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SJSoane

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

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Hi everyone,

 

It has been a long journey figuring out how to make the cannon. The efforts at pattern turning failed miserably. I used an old Vanda-Lay pattern tool for the Sherline, but I could not keep it from deflecting, and the cuts were quite ragged. Probably operator error, but not worth pursuing I decided.

 

I temporarily lost heart, thinking about the long uphill climb making 74 guns, and I looked for ways that I could have them made for me. But 3-d printing was way, way too expensive, and I did not find a source that could provide the level of quality I hoped for. I also explored the idea of having them CNC lathed, but could not find a willing machinist.

 

All of these failures were just as well, because this focused my attention again on how to do these myself.

Here is a summary of where I am so far. I have determined to turn masters in brass, then cast in pewter. I think my previous casting problems were caused by a strange pewter that I had purchased from a jewelry supply store many years ago, which needed high heat and this destroyed my moulds too quickly. I have ordered low temp pewter from MicroMark, and I hope this will work better.

 

To make the masters, I first drew the cannon in Fusion 360 (a great program, I am discovering, and free for hobbyists). I was able to create a number of instruction sheets, one for each stage of cutting, so I could dial in the dimensions with great accuracy for the fine mouldings. I used the Sherline compound angle slide for the taper cuts, which does not work with my digital displays. So I had to calculate how many turns of the dial for each manual move. 

 

I found that my attention wandered when dialing in all of these X and Y dimensions, leading to ruining parts well into the process. So I wrote down the next X and Y moves on a card taped to my digital readout. This saved me from a lot of silly errors once I got used to it.

 

I also messed up overall dimensions at one point, placing the trunnion hole too close to the muzzle (the cannon below with the turned cascable shows this error). I then figured out how to measure from a temporary trunnion in its drilled hole to the hind side of the base ring, which became a fixed measuring point for subsequent operations.

 

The cascable was cut while still using the tailstock for stability. I used the cut-off tool for cuts straight into the metal, and then files to shape the ogee and the button neck. A little scary, thinning down so much while still between centers, and also holding needle files so close to the spinning chuck. But no accidents yet.

 

On to the other three cannon masters....

 

Happy new year to all!

 

Mark

 

 

 

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Edited by SJSoane

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Brilliant, Mark! Just curious if you ever thought about adding the CNC package to your lathe and letting the program do all the work for you?  Now that you've mastered Fusion 360 imagine what you do with the mill and lathe.

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Thanks, druxey and Greg. Nothing like a few setbacks to build greater resolve!

 

Greg, I seriously thought about adding CNC to my Sherline lathe and mill; but when I looked into it on their website, I came away thinking it is not going to work well for me. I may be wrong, and would love to be corrected by someone, but it looks like Sherline has developed a system that works best with their own included computer and software. I did not see how Fusion 360 would talk to it, nor how I would be able to use my own Apple computer. Someone handy with computer hardware tweaks might figure this out, but that is definitely not one of my skills

 

Does anyone have experience with Sherline's CNC setup? In particular, with a Mac?

 

I'll bet the computer doesn't have to write down the X and Y coordinates on a slip of paper so it doesn't get confused....

 

Best wishes,

 

Mark

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Nice work on the cannon, Mark.    Have you contacted Sherline?   They might have a solution or work around for MAC's.

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Hi Mark

Very nicely done, I'm glad you have finally decided on pewter casting, please make sure you show us how you do it as I would like to also learn more about doing this.

One comment, I always thought the trunnion was off centre ie below the centre line, and is shown like this in the aots Diana not central as you have drilled, worth checking before you do all your masters, of course I could be wrong

Regards

Paul

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Hi Mark, I will talk to Sherline, see what they have to say. I may not be able to afford it, but at least I will know what is possible or not.

 

Paul, well spotted. My original drawing concerned only the lathe turning, so I located the trunnion on the center line of where the bore would be located so I could dimension the bore itself. But I have now decided initially to locate the trunnion from the finished muzzle face in the mill, when I first drill the hole. To help with this, I have relocated the trunnion to its proper location in the drawing below. 

 

The cannon I showed all had the trunnion drilled in correct position. One of the pictures I posted shows first drilling with a center drill, the only way I know to drill a hole off center on a cylinder that will prevent the drill from creeping. So far, it has worked very well.

 

I will be happy to post my experiments with casting. Recording the process will help keep me organized!

 

Happy new year!

 

Mark

 

 

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Hi everyone,

 

I finally managed to turn a good 32# master. The button still needs a little cleaning up, but here it is.

 

Mark, you are right. Even with the drawings and turning recipes worked out, It took me all day to turn this one cannon. I am sure I would get a little faster for each if I tried to turn them all, but 74 would be a long time turning. I have nothing but the greatest respect for those of you who turned individual guns.

 

I was relieved to see that the ship's cat was guarding the ship while I was at the gun foundry...

 

Best wishes,

 

Mark

 

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Well, the Czechoslovakian fellow who provided our cannons turns them out in about 2 minutes per (not including drilling the trunion holes and muzzle bores). Such is the beauty of CNC. But perhaps he has a commercial setup. I do think the look of a cast cannon gives a more realistic impression than smooth brass. Your workshop view is magnificent!

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Thanks, Greg and Mark, for your kind comments, and thanks to everyone for likes.

Greg, I don't think I am a threat to commercial cannon manufacturers, at my rate of speed...

 

I started thinking about making the King's cyphers, and assumed I would make these with Micro Mark's photo etch kit. I may still. But I realized that I only need to make 4 cyphers for the four master patterns, with perhaps some duplicates for mistakes. So then I thought that I might as well make other metal parts at the same time, to avoid wasting a sheet of photo etch on just four small parts.

