Mark's Monitor Build

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Project of the Month Winner !!!
Jan 29, 2013
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Mossyrock Washington
Marks Monitor Build

A little history can be found here USS Monitor - Wikipedia

The Iron Clad USS Monitor was designed and built by John Ericson for the US Navy during the American civil war. The contract required the ship to be built in less than 100 days for a cost of $225,000 with a money back guarantee if the ship was late or did not perform as advertised. I found conflicting information on how long it took to build the ship but 118 days was the most likely. And it more than met expectations.

Its historic match-up ( Battle of Hampton Roads ) against the Confederate Iron clad Virginia (Merrimack) lasted 4 hours and ended in a draw.

The ship later sank in a storm with the loss of 16 of its 49 man crew. The engine was recovered in 2001 and has been undergoing cleaning and conservation.

The engine is described as a Vibrating Lever-Half Trunk Steam engine. It weighted 30 tons and produced 400 HP. The unusual design allowed for a very low profile keeping the engine below water line. One of the more interesting elements of this engine was the reversing design.

A full set of drawings were produced by Mr R. W. Carlsedt after 20 years of research. The drawings are in full scale and he has made these drawings available at no cost.

Find the excellent drawings by R. W. Carlstedt here

Find an introduction to Mr Carlstedt and his fine model of the USS Monitors Engine here USS Monitor Engine

Find a YouTube video of Mr Carstedt's model here

Mr Carlsedt's model was in 1/16 scale. Mine will be a bit larger because of my old arthritic fingers. Surprisingly (with the time limit) the castings of the original engine had some fancy embellishments.

To make this part and a few other hard to make parts I decided I would need to cast them. So for five months I have been learning how to do investment casting. First I learned how to use a 3D cad program (Fusion 360), Bought 2 3D resin printers and learned how to print 3D patterns with a special casting resin and made a kiln to burn out the pattern. I bought an electric smelter to melt my metal. And I bought vacuum chamber and a pressure pot for getting the air out of the plaster investment.

Everything was a struggle. But after a lot of effort getting my equipment to work properly and a lot of trial and error I have finally started to get some decent results. I have been doing sand casting for many years but this investment casting is a world apart in complexity. But the results are well worth the effort. When everything goes to plan the rough cast parts are well beyond anything I was ever able to do before.

There are NO SHORTCUTS in investment casting. If you plan on giving it a try. Get your wallet out. As a n example a 50 pound box of investment powder cost $44. With shipping and sales tax it came to $162. I tried using scrap metal but could not get repeatable results so I had to buy brass beads made for investment casting $120 for 10 pounds but boy was it worth it. 3D resin for casting is expensive even if you use the lower cost brands. Even the flask deteriorates quickly. Make one mistake and it will cost you $$$ and a lot of time.

Here is a link to my Build of a burnout oven or Kiln

Here is a link to my first try at Investment casting. It will show you my setup and equipment.

Mark's First investment casting

Look at the top of post number 1, on the right side corner, click on the word “watch”. Now you will get a notification whenever there is any activity on this thread. Comments are welcomed. Kriticize my speeling and gramor if you like, it dosen't bother me.

This photo shows the difference in scale between Mr. Carstedt's Model and the one I am building.


Mark T
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Beautiful castings! It looks like all your time & efforts have been rewarded.

Looking forward to this!

This is a failed part that was cast in a flask that was too hot. The metal was to hot and the burnout was not complete.


Here is another failed part. This one the flask was to cold, metal was to hot and the burnout was not complete.


Eventually I started to get better results. One big problem I had was caused by my using the metal from failed parts. With each melt the metal would lose some of the zinc and that would affect the melting temperature and how the metal would flow. Chased my own tail for awhile before I broke down and bought a 10 pound bag of brass beads made for casting.

Mark T
Eventually I started getting usable parts. Here are the parts for the steam manifold. The elbows turned out OK, just a little surface issue on the flanges but a little sanding will fix that. The tube was a failure. The small amount of layer marks left from printing the parts are largely removed with a light sandblasting.


The brighter parts here were cast in Bronze. The rest in Brass. The brass I am using is about 66 percent copper and 33 percent zinc. Smaller parts like these are easy to cast. Larger parts, especially the ones with sharp edges are more difficult to cast because thermal expansion tends to cause cracks in the plaster.

