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F-1001K stainless recess

J

jwilbur

Well Known Member
There is a stainless recess (F-1001K) that attaches to the firewall. For Lycoming engines the plans say to drill out three holes to 5/8 for throttle/prop/mixture cables.

Although I used plenty of Boelube and a new (sharp) unibit, I still had huge burrs on the inside of the holes. After cleaning up the burrs, the holes are about 1/16 bigger in diameter with the edges bent inward maybe 1/32 (think a slight dimple) - I'm guessing my error was too much pressure and maybe the drill speed too fast. This was my first time dealing with stainless.

What I want to know is how critical the precision of these holes is. I'm guessing a bushing will be used and my error may not be critical, but before I install onto the firewall, I thought I'd get some opinions.

Thanks,
 
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disregard

I sent the same question to Van's and I just got this response:

Thin stainless parts will never be very easy to drill like 4130 or aluminum will be. The key is to back it with a wood block that you drill into at the same time and go slow so heat does not build up to much. The final hole size on your parts will be okay if they are over a little like you described.

Sterling​
 
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most end up using eyeball pass throughs

I did the same thing with a unibit about a week or two ago on my mostly completed fuselage and was freaking out thinking I needed to undo the recess. I had already decided to use some of the eyeball passthroughs that Van's or Spruce or several other vendors sell.

http://www.doubleteeproducts.com/story.html

If you use something like these you'll end up cutting a bigger hole anyway. The hole you have now will work for using a punch like Mark pointed out above.

If you stick w/the standard bushings you would still want to clean up the holes. David Halmos, another 10 builder, pointed out to me that you can use the tungsten carbide tip for your dremel tool and grind away a the excess. That worked great for me. It hogged out the hole a bit of course. I had something like a 1/4 to 1/2 inch of material pushed through into the cabin side trying to do exactly what you did. The end result was that the eyeball hole was a bit bigger but the whole mechanism still plugs the hole and it'll work just fine.
 
As implied above, if you use some other mechanism other than the plans (i.e. eyeball pass throughs), the holes the plan specify will most likely be too close together.

Decided the method that you are going to use, then determine where and the size of the holes you need.

Unfortunately, I did the holes per plan long before I was ready to install the cables. I had to get a little creative due to having holes where I didn't need them.
 
advice please.

rleffler said:
As implied above, if you use some other mechanism other than the plans (i.e. eyeball pass throughs), the holes the plan specify will most likely be too close together. ...

Unfortunately, I did the holes per plan long before I was ready to install the cables. I had to get a little creative due to having holes where I didn't need them.
Click to expand...

Bob, I like the eyeball pass-through idea. Looks like you can get them through Van's here. Can you tell me what size hole they require? Then based on your comment, would you recommend buying another recess and waiting before punching the holes? Right now I have three 11/16 holes.

Would you mind posting a picture?

Thanks,
 
Plane innovation

Joe,

I had Paul build a custom three bank of his 3/4" firewall pass through. Unfortunately Paul passed away the afternoon after he finished our custom part. I could send you some pictures and have them build you one similar to ours and your holes may line up as is, if you give them the dimensions.
 
Jackm said:
I had Paul build a custom three bank of his 3/4" firewall pass through. ... I could send you some pictures ... .
Click to expand...

Sure. Thanks Jack. I'd appreciate seeing the pics. Please send to joe wilbur 777 at gmail... (no spaces).
 
jwilbur said:
Bob, I like the eyeball pass-through idea. Looks like you can get them through Van's here. Can you tell me what size hole they require? Then based on your comment, would you recommend buying another recess and waiting before punching the holes? Right now I have three 11/16 holes.

Would you mind posting a picture?

Thanks,
Click to expand...

I couldn't quickly find any pictures, but there very well may be some in the firewall forward section on mykitlog site.

I ended up not using the eyeballs, but used a modified version of the standard plans. I added some stainless shields and firewall sealant. Since I had already drilled the holes per plans, this allowed me to continue. It's not a perfect solution, but I like it better than the default plans. I did have to trim these a bit to get them to all fit.

61-300LARGE.jpg
 
Sealing recess corners

The plans say to use proseal to seal the corners of the firewall recess. I've read posts suggesting this is a bad idea. What is recommended to use in its place. At the moment I'm leaning toward 3M FireBarrier 2000+. Is there any better recommendations?

Thanks
 
rleffler said:
As implied above, if you use some other mechanism other than the plans (i.e. eyeball pass throughs), the holes the plan specify will most likely be too close together.

Decided the method that you are going to use, then determine where and the size of the holes you need.

Unfortunately, I did the holes per plan long before I was ready to install the cables. I had to get a little creative due to having holes where I didn't need them.
Click to expand...

Mine is similar to Bob's in that I needed wider spacing for the eyeball units I chose. This is also a good location for a stainless doubler that could be made and drilled on the bench.

Pat
 
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