HMS Bellona 1760 by SJSoane - Scale 1:64 - English 74-gun - as designed

[dvm27]

Just curious Mark. If you sweated those cyphers and vents onto the masters wouldn’t they be incorporated into the casting?

[SJSoane]

Hi Greg,

Yes, that is my plan. I have made several of each in case I screw up attaching to the master cannons, and also to see what happens with different thicknesses of lines. I am not yet sure just how much the Micro Mark etching kit will resolve down to these fine lines.

And as long as I have to use up a 3X3 sheet, I might as well fill it up!

 

Mark

[Bob C]

I'm new to this forum although a long time modeler and I could not be more impressed by the quality of this build.  Your machining skills and use of custom tools and jigs is amazing and the results are stunning.  Your photography is also excellent and displays the work to best advantage.  I'm going to go back and spend some time carefully reading and studying the build.  Thanks for sharing your work.  I look forward to seeing more.

 

Bob

[druxey]

No need to sweat the cyphers on to the masters, Greg: epoxy would do, as mold making does not normally involve heat using room temperature vulcanizing materials. 

[SJSoane]

Oh, good to hear about epoxy, druxey,  I haven't really yet learned silver soldering. I used super glue on my previous failed effort, and it was almost a disaster when it quickly began to stick down in the wrong place. Epoxy sounds like just the right thing.

 

 

 

Mark

[SJSoane]

Hi Bob, thank you very much for your comments. As you can see, I am very often learning as I go along. And many of the great builders on this website have taught me more than I would ever would have discovered for myself. Learning from a lot of mistakes has also helped! Sometimes when the mistakes are really bad, I put those aside for a while and go onto something else to get my confidence back, and then revisit the mistake to try another approach. I tried making the cannon several years ago, and was quite discouraged by the outcome. A few years later, I have renewed energy to do it better.

 

Mark

 

 

[dvm27]

That’s how I affixed mine Mark, using 5 minute epoxy. Slightly over-contour the cypher to conform to the barrel. It’s a bit dicey keeping everything neat and tidy while the epoxy is setting but a little seep out is easily cleaned with isopropyl.

[druxey]

Just use a smear of epoxy and a bit of Magic tape to secure it. The tape lets you see that the part hasn't shifted before the epoxy sets!

[SJSoane]

thanks, Greg and druxey, this is very helpful. I face the great unknown of photo-etching next week, once my replacement chemicals arrive. No two-day delivery where I now live!

 

Mark

[AON]

Mark

Re making mistakes... I know this feeling well.  Walking away always works so long as I remember to come back.

 

Druxey

Re Magic tape

After googling it I feel a bit dumber than usual.  I normally call it Scotch tape or generically call it Transparant tape.

I never noticed the packaging claimed it was magic 😉

 

[SJSoane]

Alan, too right about remembering to come back! I put off rebuilding the cannon for several years (admittedly, retiring and moving slowed down my ship production time).

 

At the risk of making too many boring postings, I thought others might find interesting my first explorations of photo etching as I proceed. I am using the Micro-Mark Pro-etch system from their catalog. The following is what I understand will happen:

 

The system will chemically etch metal wherever it is not protected by a photoresist mask. The mask has to be applied to both sides of the metal, otherwise it would just eat through the metal from the back irrespective of what mask was placed on the front.

 

Where the masks are the same on both sides, the metal will be etched all the way through. Where the masks are different, the etch will only go halfway through, leaving a depression on one side.

 

To create the photoresist mask, artwork is created for both sides of the metal, each the mirror image of the other so the two sides line up precisely. This involves making the artwork for one side, then creating a mirror image for the other. The artwork will then be used as a mask to expose the photoresist on the metal to UV light, white areas protecting the photoresist material and therefore protecting the metal underneath from etching, and the black areas eating away the resist and therefore allowing the metal in these locations to be etched.

 

Using Adobe Illustrator, I drew the artwork, then created a mirror image for the mask on the other side. Looking at the door hinges, I created black dots for bolt locations on the front side, and removed these on the back side so they will not etch all the way through. Similarly, I added white triangles on the back side to hold the pieces in place when the etch is completed; these thinner parts will be cut through just like cutting parts from sprues in plastic models.

 

 

I need to rig a dark interior room with a yellow light so I can work with the photo resist and not expose it to UV light until everything is ready to go. The exposure to develop the resist is done with a 60 watt incandescent bulb (fortunately, I still have one in my old drafting light). Many unknowns still to go!

