Rider Ericsson Homemade Castings

[raveney]

I thought I would take a break from four stroke engines and build a hot air engine for a quiet change of pace. I had purchased the "Steam and Stirling" book, and I am attempting the lovely Rider Ericsson in 1/4 scale as drawn. This is the largest I can make with my benchtop lathe and mill. The book assumes that one has purchased the castings, but I thought it would be fun to make the patterns and cast the pieces myself. Some scaling and CAD drawing was done to come up with useable dimensions.



The base plate was fairly easy. Three pieces of MDF board cut with my scroll saw and beveled using the disc sander. I milled down the 1/4" top frame to 1/8" after gluing it to the larger base so it wouldn't break. I think I will order 3/16" plastic letters and glue them on also. Probably add some fillets to the border also.



The legs were more challenging. I attempted to steam bend 1/4" plywood and clamp in a glued up jig, but the curve didn't set right. Too much spring-back using plywood I guess. I then cut the jig up and removed everything that wasn't a leg using a coping saw and foredom tool. I still need to add the feet, but the general concept looks good. It will be tricky to mold it as I never attempted a "irregular" parting line on a single pattern.

 

[GreenTwin]

I love these backyard casting threads !

Patterns are looking great.

Its pretty easy to cope-down (I think that is the correct term) with a curved pattern (ie: ram up the curved part and then carefully dig down to it).

Good luck.
I will be following.

.

 

[Jasonb]

If you want to do the bending thing in future then either use veneers or thin "aeroply", glue them together and then clamp in your jig to dry. They will set with the bend in them.

Bonus is the pattern will be a lot stronger than one from solid wood as less risk of short grain. More an issue if sending the pattern off for casting where it may get handled a bit roughly than taking care of it when home casting. It also a good approach for any wood pattern, full size would have made the patterns from many pieces of wood due to size. Models we can often cut from a single board but it makes for weak patterns so consider planing timber down to say 5 or 6mm and glueing up with alternating grain direction particularly on things that will have a thin cross section that otherwise may have weak short grain.

I've just done a Denny Improved Ericsson but fabricated & cut from solid. Bit more peaceful to watch run than an IC.

 

[creast]

I thought I would take a break from four stroke engines and build a hot air engine for a quiet change of pace. I had purchased the "Steam and Stirling" book, and I am attempting the lovely Rider Ericsson in 1/4 scale as drawn. This is the largest I can make with my benchtop lathe and mill. The book assumes that one has purchased the castings, but I thought it would be fun to make the patterns and cast the pieces myself. Some scaling and CAD drawing was done to come up with useable dimensions.

View attachment 155684

The base plate was fairly easy. Three pieces of MDF board cut with my scroll saw and beveled using the disc sander. I milled down the 1/4" top frame to 1/8" after gluing it to the larger base so it wouldn't break. I think I will order 3/16" plastic letters and glue them on also. Probably add some fillets to the border also.

View attachment 155685

The legs were more challenging. I attempted to steam bend 1/4" plywood and clamp in a glued up jig, but the curve didn't set right. Too much spring-back using plywood I guess. I then cut the jig up and removed everything that wasn't a leg using a coping saw and foredom tool. I still need to add the feet, but the general concept looks good. It will be tricky to mold it as I never attempted a "irregular" parting line on a single pattern.

View attachment 155686View attachment 155687

Lovely work!
I built mine at 1/8th scale and used 3D printing for the leg patterns and a few other parts too.
The cylinder however was easier make from wood turned on the lathe and bosses glued on.
Without a doubt it is a lovely engine to build and run. Very satisfying.

 

[creast]

Another point.
To make my casting easier to mould I cast the part without the fancy apertures, just the beading profiles left on and cut them after using a piercing saw.
Also, I made the feet as a long rectangle to span across the legs which acts as a good feeder/runner.
Maybe I am preaching to the converted but thought it may be of help.
I look forward to seeing your progress.
Cheers
Rich

 

[raveney]

It is great to receive the useful tips and encouragement.

thank you Pat. I watched a video by Tubal Cain about the coping down process and will certainly fumble several times on it, but it doesn't cost anything to keep trying with sand and wooden patterns.

thank you Jason. The gluing up of thinner stock in the press mold never occurred to me. I am very impressed by the work you have done with the Denny too.

thank you Rich. I have resisted purchasing a 3D printer so far because I have so many tools in the garage already, but I think I will when I retire someday and have a workshop to put it in. That was a great idea on the leg to leave the cutouts intact. I might steal that idea for the displacer yoke

 

[GreenTwin]

It should be noted that if you are coping down to a curved surface, it should not be a problem to just dig 1/2 way through the window down to the parting line, just as you are digging 1/2 way through the curved pattern.

I don't recall casting a part with a window in it, but I know it is no more difficult than coping down to a curved part.

.

 

[BobsModels]

Too make that base casting a little simpler you might want to make it look like the original. The original had no lip around it. When I made mine from the casting set I removed the lip and blasted it.

Bob

 

[Jasonb]

You can avoid "coping down" if you make a "follow board" This would be dead easy with 3D printing and CAD but more work if using traditional methods.

Basically the pattern sits in the follow board which comes up to the parting line when you mould the first half. Then when you are doing the second half the follow board leaves the depression that you would otherwise have to dig out.

