Thanks for the comments guys, always appreciated.
Jason, yes my plan is also make the turntable; if you look at the beginning of the thread there is a photo of the castings.
Thanks for the tip on Tug’s thread, lots of good information there and it appears that my burner is functioning quite well. This engine should require very little heat to run so I don’t need a flame thrower. The orange flame and orange ceramic is with the air hole wide open so it is burning clean!
OK, next up is to finish the furnace. This involves some sheet metal and insulation work.
To start with I created a flat pattern and punched out a blank at work, you will see that the finish on this one looks different than the rest of the photos. This was my first pass at it and I had sanded the blank with an orbital sander. I decided to use thinner material as this one was to the print and much too thick. I also put in an offset bend, probably not original but what the heck.
David Abbot had made his furnace shell from SS and silver soldered the joint. The original engine used thin steel more like stove pipe with a single tinner’s rivet to hold it together; so this is what I decided to do.
Some slices of Ren-Shape where epoxied together and turned to make a plug. A ½” hole was reamed in each end to be used for fixturing later.
A relief was machined to accommodate the offset bend in the sheet metal.
The first order of business was to massage a curve in each end of the blank. This is take care of the area that the slip roll can’t get to.
The other end with the offset is worked on.
Here is the blank ready for rolling. My plan was originally to leave the center pieces in place to help with the rolling process but the tabs I had used proved to be too fragile, so I ended up removing them first.
Let the rolling begin, I purchased this little slip roll from Grizzly tool when I was working on my Pacific; it works pretty well and for the price I can’t complain.
The rolling has been finished and the furnace shell is starting to look more like a finished part.
The part has been clamped to the plug using some soft mechanics wire (re-bar tie wire).
Before clamping the part to the plug I laid out the position of the rivet. Here I’m using the laser pointer to center up on the cross hairs. The part has been centered on the ½” pin so it is just a matter of rolling the part on the axis and adjusting in Y to set the position.
The hole is drilled and a temporary rivet installed.
Next I need to find the center of the small hole. This will be used as my datum to machine the large holes. The part is shifted left and right and adjustment made by rolling the plug on the pins until equal reading are achieved when the beam contacts the edge of the hole.
Once the center is located, a 3/16” hole is drilled and reamed for a drill blank.
Now the part is rotated 90 degrees and the drill blank indicated level. The large holes were left undersized so they could be accurately placed at this stage. The hole center was located a specific distance from the top edge and on center line so the transfer tube will fit properly.
The first side was machined then the part rotated 180 dialed in and the second one machined. I could have punched these to size but getting them to be exactly 180 after rolling to size would have taken several iterations, so I chose to do it this way.
I have decided to add some insulation to the furnace which is not part of the plans but did exist in some form on the original engines.
Here I’m tapping holes for some standoffs that will hold the upper insulation heat shield/retainer. I have never seen the how the originals were done but in photos there is evidence of copper fasteners in this area that have been ground off and blended to match the casting.
The UPT is also a diversion that I have been playing with. It is quite addictive and fun to keep adding parts to.
I had some semi rigid insulation that I had left over from another project; a piece of that was carved into shape. The heat shield/retainer plate was punched from .05” galvannealed sheet.
Also seen in this photo are the two standoffs that were added to secure all this.
Here is everything assembled, I had forgot to put in the clearance holes for the furnace screws; so they have been added here.
Here is a view from the top, you can see that the standoffs have been peened and dressed down so they don’t show. There will also be insulation around the inside of the furnace sheet metal and on the bottom. Hopefully this will help keep the heat where it belongs.
A pair of 10-32 x 4” long round head screws were machined to hold it all together; another small deviation from the prints but more true to the original.
Here is the assembled furnace viewed from the front.
And one from the rear.
Thanks for checking in and sorry for the long winded post.
Dave