Edge 540

Whats the easiest way to alter the bolting pattern on the firewall for the engine mount on a finished plane? I need a different pattern for a bigger engine and the new blind nuts need to be installed with little or no access to the inside of the firewall.
Any ideas?
Thanks!

Rodney

Buy some threaded rod at the local hardware store, usually comes in 3 foot lengths. You can insert it from the front of the firewall, put a blind nut on the inside then put a nut on the outside and draw the blind nut into position.Make the drill hole for the blind nut the same size as the outside diameter of the threaded portion of the blind nut.

Rcpilot

My Feedback: (78)

First--knock the old nuts out.

Then line up the engine and drill your new holes.

Fill the old holes with 5min epoxy and micro balloons.

There are various ways of getting a blind nut into a firewall where access is limited:

Glue the blind nut to a long piece of fuel tubing with some thin CA and drop it down in there. Then try and get a long bolt to "catch" it from the front side of the firewall and screw it in. Run the bolt all the way down and suck the blind nut into the firewall before removing it.

Glue the blind nut to the end of one of your fingers with thin CA. Just a teensy little bitty drop. Just enough to make it stick to the end of your finger. Stick your hand in there and feel around.

Use a long pair of hemostats

Get your 4yr old kid to stick their tiny hand down in there and hold the nut for ya.

BillS

The easiest way is to knock the blind nuts out, pug the hole, and drill new holes for the blind nuts.

However in the past I have made a false firewall with blind nuts and then mounted the false firewall to the real firewall with flat head screws.

Bill

delman

The easiest way might be to make a new plywood firewall - drill holes and install blind nuts for the new eng mount - use the old mount hole pattern to mount new firewall to the old firewall. Sorry, didn't see that BillS already suggested this.

FLYBOY

My Feedback: (11)

Most have it right taking the old out first, then drill the holes. You can put the new ones in with the long threaded rod like specified, or a piece of nyrod with the right threading in, you can cut a bolt off with the dremel to get the right thread. Pull the blind nut in as tight as tight as you can, then unscrew the rod and put a screw with washers in from the front and tighten against the firewall to pull the nuts up tight. don't over tighten and break off the nuts. Its pretty easy.

bryris

How do you pull out a blind nut without taking the wood with it? I am going to need to do that soon on my cub.

BillS

Push it towards the rear.

Bill

Rodney

To remove the blind nut, thread a good bolt, like a steel socket head, into the blind nut from the front. Have a long enough bolt so that about an inch or more extends in front of the firewall. Hold the fuselage firmly in one hand and give the bolt head a good rap with a hammer. The blind nut will come out the back with usually no problems. Now unthread it from the bolt and remove it.

bryris

Do I need to heat up the blind nut with a soldering iron first to melt the glue?

2slow2matter

My Feedback: (1)

If it's epoxied in, yes. Get a soldering iron, and heat up the blind nut. Or, thread the bolt in (get a long one--two inches or so), and use a small hand torch (mapp or propane) to heat up the socket head. the heat will transfer down to the blind nut, and the epoxy will loosen in no time. Be careful not to get the flame near the covering or firewall, though!

Fill the hole with a dowell, and put some thin CA and it will never go anywhere. Or, if you like, use wood glue on the dowell before installing, and then hammer in flush. It will be there when the plane expires!

MinnFlyer

My Feedback: (4)

Heat is not necessary. Rodney's term "Give it a good Rap with a hammer" is a good one - meaning that a "quick, sharp blow" will snap the glue. Sure, you might take some wood with it, but not enough to do any harm.