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Are there any methods to scratch building?

Tom O'Connell

Bixler FPV Mods Fantastic
#1
Hi all,
ive built 3 scratchbuilds now and i completely suck at it. Are there any methods to learn how to do it or do i just need more practise?
 

ananas1301

Crazy flyer/crasher :D
#2
Always use a very sharp knife. In my build thread I use one of them HK sells one very cheap as well. That blade lasts for a while and I made one whole plane with one blade and it didn´t loose sharpness.

Try to work as exact as you can to make the final product be looking and working nicely.

Start with a little bit more easy plans which describe in written text how and what to do. They help a lot with getting into the deeper skills of scratchbuilding.

Use good components. Scratchbuilding is also about choosing some good and reasonable componentes that fit to the weight and the thrust you want and don´t be dissapoint if the plane doesn´t go vertical. Start experimenting because that is what it is all about these days.

Don´t mess up any scales when drawing out the plan (rather print these days)

Use a long! and straigt! piece of wood or aluminium or whatever sothat you can run the blade of the knife along it sothat you a have a perfectly stright line of cut. (Metals are better because good knifes do cut into wood :D )

Also practice you skills of cutting with the blade. You don´t believe how much you can do wrong but believe you can.

Also if you are unsure/not able to use a knife properly, just make a rough cut out and then try to get the actual line of cut by using sandpaper.

Puuh, that all from me from what came up into my mind :D


EDIT: Got some more :D

Use good glue! Some of the CA glues don´t work well. Actually I have one that etches away depron, which looks pretty cool but it is not the stuff you want. I personally use UHU Por but I´ve heard that you use some different stuff like Goop. Very important also the correct use of those glues.
TIP: If you glued something wrong, try to remove the glue by wishing it of with some benzin (some of that high concentrated stuff :D ) or other concentrated alcolhols or so.
 
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FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#3
Tom there's lots of great tips and tricks out there. From cutting techniques, to glue selection, to using dryer sheets, and water based polyurethane as a way to "fiberglass" the outside of the plane.

What are you specifically having problems with? I am sure there's someone here that can help you with it.
 

Tom O'Connell

Bixler FPV Mods Fantastic
#4
well i find it so difficult to get things as exact as they need to be. And then it all looks so ugly from the amount of tape used to hold things. Glue dripping everywhere. And i dont even think i could count on 2 hands how many times ive had to replace 'homebuilt' hinges and control horns/rods
 

ananas1301

Crazy flyer/crasher :D
#5
There are a few really nice ways of how to make your own pushrods or so. (in my Event 3D thread the pushrods are homemade and they last since they were made, and are very easy to make. If you want I can open up a thread with a How-To for it.)

But yeah a clean or reasonable good working area is also a good point to start if you want to do everything nice and neat.
 

Ryan2010

Junior Member
#6
I diffidently agree with having a sharp blade to cut with. It makes cutting so much easier. Some of the skills do come with practice, but you can speed up that process by looking at other peoples construction methods and how they do things. This will help give you ideas on how to construct certain parts and such.
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#7
There's lots and lots of great ideas on how to get cheap parts to modify for our purposes. Like this one...



I've used this trick lots of times. You can buy a whole bag of these floss dental tools at the dollar store, for a buck. They make cheap, easy, and durable control horns.
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#8
well i find it so difficult to get things as exact as they need to be. And then it all looks so ugly from the amount of tape used to hold things. Glue dripping everywhere. And i dont even think i could count on 2 hands how many times ive had to replace 'homebuilt' hinges and control horns/rods
There's plenty more techniques for how to make hinges. On my foam planes, I just use packing tape. It's important to bevel the edges of your foam for this technique though. Otherwise you will pinch the hinge point, and usually rip off the tape.

If you're dripping glue, you're either using the wrong type, or too much. Depending on where you live, you might look into hot glue. If you're in a northern climate, then hot glue is a great choice. In Florida, it's a bit tough to use in the summer, because leaving the plane in the car, will melt the glue and you'll be holding a bunch of plane parts, instead of a plane when you go to take it out of the car.
 

ananas1301

Crazy flyer/crasher :D
#9
That dental thing/tool is acutally a really good idea. If you keep in mind that this is how you can save quite a lot of money.

A few weeks ago I went to a local hobbystore and bought 6 control horns which cost me about 6€! So 1€ per controlhorn and that is wayy to much.

Fred´s post is the way to go guys!
 

JimCR120

Got Lobstah?
Site Moderator
#10
Tom,

What scratchbuilds did you attempt?

On cutting, a metal straight edge is really nice to have. If you can get a metal ruler that would be doubly useful. I like to use a utility knife for long straight cuts and an xacto for the more intricate stuff. I always cut on a board or something I can dig in without cutting into carpets/flooring.

On glue, I'm a fan of Gorilla Glue. This is applied to wet surfaces which actually improves the set time. It also swells up filling in cracks. You can also sand and paint this glue easily after it cures.

For foam, I use the fan fold foam from Lowe's. It about $40 for 25 sheets. If that's a lot you can maybe split it with another scratchbuilder. I also scavenge foam when I see it available. Construction sites sometimes have some think stuff that can be good fuselage parts. One side of the FFF has a plastic film which you might want to leave on or remove depending on what you're doing. Glues don't stick very well to this and when they do the film doesn't always stay. Peeling it off though is fairly easy.

On hinges, my most reliable hinge has been as Fred said, packing tape.

On push rods, I use all kinds of things. Flimsy wire like floral wire can work but you'll need to run it through some tubing to keep it true. It's thin and it can be doubled up and twisted for added rigidity. The last improvised push rod was out of these little yard marking flags that a landscaper left me. Since the rc bug has bit we pretty much are always watching for things since most things from the hobby shop are pricey. A couple things I do buy are clevises and little metal threaded ends that I solder on the end of the pushrods. This allows me to have a mechanical adjustment that I can make fairly easily.

I would like to echo the suggestion to choose your build wisely. There are easier one that you can do that will get you up in the air with less frustration. If you haven't already, you might want to consider the FT flyer or the Funbat. I've built the Funbat and it's only 4 pieces of foam that you can put together in a few hours.
 
#11
There's lots and lots of great ideas on how to get cheap parts to modify for our purposes. Like this one...



I've used this trick lots of times. You can buy a whole bag of these floss dental tools at the dollar store, for a buck. They make cheap, easy, and durable control horns.
I just break the little plastic things that they use to tie bread, in half, then use a big pushrod or something, and heat it up and burn holes in it.
 
#14
control horns

Buying control horns from Hobby King is dirt cheap ,less than then cost of the gas to drive to the LHS. Combine them with other items to save on shipping ,International warehouse has the best selection, plan ahead as it has been about a 4 week wait. and stockup so you can share with friends.
 
#15
I slap a plane together in 1-2 days....
I make changes to my original design as I go...usually to either get the CG where I think it should be, or to simplify the build.
I have little patience....but I do like flying something I built with my own hands.
The end result for me is a 50% success rate with my own designs.

Center of gravity being wrong is usually the thing that has stopped one of my planes from working.