Replacing CA hinges with Robart hinges
12-09-2003, 06:56 AM
#1
Replacing CA hinges with Robart hinges
Have you wondered how to replace a broken CA hinge with Robart hinge points ? I obtained very good results with a sharpened brass tube (aluminum tube was too soft and blunts too fast). Sharpening of the brass tube was done by inserting the tip of a dremel cone grinding stone into the opening of the tube. Mount the tube into a cordless drill or dremel, and "drill" through the previous CA hinge line using the Robart drill guide. Cuts through the ca hinge remnant smoothly and quickly ! The pic below shows two 1/8" holes drilled through a broken CA hinge.
12-09-2003, 07:20 PM
#3
RE: Replacing CA hinges with Robart hinges
Hi Ed, there will be a need to resharpen the tube every two holes or so. It is also best to push out the drilling fragment from inside the tube with a 2-56 rod after drilling a hole halfway. The CA hinge fragments are hard and if too much gets accumulated inside the tube, you'll have to drill it out with a 1/16" drill bit. I recommend preparing several tubes so that you can do a quick replacement, continue drilling, and do all the tube cleaning/resharpening at the end of the whole job.
12-09-2003, 08:36 PM
#4
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RE: Replacing CA hinges with Robart hinges
Rajul - I use brass tubing for cutting all kinds of holes because regular drill bits tear up balsa wood. For the most part, I use a counter-sink to sharpen the brass, but also do the same as you with a Dremel at times. Just depends on what's handy.
Here's an example:
http://www.airfieldmodels.com/inform...uide/index.htm
Here's an example:
http://www.airfieldmodels.com/inform...uide/index.htm
12-09-2003, 08:50 PM
#5
RE: Replacing CA hinges with Robart hinges
Hi Paul,
Thx for the comments. I have also used #11 blades to sharpen tubes. Just insert the blade tip and rotate it so as to "scrape" off the metal until it is sharpened.
Having said that, hard brass tube is preferred compared to soft annealed brass.
Thx for the comments. I have also used #11 blades to sharpen tubes. Just insert the blade tip and rotate it so as to "scrape" off the metal until it is sharpened.
Having said that, hard brass tube is preferred compared to soft annealed brass.
08-24-2013, 08:07 PM
#6
I am in the process of re-vamping a never flown 1/3 scale Pitts that I have had for years. I will be going with a DLE55 on this plane for power. I went out and bough all sorts of heavy duty hardware for the control surfaces and guess what? Yep, when I assembled this plane all those years ago I used CA hinges 
Oh well, the first thing out of the shoot is to replace those CA hinges with heavier Robart hinge points. One thing that I have done in the past before installing the hinges is to clean them in denatured alcohol prior to use so that I am sure all the release agent that is used in the plastic dies is removed. I also always rough the hinge points up as well before I epoxy (30min) them in. I cut small relief's in the control surface to give it clearance for the hinge knuckle.
Oh well, the first thing out of the shoot is to replace those CA hinges with heavier Robart hinge points. One thing that I have done in the past before installing the hinges is to clean them in denatured alcohol prior to use so that I am sure all the release agent that is used in the plastic dies is removed. I also always rough the hinge points up as well before I epoxy (30min) them in. I cut small relief's in the control surface to give it clearance for the hinge knuckle.
