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Scram

Wipers, replace/repair question

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Scram
6 minutes ago, Phil.Taylor said:

heres one I did earlier - comb binding could be your new friend :)

http://www.rcgroups.com/forums/showthread.php?t=2095531

Phil.

That looks good Phil but one slight problem for me.  Seems you did this with a detached aileron?? 

I don't think I will cut off the flap to do it that way ......  ;)

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oipigface

The blue Australian stuff sounds very similar to Frog tape, which I have been using a lot of late. You can get Frog tape in two flavours: green is the regular variety, and yellow is a low adhesion version. You can get it at B&Q., Travis Perkins, Axminster Tools and probably loads of other places as well.

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2 hours ago, Scram said:

That looks good Phil but one slight problem for me.  Seems you did this with a detached aileron?? 

I don't think I will cut off the flap to do it that way ......  ;)

Detaching them makes it much simpler to do. They are very easy to re-attach.

Just think-typing

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isoaritfirst
15 hours ago, Woodstock said:

Isn't the tape just going to blow back in the airstream?

 

Radical Pro is done like this. The tape sits in the recess. Doesn't ever blow out. although tape is more the thickness of Book tape.

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Les

My Caldera has tape as well, never had any issues. 

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Scram

As I said, there was some tape like that on the edge of the aileron but it must have been magic tape, not very stiff and so wide it was all folded up.  Could not see it being of use :huh:

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satinet

What's the rest of the model like? Assuming it's a nice model, it seems a shame not to do it.

Tape wipers work okay on tails and ailerons, I'm not sure they are as good on flaps, because they open out beyond the wiper. I don't recall a model with tape wipers on the flaps (cue flame war of correction).   A lot of models have tape on the elevator (freestyler 3), on the ailerons (radical) or the trilerons (crossfire 2). 

Realistically what you will need it some SLOW epoxy, some thickener, micro balloons and maybe flock. You need to find out what a recipe is. This could all get very expensive if you don't have these things already.

I would certainly practice before tackling the wing proper.  You would want some glue that doesn't set too rapidly. I have west system epoxy with the fast cure hardener. Bear in mind the fast cure is still way slower than workshop epoxies like zap. Even so you would not be able to muck about before it started going off.  Looking at that video it's a question of getting the right mix consistency and working at the right speed so it doesn't go off. Both things require practice. I'm speaking from the position of getting it wrong with glues more often than right, btw! He's really got it right because the ******* doesn't drop off the tape, but it can still be worked with.

The first rule of glue club is that it always does the opposite of what you want.  e.g. 24 hour epoxy goes off like thin CA when you don't want it to, and CA suddenly decides not to stick (until it flows through and sticks to the work bench).  e.g. It takes on the tensile strength of superman's underpants if you glue get glue where you shouldn't, but sticks like 10 year old prit stick when you desperately need it to perform.  Never mind the dreaded finger print fairy. 

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Scram

Thanks Tom, all good stuff.

This is for a certain Vampire, pre-owned by a certain flier conversant with collecting poles at competitions, so pristine it ain't  and not helped by my own ministrations  :blink:

However, it is sufficiently sound for me to want to replace the missing wiper.  I'm not happy with bits of tape but it's going to have to wait till after this w/e - if it survives  :rolleyes:

I have the necessary suggested materials except for the ScotchBlue tape which is on its way here in a few days.  I will report on the repair job when done.

I can also concur with your First Rule of Glue!!

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MikeDaBike

As epoxy mixes are being discussed, can I ask what people use to contain epoxy whilst setting ; I need to firm up
two flap horns (which move very slightly) with epoxy so was thinking of making a putty/fimo surround around the
horn, then filling with cabosil/epoxy mix , waiting to set, then removing the putty. Just don't want epoxy spreading
to the hinge line.

Not trying to hijack this very interesting thread so will start a new thread if need be.

Mike

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isoaritfirst

- make the epoxy thick enough with balloons etc so that it stays put.  Also as it dries squeeze with damp fingers to mould into shape. 

- not tried it but how about hot glue . Rough mould then shape with hot knife. Then put in place by melting edge with hot knife and positioning. 

