Yah, that's the rod I was mentioning. I figure it only needs to be an 1/8" or so and left extended out the ends, I could mount a simple degree wheel and then would easily mount in a clocking and assembly fixture. The 1/8" hole would also serve as the mounting hole for the foam piece parts in router templates. The rod could then be cast in place and trimmed out or potentially removed from a rigid mold before casting.....I'd like to try it. It would be interesting to see how it compared to hard pattern and sand, especially in the hands of ESC. ESC, I think in a few hours I could knock out the fixtures and a half easily dozen patterns, and more patterns would come very easily from that point. If you're up for that I will need a working drawing of the crank casting blank. Best, Kelly
The stroke is 1.16". I have good tracings of the counterweights and just need to mark the clocking. It is 90 degree for the outers and 180 for the center. My drawing of the crank is pretty cluttered, so I will need to clean that up.
https://grabcad.com/library/chevy-crankshaft Not sure if this helps any. I can 3d print one in about 15 hours. 400 mains though...
The 400 mains are full size 2.65", but that just gives additional machining allowance. Out of curiosity can you scale for the shrink? I use x/3 x 101%. Also that is a 400 crank so the stroke is .100" longer. David, you should just do one for yourself in bronze shell. Car trophy/ Award/ man cave junk.
yes it can be scaled. The slicer uses a scale factor of 1.00 so i guess you would want .34 ??? The model if a full sized crank...
Edit, sorry it a scale factor of 100% so you would want 34% ??? that would make the crank 223.11 MM total length.
mm? What's that...this a Chevy crank boy! We speaketh in inches please. Whats' your print resolution? Can you print &' deep? Ideally isn't that how you would want to do it? Is PLA fairly stiff? K
pla is very stiff.. I can get 100 micron prints pretty easily. The 15 hours to print was at 200 microns resolution, at 100 microns it would take 28 hours. Im printing it now just to see how it comes out. there is alot of support material when it is printed vertically that could be troublesome. the other thing is that this is a modeled to be a crank, not a casting of a crank (big difference) but I could likely model a casting in a few minutes if given the dimensions. I also see what I think is an error in the file from grabcad..... gap between rear main and counterweight.
Think I will.. 1/3 scale is nicely sized. I stopped the print early due to concerns from all the support and its removal. It came out much better than I was expecting it to. With the removal of some holes and a bit of disclosing wax to touch it up I think it would be possible to cast it. Going to re start the print tomorrow...
That looks pretty darn good to me. I don't think you can beat the dimensional accuracy compared to the rest of the approaches in the discussion. If it can be invested, burnt out, and cast as iron in that investment, winner winner chicken dinner. Of course, it does need to dimensionally conform with ESCs specs and machine stock. Best, K
That really looks nice. It would be great polished in bronze, but tough to make into a useable part without adding to the journals in order to keep the length correct with the shrink.
The heck with bronze, i want to try out the ferrous rated investment ive had sitting around for way too long...
I don't remember what cast iron you have done, but Ironsides had a thread on ferro phosporous innoculation to lower the melting point and create a more fluid melt. I use broken up steam radiators. They are high phosphorous and as long as your TC is high enough they make nice machineable castings. The original smallblock was done with that feedstock. When I researched cast iron investment I thought it required an acid bath to remove because of the higher temperature. Have you found something else? I tried cast iron in jewelers investment and saw no reduction in performance even though the casting itself failed. I was no where near hot enough and it was a split pattern and I had a runnout. Probably still some moisture from a short burnout.
I have some scrap 30 class that works out great for me with just a pinch of f.s. Plays hell on my furnace lining though.
Yep, I see 2850 on the furnace wall with the pyrometer and the castable is only rated at 3000, so it starts to fail.
When i tried iron in regular gypsum based investment it actually seemed like it melted the investment and turned it into flux. The investment i will be trying next is phosphate bonded and was told by the folks at R&R would hold up.
ESC, how did you handle the cooling system? Is the blocks water jacket cored out with the cylinder walls cast in, or just machined later and sleeves installed??
The block water jacket was cored but has machined cast iron wet sleeves pressed in. The head has a cored water jacket. The blocks are an original second, and an aluminum cast from the double shrink pattern for the blower motor project.
