Wet forming?

[KnifeEdge51]

I recently downloaded a few of Paul Bradley's plans, and tried to start on the Fw-109. However, when I got to wet forming the wingtips, I couldn't get my balsa to bend. Instead, it bent a little, and then creased itself, which isn't what I wanted. I am using old Guillow 1/16 strip wood, so maybe it's the wood quality. I tried the "saliva method" described by Rifleman. Any hints or tips, or am I just using bad wood?

Nick

[T. Lyttle]

Yes, I wet the wood, and while it is soaking, I either cut a template of the tip minus the thickness of the laminations( i always laminate 2 pieces at least, up to four) or just stick pins in the plan , again minus the planned width of the part. Once that is done, I take my #11 knife, or a pencil, or anything round, lay the wood on a writing pad/newspaper/workboard (you have discovered ceiling tiles, haven't you?) and roll away. When the wood assumes the correct curvature, pin it in place, followed by another piece. Apply glue to the second piece first, then glue it to the first and pin tightly. Keep adding laminations as required. Allow to dry overnight, remove pins, sand. Final part is amazingly strong.

I have used this method to build fuse formers as well; result is a very strong structure!

[KnifeEdge51]

Terry,

So you soak your wood, and then "crush" it under a pencil or hobby knife. THEN you wrap it around the template. Then you repeat this again, and you apply (aliphatic?)glue to the second piece, and apply it to the first, making sure it aligns properly. Allow this to dry (or repeat again if desired), and you have a complete form, correct?

I was just soaking the balsa in my saliva for about 5 minutes, and then attemptin to form the whole things, uncrushed or anything, to the tight curves of the wingtip. I'll give your method a try. If it works for you, it must work for me! Thanks!

Nick

[Bob Chiang]

I've read about another method of forming curved parts:

wet the stick
bend it while rubbing it against a hot soldering iron, rewetting as necessary

This method is supposed to result in bent single sticks (ie 1/16" square) that keep their shape without laminating.

I've tried it but have not been successful yet: the wood chars before I get it curved.

-BC

[T. Lyttle]

got the burn scars to prove it... :D

As far as my method is concerned, KnifeEdge has it about right. Balsa is amazing stuff, and I have tried rolling 1/16 sq to the required shape, pinning it and leaving it overnight. It expands back to nearly 1/16, but not quite. Also that doesn't leave much room to sand out any errors in its shape, and it ain't near as strong...

By laminating around a form, or the row of pins, there is virtually no finish work to the part until it is glued into the wing (or fuse) structure. I don't spend a lot of time building any other way now, and for Peanut tail parts I go th 2 lams of 1/16x1/32; just as light, 5 times as strong. For all the airplanes I have busted in other ways, I have yet to bust a laminated tip, period.

You will see how easy it is when you try it: if you use a fairly soft surface, you will see the part assume nearly all the necessary curve develop before your eyes. A little adjusting, and the curve requires just a few pins until the laminations are complete. I may have generated some confusion: you do understand that the roller is 90deg to the strip, right?

[Rifleman]

I guess I wasn't clear on the fact that you pull the fibres of the wood to make it conform to your form....you need to anchor the wood on one end, then you can either pull or push the wood to bring it around the form.....in doing so, you will stretch the fibres and they will follow the curve(don't use punky "A" grain, use "C" grain with visible grain)....in the event I am using a tight curve, I have on occasion, used the roll (rolling along the length of the strip) and squeeze method (this compresses the fibres making them more susceptable to stretching) described above....that works fine too.

[KnifeEdge51]

Terry,

You lost me on the 90º to the strip part. Can you clarify? I'm about to try laminating the tips (just got done steaming teh ribs. Harder than it looks! I think the under camber for the Fw is a bit more than the balsa wants to curve, but what I got out of it will work). I just take a piece of 1/16, and soak it for about 10 minutes. Then I take it and lay it flat on my table, and roll my Xacto handle over it until it's relatively flat. Then I'm going to curve it around my foam template. I'll then repeat this for the second piece. Does this sound right? I'm just curious how the "90º to the strip" works in. Thanks!

Nick

[BMatthews]

Nick, I was a bit confused about the steaming the ribs part so I went and had a look at Paul's plan. The plan calls for cutting the rib IN THE CURVED SHAPE from sheet wood.

As for your bending troubles I have done outlines like this by laminating them from two layers of 1/32 soaked in hot water and using a thin wipe of PVA glue inbetween while wet. This bundle is then stretch wrapped around the form. I have used pins but if the outline is fairly tight I found the balsa kinks at the pins so for anything other than a light curve I use a proper form.