 

But then I noticed that the metal in the kit is only .005" thick, which at 3/16" scale is 5/16" at full size. I looked through David Antscherl's and Greg's Fully Framed Models series for an inventory of metal parts needed, and the only other parts I could find that thin are door hinges in the various cabin partitions. So photo-etch looks pretty inefficient in the big scheme of things for my project.

 

I will try a few other ideas, like Doris's use of modeling clay, or David Antscherl's suggestion of piping glue through a hypodermic needle. I welcome any other ideas!   2 of these will be 3/16" long and the other 2 will be 5/32" long.

 

Best wishes,

 

Mark

 

 

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These are really tiny!

 

Mark Taylor (post 1021) mentioned where you can buy them that small.

 

One of the fellows in our local club is sculpting his monogram on his barrel with liquid metal, dental picks and files.

I'm not sure if this is an option but thought I'd throw it out there

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Hi Alan, Hmm, sculpting in liquid metal. I'll give that some thought. Does he have any pictures of work so far?

 

My new pewter just arrived from Micro Mark. It looks significantly more refined that the stuff I got at a jeweler's supply place in Denver many years ago. Here is a photo of the pewter I got from Micro Mark on the right, and the old stuff on the left. The old stuff looks discolored and much rougher. Now it could have been the moulds they were cast into, but the Micro Mark material looks much cleaner and close-grained.  I am hopeful this might have been my problem with casting in the past. We will see!

 

Mark

zOBJ_Bellona_20190103_3.jpg

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He mentioned it at our last meeting and I can only hope he has done one of the two and will bring it to our next meeting on the 13th of this month.

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Pewter will tarnish with time, and there will likely be dross to skim off the melted metal before you pour it. Do you know the composition of your pewter? Hopefully it is the lead-free variety,

 

Another tip: dust the inside of your mold with talc before pouring,

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Hello Mark, following Druxey's comment about dusting the inside of the mold with talc first, I totally agree, once dusted however make sure to bang the open faces of the mold on the table before closing it. this will remove any loose particles of talc. I say this after casting thousands of pieces of jewelry in pewter and white metal in centrifugal vulcanized molds when I was a young man.

 

Beautiful work on the turning. and I agree with Greg's comment about the view out your window as well

A happy new year to you and your Family

 

Michael 

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Hi Alan, I look forward to seeing what he has done, if possible.

 

Druxey and Michael, thanks for the additional advice on the pewter. 

 

The pewter I bought from a jewelry supply in Denver, and which led to disappointing casting the first time around, is labeled R98. Online I discover that it is 98% tin, 1.5% bismuth, and .5% copper. It melts at 466 degrees and pours at 590 degrees.

 

The better looking pewter from Micro Mark is Type 280, which is only listed as a mix of tin and bismuth without proportions. It melts at 280 degrees.

 

So the pewter that led to disappointing results for my model had copper and a much higher melting point. I wonder what advantages it brings to jewelry making?

 

Thanks, Greg and MIchael, for the comments on my window view. We moved to the countryside to get closer to nature and a slower pace of life; but I am still getting used to the idea of bears and mountain lions that sometimes roam around near us. I am beginning to think that I like nature best when looking at it out of a shop window!

 

Mark

 

 

 

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I think lower melting point pewter is a tin/antimony/bismuth mix, but not copper.

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Hi everyone,

 

Another day, another cannon. Here are the 32# and 18# together. Just the 9# long and 9# short still to go.

In the spirit of full disclosure, here are a few mistakes --I am sorry, experiments-- while figuring out how to turn these...

 

Mark

zOBJ_Bellona_20190106_5.jpg

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Hi everyone,

 

Cannon masters finally done. Here are the four guns of the Bellona: 32# on the gundeck, 18# on the upper deck, 9# long on the forecastle, and 9# short on the quarterdeck.

 

Now on to the king's cypher. I have even additional appreciation for Doris's amazing work with clay. I was not able to get anywhere close to her skill trying to make the cyphers that way. So I will try my Micro Mark photo etching kit and see how well I can do with that. The chemicals were way out of date, so waiting for renewed stock in the mail.

 

Mark

IMG_8231.jpg

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Thank you, Jorge, druxey and Doris for your kind comments. And Doris, again I am amazed what you can do with clay, now that I have tried and failed to create details like you have done for your projects.

 

Drawing the cyphers for photo-etching is proving to be challenging, given their size. Working in Adobe Illustrator, I discovered that they need to be  fattened up, or the fine lines just disappear when shrunk down to scale. I don't know yet how fine the Micro Mark photo-etch paper will resolve either, so a little experimentation in in order now.

 

Mark

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Hi everyone,

 

I spent a little more time in Adobe Illustrator, trying to get cleaner drawings of the king's cyphers for photo etching. Once I got the hang of the pen tool, I was able to draw the forms rather than filling in the backgrounds (my previous attempt). And this allowed me to vary the thickness of the lines. Since I don't know how well the photo etch will deal with fine detail, I will try a couple with different thicknesses of line, hoping some good ones come out of the mix.

 

Thinking about other metal objects that would be 5/16" thick real size to fill up the sheet, I have drawn up the door hinges for all of the partitions. I also drew some vent fields for the cannon.

 

Can anyone think of other metal objects this thin, while I am at it? I thought about the compass. The etching process is supposed to etch from both sides, which means that there can be recessed parts not cut through all the way depending on how the art is arranged. Maybe cut the compass rose into one side? Not sure how I would color that to pick out the raised parts later.

 

Maybe the pump rhodings?

 

Mark

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