The Birth of a Swan

[cfellows]

So how are you going to keep those aligned when you install them, clamp all three to a long straight rod?

Chuck

 

[maury]

Chuck, two of the 3 brackets mount to the bed plate, I will be using my DRO on the mill to locate the mounting holed for those. Hope that works. id not I'll have to use pins. The third bracket mounts under the head. That one is a bit more tricky, but it doesn't have the 45 deg offset for the cap. Haven't gotten there yet.

maury
www.lonestarengineworks.com

 

[JorgensenSteam]

Great photo sequence Maury, thanks for showing that.

Very nice castings, I know how much work goes into patterns.

Pat J

 

[maury]

Y'all, a big day for the Swan. I got the first group of iron castings back from the foundry today, it looks like the mold went well and the cores fit well. Registration is very good, minimal core issues, a little flashing, but the mold closed properly. I'm excited! Can't wait to make chips to check the parts fit and drawing details, but most of that will have to wait until after the holidays. The first picture is the bed plate and main bearing caps. Second one is the cross slide, rails and guides. Third is the head and cylinder liner. Incedently, I cut the water jacket out of tubing, machined and went to friend to get some welding dine on it. Fourth pict is of the valve cages, covers and the hot tube chimney. The hot tube is done. but I will use spark ignition for the first startup.

I will try to restrain myself when machining the bed plate to show my method. THis has been discussed before on this board, but one cannot over state the importance of getting things lined up accurately on the bed plate.

Enjoy the picts

maury
www.lonestarengineworks.com

 

[myrickman]

Nice work! I have seen the Swann at Coolspring and she is impressive- your model seems to be doing the old girl justice.

 

[Lamachina58]

I am trying to follow along as you go but one question, in the air boxes what is the blue material? Does is coat the cavity for release? Is is applied then hand worked away? Thanks for sharing the photos! And are you modeling this in solid models as well?

 

[cfellows]

great looking set of castings, Maury. Did you just do one set or several?

Chuck

 

[maury]

Y'all, thanks for the kind words.

'58, the blue stuff in the air set box is the actual pattern for the part. It's cast out of urethane and is replacable in the box. In case the foundry damages one of the patterns it can be replaced without trashing the whole box. In my case, if there is a modification I can replace a pattern without disturbing the rest of the mold.

I had two sets made, these are reasonably expensive castings and I need to verify they are good before getting too many. I'll clean up and machine one set and keep the other as a record of the exact imprint in the mold in case there need be modifications.

maury
www.lonestarengineworks.com

 

[Lamachina58]

I think I get it. You make a master pattern then a rubber cast that you can put the polyeurethane in, the blue stuff. Is that repro30? I have been an injection mold maker for many years and only once had to do this many gyrations and that was to copy and make a four cavity s7 toolsteel mold of an actual velociraptor claw from the museum of the Rockies . What was crazy was accounting for all the shrink factors. You aren't mentioning that yet but I am facinated by casting and i never realized how many tricks there are to it. And really the amount of work to get to the point of casting the poly. I can see the desire for backing up your work with the copy in blue poly. Something we can't afford to do in injection molds. Very nice work and your casting sets look great.

 

[Lamachina58]

I'm sorry is the Urethane like dynacast? The repro is the rubber we used. This woke me up like a bad dream! The other thing that Maury is doing so well is getting a smooth urethane part in the end. Now what I recall from my amateur experience with the silcone and urethane was air bubbles . Maury , do you have a vacuum involved with both as well?
Sorry I have so many questions but it is amazing when you see what goes in to a cast iron part. Thanks,
Tom

 

[maury]

'58, Thanks for the interest, I don't mind the questions.

The silicon rubber I use is MoldMax 30. I do not have a vaccum system, do I pour the rubber in a thin stream from about 12" above the mold. This allows a smooth surface to flow over the pattern (quite slowly) breaking most of the bubbles. There are always small bubbles embedded in the final mold, but these don't seem to harm anything.

The urethane I use is Repro 83. It comes in a variety of colors. The foundry
adds a coat of Zip Slip to the entire mold, giving it a silvery color, and allowing the sand
to slide out as smoothly as possible.

THe shrink factor is built into the master pattern. As you probably know, Repro 83 and Mold Max 30 have very minimal shrink factors, and we are not worried about very small error. With sand casting, there is always going to be a small error introduced just because of the production process.

Have you made molds for wax investment casting?

maury
www.lonestarengineworks.com

 

[Lamachina58]

Thanks Maury . I had no one to help when I did my claw project and this would have been such a help. The end result went to 3M and was cast in a sintered s7. That also had about 17% shrink. I did make a couple lost wax molds for bronze tailpieces for weber mandolins. That is much more like injection molds which I have made hundreds of. I'll let you get back to work and I am glad you don't mind the questions I think I get the idea this is certainly an art!

 

[maury]

OK, the holidays are over and back to the shop. I started cleaning up the bed plate, and stopped after the bottom was done. I ordered a piece of steel to mount it on, so while I'm waiting for it to come in I started on the head and associated parts. These parts are mostly generic work, no really tough spots.

