrough has been
shaved off. But that would mean drilling through the spring gear SG1
itself. Not good.

Moving the bolt toward the center along the radius of the carrythrough
gives more edge distance but runs closer to the bolts connecting the two

carrythroughs, running 90 degrees to them. This brings about another
question.

Even if I don't move the bolts toward the center along the carrythrough
they would pass ~1/4" away from these carrythrough connecting bolts.
Would this bother anyone, especially those that would fly with me?

And as long as I am talking about edge distances with bolts I've notice
that SG5, the spacer block, 1 1/2 x 1 3/8. Murphy's 3/8" bolt would
require 3/4", so the 11/2" direction would just barely fit ane the 1
3/8" direction would be a bit short. Again, stress direction might void
these requirements. Upgrading to New Zealand's 7/16" bolt would make
things even tighter. What did you do Alister?

Thanks for your guidance,
Dan
R280






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[Mike Davis]

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Yippee Skippee!

Thanks Alister.
Dan

Alister Yeoman wrote:

Hi Dan,

I think you have summed it up when you said 'stress direction might void
these requirements'. .....

Cheers

Alister

-----Original Message-----
From: Dan Morehouse <danmorehouse@webcombo.net>
To: murphy-rebel@dcsol.com <murphy-rebel@dcsol.com>
Date: Wednesday, September 08, 1999 11:28 AM
Subject: Spring Gear: Bolt Hole Placement