Reconstruction of hull, Battleship BISMARCK, 1/100 scale

[DrPR]

I have experimented with photoetching at home. I got some tips from a professional.

It is very difficult to control the etch in a simple plastic dish. The process generates residue that builds up on the sheet and inhibits the etch process. If the residue builds up different parts of the sheet will etch at different rates. It is better to stand the etch sheet vertically in a deep plastic container. I use a fish tank aerator (aquarium hobby store) to produce bubbles that flow around the sheet and stir things up. The residue precipitates to the bottom of the tank. I also remove the sheet periodically and rinse off the etch residue and examine the progress. This is critical for very narrow width parts.

The best etch method is to spray the etchant onto a vertical sheet and let it run off, carrying the residue with it. This takes longer and more work than tank etching, but you can stop the etch quickly.

While the general rule of thumb is that you cannot reliably etch parts narrower than the thickness of the material, this is actually a bit too thin for a photoresist pattern. The process undercuts the photoresist pattern, creating a narrower part. This effect is more pronounced with thicker materials where etching takes longer times. My friend recommended a narrowest width of 1.2 x thickness in the pattern for 0.010"/0.25mm thick material. So for a 0.010" thick sheet the thinnest dimension in the photoetch pattern should be 0.012"/0.3mm. This typically will over etch to a part width of 0.010". With thinner materials (0.005"/0.125mm) the under etch is less pronounced since etching takes less time. You can get away with a 1.1x pattern width.

If you heat the etchant etch times will be reduced, but since the process works faster you still have the undercut problem. Faster etching is harder to control. Thin sections disappear very quickly. For best results etch at around room temperature (20C/72F), and I do not recommend going higher than 37C/100F. Flood the piece with cold water to stop the process.

For best results with grills, ladders, etc where openings go through the sheet, put the photoresist pattern on both sides of the sheet (aligned carefully) and etch from both sides. This minimizes the undercutting. You can etch from one side only to create patterns like rivets, bolts and weld beads. I have seen triple etched pieces with multiple levels of details like washers under bolt heads.

Be careful! Etchants attack all metals and they may leave bad stains on some plastics, stone, concrete and wood. Always work where you can flood spills and splatters with large amounts of water.

[109]

Hi Peter,

ok, now I got it...

outer frame is 0.2 mm, bars are 0,15 mm.

time for shopping ...

Bye!

[ingura]

...

[109]

I have experimented with photoetching at home. I got some tips from a professional.

It is very difficult to control the etch in a simple plastic dish. The process generates residue that builds up on the sheet and inhibits the etch process. If the residue builds up different parts of the sheet will etch at different rates. It is better to stand the etch sheet vertically in a deep plastic container. I use a fish tank aerator (aquarium hobby store) to produce bubbles that flow around the sheet and stir things up. The residue precipitates to the bottom of the tank. I also remove the sheet periodically and rinse off the etch residue and examine the progress. This is critical for very narrow width parts.

The best etch method is to spray the etchant onto a vertical sheet and let it run off, carrying the residue with it. This takes longer and more work than tank etching, but you can stop the etch quickly.

While the general rule of thumb is that you cannot reliably etch parts narrower than the thickness of the material, this is actually a bit too thin for a photoresist pattern. The process undercuts the photoresist pattern, creating a narrower part. This effect is more pronounced with thicker materials where etching takes longer times. My friend recommended a narrowest width of 1.2 x thickness in the pattern for 0.010"/0.25mm thick material. So for a 0.010" thick sheet the thinnest dimension in the photoetch pattern should be 0.012"/0.3mm. This typically will over etch to a part width of 0.010". With thinner materials (0.005"/0.125mm) the under etch is less pronounced since etching takes less time. You can get away with a 1.1x pattern width.

If you heat the etchant etch times will be reduced, but since the process works faster you still have the undercut problem. Faster etching is harder to control. Thin sections disappear very quickly. For best results etch at around room temperature (20C/72F), and I do not recommend going higher than 37C/100F. Flood the piece with cold water to stop the process.

For best results with grills, ladders, etc where openings go through the sheet, put the photoresist pattern on both sides of the sheet (aligned carefully) and etch from both sides. This minimizes the undercutting. You can etch from one side only to create patterns like rivets, bolts and weld beads. I have seen triple etched pieces with multiple levels of details like washers under bolt heads.

Be careful! Etchants attack all metals and they may leave bad stains on some plastics, stone, concrete and wood. Always work where you can flood spills and splatters with large amounts of water.

Hi Phil,

thanks for that info!

How is your project coming along?

Bye!

[109]

Hi Bernd,

ok - for Egbert this would be a "piece of cake". I'm sure he can help you out with that. Say hi to him for me please.

Peter.

