Help with cast cylinder motorcycle

Discussion in 'Sand Casting' started by carlos gualberto, Aug 16, 2023.

  1. Hello friends, I'm following the forum with great enthusiasm, I've already made some casts successfully thanks to contributions I've found here, I'm trying to make this attempt to make a cast, it's a motorcycle cylinder, my big problem is the fins, I tried to do it using the method of sand, but without success, the fins come out deformed or brittle, I also tried the investment method and I find the same problem with the deformation of the fins, the sand sticks to the fins and ends up deforming, I'm using talc as a release agent but without success, can anybody help me? I'm trying to make the copy using the aluminum cylinder itself, would it be possible any other method to successfully copy this cylinder? I don't have a 3D printer at the moment, I had fun trying the lost foam methods also using expanded polystyrene (EPS) I found a lot of holes, I'm trying to be as creative as possible to accomplish this feat, but I need help, the fins have a diameter of 10mm .

    Attached Files:

  2. Billy Elmore

    Billy Elmore Silver

    Lot of variables to consider and without a lot of the missing info my first guess would be to pour hotter and faster. Casting placement in the mold may help..more head pressure.
    carlos gualberto likes this.
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    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

  4. Hello Billy, the big problem itself is the mold, by trying to cast it in sand, the sand ends up gathering on the fins and does not come off even using talc as a release agent, I will not give up, I am looking for alternative methods to succeed, following some foundries on youtube I came across this video, somehow they manage to make the mold without the difficulties I'm experiencing

  5. Hi Kelly, I followed the series of your videos on your channel, you achieved a high quality standard, I admire your genius with the resources you had available, I tried using the foam method, the only difference I made with expanded polysterene was I got some imperfections , I purchased some extruded polystyrene plates to try again, I will not give up, I do not intend to cast on a large scale, just as a hobby to test new cylinders as a new standard for my motorcycle, I am testing new parts and engine development
  6. Here I found another video that expresses where I want to go, it got excellent quality.

    I'm not sure if when trying to copy a piece that is made of aluminum the sand is influencing the fins of the piece, I'm using sand similar to PetroBond, I've carried out tests with other types of sand as well.
  7. This video is also very interesting, it is a complete construction of an engine, does anyone know what kind of resin is mixed in the sand to obtain this result?

    The type of molding impressed me, I'm looking for a lot of information to make new attempts, the next attempts I will send photos so you can see.
  8. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    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.

  9. Grande sabedoria Kelly, você tem toda razão, vou aplicar seu conselho e observar onde estão minhas falhas para um melhor processo, comprei uma impressora 3D e estou esperando chegar, não sou profissional de CAD mas já desenvolvi alguns projetos e esboços em SolidWorks, obrigado pela colaboração, volto em breve

    Translation: Great wisdom Kelly, you are absolutely right, I will apply your advice and observe where my flaws are for a better process, I bought a 3D printer and I am waiting to arrive, I am not a CAD professional but I have already developed some projects and sketches in SolidWorks, thanks for the collaboration, I will be back soon
  10. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    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,
  11. Melterskelter

    Melterskelter Gold Banner Member

    I could not tell what kind of resin was used in this video. However, I can say that common 1:5 epoxy mixed with maybe 120 mesh or a little finer sand could be expected to bind the sand firmly and cleanly. I have used epoxy to make a good number of cores and find it easy to use. I use about 3 or 4 parts epoxy to 100 parts sand by weight. I also commonly use sodium silicate RU to make cores and have posted about the process on this forum in the past. Sodium silicate also makes excellent molds and cores.

  12. Billy Elmore

    Billy Elmore Silver

    Are you trying to draw a pattern from the sand and it is sticking to the pattern? May have to add more draft if you are trying to draw it out of the sand. Those fins would be tough to fill out and draw with a pattern. I think most use lost foam or investment.
  13. Matth

    Matth Copper

    You'll have quite a learning curve just setting up and getting this into a successful print. I looks like you already have a CAD model of some sort. Let me know if I can help you change the CAD, draft, offset faces etc. If I can help, send me a PM for email address and reply here to have me look for the PM.
  14. Harry Cowley

    Harry Cowley Copper

    Hi Billy just seen this tip on Facebook , its an old trick but it works !! You make this stripping tool, thats the alloy profile you lay on the sand cast part , and pratice makes perfect ! Good luck

    Attached Files:

    Tobho Mott and Tops like this.

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