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Wessex HC2 Crab Cabs Pt II (Fly Wessex - why on earth did I?)


hendie

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On ‎29‎/‎11‎/‎2017 at 16:36, Ex-FAAWAFU said:

Ooh, rivets!

 

[Nice CAD-ery, Hendie!]

Now look what you have done Hendie; Crisp is getting all over excited now! Bucket of water somebody!

 

Martian

 

 

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49 minutes ago, Ex-FAAWAFU said:

Thise 2 Wessexes certainly fizzed; magnesium alloy + salt water under pressure = bad news.  I think I am right in saying that one of them never flew again.

Ah, this reminds me. On Wessex major servicings we had to use chalk to outline the corrosion.

We had one in for the time of the AOC's annual inspection of the base. The chalk was duly used.

Our Corporal had scrawled RUST in these areas. The AOC questioned this, the reply was, 'Can't spell corrosion, Sir'

Exit AOC and party, chuckles all round and a glare from the Senior Engineering officer!

 

(AOC - Air Officer Commanding. Air Vice Marshall or similar used to do annual inspections of all the bases under his command)

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  • 4 weeks later...

Now where was I ?  Oh... buried way back in the depths of page 8 after my vacationary jaunt back to the motherland. 

It was pretty much as I remembered it. Cold. Wet. Miserable. Wet. Cold.  Wet.  It only rained twice but the ground was wet the entire time I was there, and it was cold and wet!  Now I remembered one of the reasons I headed over here.

 

But, modeling... 'tis after all what we are here for is it not?  Well, I have hardly been anywhere near the basement in the last few weeks except to grab a few tools to carry out SWMBO's honeydoo list.  Sadly, today she got called into work - I was gutted.  That meant I could do things that I wanted to do - such a strange feeling.  Strange indeed.  It seemed so long ago that I had to read back a few pages to see what I had been doing before I left. Not much it seemed.

 

But today we have an update!  Of sorts anyways.  

 

One of the last tasks I accomplished before leaving was to glue a little square f plastic and 4 x Meng Bolts and washers onto a piece of something from the spares box.

 

PB290001.jpg

 

Which then in turn got glued onto the end of the tail rotor gearbox.  This is visible through a small opening in the tail and while not strictly accurate is enough of a representation to pass, considering it's/was Christmas.

 

PB290002.jpg

 

Another task saw me ruining my eyesight while attempting to drill into this piece of tiny brass tube. 

 

PC010004.jpg

 

Which in turn had a piece of brass rod inserted into the hole then soldered up. The tube was then cut as close to the rod as I dared...

 

PC010005.jpg

 

... and then it was filed down, again, as close to the rod as I dared - can you see where I'm going with this?  Hint: There's a tail involved.

 

PB290003.jpg

 

That tube drilling soldering cutting filing operation was repeated on the other side of the brass rod.  Yes, I'm trying to make a hinge thingy.  Fly for some reason do not even attempt to make any kind of representation on the hinges inside the tail. So that's going to be left to me I'm afraid.  They do seem to have some kind of hinge present on later kits but not the HC2, or at least the one I have.

A small wedge of brass was then soldered in to the vee area.

 

PC010007.jpg

 

And a dry fit to see what's what.

 

PC010006.jpg

 

Then I decided I didn't like it and put that aside for a while - while I ponder.

 

Now it was time to try something new... Yes, Alchemy!   I have been threatening to try this for sometime and decided that I wanted to use PE in the tail area (or so I thought)

I had now gone as far as I could building the tail without the PE so it was time to cast some runes, some chicken bones and get out the UV Nail Lamp.

@Fritag had made it look so easy. All I needed was a few hours one afternoon and I'd be done. Simple.

 

Fast forward about three days.

 

I followed all the instructions.  I sacrificed the right small furry animals.  Lots of coffee.   Boy was it a lot more difficult than I had imagined... mainly due to my own ineptitude it must be said.   The steps themselves are straightforward, however, there is a bit of technique involved and it took my dumb bottom a few attempts to realize there was a technique and actually start to apply it.

 

Note - this process was so intensive I forgot to take all the necessary photo's so you'll just have to bear with me.

