birds mouth for joining plastic rod

[Kit Basher]

I'm talking about the joint where one plastic rod meets another, either perpendicular or at some other angle. I've seen some very clean joints on here, and I'm guessing it's done by cutting a hollowed end (bird's mouth) on the rod that meets the side of another. I would like to hear ways of cutting that hollow, or other ways of cleanly joining plastic rod. Thanks in advance.

[Mike Kucaba]

There are "notchers" in the 1:1 world of tube chassis and other areas of metal working. Maybe studying that tool,a smaller ( 1/8th--1/16th) scale could be made would work. Failing that, Daves mention of a small round file is the usual method.Does everyone use tubing though? I made some repairs to a warped 1/16th fueler chassis and used round rod.

[Kit Basher]

My attempts at filing them freehand have been pretty inaccurate and slow. If that's how the folks making those beautiful tube chassis on here are doing it, I need a lot more practice. I'm hoping for a better way.

[Kit Basher]

Thanks, Dave, I will practice. And maybe get one of those Kevlar thumb guards!

[Mike Kucaba]

An easy to make jig could be made from a block of wood or maybe something harder. Drill a hole that the tubing can slip into and hold it snug.File a goove(use the round file for the fishmouth size) across the block intersecting the hole. Now slide the tubing into the block and use that groove to guide the file across the tube. Sorry I don't have one of those drawing programs to illustrate this better.

[Evil Appetite]

The first time I read the fishmouth term here, I went and tried it. I made a notch with my xacto, then used a small triangular file to get some depth going. Then switched over to a small rounded file. Set it over the groove and worked it back and forth afew times, slowing to one - way when i figured i was close to fit size. Worked great for me

[Kit Basher]

Mike K., I understand exactly what you mean. I was thinking today about drilling a hole for the rod and another hole that intersected it for the file, almost exactly what you're describing. It would only be good for one size rod and one size file, but it's a start.

Mike R., I'm glad Dave's technique worked so well for you, I haven't had a chance to try it yet. I want those invisible joints that I've seen on here!

[Bartster]

Drill different size holes in the block of wood & you'd have one tool for any size rod you use.

[Kit Basher]

I'm gonna make one of these things. I'll post pics when it's done.

[Psychographic]

I just use my thumb and index finger as a guide while holding the rod or tube. When filing it will leave some "flash" on the edges, don't trim it off. The flash will help mold the two parts together and make a smoother joint if you are using a liquid cement.

Edited February 8, 2012 by Psychographic

[Kit Basher]

Here is my understanding of the jig Mike K. suggested.

My first attempts at 90 degrees were not much easier than freehand. But 45 degrees worked really well. The joint shown is unglued.

I think with some refinement this thing might work pretty well, although it's still pretty slow. I'm already pondering something involving a Dremel. Thanks for the heads up about the flash, guys, I would have carefully removed that!

[Mike Kucaba]

That's fantastic and you even did a 45 degree angle. If you wanted to expand on this you could drill holes at 90 and 45 degrees for various size tubing,as long as you could get a near perfect intersect of the two holes,you would only have to insert the drill in one and the tubing or rod in the other, and run the bit thru.When the tubing or rod is pulled from the block you would have two fishmouthed ends.

[Kit Basher]

I will try it, Mike.