3D Printed Pattern and Core Box

Thought I'd share a pattern and core box that I've been working on (slowly) over the past 6 weeks or so. It is a decorative dome/cover for the safety valves on a 7 1/4" gauge live steam locomotive. The original part was too small for the boiler (as it was built) so a slightly larger casting is needed. The complicated part was the fact that the boiler on this particular engine is angled so the curves are different on the "front" and "back" sides of the dome. This proved to be quite difficult to draw in fusion 360.

This will be cast in yellow brass, hopefully in the next week or two.

 

Looks like a very fine pattern. Lovely finish and curves.

The core will be green sand?

Denis

 

Nice work with all those curves.
Tricky stuff.

.

 

Just realized I never followed up on here with pictures of the casting.

Here it is right after cleaning up with files and sandpaper:


Part way through machining (picture and machining by customer):


Polished up and on the customer's locomotive: (note the engine is not yet complete, there will be painted shrouds covering the steam lines that come out the sides of the dome.)

 

Very fine work! Handsome.

Denis

 

Beautiful! What did you paint the pattern with? And what did you use for the registration pins? Thanks

 

Thanks!

I get the finish by using layers of 2-in-1 filler primer spray paint and bondo spot putty. Its very time consuming as I typically wait a day between every layer but its necessary in order to get a good surface finish on the casting.

I order dowel pins from McMAsterCarr in the sizes that I need and that is what I use for index pins. The holes are printed right into the pattern and if you do your design math right they are a press fit in one side.

 

Fine looking P-51 Mustang wing in the background! Somebody likes flying RC airplanes! Nice job on the casting!

 

What scale is the loco ......nice

 

Oh boy! The dedication. Greatly admired.

 

7.25" gauge I believe it is 1.5" scale.

 

Hey Frank. I feel your pain trying to draw a complicated piece like this to suit your boiler. I've found that drawing the boiler as well as the chimney works best in this situation. I simply use a boolean "subtract" operation to remove the boiler portion of the chimney and voila instant perfect tapered compound curve on the underside of your chimney.

I hope I explained it correctly. LOL

Chris

 

Hi Chris,

That is exactly how I drew the dome in fusion with regards to drawing the boiler in. The complicated part was the fact that I was reverse engineering the original dome casting which was too small and I didn't have access to the actual locomotive or boiler as it was at the customers shop half way across the country. It all worked on in the end and the dome and locomotive came out beautiful!