Sand Mold Casting Problems

[jimsshop1]

Have you thought about using the Williams "saved wax" sand casting technique? It produces highly accurate product. It will even show fingerprints in the casting if they are not removed prior to casting.

Are you sure you don't mean "lost" wax technique? Show me the site please as it doesn't come up.

 

[dottedline]

Are you sure you don't mean "lost" wax technique? Show me the site please as it doesn't come up.

Yes, I an sure it is "saved wax." I found the instructions for it in the International Sculpture Conference of 1972 or 1974. I have the book somewhere...
It is the most revolutionary casting technique that almost no one has ever heard of.

 

[dottedline]

Ok, I will track down the info. This guy Dr. Williams ran the Industrial

 

[dottedline]

Arts dept at I think maybe Ohio State

 

[jimsshop1]

Arts dept at I think maybe Ohio State

Sounds interesting but I am done casting for a while. Casting all the parts for The Atkinson Differential Engine was a great learning experience but I doubt I will ever do it again on that scale. Maybe a flywheel or two in the future. Now I am concentrating on making all the fiddly small parts so I can finally get it to the run in stage. Thanks for your offer though.

Jim in Pa

 

[jimsshop1]

How is your furnace look like?
I'm an absolute beginner, i will make an oven fot 1.8 Liter crouse.
Can you give me some indicators??
Thanks,
Pierre

Hey Pierre, where'd you go? I took a lot of pics and measurements for you or are you just, never mind.

 

[machinejack]

Like you I had many failures using home made sand. Finally started using a green sand that I made from bentonite clay in the form of "pond seal" from a farm supply and 30 mesh sand. I mixed the clay and sand, and water and let it stand in a sealed bucket to let the clay absorb the water. Can't give you the recipe, made it on the the fly. Real coarse finish but worked OK. I am lucky to have a muller so it makes the job easier. I have since moved on the Petro Bond.

 

[jimsshop1]

If I cast again I will get some Petrobond, Thanks.

 

[stragenmitsuko]

My , notreally mine found it on the net once , greensand recipe .

All% are by weight !

100% white sand
Don't know it's real name , round here it is used for pavement .
It has a pretty fine grain . Play sand also seems to work .
12 % powdered bentonite clay , has to be fine like flour , no grains .
Can be found in the home and garden center as a soil improver .
5 to 7% of water

I have a paint shaker , so I first shake the two ingredients dry ,
add the water and shake again for 2 minutes .
I use a closed metal paint can .
Then I store it in a closed palstic bucket for at least a couple of days .
It can be stored like that for months without loss of quality .

Once used , it can be sifted and used again , and again .....
I let my used sand dry compleately , in the sun or on the stove depending wichever is avialble .
The I sift it , and add the water again just like a new mixture .

The structure of the sand seems to ba a bit coarser after the first use , but for my purposes it's fine .

Pat

 

[Pierkemo]

Pierre,
I made the furnace from 1/8" rolled steel. It is 13" high and 13" around. The top is 2" high hinged to the bottom and with wool type fire proof insulation. There is also insulation in the bottom under the plate riser the crucible sets on. The burner is made from a 2" tee bushed down to a 1" pipe 10" long. There is an .068 orifice in the tee. I have 2 crucibles I made. 1 is a 3" pipe 5" long and the other is a 4" pipe 9" long. Both have 1/4" steel plate welded in the bottom. I had access to a rolls set at work to roll the plate and my own welder for the rest. I am very pleased with the speed this melts ali and brass and how little propane is used. If you have more questions, please ask. Have a nice day.

Jim in Pa

Hello Jim,

thank you very mutch for the pictures! i'll try to make an also one. I place pictures from the build.
Pierkemo

 

[jimsshop1]

I am turning it with the electric motor but have the fuel and ignition also working. It is starting to sputter but the compression is still to low for a good firing. I am using CI rings. It is improving but I have only been running it for less than an hour. Gingery says he ran it that way for as long as 40 hours.

