basmntdweller

My Feedback: (9)

First, I am going by the procedure outlined in the thread here on RCU. I thought I had .010 glass sheet but mine is .015. Is this too thick to get a decent hinge? I ordered the correct sizes from ACP but that may take a while to get here. Also, I am getting ready to glass the tail section on my Racer II and planning to do the skin hinge as Bill says in the instructions. I have read on here that glass hinges should be on a 45 degree bias. So should I glass the stab/elevators on the bias? I thought I may even add a first layer of cloth right at the hinge line and then glass over the entire unit. The single layer of 3/4oz cloth doesn't seem strong enough to me. Maybe it's plenty though. Lastly, I have read about slotting the leading edges of the stab and insetting 1/64 ply to help maintain a sharp edge. I didn't find anything in the instructions on the Racer II about doing this. Is it needed or even desired?
Thanks,,,basmntdweller

JohnBuckner

My Feedback: (1)

since you are doing skin hinges on the stabs with glass over the entire top surface then hardening the leading edges with ply is not really neccessary.

Do apply your glass with the bias. I had forgotten to do so on
some and the ends of the aileron slots tend to fray. In my case the solution is crashing the airplane for other reasons .

I have also done some with heavier cloth but noticed no real advantage or disadvantage. I have had more failures (uneven bonding read: ugly) using heavy cloth I think due to the lack of a vacuum bagger, thats my next step.

John

daven

My Feedback: (1)

On the tails, I'm using 2oz cloth, on the bias, with the 1/64 ply inset. It may be overkill, but my tails are still coming out at about 2oz which I am satisfied with.

I would not use the .015 glass laminate for the aileron hinges. .010 is perfect, and if you use it on the tail you can get away with .005.

Dave

Bill Vargas

My Feedback: (5)

http://www.rcuniverse.com/showthread...80&forumid=111

B, here's a link to a skin hinge thread! and yes, if using 3/4oz cloth,,,, double up on the hinge line,,, but if your using 1.5oz or 2oz then there's no need to double up on the hinge line.


BV D

SSAN

basmntdweller,

There are many different ways one can do skin hinges, and they all works well. However, I went a different route than the usual heavy glass way for weight reason.

I glass both my ailerons and evelators with 1" strip of Kevlar .5 oz. mat underneath the 3/4 oz. glass cloth for the upper surface. This will assure me it will not rip or tear apart and still have the light weight I'm looking for. That's just my way or another way of doing skin hinges I should say.

basmntdweller

My Feedback: (9)

Apparently, the pics didn't stay with the link. I have an old AC vacuum pump that I may try to adapt. I'll have to do some more investigating to learn the basics of bagging. That may have to wait for the next group of planes. The two I'm building right now are due at a race in about a month.
Thanks,,,basmntdweller

Bill Vargas

My Feedback: (5)

Hmmmm??? they were there

oh well, they can be seen at the www.nmpra.org or www.********.net sites!


BV

PylonWorld

All of the pictures from that thread are missing ... that seems to happen from time to time, and I don't know what the cause is ... It happened to the F1 thread, too.

I have a couple of theories, but I'm not sure if any of them are correct. One is that threads that aren't viewed often enough lose their pics. The other is that system changes in the size of files allowed causes it. I think the original limit was 100,000 bytes, then it was 80,000 bytes, and now it is 70,000 bytes max for an image.

I'll post a message in the moderators forum and see if I can find out. Losing the pics in threads is almost as bad as losing the thread, especially if it is a pic heavy thread.

Alabama Racer

The beginning of this post mentioned slotting the edges of the stab to insert 1/64" plywood. A neat tool to make a simple task of this job can be fashioned with a #11 blade & a few scraps of wood. Sandwich the blade between two 1/8" balsa scraps and make a couple of fences that go above the height of the blade.
The 1/8" scraps would be if working on a 1/4" stab - this will center the blade between the 2 fences. Rough up the sides of the blade so that CA will stick it to the wood.
This tool is also good for making hinge slots on traditional hinged surfaces. The slots will be exactly centered in your work.
If my attached photo comes thru, this will make sense. If not,
it will seem like absolute balderdash.
Brad

basmntdweller

My Feedback: (9)

I thought about some thing like that but was afraid forcing the ply in the slot might be enough to cause the wood to split after sanding it to the airfoil shape. I was going to use the saw blade that dremel used to have but it seems they no longer carry it. I found another one but it's only .005 thick. I was going to get 3 of them and stack them together. I was going to put my dremel in it's router attachment and center the blades. But from what I have been told it's not absolutely necessary to put the ply in. I'm guessing that even if I had the fastest plane at the race it still wouldn't matter, the best flyer of the day is going to win. That won't be me for many races!
basmntdweller

PylonWorld

You are correct that Dremel dropped the little saw blade. I looked all over for them before finding one at my dad's. In the 70's it was Catalog No. 400 and it was a .023 Steel Saw. I think the number in later years was 704 or 705 (maybe 604 or 605).