 

Cleaning the brass was easy enough.  IPA and elbow grease - lots of it.  However the next step was a bit of a surprise. Getting that photo resist film onto the brass drove me nuts.  I kept getting water trapped under the film and it wasn't apparent until I'd fed the brass through the laminator.... a small bubble of water, apply lots of heat and what does water do ? Of course it boils!  A fair bit of film was burned (aha a pun) doing that.

I eventually arrived at a workable solution.  Place the brass on a piece of kitchen towel and apply film to one side of the brass. Don't use too much water - it doesn't take a lot.   As you work the film down on to the metal, the kitchen towel will wick out the surplus H2O.

 

PC270016.jpg

 

Once one side is done.  Trim the excess film away from the brass - using sharp scissors.  I found that if I left too much overhang, then when I tried to bed the second side of film down, the two films clung together making it impossible to get all the water out.

Cue missing photo.... just imagine it.

 

This was one of my first attempts.  The navigators, sorry... observers among you will note that I didn't use black ink.  Simple reason - Epson printer, and the black print head has a small blockage that I can't seem to clear so I opted to use a color, in this case a dark green.  I used the "best photo" setting with semi gloss paper selected at the highest print setting.  I also set all my line widths to 0 in the pen settings and was actually pleasantly surprised at the quality of the print.

 

PC170008.jpg

 

Ooohhh it's getting exciting now.... even the clamps are happy!

 

PC260013.jpg

 

Note that I have taped a section of sandpaper to the back of the glass to prevent light bounce.

 

Unfortunately that first attempt went the way of the dodo when I tried to develop it.

 

PC170010.jpg

 

Cue trial number > 1

Then guess what happened at the next attempt ?  Seem familiar?

 

PC170012.jpg

 

At this point it was time to take a step back and follow the old adage... RTFM !   Yes, dear readers... Read The Fritag Manual !!!

I had originally been following @Cheshiretaurus's instructions - and great they are too, however something wasn't working for me.  I was sure I had followed the ratio's of the different solutions correctly and it wasn't until I reread Fritag's comment about dunking the brass in the developer solution for a few seconds then dipped in water and attack with a soft brush and though I'd give that a try.

Well, I found that it only took about 5 seconds in the developer then quickly under the tap and wipe gently with a soft brush was enough make things work.

Eventually I arrived at this.

 

PC260015.jpg

 

Looks great doesn't it ?  Nice resolution of detail, rivets and all.

But prior to that, I had broken rule number one - print the negative version stupid !!!!  In my defense I argue that since I was designing Draftsight and had my background color set to black, it confused my already addled mind and a stuffed up!  Once I changed the background color to white (which I hate) I could see what I needed to make positive and what needed to be negative.  Here's what NOT to do!

 

PC170011.jpg

 

Cue attempt >1+ne   Eventually I got things right and in my naivete decided I would try double sided detailing.

 

PC270018.jpg

 

Well it nearly worked!  Sort of.  Maybe.

 

Well, believe it or not but that was actually encouraging - it proved I could dissolve metal - all I had to do was get the other steps before it right and I was on to a winner!

 

Cue yet more attempts... At least the green seems to work fine.  Note: The blue backing paper is still on the one on the right here in this shot.

 

PC260014.jpg

 

Since I had stuffed up so much I reckoned another few stuffers wouldn't go amiss. So in the interests of scientific discovery I decided to print one version with the ink side in, and the other version with the ink side out to see if any difference showed up in the results.

 

PC270017.jpg

 

This (hopefully) is a slightly better shot showing the amount of detail you can capture in the print.

 

PC270019.jpg

 

What is doesn't show the laws of physics and the laws of chemistry.  Yeah, I can capture that detail in a print but I forgot some basic rules about etching - the relationship between the thickness of the metal being etched and the smallest gap that can be etched.  Suffice to say that a lot of those rivets are not going to show up in the final etchery.

 

However,  after yet more attempts at alchemy we have now progressed to this stage.  It's only taken me around three days of failure so far.

 

PC270020.jpg

 

Encouraging is it not?

 

Well, we'll wait and see what happens.  Back in an hour or two....

 

 

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I’d say you’re doing pretty well; Steve told us he had numerous experimental failures before it started to come good, and no matter how excellent his and Cheshiretaurus’ instructions, I suspect (without having tried it myself) that this is a skill where you need the personal scars rather than vicarious ones.  My early attempts at soldering were a complete disaster, but you and others told me to stick with it, and now I’m reasonably confident with it.

