D-shaped hole for bulkhead connector

[flion]

I'm going to be using some RG-400 bulkhead connectors to get the LSI cables through my firewall (so maybe this technically belongs in the ignition section) and they call for a D-shaped panel cutout, which prevents them from rotating as you attach a cable to them. Is there a tool to make this cutout? A punch of some kind? And, if so, where would I acquire one of these?

[Jeff A]

Depending on the size you need, Google "Greenlee" and the approriate part numbers:

60077 - 1/2"
61080 - 5/8"
61083 - 3/4"

You won't like the prices! My opinion....drill undersized and file as needed to make the connector fit....

Good luck.

[Mike S]

Another option is to make a doubler plate, with the "D" shape in it. You can even use two pieces to make it easier.

Drill an oversized hole in the fire wall for clearance, and install the doubler with a couple nut plates.

[flion]

Jeff, you're right, I don't like the price. But I like filing stainless steel even less. That's the info I was looking for, thanks much. Mike, the doubler plate doesn't buy me much. Either it's stainless and difficult or aluminum and not suitable for the firewall. And both require attachment hardware, etc., which complicates the whole thing. But, as you can see, I did consider it.

[Rick_A]

I just drilled a couple of small holes in the firewall big enough for the RG-400 coax and a grommet to protect it. By LSI, I assume you're talking about Lightspeed Plasma systems. When I got mine, the coax was only terminated at one end, so I ran it through the firewall before putting the connecters on.

It's would be the rare event that would require you to disconnect the coax at the firewall connector.

I also covered the holes & grommet with a preformed SS shield.

[az_gila]

I'm not sure what material this is made from, but the style would get rid of your twisting problem...

http://store.haveinc.com/p-49451-can...ush-mount.aspx

[flion]

Dang, Gil! I spent hours looking though Digikey, Spark Fun, etc. and only found the normal bulkhead connectors. Those would be not only beautiful but more fireproof.

As for the passthough with grommet, I have already had to replace the firewall on my -6A and the struggle to get terminals and such through convinced me there had to be a better way. Also, I don't feel the grommets and shields are enough protection. As a result, the -10 will have firewall-rated CPCs for the sensors and bulkhead connectors for the power cables. The Lightspeed Ignition cables were the last problem to solve and I found some isolated bulkhead connectors that would do the job. I may yet change to the ones Gil found, though.

You will be able to disconnect the engine completely from the firewall without disturbing its integrity. Or, as I had to do, you will be able to remove the firewall without struggling to thread stuff through too-large holes or, at worst, cutting wires.

Update: I went to the Canare site and found some documentation on their bulkhead connector. It's really just a normal connector with an isolation ring in a flush mount 'tub'. Unfortunately, the isolation ring is ABS and the 'tub' is nickel-AL. The connectors I found earlier (I don't have the part number or mfg handy) are the brass-nickel plated steel, like the Canare connector, but the isolation ring is teflon. Still not as firewall-safe as I'd like, but the connector can be oriented so the isolator has minimal exposure on the hot side of the firewall and then protected with firewall putty, to the point where it won't be any worse than the aluminum rivets burning through. I'd like some opinions on that nickel-AL tub from Canare, though, because I could always swap their connector and ring with the ones I have now and the installation would be easier (or cheaper, anyway, if I don't have to buy that punch). But right now, I'm leaning toward buying the tool and going with what I have.