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Avro 504K, 1/32, Scratchbuild


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On 5/18/2018 at 8:39 AM, Bandsaw Steve said:

the fact that the two halves of the fuselage have been accidentally glued lightly together

 

Meticulous planning and forethought as always!

 

 

On 5/18/2018 at 8:39 AM, Bandsaw Steve said:

In order to preserve some structural integrity the cockpit is going to be a bit shallower than is strictly accurate - if I cut it full depth I'm sure the entire model would just snap in half.

 

Now that you have split the fuselage in half wouldn't it be possible to route a small channel along the inboard side on both halves between the cockpit and wing cutout, then insert a stiff something or other in there for added strength (sorta like the truss rod in a guitar neck) - thereby allowing you to deepen the cockpit area?  Invisible when closed up.

 

 

On 5/18/2018 at 8:39 AM, Bandsaw Steve said:

- if I cut it full depth I'm sure the entire model would just snap in half. 

 

Hhhhmnnn... see above^^. Nothing like a challenge is there?

 

Honestly now,.. no need to thank me - it's all part of the service

 

 

On 5/18/2018 at 8:39 AM, Bandsaw Steve said:

I don't know why it's called an 'illegitimate child' file, but it is.

 

When using this file type isn't that usually the exclamation given forth when you discover you've taken off too much material 'cos it's so coarse?

My personal favorite is the three square.

 

 

 

 

On 5/18/2018 at 8:39 AM, Bandsaw Steve said:

Sorry about the blurry photo.

 

We appreciate your effort, we really do, but there's absolutely no need to swear.... this is a family forum after all.  

 

 

 

 

 

Edited by hendie
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Hello Hendie,

 

I too have been thinking along the lines of a bit of added reinforcement - possibly using carbon fibre, but now that I know it’s called a ‘truss rod’ I’m scared of what the moderators will think. As you rightly point out, this is a family- friendly site and I’m not sure anyone wants to hear about our trusses

 

I didn’t realise ‘blurry’ was a swear word. 😱 I’ll have to be very blurry careful in future.

 

 

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You know the aesthetics of watching you work and shape the wood like this is an excellent reminder that there is so much more to modelling than plastics. That's not to deride them, but simply to say that the particular material that your using here is so much in sympathy with the subject.

 

Really enjoying and learning from your work. :thumbsup2:

 

Tony

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On May 13, 2018 at 1:02 AM, Bandsaw Steve said:

I agree - there’s no doubt that I am a good kind of crazy.🤔

It’s the damned voices in my head that are the bad kind! 🤪

Aggravated no doubt by dubious company and timetables. 😎

It was enjoyable to fondle your timber and inspect the plans. 

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Hmmmm... yes.... hmmmm, the cockpit sides.

 

I too am wondering how I will do them. I can think of several ways ranging from ‘simple but inaccurate’ to ‘difficult but (a bit more) accurate’ 🤔 

 

Hopefully the forces of dilligence and ability will overcome those of laziness and ineptitude. 

 

We shall see...

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Wings and a big win!

 

OK - there's no putting it off any longer - let's have a crack at getting the wings into the right cross-section shape.  Heaps of photos this time.

 

Here's a nice cross-section view of the aerofoil.  Let's stick it onto a bit of old litho-plate aluminum and cut out the shape so that I will have a permanent template to work to.

IMG_5296

 

Cut the template with a pair of scissors and check it against the, currently non-existent, curvature of the top of the aerofoil.

IMG_5299

 

Mark a red line running along the top of the thickest part of the wing and another one on the lower half of the leading edge.  Whatever happens do not remove those lines through excessive sanding. If they stay intact then the point of maximum thickness of the wing is intact and the plan view shape of the leading edge is still O.K.

IMG_5300

 

Attack the top of the leading edge with the belt sander.  Start with the quick and aggressive tools and progress to slower finer tools as you get closer to the finished product.

IMG_5301

 

Oh - nice! I nearly forgot that I had this one. The hand-sander is good for this kind of work.

IMG_5306

 

Work on both wings at the same time - whatever you do to one, do to the other one also. Otherwise the wings won't match each other and the model will look wrong.

IMG_5307

 

Check against the template - there's miles to go...

IMG_5309

 

Turn to the trailing part of the aerofoil - the bit behind the red line. I used the disc sander at this point and it was good but I came very, very close to removing too much at one point and in one area cut the trailing edge precariously fine.  That sounds like a good thing, but a knife sharp edge on wood might not survive all of the work and handling still to come. It might erode away - we shall see.IMG_5314

 

Am still managing to keep the two pieces reasonably similar to each other.

IMG_5319

 

A bit more work to do - but the profile is getting closer and I'm managing to preserve that red line.

IMG_5318

 

Hand sanding now - trying to achieve a fine trailing edge without eroding away the plan view shape.  have to work slowly at this point.

IMG_5322

 

Here's another tool that's useful - a razor blade scraped backwards over the surface removes a few atoms of wood at a time - very slow progress but good control.

IMG_5324

 

Leaving something like this. The final trailing edge is a bit finer than shown in this photo, but as I said before, it must not be made super-sharp because there's a 'balancing act' going on between getting a nice sharp edge, preserving the plan view shape and not leaving a wafer-thin slither of wood that will just break at the slightest provocation.

IMG_5329

 

And now for the big win.  During the Mig-15 build - @Churchill recommended I try some repositionable spray mount adhesive as he thought it would be much better than the PVA I was using. This year I finally bought some and have been really happy with it - thanks for the suggestion Churchill!

 

Now comes the time to see if I can remove the stuff! After trying one or two concoctions - meths for example,  I tried some white spirts...