Bob Chiang. Get yourself a heavy duty 400 watt lamp dimmer and set it so the soldering iron is hot enough to sizzle with a bit of water on it but not so hot it chars the wood. This works great on Old Timer bamboo tips for me and I'm sure it would work on the balsa. And less heat and more patience to let the area heat soak ensures a lasting bend. You need to let the heat work it's way all the way through the wood. And with balsa being a pretty darn good insulator this can take longer than you think. Done a couple of music instruments using this method with a 250 watt Big Bertha soldering iron on maple and black walnut. Haven't tried it with balsa yet.

[steve lewin]

Originally posted by Rifleman
(don't use punky "A" grain, use "C" grain with visible grain)
This part caught my attention. Did you really mean C-grain ? I've never had any joy trying to bend C-grain balsa. Indeed I only use it specifically for things like ribs and sometimes formers that I don't want to bend. I've always used fairly firm A-grain for laminating. Have I been doing it wrong all these years ? (I wouldn't be surprised if I had ;)).

Steve

[Rifleman]

Thanks for being my proofreader Steve, you caught one that should have been reversed........you are right, if you try to bend some "C" grain around a form, you will arrive at nothing but frustration....you do need "A" grain and time and patience......
my appologies for the incorrect info, but to my defense, it was late here and between the build that I am doing and documenting with the camera and photoshop, I get a few things too many spinning in my head, which at the best of times doesn't multi-task too well.( I can almost walk and chew gum, but not consistently)

[KnifeEdge51]

BMatthews,

I know it calls for the ribs to be cut from sheeting, but I thought this to be a good time to learn how to steam ribs. :D Never hurts to try and save a bit of weight either. But, I think for my next no-cal, I will be cutting the ribs from sheeting.

Nick

[Rifleman]

Nick, if you check the photos I have posted on my NoCal, you will see some of the rib templates which I have used in the past.....now I only use a few and don't try to get too fancy with the low speed airfoils which really don't make a huge diff one way or the other....I have never bent a rib....always sliced them.
BTW, any guess on what I'm building ?

[KnifeEdge51]

Rifleman,

Sounds like good advice. I believe that steaming the ribs was a bit more trouble than it was worth. It was rather interesting to see the results, however.

Nick

[T. Lyttle]

I used to steam ribs, found that the airfoil(!) was inconsistent; slicing ribs solves that. If you roll and laminate ribs, it takes more time, but the strength goes up and the airfoil is consistent. I found that sliced ribs require very careful sheet selection, and here in the bushes, we don't necessarily have that luxury (90 miles to the closest hobby shop).

As far as rolling is concerned, the stick faces north-south, the roller east-west. The hardness/softness of the paper pad has an effect on how sharp a curve you get; like I said, if you do it right, there is virtually no further bending required, even on peanut tail surfaces. Make the strip overlength, trim off excess after laminations are done. The marks/irregularities on the inside of the curve are easily sanded out.

[BMatthews]

Originally posted by T. Lyttle
..... and here in the bushes, we don't necessarily have that luxury (90 miles to the closest hobby shop...

What? You don't use split Sage wood? Git yer butt out into that cold and pick up some o' dem rollers passing by.... :D

[T. Lyttle]

Ya forget how old I am, I no longer have the speed to catch a tumbleweed! And, you should know they don't work unless you catch'em live:D :D

Woudn't be the first time I've resorted to alternate woods. In my highschool days, I used to hunt up the lightest piece of pine or spruce int the wood shop, and slice it into strips, had to be secretive about it or the shop teacher would go ballistic....

Tried willow when I worked on the dam survey north of Campbell River, used office elastics for power; part of the learning curve. :rolleyes:

Life is better now, for us. The kids would NEVER commit that kind of time and energy to something that wasn't guaranteed to work, and work well. Any models I see kids flying now are E-Chargers or AirHogs, and that is only for 20 minutes or so.:confused:

So, where is freeflight heading? And do we have the ability to control its destiny?:)

[KnifeEdge51]

I will admit that the most successful FF plane has been the one I almost OOSes the other day, which is electric. However, now that I have good CA again, I can finish my Guillows Cub (but I also need gears, need to make a battery, etc). That too will be electric, but I did build it. :D Not to mention the two Peanut I have, and the Nocal I've got the wings built for! Money and time are the biggest limitations for me, but when I've got enough of them, I' like to pick up a nice sized rubber FF for outdoors, and make it OOS for good. :p

Nick

[billystiltner]

I was trying to bend some wingtips the other day. I was copying the design of an echarger plane. I broke about 12 sticks to get the 2 wingtips 1/16" square. I think it's all in the wood. Some sticks bend easier than others. Has anyone tried soaking in ammonia? I read that it loosens the natural glues.