 

Even the (entirely excellent) Flightpath PE in their Sea King conversion set relies on the modeller to add their own rivets.

 

In short, I reckon this is a great effort for the first time.

 

[Incidentally, where IS Steve?  Any Northern BM-ers aware of rumours of ex-Crab Lawyers being kidnapped by the North Riding Liberation Front? (Splitters!)]

Edited by Ex-FAAWAFU
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16 minutes ago, Ex-FAAWAFU said:

In short, I reckon this is a great effort for the first time.

 

Thanks Crisp. 

 

You're right of course.  As in riding a bike, you can read up all you like on the theory and execution, but the only way to actually move forward is to actually try it and fall off a few times.

I think I'll have something to work with from this session, but have learned a few things that I hope to remember and add in to my next attempt

 

 

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To be honest H, I really do like the way you went into this and spent time explaining the problems and what you did next

 

It may (did do)have cost some materiels and time but it's a really good way to show us the warts'n'all stuff of the alchemy

 

Thanks

 

Did you go somewhere oop north when you came here?

 

Should have come down here, there'd have been daylight and a few pints in it for you

 

anyway, digression over, carry on sir, I am all ears eyes

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Great stuff Hendie and thanks for sharing the ups AND the downs - always encouraging for others trying new techniques.

Looks like you're on your way to mastering this :)

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Hi Hendie, Happy Holidays.

 

Thoroughly enjoyed your account of the etchery adventures. I applaud you (and everyone else who perseveres with this most complicated of procedures).

How the dickens do you manage to drill a hole in a tiny brass tube with one of those brittle micro drills? I have enough of a job drilling flat plastic let alone a metal cylinder........

 

I recently got up close and personal with "Argonaut" at the Newark Air Museum. Would love to build a Wessex with all of the raised rivets. Such a characterful aircraft and beautiful in her own way too.

 

Keenly following your progress and eager to see how the final etchings turn out.

 

Keep at it. 

 

Cheers. 

 

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No less than with Steve's work in this area I want to thank-you hendie for taking the time during a fraught process to document and rationalize the procedures and results for the rest of us to follow. A second Scottish Enlightenment no less.:thumbsup:

 

My definition of technique:

Techne:Ancient Greek, meaning 'art' or 'craft'.

que? :Manuel from Fawlty Towers, meaning 'what'.

Technique = 'What? You mean there's an art to this?'

 

Keep going!

Tony

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Hendie, humbelest apologies, I've only just stumbled upon your Wessex buid. How could I have missed it? Great work on the cabin and now the tail cone, I'd have expected nothing less form you. Have you seen a guys is building a 1/8th Wessex elsewhere on BM, he's had cockpit seats made at Shapeways, they look superb? I think they would be able to scale them down, I need twenty!!!

 

Season greetings.

Colin

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thanks Colin, no need to apologize.  I saw the 1/8 Wessex build a while back.  There's a whole bunch of stuff on Shapeways for the 1/8 Wessex - it's certainly not cheap at at that scale. 

The number of (particularly simple) parts struck me as a bit odd at first since scratch building at that scale would be relatively easy compared to scratching in 1/72 or 1/48 but I guess these guys are more interested in getting the things airborne, and building the things is just a necessary evil.

 

At that scale I'd be tempted to add real rivets!

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Here we go - time for the big reveal....

 

After about  an hour I decided it was time to pull the brass out of the etchant.  The fret on the right had been out of the solution for a while and the blue photo resist started peeling back by itself.  Both frets were then dunked in an acetone bath until the blue areas weren't blue any longer

 

PC270001.jpg

 

Which left me with these...

 

PC280005.jpg

 

Okay, so they're not perfect, but they are probably a heck of a lot better than if I'd tried to hack these shapes out of brass sheet by myself.  There would have been absolutely no way that I could have carved/hacked/filed those 4 cut outs (on the right hand side) so close together without seriously damaging the surrounding areas.

They are a bit bland i.e. no rivet patterns, but the basic shapes are there and for a first attempt(s), I'm going to call this a win.

