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Danny's "poor mans Spitty"


Danny Fenton
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Lol thanks Nigel jsut try not to laught too hard when I get things wrong (inevitable)

I have snook a coffee break in on the bench and made a pocket for the hinges in the fin.

0044.jpg

0045.jpg

These are made quite simply of some 1/8 strip and ensure that the hinge sits centrally in the slot. The slot in the fin post is easily opened up with a flat but curved to a taper needle file

Sorry for the poor pics i am abandoning my usual strict picture code so that i can take more pics......

Cheers

Danny

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Posted by Terry Walters on 02/10/2014 12:43:14:

Coffee Break!!! surprise!!

Good grief man you'll be wanting a 35hr week!!. Britain didn't get where it is today with coffee breaks!!! Get on with it! wink 2 I've shifted about 4 cu metres of wood this morning and go the back to prove it!

Terry

LOL Terry I do have a day job you know embarrassed the coffee break was used up on the fin!

You have been on those logs all day, extract the digit! theres Chippys to build

Thanks Nigel

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Danny, I know it must be a pain to take so many pics and offer a much fuller write up than you normally would. I am very grateful that you are producing a sort of "Dummies Guide" on this thread. I hope Dennis is enjoying this, and, learning as much as I am. I know you want to press on but please keep the tutorial going, it's great. Thank you.

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Hi Andrew as long as you guys are getting some benefit from it then i will try and keep going. Please remember this is just my way, each have their own way and preferences.

Okay sheeting. I am using 2mm instead of 1/16 so I have to make sure I sand the extra .4mm off, wont be a problem.

The balsa sheets should be joined and sanded before attaching to the airframe. The reason is that when you sand, the pressure could mean you take more wood off where the balsa is supported by ribs and underlying structure. This will result in the "starved Horse" appearance sometimes seen.

Another mention on sanding while I am here. The paper you use needs to be quite coarse. I use 120 grit aluminium oxide, glued to a small wooden block. Very light pressure really cuts the balsa. If you use a finer grade it tends to "polish" the surface and the pressure required causes the ripples and ridges. Your paper should cut the balsa really easily. To final sand the sheets before final fitting I use a large flat wooden balsa block with a medium paper attached. The sanding blocks come from the Balsa Cabin £1 each, fine one side medium the other, grab some when you are next at a show

0049.jpg

Panels joined to make sufficient sized sheet to cover in piece

0046.jpg

The first side is easy as you can get to the inside while using thin CA

0047.jpg

Nice and smooth surface

0050.jpg

Preparation for the other side

0051.jpg

Titebond II dries a bit faster than Titebond Original

0052.jpg

I need to source a new bottle to dispense this stuff more easily but for now a stick will do

0053.jpg

0054.jpg

Place the sheet over the assembly noting where the ribs are so yo u can pin through the sheeting and find some meat to pin the sheeting too.

Then go and get a coffee and a rich tea or two.....

Cheers

Danny

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Just re-read that and its not clear about my small wooden block....

0056.jpg

0055.jpg

This is said block, it must be ten years old and has done every model I have built. It does most of the part sanding. Eventually it gets blunt though i am careful to only use the block on balsa, inevitably its closest to hand when I want to sand the edge of ply or even glass board. You can just about make out the layers of paper that are simply evo stuck onto the previous layer.

They say "never say never", but I say never sand with paper in your bare hands, always use a block or backing of some sort.

Hope this clarifies that?

right where are the Rich Teas....

Cheers

Danny

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Hi Danny

What is the notch for in the second piece of fin sheeting? Have you glued the hinges into place yet? if so what glue did you use?

Martyn

PS - I am going to be late starting - possibly a few weeks. I have got the back of the house being extended then demolished - I don't want to start something this important in case I have to lose my shed in a hurry (for storage)

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Hi Martyn, its just the offcut from the sheeting, turned around and glued back on the edge to make it bigger. Waste not want not. It gets trimmed flush

The hinges are not glued yet, I am in two minds, I could glue them now but then you have to protect the hinge from glues, epoxy etc through out the build, so I try and leave them dry fitted for the time being.