 

Mark

 

 

 

Edited January 12, 2019 by SJSoane
added image

[druxey]

I thought one could expose the photoresist with sunlight. I don't think one gets much UV from an incandescent bulb!

[SJSoane]

Hi druxey,

 

The exposure part has me nervous. The instructions from Micro Mark say it can be exposed either by sunlight (noon, on a bright, cloudless day for 15 seconds each side), or a 60 watt incandescent bulb for 10 minutes each side, with the bulb 4" from the surface. However, earlier in the paragraph it says a 100 watt bulb.

 

My part of the country hasn't seen a bright, cloudless day in some time (yesterday was completely fogged in). So I was reconciled to using the light bulb. But 100 watt or 60 watt? I think I will call Micro Mark on Monday to get further guidance. What happens when we can't buy incandescent bulbs for love or money? Does an LED bulb give off UV the same as an equivalent incandescent bulb?

 

The eighteenth century model builders didn't have to worry about things like this!

 

Mark

[druxey]

The issue with a bulb close to the surface means that light rays are spreading rather than parallel. The more off-axis parts of the image are, the more any distortion. Surely you see the sun occasionally in Montana?

 

Reminds me of the Noel Coward song, "Mad dogs and modellers go out in the mid-day sun." Sorry, Noel!

Edited January 12, 2019 by druxey

[Mark P]

Good Evening Mark;

 

Thank you for taking the initial steps with photo-etching, so that those who come after can learn from your experiences, and most importantly, any mistakes!

 

Keep up the great posts!

 

All the best,

 

Mark P

[SJSoane]

Thanks, Mark, I am happy to share what I learn, including mistakes and missteps.

 

Druxey, your comment about parallel light rays makes sense, particularly with the fine detail I am hoping to make.

 

I have a potential window for the sun on Monday, the only day for the next 15 days (see the weather forecast below; it reminds me of when I lived in London in the mid 70s to mid 80s). I will see if I can get everything ready by then. If not, or if the weather projection is wrong about Monday, then I am looking at a long delay...

 

Or maybe I can send my metal blank to one of you who sees the sunshine more often! It will only take 15 seconds of exposure on each side.😊

No, that won't work because it needs to be developed very soon afterwards...

 

Best wishes,

 

Mark

 

 

 

 

 

Edited January 12, 2019 by SJSoane

[druxey]

Well, at least your weather isn't too cold, Mark! It's currently 21F in Niagara and falling....

Edited January 12, 2019 by druxey

[SJSoane]

Hi druxey,

 

Quite true. They call my area the "banana belt" of Montana, ignoring the grey in the winter.

 

I just heard that I can drive to the top of a ski resort near here, where the lodge is at the top of the mountain. It often has sunshine when the rest of the valley is socked in due to a lake effect. That might be a way if the weather here does not cooperate. But then I will have to ski first!

 

By the way, do you think the Micro Mark instructions would be correct in saying that I can pull the photo resist material out of the black bag while using a yellow bug bulb, to avoid exposure to UV until everything is ready? I used to use a red light for old time photographic development, but this appears to be a different kind of exposure to a different aspect of the light. Wish I had paid more attention in those physics classes...

 

Mark

[druxey]

Yellow or red light? I don't know the answer to that, other than those are the longer wavelengths of the color spectrum, whereas violet is the short wavelength end. I imagine a very low wattage of either would be O.K.

[bartley]

Yes indeed. Ultraviolet light is past the blue end of the visible spectrum.  Red is at the other end (and infrared is past that end)  Yellow is in the middle of the visible spectrum (between red and blue) so you should be pretty safe with red.  Even the yellow light probably shouldn't emit much uv but I would stick with red if you have it.

 

Incidentally I have done some of this etching but I just bought my stuff from my local electronics shop.  I printed on one side only but I taped some polystyrene to the back so that it floated face down in the etching solution.  It worked OK but printing on both sides would be a much better idea. 

 

John

[SJSoane]

Thanks, druxey and John, this makes sense. I will see which bulb I can find!

 

Mark

[EdT]

Mark, on Naiad, I photo-etched brass rings on capstans, stove parts, plate knees.  I would think gun door hinges, chain plates would be good candidates - if you enjoy photo-etching.  I did not, particularly.  A bit messy - nasty chemicals.  On suggestion I would make - keep the black areas on your masks to a minimum - they eat up the etchant.  Forexample, you may wish to add dummy white areas between the crests and whited rectangles into the black areas around the hinges.

 

Ed

 

Ed

[SJSoane]

Thanks, Ed, that was good advice. I have blocked out some of the wasted cutouts.