Ok, I�ll contact him. There is an egberth in the member list... is this the guy?

Erst eben gelesen... Wahnsinniger - das sind doch alle Modellbauer!

[ingura]

...

[DrPR]

109,

My 3 year old great grandson was visiting the other day, and when he saw the hull he said "Let's finish it!" (Maybe a born modeler?)

I told him he would probably be in high school before it was finished. That's how it is going.

I am still in the planning stage, working on drawings of details - there are a lot of details at 1:96! Just finished the SPS-10 radar, and I have finally found photos to let me finish the SPG-49s. SPS-30 and SPS-43 follow that. I have a new photoetch technique to try, for the catwalks around the funnels and some radar parts (very fine detail). After that I will install the decks on the hull (already cut) and start on the hull plating. Then on to wood deck planking.

[TRM]

Bernd,

I played around with some etching, even made a simple bubble tank for the process out of plexi-glass. Etching vertically in the tank allows the residue to fall away while you etch. I set it up to see if I could do it, and it actually worked really well. I used Ferric Chloride (nasty stuff but effective). It did work better with heat and even better with citric acid (I used lime juice). All plastic with an air line with holes drilled into it, I made the line to hook up to my compressor so I could regulate the bubbles. There are clener and safer chemical on the market...which always cost more, but no as much smell and mess if you spill....not including the faact of enviromental issues with disposal. Good luck, you drawing are excellent and I am looking forward to seeing your progress.

All else fails....try here - http://www.etchingservice.eu/


Cheers!

[109]

109,

My 3 year old great grandson was visiting the other day, and when he saw the hull he said "Let's finish it!" (Maybe a born modeler?)

I told him he would probably be in high school before it was finished. That's how it is going.

I am still in the planning stage, working on drawings of details - there are a lot of details at 1:96! Just finished the SPS-10 radar, and I have finally found photos to let me finish the SPG-49s. SPS-30 and SPS-43 follow that. I have a new photoetch technique to try, for the catwalks around the funnels and some radar parts (very fine detail). After that I will install the decks on the hull (already cut) and start on the hull plating. Then on to wood deck planking.

Hi Phil,

yeah - let�s finish it! my wife is not amused about acid baths at home - I will use an etching service. Well, I am a sailor and she�s the captain!

Bye now,

Bernd.

[109]

Bernd,

I played around with some etching, even made a simple bubble tank for the process out of plexi-glass. Etching vertically in the tank allows the residue to fall away while you etch. I set it up to see if I could do it, and it actually worked really well. I used Ferric Chloride (nasty stuff but effective). It did work better with heat and even better with citric acid (I used lime juice). All plastic with an air line with holes drilled into it, I made the line to hook up to my compressor so I could regulate the bubbles. There are clener and safer chemical on the market...which always cost more, but no as much smell and mess if you spill....not including the faact of enviromental issues with disposal. Good luck, you drawing are excellent and I am looking forward to seeing your progress.

All else fails....try here - http://www.etchingservice.eu/


Cheers!

Hi,

thanks for the input. I came across the website you mentioned a few days ago - have you been a customer there?

Bye!

[TRM]

No, not as of yet anyway. But heard some good things from another forum. Some wooden ship builders have ordered parts to spec and have been pleased. I had another listing, but seemed to have missed placed it. I will search around for it. I will post it if I find it.

Cheers!

[109]

Hi again,

hope you are all fine!

I had to spent quite some additional hours on fine tuning the shape and finish of my hull as I experienced some problems after applying a coat of paint. It revealed some issues that required work ..

Here are a few shots with red primer and I am now able to go ahead with rectangular sea boxes and after them I�ll do the bilge keels along with some large inlets on the hull sides.

Bye now!

[Dave Wooley]

This is truly magnificent workmanship and only the primer
Dave Wooley

[TRM]

[JIM BAUMANN]

very very sharp work! ( hervorragend! )

Will you mount the completed hull on a mirror base--so that one may observe all your hard work iwhich lie in otherwise concealed( once the ship is upright) areas such as between the screws...?

Jim Baumann

[109]

Hi Jim,

yes, I will try to use a mirror, probably v-shaped with the ridige running along the ship�s length axis.

Bye now,

Bernd.

[Capit�o Norbert]

fantastic work on hull .... fantastic

[109]

Little update.. some sanding (what else?!?! ) and added some reinforcements around the circular openings.

Bye!

[TRM]

Nice touch!

[109]

Hi,

besides drawing PE-parts I did some basic work on the reconstruction of the forward log ("speed measuring installation") on my Bismarck.

Here is what I researched so far:

- the device worked on the principle of dynamic pressure
- it was retractable (approx. 1.000 mm)

If you have some knowledge on such devices please discuss it here with us!

Good night,

Bernd.