I am pretty sure the drawing is wrong in the amount of hinge inset/offset at the top hinge, it works better if it is closer to the fin and not inset so much.....

I look forward to you starting your build Martyn

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Hi Charles, I used CA in this case as it was just pushed together and glue drizzled in.

If it were a full sheet of balsa then I would put masking tape all the way along the joint, flip it over and let the tape act as a hinge and use Titebond in the gap. close and flip so the tape was on top again. Stack some magazines on the lot and walk away. So I guess my answer is it depends how long the joint and if you need time to work.

You probably already new all that, forgive me for using your question as a vehicle to pass on the method

Hope that helps

Cheers

Danny

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just to interject fellow modellers Danny mentioned needle files well at the moment Aldi sell diamond needle files (10) of different types round triangular etc for £4.99 the same files in Hobbycraft are £12.99 for 5 I got some and they are pretty good.re the sanding block I use the rolls of green carbide paper quite a far length on the roll and cut to any size to make all sorts of blocks and as Danny has said just renew when worn.

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Thanks Martian that is a good find.

Those steely eyed amongst you will have noticed that i have ended the sheeting at the trailing edge of the fin. But the plan says to extend the sheeting to form a shroud for the rudder? I can hear you all mutter over your hob nobs. Well a 1/16 balsa shroud wouldn't last two minutes around me so I do mine slightly differently.

Here is a nifty little way of making surface shrouds.

0060.jpg

Firstly we make a little block like this, mine has two blocks in one, 1/4 inch overhang one side and a 1/8th on the other. We will use the 1/8 section.

0062.jpg

Sand until you have made a channel 1/64th deep, it only takes a few wipes

0064.jpg

Take a strip of 1/64th ply, it needs to be twice the width of the slot you just sanded. We used the 1/8th side so the ply is 1/4 wide

0071.jpg

Glue it into the channel and if you have got the depth right it will sit perfectly flush with the sheeting

0074.jpg

And there you have perfectly shrouded surfaces, this works for elevators and ailerons too of course.

Right has Terry sorted out the tailplane yet....... no, better get another cup of coffee then...

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Hi Dennis, if you make it from a single piece cut then there would be little strength in it because of the grain direction. You could I suppose make it from several sections splicing them together. But I think it would be far easier to use 1/8, and then laminate another piece straight over the top to get your 1/4 inch.

If anybody is following along i am still not happy with the rudder the hinge recess and rudder thickness is not right. If you are shaddowing, I would build the fin first while we all investigate what's going on. The elevator may well be the same I am just playing with that now.

Cheers

Danny

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Danny - great technique for the shrouds - will give that a go. 1/64th is that between a smidgen and a tad? cheeky!

Sorry - tailplane not finished today Boss - will be sheeted tomorrow!

How do you get time to do all your write-ups? Takes me more time to do them than I spend in the workshop! Do have you a voice dictation system like you see pathologists using in the morgue with a hanging microphone or does the SWMBO at your end 'take notes'

Terry

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Hi CS and thanks matey, its the piccy composition I am ignoring, also the light isn't perfect but hopefully you can still see whats happening

Well two rudders in the bin, the third one is looking better.

jb rudder to scale.jpg

If you study the Jerry Bates fin and rudder for his 1/4 scale version you will see how it should have been designed, notice the hinges one above the other vertically and the gap gets wider at the top as the rudder leading edge gets thinner. So Iam trying to see if I can make the hinge positions we have work.

0078.jpg

The new rudder was made well over thick and using the fin post to mark the thickness required was then sanded to match the fin post

0079.jpg

The leading edge of the rudder just needs carefully rounding off now, but first as a guide the radius needs drawing onto the top and bottom rib as a guide.

________________________________________________________________

While I was building the rudder I used a technique that is very obvious but may not be so for some. If you are adding ribs to either side of a balsa core many people use the plan to mark BOTH sides of the core, and invariably they don't end up perfectly symmetrical.

If you do one side then push a pin through from the completed side, right up against the ribs, pin holes will be visible on the the other side, makes symmetry simples

Okay off to round that rudder leading edge, at least that way it will fly into the bin more accurately....

Cheers

Danny

Edited By Danny Fenton on 03/10/2014 15:35:25

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