 

Also note that my trademark labeling did not really etch at all, whereas it etched perfectly on my very first attempt (way up top of page).  I found that there is a critical relationship between how long the fret is exposed under the UV lamp, and how long it is dunked in the developer solution.

Since I followed the 5% solution for the Sodium Hydroxide developer and found that a 5 second dunk was about right, I'm going to add some more water to dilute it down to a 2% - 3% solution to allow me more time/control when in the developer.

My first attempts took me almost a full day from start to finish and as with most things I found that after I had repeated the exercise a few times, I became a lot more efficient with the process, particularly applying the photo resist film.  - I just ran another fret this morning and it took me about half an hour from cleaning the brass to dunking the fret into the etchant.

This mornings attempt also had an additional 2 seconds in the developer and was cleaned off with a stiff brush in the hope that I got the developer out of the rivet patterns.

That fret should be ready in about an hour from now.

 

For those of you that are so far gone on glue fumes that you are seriously considering joining the ranks of the BM Alchemist Society (I'm sure another 'S' could be added there), I'll recap the main points of my last few days adventures

 

  1. Design artwork. Ink should be in the areas you want to remove ! 'doh!
  2. Print artwork on good quality film.  This has a large effect on the quality of your final product.  I used a standard Epson printer with print settings at the highest they would go ("Best Photo") and selected semi-gloss paper - this gave me good results.
    1. I used Waterproof Color Separation Film for T-Shirt printing from KimberlyUSA.com.  It appears that this is designed to work with Epson inks so that was a bit of a bonus.
    2. Print color does not need to be black.  I used a dark green. All that matters is that you get a good solid coverage on the sheet.
  3. Clean brass with IPA and wet and dry. I used 400 grit. Wear some kind of rubber glove to prevent handling the brass.  Run it under the tap when finished to ensure all the crud is removed/washed off.
  4. Apply film resist to one side of brass.  I laid the brass on a sheet of kitchen roll to help wick away excess water. (Make sure nothing is caught between the film and the brass as you are pressing it down.)
    1. When one side is covered, trim back the excess film with sharp scissors. 
    2. My method was to use another (dry) piece of kitchen roll to apply light pressure to lay the film down and once I was sure I had got rid of all the bubbles, I used more and more pressure in a circular motion starting from the center and working my way out to the edges to fix the film in place. 
    3. I used kitchen roll as I found that when using my finger alone, it stretched the film quite easily - dry kitchen roll slides effortlessly across the surface.
    4. Apply second layer of film on the opposite side of the fret, again laid on a piece of kitchen roll.
  5. Once the brass has photo resist on both sides, slip it inside a piece of folded paper and run it through the laminator. (I used a cheapo Amazon branded laminator set on 5 mil thickness).
    1. Run it through twice.
  6. Check the fret for any surface irregularities as these will impact your final product.
  7. Prepare the artwork ensuring it is properly aligned - take extra care at this point as any misalignment will (as always) affect the final output
    1. Once you're satisfied the fret is ready for production, sandwich it between your two pieces of artwork.
    2. When I am happy with the positioning of the fret, I secure it in place with another piece of tape - this prevents the fret moving between the two pieces of artwork when you are moving it about, or when you turn it over during exposure to the UV lamp.
    3. I ended up using a 50 seconds exposure each side
  8. Remember to remove the additional protective layer off the film at this stage, if you haven't already done so.
  9. Now it's time for the developing.  As mentioned above I found that a dunk of about 5 seconds was enough in a 5% solution. Immediately after removing it from the tank I stuck the fret under a cold running tap - don't use warm/hot water as it softens the film.  I quickly doused both sides of the fret and gave a quick brush just to ensure I had got rid of any excess developer. Then still under the tap I continued rubbing with a reasonably stiff brush - after a few seconds you will see bright brass appearing as the resist is removed.  Remember - you can always dunk it back in the developer solution for another second or so if you have to.
  10. Once you are satisfied that all the necessary resist is removed it's time to drop it into the etchant tank.
  11. Sit back and relax - but remember to agitate the etchant tank every 15 or 20 minutes
  12. With those settings I found it took roughly an hour to etch the fret sufficiently.

 

Don't just rely on my ramblings for this type of thing - I thoroughly recommend studying @Cheshiretaurus tutorial

 

 

as well as the trials and tribulations of @Fritag starting from somewhere around here...