Mark T
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These parts are the base of the steam chest. The valve surface will be milled flat and made smooth after the parts have been attached to the cylinders. I was thrilled to be able to cast these with the steam passages. The drawing shows a cutaway of the part.


Valve chest and cover.


Steam chest covers. The tiny bolt is a 2-48 with a smaller than normal tall nut. It was this part that decided if I would attempt this build. The decretive feature would have been very difficult for me to machine.


I am now working on turning the cylinders and will post again when that is completed.

Mark T
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I just found your postings and am very impressed with your work and progress- outstanding !
I had a smile on my face when I read and saw your Valve Chest challenges . Now that is a very tough part !
I spent 6 months trying to do the chests alone and had 56 casting attempts --all failed so i switched to machining and fabrication .
I did the lost Wax route , but that was 20 years ago so and used the rubber mold technique .
Some of my failures looked exactly like yours. Also, you are dead on with the metal alloy mix.
I had various brass/bronze hoards of metal and I did not want parts on the engine to have different color metal, so I made a big melt of alloy Bronze (very little Zinc to loose) and made ingots to use for casting or machining. My attempts at casting were not successful so I made the chests from solid .
Here are a few pictures, first, the valve chest rubber mold and pattern for a lost wax attempt ( that failed and I gave up)and then I cast " Blocks" for machining that you see in the forth picture
Please send me a email at grnbaystmr
FYI , I left a space above where the @ would go so I don't get spammed
Nice work on a very complex engine !

monitor1 550.jpg
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Mark, if I were to decide to make a Monitor engine, would it be possible to buy your CAD files for the intent of casting my parts also?

If you are referring to the 3D files I could give you the STL files ready for your slicing program.

Mark T
I have sent e-mail to both Mr Carlstedt and Davidyat. If you guys don't receive them let me know.

Mark T
Hi Rich. I double checked the address and I got that right. So I did a cut and past of your address filling in the blank and sent again. If that doesn't work PM me and I will give you my address.

Mark T
OK, My boo-boo Mark
I did receive a email yesterday and replied to you - Did you get it ?

I thought you sent me a second email at ( "Yesterday 9:01 PM) which would be after my email
and that's why I said no.

So now I just received the same early email ( 2 nd time ) ?
This is fun !:)
Rich, I found your emails in my spam folder. It was great reading. I will respond tomorrow evening as I am on a road trip till then.

Mark T
Awaitng your next post!


First let me thank all of those that have viewed this thread. Just checked and over 800 views so far.

And a special thanks to Mr Carstedt for dropping in and offering to share his experience and considerable knowledge of this engine.

I have been working on the cylinder. It was turned from 3” brass pipe. The inside bore was no work at all. The pipe had a perfectly round ID with no taper and a polished surface. The OD was a bit off center to the ID and had some bumps. I turned the pipe down to give a .09” wall thickness.


The engine has two cylinders so my pipe needed a bulkhead in the center. I'm not trying to replicate inside details that can not be seen. I cut two .15” thick disks. one fit the ID snugly and the other with a little clearance for solder to wick in. To hold the bulkhead (center head) I cut a bit of scrap to support the disks at the proper height in the pipe. I tinned all the surfaces to be soldered and then use an oxy/acetylene torch to heat up the pipe and bulkhead for soldering. A short dip in a mild acid solution cleaned it up pretty well but it still need to be cleaned a bit further with a scotch-bright-pad.



Mark T
From there I moved the cylinder assembly to the mill to cut the steam ports. I test fit the bases for the steam chests. These parts and the other parts to be assembled to the cylinder will be bonded with JB weld. I don't want to heat the cylinders any more than I have already. And that will allow me to fit and bond the parts as I go. Over the years I have had many occasions to go to remote areas of Alaska to work on aircraft and boats. I never went without lots of JB Weld, duct tape, steel wire and a .22 for mosquitoes. This is the first time I have used it on a model engine.



The photo above is just a test fitting. Heating of the cylinder changed the color of the brass. The cylinder and steam chests will match when completed (I hope)

Mark T

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