- moulding wipers as in the video on to tape , why not run some thin card with a curve bent into it by scraping the one side. Slide the card down onto the back of the tape before inverting the wing for the epoxy to sit in place and dry nicely curved

 

 

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satinet
As epoxy mixes are being discussed, can I ask what people use to contain epoxy whilst setting ; I need to firm up

two flap horns (which move very slightly) with epoxy so was thinking of making a putty/fimo surround around the

horn, then filling with cabosil/epoxy mix , waiting to set, then removing the putty. Just don't want epoxy spreading

to the hinge line.

Not trying to hijack this very interesting thread so will start a new thread if need be.

Mike

I don't use micro balloons for control horns. I find normal 30 minute epoxy thickened suitability is fine.

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isoaritfirst

I agree with tom if you are fixing horns into holes. 

if they are just wobbling a bit then just hit them with a little penetrating cyano. 

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chiloschista
On 10/11/2015, 19:47:43, Scram said:

Thanks Ric.  For making stronger joints with epoxy, I do use microfibers which I find are also described as cotton flocks and I have a large tub of colloidal silica which research shows me is your thixotropic agent.

So now I just need the tape.

It's more like fumed silica, but hey, if I'm not wrong that's your field of knowledge :D

Anyway if you want to really thicken a resin you should use cotton flocks. This way you could even use less thixotropic agent.

With thixotropic agent in the right amount, the resin does no more drip (strain?). You can reverse the mixing cup and nothing moves. I make large use of it and it is really cheap at about £4.-/1000ml. Really useful when gluing things inside a fuselage or horns or ... without any resin flowing around. Also no need to use anything to hold it in place it, it stays where you put it and in shape.

Ric

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Scram

I would never use micro balloons in a mix for securing something needing strength.

My understanding is the micro balloons are for thickening and lightening the mix for things like filleting a joint.

The problem for security is the micro balloons make the cured mix brittle, you loose the toughness of plain epoxy. 

On the other hand, micro fibres (cotton flock) strengthens the epoxy, increases its toughness, whilst also making the fresh mix stiffer for shape retention.

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isoaritfirst

Alternative view;

Then again epoxy is much stronger than the wood so weakening it might just be the right call..

But we all over-build, I suspect...

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Scott Ravenscroft
On 11 November 2015 14:34:02, Scram said:

Thanks Tom, all good stuff.

This is for a certain Vampire, pre-owned by a certain flier conversant with collecting poles at competitions, so pristine it ain't  and not helped by my own ministrations  :blink:

However, it is sufficiently sound for me to want to replace the missing wiper.  I'm not happy with bits of tape but it's going to have to wait till after this w/e - if it survives  :rolleyes:

I have the necessary suggested materials except for the ScotchBlue tape which is on its way here in a few days.  I will report on the repair job when done.

I can also concur with your First Rule of Glue!!

Only just read this, I don't hit that many poles, do I ?

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oipigface
On ‎09‎/‎11‎/‎2015‎ ‎17‎:‎58‎:‎38, mtreble said:

There is a Video here:

From 15 mins in he does the wipers.

13:45 is better. The first part of the video is very instructive as well. Good spot!

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Scram
1 hour ago, oipigface said:

13:45 is better. The first part of the video is very instructive as well. Good spot!

I got the Scotch Blue masking tape yesterday, just took about 2 weeks from Amazon with free postage  :huh:  so will be having a go in due course.

This Vampire wiper however, needs to be quite a bit larger than the one made in the video and Phils method would n doubt guarantee a better profile.  There is no way however, that I will cut off a perfectly well attached flap.  May have to think of something else.

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tatsy

Hi

try using a binder plastic coil its about the right size for wipers

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mark_r

Quick comment on wiper tape - as Mike said, the Radicals use the tape method. It's dymo tape, which very conveniently has the backing split along its length. You remove 1/2 the backing and then rub micro balloons on the sticky edge - stops it sticking and makes it white in the process. Then peel the other half of the backing pressing it in to place as you pull the backing clear. Fold the aileron back to tuck the tape inside (running the back of a scalpel along the wiper length makes this easy). Makes a very easy effective wiper.

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