I did add a pict of the intake cage being drilled because there is an angle and it may be helpful to see it. The angle is not really critical, so I used a 30 deg drafting triangle to set up the part in a vise. The other interesting thing I did, since the hole is at an angle was to make a flat bottom
counter drill with an end mill so the drill will not fight me on the way in.

The head was machined out on the lathe to get the bore and ends faced. THen I made the bolt circle and the water passage holes on the RT. Note the plastic centering and sacrificial material part under the head. After centering the RT it is often inconvenient to center the work above it, thus the plastic. It's also reusable.

I finished the exhaust valve cage and show a pict of the assembly. I use SST threaded rod to make studs, then I make nuts from SST hex stock for the assembly. That way I can get the old fashioned, more authentic look with the taller pattern nuts.

maury

 

[maury]

Here is a nifty little gadget made when I first started the hobby. I got the ides from the one of Lautards Bedside Readers. Highly recommended reading.

THe block is most useful for holding small parts that don't work well in a vice. I also made a set of small hold downs which use 8-32 SHMS for tightening. THis setup has server me well over the years, and if out don't have one you should take the time to make one. Well worth the time and cost.

Here we see one of the side shaft bearings for the Swan being machined. This one does not have the 45 deg angle for the cap.

maury
www.lonestarengineworks.com

 

[maury]

I started on the bed plate. There are 5 major setups for this casting. THe bottom cleanup, cross slide, main bearings, side shaft & mains, and the front bonnet. I am making a plate to mount the casting to aid in these setups, as each setup uses the engine centerline as the datum reference. Also, it's a good idea to have the parts which mount to the bed plate machined or at least roughed out with the mating surfaces cut to print, before the bed plate is begun.

THe first pict is of the main bearing caps and the cross slide parts. These are roughed out, as theere will be machining steps after they are mounted.

Next I made the plate. I used a 1.2" steel bar a inch or two wider and longer than the casting. Cleaned up and squared the ends. The sides were already clean. I centered the casting and drilled & reamed the bed plate mounting bolt pattern. Here I used 3/16 dowel pins and will drill the bed plate 3/16. The holes in the bed plate will be enlarged to print later. This provides a good slide free mounting for the bed plate which can be squared with the machine with repeatable accuracy for the 5 setups.

Setting this stuff aside, I made the setup for cleaning up the bottom of the bed plate. This step sets the position of the machined surfaces within the casting, and requires careful layout and measurements to get the casting positioned so the machined features will later be in the correct place relative the cast features.
Later you will note a number on the side of the casting. THis represents the distance from the machined bottom of the casting and the centerline. A number you will want to have available, since in this case it's a little more than the prints call for.

Next the casting is mounted on the plate and set up in the mill to rough out the cross slide bed. Since this casting set is in development and there were a few problems with the core for the top part of the casting a few things will look unusual. The right side of the casting has too much metal, and to get the cross slide to fit per print, that will have to be removed. The bed rails are also a little short, and a modification will have to be implemented for that. The goal is to install the cross slide per print.

maury
www.lonestarengineworks.com

 

[maury]

Ok, it's time for the cross slide.

I often layout a part with dye to help avoid mistakes when machining. I use the lines as a sanity check for my cuts, and use the dials or DRO for accuracy.

Laying out the cross slide is more or less strait forward.

The cross slide is machined where it fits the rails, and checked for fit. The fit is nice, smooth sliding with a hint of drag. The piston rod hole and the con rod bearing holes will be machined later after making sure there weren't any off dimension issues so far. The piston rod has to be on dead center or it will bind.

Last, just a look at how it will all fit together.

maury
www.lonestarengineworks.com

 

[idahoan]

Maury

This is really an interesting project and very nice work; I remember years ago following along When Craig Prucha restored the 25hp Swan. Craig's web site hasn't been updated for years; I'm not sure why.

Looking forward to more updates to the Swan Build.

Dave

 

[maury]

Dave, this is a very interesting project to me too. I would much rather build a new engine than one of the highly advertised popular ones. Additionally, the Swan has a lot of unique features and challenges.

As far as Craig Pruchas web site goes, I think it's a bit like New York cheese cake. Anything added to or taken away from it will make it less excellent.

maury

 

[maury]

Next thing is to add the bearing caps to the base. They will be bored later, but a setup at 15 deg is necessary to assemble them to the base. The inside and outside dimensions will also be machined.

The setup is on a tilt table which has been squared with the bed.

The bed plate is cut to dimension, then the holes are drilled and tapped.

The inside and outside dimensions are cut. Note the roughing end mill. I like to use these to get close to the number, then switch over to a conventional end mill. That keeps them sharp longer.


Then the final assembly is shown.

maury
www.lonestarengineworks.com

 

[maury]

Well, things are progressing, but I'm getting a bit behind on my posting.
I spent a day ramming molds and pouring a few castings. The rocker patterns needed some touching up, and the lettering problem for the head cover was solved. I have a simple setup, but it works well for making a few prototype bronze castings.

maury
www.lonestarengineworks.com