IMG_5326

 

Oh my God! Look at this! The paper - so securely, beautifully and smoothly stuck on for the last couple of weeks just lifted off without so much as a squeak of protest.  This is brilliant! This is a major win for me because I now have a 'go to' adhesive for sticking paper plans to wood and a 'go to' method for cleaning it off! This is fantastic! Thank you Mr Churchill! 👍

IMG_5327

 

Look - I've cleaned all the scrubby bits of paper off the back of the fuselage as well! the model looks clean and attractive after that treatment - which goes quite a long way to maintaining enthusiasm for the project.

IMG_5333

 

So there you have it - two wings of the, roughly correct, cross-section and a new and highly satisfactory means of sticking paper on and getting it off again without leaving a mess.

 

How happy can you get all at once? 😊

 

Bandsaw Steve.

 

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Making a profile gauge is a great idea, consider it stolen. Your build log is very inspirational.

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Superb, just superb work on profiling those wings Steve. I use the same razor blade trick all the time for and planing and shaping surfaces - the information you get back through your fingertips is just about right.

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7 hours ago, Courageous said:

Excellent work with those wings, you have used the 'force' well Padawan.

I would've liked to have seen a photo of the final wing contour against your template😎.

 

Stuart

 

Like I say - the wing cross-section is only ‘roughly correct’. I’ll post a photo tonight showing the profile against the template so you can see just how rough. 🙁

In my defence, there’s not a lot of leeway with these particular wings. Compared to making them long enough, thin enough, rigid enough, symmetrical enough and uniform enough, the exact accuracy of the aerofoil section is not keeping me awake at night. 👍

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Nice work! It's great to see a scratch build like this!

 

On 5/11/2018 at 6:10 AM, Bandsaw Steve said:

...

Trim that great big block off the back of the fuselage. At this point - ideally the two halves of the fuselage should just drop apart because I tried not to get any glue on the actual mating surfaces. In reality it seems a bit got in there somehow so the two halves are still lightly attached. I don't think that it's a problem because I think they can still be worked apart without too much fuss when I eventually need them separated.

Regarding temporary gluing. Ship modelers use Ambroid or Duco (nitrocellulose-based glues) for temporary glue-ups because acetone will dissolve the glue yet won't discolor or swell the wood.

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Never ignore a pooh-pooh... 😮

 

I'm sure that @general melchett would agree, that one should never ignore a pooh-pooh! 🤔 

 

Now that you have split the fuselage in half wouldn't it be possible to route a small channel along the inboard side on both halves between the cockpit and wing cutout, then insert a stiff something or other in there for added strength (sorta like the truss rod in a guitar neck) - thereby allowing you to deepen the cockpit area?  Invisible when closed up.

 

Now I'm not sure - but I think that this chap might be pooh-poohing me - saying I lack the courage to cut the cockpit to full depth!  I'd better not ignore this least the pooh-pooh should spread...  🧐

 

Let's revisit the depth of that cockpit cutout!   Here's where I started, note the thickness of wood left between the top of the wing root and the cockpit floor. Nearly 10mm - strong enough, for sure, but the cockpit has been intentionally left too shallow.

IMG_5310

 

After a bit more bandsaw work and some sanding as shown - we are left with...

IMG_5338

 

less than 4mm of wood between the top of wing root and the floor of the cockpit. It turns out that even 4mm of jarrah is sufficient to hold just fine. And the cockpit is now going to be full-depth!

IMG_5339

Ha - one pooh-pooh destroyed! 😀

 

Now to the next one...

 

I would've liked to have seen a photo of the final wing contour against your template.

 

Hmmmmmm… even more subtle this one. I suspect that this chap is saying that I have intentionally not shown the finished product against the template because the two don't match very well... Hence a pooh-pooh!  😨

 

Well - actually he would be dead right. I was hoping no-one would notice... Here's the current state of play with the aerofoil versus the template. There's still about a 1.5mm gap between the top of the wing and the template cut-out - so this is not great.

IMG_5375

 

There are various ways to fix this including, horror of horrors, adding a thin skin of balsa to the top of the wing and sanding that down to 'fill' the gap.  Another option is to ignore the issue and live with thigs as they stand, which is,  in effect, ignoring the pooh-pooh. :shocked:

 

In any case - I'm not going to fine tune this too much until I've sorted out the dihedral, which will probably be what the next post will cover. I suspect that getting the dihedral right is going to be very 'challenging' and think that there's going to be loads of opportunities for pooh-poohing! :happy:  I for one am looking forward to it!  Never ignore a pooh-pooh! - just encourage more of them...

 

Steve

 

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8 minutes ago, Bandsaw Steve said:

It turns out that even 4mm of jarrah is sufficient to hold just fine. And the cockpit is now going to be full-depth!

 

See!   I'll bet you feel much better for that now.

 

 

As I mentioned before... no need to thanks me, it's all part of the service

 

 

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Bandwidth,

Quote

I'm sure that @general melchett would agree, that one should never ignore a pooh-pooh!  

You know my feelings regarding pooh-pooh!  wonderful progress and well done for not ignoring the current rash of alleged pooh-poohs, well, except for the last one which of course you do at your own peril, (just claim the template's wrong). 

Quote

and think that there's going to be loads of opportunities for pooh-poohing! 

Let the dihedral pooh-poohing begin...(and end), without blood being drawn or the need for hospitalization.

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Loving the work Steve, the courageous deepening of the cockpit and the fine work on the wings, the work of a master builder. Looking forward to see how the cockpit unfolds....not literally mind !

With regard to the profile gauge, make one that fits the wing, no one will notice :whistle:

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