I am green at this my good castings are about 25 %lol We are doing a group build of 5 .291 scale 25 up waterloo steam engines
Welcome to the forum Sawyer. Looks like you are having a bit of trouble with shrink. What alloy are you using, and do you have any shrink bobs added in there??
Welcome Sawyer. I assume it's a 25 hp engine you're trying to build. Please elaborate on what your issues with your castings are. Pete
Yes the trouble I have the most is blow holes small but there I vent fairly large I think YESTERDAY I poured a governor body and top came out nice but one small hole still usable And today I split my crucible was use to pour about 200 lb of iron mostly 20 lb at a time 4 times full to top the crank I tried 4 times does not fill in the same spot it is thin but fills the other side no problem It is always the same side I added material to the out side have not tried it since Thanks in advance Todd
Hmmm. A bunch of clear photos might help. The details of your pattern, mold, and resulting defects would really help address the problem. Also, How are you determining pouring temperature? What sand/bentonite/water/coal formula are you using? Sorry to ask so many questions, but all of these variables and more are in play as you know. Denis
I'm using green sand 10% bentonite as little water as possible I do pack my sand high as I tried to pack it loose and dump the sand when I flip it The pictures are helpful I hope can send the pattern pick tomorrow the a in garage lol
Let’s start with the sand. 10% bentonite ( Southern or Western i.e. Calcium or Sodium bentonite.) seems like a lot of bentonite. The US Navy foundry manual recommends 4% which is what I use. To that mix I added 4% water. https://maritime.org/doc/foundry/index.htm#pg44 Your castings as best I can tell look to have a lot of sand burned on. I am thinking you are not adding sea coal to your sand. 5 to 6 % added sea coal may help that greatly. What type and mesh sand are you using? I appreciate your photos but the images are awfully blurry (greasy lens? Camera not focusing on the subject but rather the other stuff?) the light is poor and it’s direction not helping. If you could get the subject outdoors on a plain background—-the sidewalk maybe—- with the light source behind the camera it would help a lot. All the extraneous stuff in the photos make it difficult to see the subject. Sorry for complaining. Denis
I hope these pictures are better than the other the first two are the governor body I vent in 3 places the middle and each end with .375 dowels The next set is the top of the govenor and the pattern I use the vents on the later and cut a run in the opposite side .5 square The others are the cylinder you can see the vents and find in the casting hope this helps
Sawyer, I can see you have put some effort into your reply. Unfortunately, I can not figure out what is going wrong with your casting. I hope someone can help you better. Sorry. Denis
where did you get the plans for the parts? I would love to cast a larger steam engine. most of the kits are way too small. Alex
I am just starting out so I can't be of much help with your casting problum. I have seen several places the importance of powdering the surface of cast iron sand molds with coal dust to get a good finish and avoid sand entrapment. Also what size and type sand are you using. The surface finish makes me think the sand granes may be to big. Someone with more experience may be able to recomend the correct sand grane size and shape.
Getting a bit better Burnt the sand with lithium grease in a spray can No blow holes much softer irion Saturday I'm going to try crushed charchol and one with neversize in a spray can
Spraying on graphite powder or plumbago mixed with alcohol works well on silica sand to give a fine finish for iron. After it's sprayed on you can flare off the alcohol with a match. Use a cheap spraygun as the mix is abrasive.