 

 

With all that information, I'm sure you can manage to produce some quality etchwork. 

 

 

and special thanks to Fritag and Cheshiretaurus for goading me into the ranks of Alchemy

 

 

 

Edited by hendie
can't spelll korrectly
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2 hours ago, hendie said:

I'm going to call this a win

... and a well deserved one too. Thanks Hendie for the very useful summary, bookmarked in case I feel the need :)

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Great stuff Hendie. Many thanks for the in-depth tutorial and notes. Very useful. 

Please remind me why you left the rivet detail off the final artwork. Was it a resolution issue?

 

also, what's taking you? Should n't you have these all glued together by now? Come on man, clock's a tickin'...... :P

 

Cheers.

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4 hours ago, geedubelyer said:

Please remind me why you left the rivet detail off the final artwork. Was it a resolution issue?

 

Kinda sorta maybe perhaps.   I didn't leave the rivet detail off the art work, it was there all along - it just didn't etch as I had hoped.

I think there were several factors at play here... my inexperience, dumbassery, and lack of proper planning being a few basic attributes I forgot to account for in the process.

There are some limitations to the etching process and most of those are based upon the thickness of the brass sheet you are trying to etch.  For example when etching a fold line, you want to etch 2 x the sheet thickness as the line width.

 

I was using 0.005" sheet which equates to 0.127 mm.  So in theory I should have been able to etch a line of 0.25 mm width or a rivet of Ø0.25 mm.  If you look at my original artwork  shown here again - In the tail section on the far right you can just make out a vertical line in the center of the part.  Now look at my finished frets above in post 340 - there's no sign of that line being etched.

 

Hends_Etch01.jpg

 

  1. That vertical line was 0.25 mm in width and in theory it should have etched.  So why didn't it etch?  I think there are a combination of factors at play: 
  2. The printer is just a standard household printer. I have no idea how good the sharpness of the final image is. Is it 100% sharp or is there a bit of aliasing going on? Was there any bleed of the ink on the paper?
  3. How good was my alignment of the top and bottom sheets?   Any misalignment of the sheets is effectively going to reduce that available line width, or rivet diameter.
  4. Did I get all the photo resist film off the fret?   It's easy to tell in larger areas as you can see nice shiny brass, but in a Ø0.25 mm dimple in the film how can you tell if you go the resist out or not?
  5. Add to that the fact that I left the protective film on the resist while I was exposing it under the UV and there's the potential of shadowing going on too.

 

Any single one of those could have affected the outcome of the etching process though mu gut instinct is that numbers 3 & 4 are the most likely culprits.

 

Oh, one thing I forgot to mention earlier - In post 340 above, in photo number 2 of that post, one fret was exposed with the ink to the inside (towards the brass), and one fret exposed with the ink to the outside (away from the brass).   I can see no discernible difference to the sharpness of the etching in either fret.

 

I have the last fret now sitting in acetone and it should be ready for me this morning. I'll post results of that once I've had my morning coffee

 

 

 

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and the results are just in....

 

Some good news and some bad news.  The good news is that the quality of the etching has been much improved though still not perfect.  You can clearly see that some rivets have started forming, but a lot just didn't make it through the process.  However, I believe I now have a grasp (albeit very slight) on the process.

 

PC290001.jpg

 

The bad news is that the fuel filler strengthening plate (top left) went awry during the hatching process.  During my rework of the plans I never noticed that the hatching had filled in the interior of the fuel filler point - this should have been fully etched through.  Live and learn huh.

 

The really good news is that the vertical line I mentioned earlier has been fully etched and can be clearly seen as a slot.  That was an important part as the  almost rectangular thingy adjacent to it  is intended to be folded and inserted through the slot to make the support rib.  That task would have been impossible to accomplish using conventional means.

 

So, what were the differences in this attempt?   The vertical slot width was increased to 0.4 mm and rivet sizes were increased to Ø0.35 mm.  UV lamp exposure 50 seconds. Dunk in developer solution 7 - 8 seconds.

This is certainly good enough for me to work with though I may still have another attempt.  I think I should go for rivets at Ø0.4 mm with less of them, and correct that fuel filler stuffup.

 

The biggest question still remains though - Does anything actually fit ???

 

 

stay tuned

 

 

 

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