Help with cast cylinder motorcycle

Hi Carlos,

I dont know how I missed this post. Or did I comment in a different thread? Is your goal to make one/several or many copies. Given the complexity of the features fins/coring, IMO, it is an ideal candidate for lost foam for one or low quantities......but you must be able to make the foam pattern.

You may have given up too soon. That is certainly correctable, and it's not a certainty there would not be simlar issues with other casting processes. Here are a couple threads with cylinders done with lost foam that have much more delicate fins than yours. These patterns were made with woodworking tools. I use a cnc router these days for most patterns but for years I made some fairly complex patterns without.

Motorcycle Cylinder Sample | The Home Foundry
Chainsaw Cylinder & Head | The Home Foundry



Best,
Kelly

 

After the lost foam pattern is constructed there are still quite a few things that can influence the result. How and where you gate and feed that pattern, as well as how it is positioned in the mold can be very significant. The pattern needs to have a permeable refractory coating applied so gas produced from the evaporating pattern is controlled, and of course your melt/molten metal quality must be good. Many times I have had people attempting lost foam castings that get porosity and defects they attribute to the lost foam casting process when in fact, the molten metal was so laiden with hydrogen gas the casting would have been poor with any casting process.

Hard to say. It could be sodium silicate, PUB, or even just an epoxy resin. Chemically bound sand molds are strong. That really isn't what you should ask yourself after watching that video because it's probably the least significant aspect of your trying to emulate that process for your project. The video footage of all the tooling necessary to produce those castings by itself should be enough to convince you that you don't want to take that approach to make several castings.

I'm not criticzing those patterns; quite the contrary, but the video views like oh yah, here's all the tooling we made to make these castings and we just packed them in sand molds and poured metal in the molds to get these wonderful castings. (and that pour at the foundry was an uncontrolled mess!). I call that the big "Arm Wave", meaning oh it just happened. Even if you have the CAD skills to model all those features and parts, the CAM skills to create the machining programs, and the CNC machine required to cut the patterns, and then a whole bunch of hand work to finish the pattern surfaces to a smoothness and standard that will release from the mold media it's an enormous job. The urethane model bodeling board used as the material for those patterns would have cost in the $x000s by itself. It's an enormous undertaking requiring many, many, hours to execute. I use CAD/CAM/CNC with hobby level software and hardware. I'm still not proficient enough but seem to get by. However most hobbyists don't possess these things.

Now, you could make all this tooling with artful old school processes, but producing all those features and interdependent tooling in that manner takes a good deal of skill too. Perhaps that's how you made your patterns? Or were they printed?

For a hobbyist to make a few parts like this, it's much more practical to use an evaporative casting process like lost wax, lost PLA, or lost foam because there is no need to make hard tooling, just the expendable pattern. There are no master patterns, no core boxes, no complicated parting lines, no cope/drag because the pattern is just completely immersed in mold media whatever that may be. It's also worth noting how much space all that hard tooling would take to store. I've made so many different castings I would literally have a garage stuffed full of tooling if I used the conventional hard tools and sand casting process. Instead, I have electronic files stored in my computer if I ever wish to make them again.

But, you must be able to make the expendable pattern. For lost PLA, you can 3D print the pattern assuming you have the CAD skills and the 3D printer, and the experience with both necessary to succeed. For lost foam, the patterns can potentially be hand fabricated without CAD/CAM/CNC. I suppose the same is true for wax if you are really good at modeling it. But if your casting fails, you get to do it all over again.

The big difference between lost foam and other evaporative pattern casting processes is you do not need a large oven to burn out the pattern and cure the mold because the molten metal evaporates the foam pattern during the pour. The cost of pattern material, mold media, and amount of labor is also much less with lost foam (almost $0) because EPS is very in expensive compared to PLA, and dry silica sand is very inexpensive (and can be reused) compared to investment or mold media, and the sand mold is just filled and vibrated. To demold a LF casting you dump it on the ground and remove the casting. To demold an investment casting you chip away the hard mold sometimes requiring hours. These differences are smaller for very small objects but grow dramatically with the size of the casting such as yours. I make fairly large (can pour up to 60lbs) castings by hobby standards and the cost and labor difference for me would be quite large..

These are among the reasons why I use the lost foam method in preference to others.

Best,
Kelly

 

As habilidades de CAD e impressão 3D abrem novas oportunidades para os entusiastas fazerem peças fundidas de alta qualidade. Por favor, mantenha-nos informados sobre o progresso do usuário.

Translation: CAD and 3D printing skills open up new opportunities for enthusiasts to make high-quality castings. Please keep us informed about the user's progress.

Best Regards,
Kelly