[Rifleman]

Billy, ammonia is an old fav among some modellers but not with me 'cause of the smell....if you are trying 1/16 sq it may be too much to get the fibres to stretch in the wood, you will probably have more luck in doing it with 1/32x1/16 and laminating the two to make a stronger piece anyway....

[Dave Lofthouse]

I have not tried this with balsa but in my wood working I have had occasion to try soaking wood in fabric softner/water before bending. I found that it worked quite well. You may be concerned about residue. I was too since I was planning to finish the wood later with both a stain and urethane......no problems were noted. It may be worth a try and it will save you the amonia fumes.

PS
I am new here - good to see there are still a few who enjoy the art that is FF.

[KnifeEdge51]

I'll second Rifleman's suggestion on using 1/32x1/16 balsa for laminating. It worked great for me! It's an unfinished project, but I hope to have some pictures of a NoCal FW-109 I built. The vertical stab looks great, and I used the 1/32 balsa laminations.

Nick

[T. Lyttle]

I guess I should have included the fact that I use the thinnest practical wood for the laminations, ie 1/32 for Peanut, NoCal, etc. Using the roller method, I regularly laminate wing tips and tail parts, some wingtips up to 10" long, using 1/16 or 3/32 to come up to the required (or designed) 1/4 or more width. If you have a wing tip that is semicircular or elliptic, you can laminate to 1/2" or more, and still sand to knife edge without losing any strength. As I said, the time to do tips this way is no longer than cutting segments; I know, I've tried!

[Oian]

I used to have trouble sometimes breaking laminations when wet bending and then I read somewhere that the problem was that the wood was not saturated enough, It was said that it took quite a while to soak even a piece of 1/16 balsa. An overnight soak does wonders as the wood gets very floppy and easy to bend. To soak I use a piece of cheap PVC pipe with a glued cap on the bottom and one pressed on the top to hold the wood in the water. As for amonia, the article stated that balsa has very little lignin (that's what the amonia softens so it doesn't do that much).

[Applehoney]

I usually use lams 1/32" thick and I never presoak them - find that applying Ambroid or Elmers makes them instantly supple enough to go right around the forms. However, I do not build small scale or similar models with might entail small forms with tight curvature.

[tljohnson]

I have bent Balsa around my living room 3 way light bulb after soaking in water. Soak the wood, not the light bulb.

I have also obtained 12 inch bamboo skewers (obtained at the local grocery store,about 1/8in in dia) and bent then around the light bulb after water soaking. The nice things about bamboo is that the grain is straight/clear and is cheap. It can also be easily split to a square shape.

With the bamboo, you can shape the Bamboo up to about 3/32 square before bending or anything smaller. One of the old time flyers said he shapes Bamboo around/near a candle flame.

[TLyttle]

Hawww!!

Not only do all the trees here grow on a 10deg angle here (which makes the tumbleweeds hard to catch, but I never see any go by that would supply the sizes I need, nor are they straight enough!!

Keep the good ideas coming, though...

[tljohnson]

This website describes construction ofLarry Park's Indoor RC - TigerFly_

http://www.smarttoolsinc.com/Model_Kits/TigerFly/TigerFlyConstruction.html

In the article with pictures, he shows how to first form sheetstock into the desired rib form and then how to cut each rib. He uses the heel of a common iron to make the rib sheet conform to a balsa or pine wing form using wet paper towels on top of the sheet blank. Have a look

[KnifeEdge51]

Wow! I never thought I'd see one of my thread get resurrected after this long! Sad part of it is, I still haven't finished the Fw-109. I've got the frame built, I just need to cover it, and either roll a motor tube, or cut one. I'll have to make a seperate post on that in a while here. After all this time, I'd really like to see the thing in the air. And I'm glad I kept the plans, as I can't seem to find Paul's website anymore. I'll keep looking. I printed a few others, but if anyone has a good source for No-Cal plans, I'd be interested!!!

[tljohnson]

Wow! I never thought I'd see one of my thread get resurrected after this long! Sad part of it is, I still haven't finished the Fw-109. I've got the frame built, I just need to cover it, and either roll a motor tube, or cut one. I'll have to make a seperate post on that in a while here. After all this time, I'd really like to see the thing in the air. And I'm glad I kept the plans, as I can't seem to find Paul's website anymore. I'll keep looking. I printed a few others, but if anyone has a good source for No-Cal plans, I'd be interested!!!

Is this the website you want?

http://www.parmodels.com/Techniques_and_References/index.htm

[KnifeEdge51]

Holy moly, TL, that's the one! I bookmarked it, and will be downloading all the plans tomorrow or in the next few days. I really enjoyed building that Fw-109. Now to just get it in the air . . .