Pattern

Patern and Follow board

Pattern in position

 

[Jasonb]

Bob brings up a good point about altering the base. When you are making your own either from solid or your own patterns it is a good opportunity to correct any details that may have been missed by the original designer, sometimes there are left off to make production easier and therefore less costly, sometimes just missed or they may not have had the information that we can now easily get off the net.

Another example is the beading on the legs that goes right down and does not break where the stretcher joins the legs and feet are smaller & rounded.. Also don't think the cast writing is correct, there should be more but was obviously hard to do the small print at the time the model patterns were produced.

https://salterbros.com.au/rider-ericsson/

Just upto the individual how far you want to go. I tend to modify casting kits when I make them to add detail so no surprise I do similar with my own builds. But we now have far easier research material and methods to reproduce the detail that the old kit designers did not have so may as well make use of it.

 

[raveney]

Thank you Bob and Jason. I liked the look of the raised lip and also have never tried lettering. I'll learn from this model before getting fancier.

I generally use scrapwood when making the patterns, but made an exception today and was really pleased with the finish I got turning this part in the lathe. I had bought a 3 foot piece of basswood to make a poster bed for my Granddaughter to use with her Barbie dolls. No knots at all and a very fine grain to it.


I cut some into (6) 1-1/16" squares and glued together with two sided tape in between so I could split the pattern apart later. Also used the offcuts to make the various projections for the walking beam bearing, bracket and pump. Very nice finish was easily obtained without the grain tear out and general wooliness of pine lumber. I used a tangential HSS tool and was able to tightly control the dimensions without much sanding or repeat measurements.



For the flywheel bracket I used 1/8 masonite for the center web and used milliput putty to blend the small pine bits. I carefully added about 6 degrees draft to all pieces by hand sanding with 80 and then 220 grit.


No paint on them yet, but it looks promising. I'm not confident I could core the water jacket properly so I will leave it solid.

 

[GreenTwin]

A follower board does not necessarily have to be very precise.

I have made them from plaster, bound sand, bondo, etc.

Just put a piece of plastic wrap over the pattern, and press it half way into whatever you make the follower from.

.

 

[Jasonb]

You could always do a parallel core and then just machine out the water space, would keep wall thicknesses more constant. Poplar is another wood similar to bass (lime) that is easy to work but being a "soft" hardwood has quite close grain.

Pat I was just thinking that now with 3D printing a follow board would be so easy. Just one Boolean subtract and you have the file ready to print, would not need much fill or a particularly good surface so quick to print. And unlike plaster and plastic wrap will give a good crisp part line so little risk of flash.

 

[raveney]

Thanks Jason. I am going to do a parallel core like you suggest. It would probably shrink and leave low spots if I don't not to mention that my largest crucible may not be enough if I leave it solid. I'm going to attempt a core using a split piece of 1-1/2 PVC pipe as the mold and attempt the traditional molasses and flour recipe.

I've got the flywheel puttied, cylinders in prime coat and completed the finish coats on the base, leg and flywheel bracket. Roughed out the walking beam and letting it set up tonight.

How about ideas on how to pattern and cast the displacer yoke? I was thinking to leave the open semicircle solid, but that's a deep pull (about 2") out of the sand. Anybody have a suggestion?

 

[GreenTwin]

You have a lot of options of you use bound sand, and even more options if you clamp and cement multiple bound molds together.

Here is how I would do it.

Parting line in yellow.
One side of the flask shown only for clarity.

Elevate the sprue taller than vertical piece with a tall pouring cup.

Small riser above vertical piece.

Cement and clamp all the mold pieces together.

Sprue vertical in green.
Knife gates in green solid.
.

 

[Jasonb]

I'd pattern it for moulding it on it's side and use a D shaped core. Split line would be horizontally through this image.

I tend to think in terms that a commercial foundry will be casting anything I pattern and keeping it simple keeps the cost down. Once you start having to stick patterns and or cores together the time factor goes up and so does the cost.

Make sure you vent that cylinder jacket core as the organic binders will give off fumes.

 

[creast]

I did mine like Jasonb.
Was a bit of a flashy casting but did the job when cleaned up.
Ruch

 

[GreenTwin]

Some folks don't like keeping up with multiple pattern parts, but using retracts would be an easy way to cast the bosses on the non-forked part of this pattern.

Retracts have been used in the foundry business for a long time, and are quite common.

Many of the foundry "tricks-of-the-trade" get overlooked or dismissed in the hobby world, but they can be quite useful if you are willing to learn them.

.

 

[creast]

Some folks don't like keeping up with multiple pattern parts, but using retracts would be an easy way to cast the bosses on the non-forked part of this pattern.

Retracts have been used in the foundry business for a long time, and are quite common.

Many of the foundry "tricks-of-the-trade" get overlooked or dismissed in the hobby world, but they can be quite useful if you are willing to learn them.

.

I am not sure what you mean?
My/Jason's method retains bosses on all fronts.
Rich

 

[GreenTwin]

I don't see the bosses on Jason's post #16.
Creast's casting looks perfect, but I am not sure how he molded it.

No problem with simplifying a casting like Jason's method, but keeping the bosses is not that difficult.

.