 

In case the sun does not cooperate with me in the next little while, did you have any experience and success with exposing the photoresist to an incandescent bulb?

 

Mark

[druxey]

Thought: what would happen if you swung the light source around in a circle while exposing the material? Might that minimize the spreading rays effect?

[bartley]

Mark,

Just in case you are interested we have a top of  31 C in Brisbane at the moment . Sunny and lots of UV.  In fact we are the UV capital of Australia!   Perhaps you need to move down here to do your etching.  Mind you it drops to 21 C at night!

 

John

 

 

[SJSoane]

John, I once lived in Denver, Colorado, which also had something like 300 days of sunshine a year. I appreciate what you have got in Brisbane! I should have done these guns two years ago before I moved. The weather report for here tomorrow no longer shows sunshine, which was going to be the only sunshine for the next 15 days. Druxey, I am going to call Micro Mark tomorrow and see if they can shed any light (so to say) on how I can do this with a lamp. Moving the lamp around is an interesting idea.

 

As usual, nothing quite goes as one expects. I printed out the artwork on the film and got satisfyingly high resolution, higher than the printer does on regular paper. However, I did not read the fine print in the instructions that the maximum recommended size is 3" by 3" for the metal, not the artwork; the artwork needs to have a margin of  ½" within the metal all around. So my artwork was too big. A few failed attempts later, I finally got the film printed to the correct size. Used up the entire first sheet of film getting it right. And I don't have enough door hinges at this point. So there will be a round 2...

 

Best wishes,

 

Mark

Edited January 14, 2019 by SJSoane

[SJSoane]

I learned a lot today about photo etching. First, the instructions and I came to a misunderstanding about the required length of the artwork film on front and back. They have to be taped together back to back while registering exactly. One side has to be longer so the other side can be taped to it, to form a hinge at the top. The metal then slips in between. I did it wrong, leaving too short a distance at the hinge to allow the artwork to slip down to be centered on the metal. So as long as I had to do the film again, I reworked the art so that I could get all of the hinges on. I also placed registration marks at the corners to help with aligning these to each other.

 

I also talked to tech support at Micro Mark. They were very helpful. They said that the exposure to a 60 watt bulb will do the job well. 100 watts tends to deform the plexiglass that the metal and artwork is temporarily sandwiched within, and fluorescent takes all day. 60 watts takes about 10 minutes per side. Time does not seem to be critical; the film will turn a darker blue when properly exposed, and there is no danger of too much exposure. Basically, the resist under the exposed areas (white) is being hardened by the UV light, so the unexposed areas (black) can be washed away to reveal the metal for etching. It apparently cannot be over-hardened with too much exposure.

 

Also, the ink side of the art work is placed directly against the resist film on the metal, which is why the artwork has to be reversed to read properly. So there is only the thickness of the ink to cast any shadows when being exposed, which appears to be negligible.

 

I had hoped to be further along today, but there was no rush because the sun never showed up here...

 

Mark

[bartley]

I will be interested to see how this goes Mark.  Particularly with respect top the resolution.  I thought that I had invented this technique using Circuit board film.  Clearly there is nothing new under the sun!  However, the circuit board film works the opposite way from this Micro Mark stuff.

You Iron it on and then the CLEAR stuff washes away.  So I suppose that is a positive image and yours is negative.  The resolution of my method was quite good I made some friezes with leaves etc.  But I think your detail will be finer.

 

I hope it goes well.

 

Regards,

 

John

[SJSoane]

Hi John,

 

It has taken a little mental adjustment to think about everything as a negative. It makes intellectual sense as I read it, but it doesn't stick intuitively that the black is what will be eaten away, especially since it is exposure to light that makes the mask.

 

I am intrigued by your circuit board experiments. How did it go?

 

I hope to see soon just how well this resolves. Interestingly, I had access to two printers for making the artwork; a relatively high end large format Canon printer that my wife used in her architecture practice, and our cheap home scanner/printer also by Canon. I was pretty amazed to see that the cheaper printer had finer resolution. It is a few years newer, but I didn't think the print resolution on inkjets had improved that much, and lower down the price range.

 

Hard to keep up with everything!

 

Mark

[bartley]

Mark,

 

This was a frieze I made using the circuit board etching technique.  It is about 6 cm long and at the time I thought it was OK but it is pretty flat for a frieze although after it was done I painted some etchant in places on top to give some texture.  It was originally much flatter than this.  However, my carving techniques are much better now so I can now produce better looking friezes that way.  Even so you can get an idea of what the resolution was like.  In fact I made some about half this size but don't have photos of them.t have any photos