Micro-Mark sells blades and blade/mandrel sets that will work. Check out Miniature Saw Blade and look at at the alternates.

Another option is to use the thinner blades you found and use carbon fiber laminate that is appropriate for the slot width. If the blades you found are the .007-.010 thick ones at one of the predominately Chinese produced tools stores, they will probably work well with .007 CF laminate.

The .007 CF laminate also works well if you make the #11 blade device.

PylonWorld

Another alternative is to use a Dremel 409 cut-off blade. It's not as fast as a saw, and you'll have to be more patient, but it makes a perfect slot for 1/64" plywood.

DMyer

My Feedback: (2)

Rather than use the dremal router and the mini-circular saw.... chuck the blade up in your drill press, raise the work table until the blade is centered on whatever thickness of balsa you want to slot, set the drill press for it's highest speed and then run the part's edge all they around cutting the slot. I usually make two passes... first 1/2 depth, second all the way up to the arbor. You can perfectly, and safely, slot all your tail parts in less than two minutes. This is how I slot conventional CA hinge lines also... just make sure you keep the top up on all parts slotted so that if you are off a tad on your centering... everything will still match perfect.

Pete Bergstrom

The Drill press method as mentioned above has been my favorite for about 15 years. You really won't notice that much of an increase in speed of the racer but the durability of both the leading and trailing edges of your tail assembly is well worth the little extra effort that this takes. No more dings and handling dents. It will hold its edge forever (or until the inevitable happens!).

Pete

daven

My Feedback: (1)

I've not tried the drill press method, but we basically do the same thing with a dremel mounted upside down in a router table. Once you get the correct height set, just buzz around the wheel. It takes more time setting up the router table than cutting them. I try to do a couple at a time when I do them. I can see that doing it on the drill press would be quicer to set up.

This method works great, but you gotta be carefull with that little spinning razor blade. The main reason I like inseting the ply is it makes it much easier to sand the airfoil knowing where the center of the LE/TE is.

Bill Vargas

My Feedback: (5)

I hate that when the inevitable happens,,, the good thing is, the tail survived and is now on a new plane


BV

daven

My Feedback: (1)

Looks like you broke the CF Gear. You must have hit something pretty hard.

SSAN

Aaah shuck, Bill!
It looks like my SAM-RAI Q500 a couple of weekend ago.

Dang... I hate it when that happened!
And the same tail will be on the new improved SAM-RAI quickie coming up.

MikeyD

I have tried both the drill press and the router thing. The drill press in my opinion is the only way to go. It's easy, a cinch to set up in the press, and the torque of the drill press makes it a snap.

Matt, the cutting saw can be purchased at Hobbytown USA in Castleton if your intersted. The bad thing is that they are pretty expensive.


Mikey D

PylonWorld

I usually use my drill press also. The Dremel #212 Drill Press Attachment also works well for slotting and other uses like routing out a piece of plywood in certain locations to save weight. It normally costs about $30.

When I do them on the drill press, I get a piece of scrap from the same piece of wood the tail was cut from if possible. I set the basic table height. I sometimes mark the scrap, but usually eyeball it. Make a cut, then flip the scrap over. You'll find out real quick how close you are. Make an adjacent cut. Then loosen the chuck, and set the saw to the middle of the two cuts. This usually gets you there in 2 iterations, 3 max.

vector-RCU

My Feedback: (8)

Hi Dave,
Yeap BV broke my gear and was nice enough to send the two pieces back to me. Since this is the first one that actually broke I really wanted to see it.
I am working on a slightly different version that will give you more axle height adjustment like you suggested Dave. I am also going to see if I can make the BV proof

Lewis

Bill Vargas

My Feedback: (5)

DN, yea it came in nose first and smacked a hard packed dirt road. The tail survived just fine without a scratch and is now on another Racer II


BV

kane

I too use the drill press method.

Pay attention to getting the slot in the center. The trick is to turn the part over (as Don mentioned) to make sure you are in the center.

I also made a guide fence similar to router tables or table saws. It is simple to make using a piece of MDF and bolt it to the base of your drill press. (Sorry I don't have pictures, but will try to post some later.) The MDF provides a good base for the balsa to slide over. And a second piece of MDF used for the fence provides a stop for going too deep into the balsa.

Just my two cents.

Dan