Tip: Engine Holes to Firewall simplified

Over the weekend I drilled out three of my (6) motor mount holes into the firewall and by the time I got to the forth one that's in the firewall the last hole went to ****!

What happens is with every hole you open up, the subsequent hole gets harder to nail and locate than the one previous. Now I?ve got a slightly oval hole that I?ve got to fix with a oversize bushing and you just can?t imagine how mad it made me!

While at work today I came up with a simple solution so this won't be a problem for the rest of you; I came up with a simple drill guide. Check it out and I hope it prevents some of you the agony I caused myself last night.

http://picasaweb.google.com/Lechair/EasyDrillGuide

I'd certainly be interested in how you're planning to "fix" your bad firewall hole.

I've worked MRB on the F-22 and I've seen worse!

Greg,

I oversided the hole to a .500 OD from the original .375 and am going to put a .300 long steel bushing cylinder in the enlarged hole and it will have an off centered .375 lined up with the motor mount.

It's a lot of extra work for something had I quit early I wouldn't have butchered it up so. Heed my warning! Step away from the power tools when you start feeling yourself get tired!

See you in the air in about year! Lech

Jim, where did you get the steel sleave that you used?

Thanks,

Jerry

Steel Sleave used to make my bushing from

Jerry,

I'm an aerospace engineer and what I wanted was either 1095, PH13-8 or 4130 steel material to fabricate my fix/repair.

After work I went to a local machine shop and asked if they had any scrap steel bar or rod stock that I could buy from them to fabricate my new bushing from. He gave me (2) pieces of bar about 1" diameter and 4" long FREE! The down side is that what he gave me is A-2 Tool Steel which after I machine it down and drill my new hole I'll have to have it heat treated to get the hardness I need to repair my enlarged bolt hole.

If you need a picture of my enlarged firewall hole to visualize my bushing repair idea, let me know and I can send you one.

Had I been more careful to begin with (and or used my handy tool I put on this website) this never would have happened in the first place.

I hope this helps you and others. Lech

N702PL said:

Step away from the power tools when you start feeling yourself get tired!

Click to expand...

This is the reason I prefer to work in the morning rather than evening if have to choose. After some building, you can go to work to r... I mean work.