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Author Topic: Robart Hinge Points  (Read 1906 times)

Offline Vincent Judd

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Robart Hinge Points
« on: August 03, 2013, 02:31:18 PM »
I've been using these for years in my R/C planes and really like them.  They're easy to install, very low friction, and have held up well for me.  I was wondering if they were ever used in a stunt ship?

Vince
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Offline Jeff Traxler

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Re: Robart Hinge Points
« Reply #1 on: August 03, 2013, 02:54:32 PM »
Hi Vince,I can't answer that question and if you don't mind I am going to wait to see your replys.I have a BUNCH of them and have been wondering exactly the same thing.There is far less surface area between the hinge and the pin so the friction in theory should be less.Have you ever weighed them vs. conventional flat hinges?Trax
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Offline Steve Helmick

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Re: Robart Hinge Points
« Reply #2 on: August 03, 2013, 03:10:32 PM »
Norm Whittle used Robart Hinge Points in the Eagle that I'm currently flying. It has squared off wing/stab TEs and bevelled flap/elevator LEs, with the hinges notched into the movable surface. Clearance is minimal, about .017", and there are no hingeline seals. I've looked at doing that, but don't see how it would work, with the pivot axis being behind the gap. The controls are very nice and free.

I don't see a thing wrong with the hinges, but I think I'd want to put the pivot pins on the point < of the flap & elevator, so a tape seal could be applied. I do not understand how to install those hinges without putting them in twisted & pins not square to the hingeline, but maybe one of you could 'splain?  H^^ Steve
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Offline Will Hinton

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Re: Robart Hinge Points
« Reply #3 on: August 03, 2013, 05:51:52 PM »
I just used these on my Pawnee project.  I don't know if my process was typical or not, but I did as Steve said and put the hinge pins on the leading edge line.  That required notching the LE of the moving surface, but I installed them by epoxying them in and they seem okay.  When I put them in place on the first surface, I used a 90 degree triangle to make them square with the surface while pointing straight down.  (Or up, your choice as long as you get the 90 degrees.)
They seem to be very free, so now we'll see how they hold up.  I like them, but getting a good hole drilled at 90 to the LE is a pain.  If they weren't going in balsa it would be easier because we could make up a good jig for the drill press, but the balsa is so bloody soft that really didn't want to work for me.
How is someone else drilling their holes? 
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Offline Vincent Judd

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Re: Robart Hinge Points
« Reply #4 on: August 03, 2013, 08:04:51 PM »
There is a jig available for drilling the holes.  It may even be made by Robart, I'll have to check.   I have one, it's easy to use and always gives you perfect 90 degree holes.  I'm pretty sure I bought it from Tower Hobbies.  As for the installation, I pretty much did exactly as Will suggested.  I put them in the trailing edge first with 30 minute epoxy.  Point them down and check with a triangle.  Let them sit until dry and then install the movable surface.  Oh, the really important part is that you have to melt vasoline into the hinge and then clean everything off with rubbing alcohol.  This keeps the epoxy from getting in to the hinge and gumming things up.  Works great every time.

I've used these hinges on all of my 3D ships and they work great.  Only difference is I have a beveled trailing edge on the wing and a beveled leading edge on the aileron. I countersink the knuckle of the hinge into the trailing edge to minimize the gap.  Of  course I'm looking for at least 75 degrees of travel on my ailerons and elevators, much more than we use in stunt.
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Offline Steve Helmick

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Re: Robart Hinge Points
« Reply #5 on: August 04, 2013, 03:44:03 PM »
I'd like to use a single hinge pin per elevator and flap. Could I do this with the Hinge Points? How big a pin would it take? I'd also like to adapt Gordan Delaney's hinge installation method (silkspan and CA), see file attached.   y1 Steve
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"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Will Hinton

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Re: Robart Hinge Points
« Reply #6 on: August 04, 2013, 05:01:37 PM »
Wow, wish I had read this a week & a half ago!!!  I sure would have tried it.  Thanks!  I typed it out for the next plane!
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Offline Paul Wood

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Re: Robart Hinge Points
« Reply #7 on: August 04, 2013, 06:08:17 PM »
Vince,

Those are the only type of hinges I use.  They work great, just as in you R/C experience.  The only issue I've had is that the C/L plane surfaces are usually thinner than the R/C planes and that forces me to use the smaller hinges.  I just use more of them per surface.  Here's a picture of my Nobler where you can see the hinge on the wing flap.

Paul
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Offline Allan Perret

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Re: Robart Hinge Points
« Reply #8 on: August 04, 2013, 08:21:49 PM »
I have used them on a 40 size Stearman profile and also on a Magnum.  Nothing different about the installation vs barrel type hinges, except that all you need is a hole instead of a slot.  They work good, and I have installed them with a continuous wire in place of the individual pins.  The drilling jig is a Robart item, and you can get the hinges un-assembled (no pins) in a bulk pack if you plan on doing the single wire.
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Offline Avaiojet

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Re: Robart Hinge Points
« Reply #9 on: August 08, 2013, 06:35:19 AM »
I've used them on plenty of R/C models over the years.

Here's the tail feathers of a F3F that will be CL.

Probably the next model I work on.

Set the hinges up years ago and I see no reason to change them.

Charles
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