Hi Gordon,

I have assembled the engine with the exception of the valve bodies which I will make while listening to the electric motor run the engines rings in or seating as others say. I am not sure if I have the cylinder positioned correctly though as there seems to be a substantial suction in the spark plug hole when I put my finger over it. Also it is blowing out the intake hole in stead of sucking as it should. Maybe I should complete the valve assemblies and see what happens when I run it that way. Any suggestions Gordon? Thanks,

Jim

 

[Gordon]

Hi Gordon,

I have assembled the engine with the exception of the valve bodies which I will make while listening to the electric motor run the engines rings in or seating as others say. I am not sure if I have the cylinder positioned correctly though as there seems to be a substantial suction in the spark plug hole when I put my finger over it. Also it is blowing out the intake hole in stead of sucking as it should. Maybe I should complete the valve assemblies and see what happens when I run it that way. Any suggestions Gordon? Thanks,

Jim

I still do not have it running. Daughter and son in law have kept me busy working on their cars. Dad is cheaper than the mechanics.

I am having a problem with getting the cylinder positioned correctly. As I indicated before I was not sure where the pivot pin hole in the oscillating arm should be and I guessed wrong so I made the connecting rod 1/8" shorter to compensate but I have a problem getting the position right either on one end or the other. I have tried different length of linkage rods without any luck and presently I am making new connecting rods 1/16" shorter. Not sure yet if that is going to fix it.

In any case you are always going to get pressure through the intake hole until it passes right dead canter. The intake valve is held closed by the valve and spring until it passes right dead canter so that the exhaust valve can open. Once it passes right dead center the spring holds the exhaust valve closed and there is now suction on the intake valve as the as the piston travels to the left until the right hand piston again closes the intake hole.

Confused yet?

 

[jimsshop1]

I still do not have it running. Daughter and son in law have kept me busy working on their cars. Dad is cheaper than the mechanics.

I am having a problem with getting the cylinder positioned correctly. As I indicated before I was not sure where the pivot pin hole in the oscillating arm should be and I guessed wrong so I made the connecting rod 1/8" shorter to compensate but I have a problem getting the position right either on one end or the other. I have tried different length of linkage rods without any luck and presently I am making new connecting rods 1/16" shorter. Not sure yet if that is going to fix it.

In any case you are always going to get pressure through the intake hole until it passes right dead canter. The intake valve is held closed by the valve and spring until it passes right dead canter so that the exhaust valve can open. Once it passes right dead center the spring holds the exhaust valve closed and there is now suction on the intake valve as the as the piston travels to the left until the right hand piston again closes the intake hole.

Confused yet?

Oh yes, kid and cars, been there done that for many years. Now I only do small things for them as they both have new cars and can afford to have the dealers service them. Both my kids, man and woman now, are very independent so I must have done something right. Or wrong> I am very proud of both of them and they still reward me like they did today on Fathers Day. By the way Gordon, Happy Fathers Day to you!

Your explanation is much more understanding right now than what I believed before. I am going to finish the valve assemblies and see what happens then. Are you moving the cylinder horizontally or vertically or both? If so did you enlarge the mounting holes in the plate to do this? There isn't much room to do that only maybe 1/8" each way. Thanks for trying to help me. Tomorrow's another day.

Jim

 

[Gordon]

Jim: I made mine from bar stock and I do not have the pad on the face so I can move it to most any place on the face. I discovered that it is important to have the pistons positioned so that both pistons are at the end of the cylinder in the extreme position. In the firing position there is a rather small window where the pistons have an opening to the spark plug hole. In the exhaust/intake position there is a rather small window where there is a opening to the intake port. No matter what I do with my present setup I cannot get both right and left piston to both be in the correct position. If I move it up/down or right/left one or the other is not in the correct position. Very frustrating so it is kind of a relief to have car frustrations instead of engine building frustrations for a while.

 

[master53yoda]

I've learned over the years when casting ali , there's scrap and there's Scrap .

It caused a lot of hydrogen inclusions , pitting , although I degassed the crucible 2 sometimes 3 times .

Pat

for quality casting you want to use something that was previously a casting, automotive or marine engine parts such as intake manifolds, cylinder heads, engine blocks, rocker arm covers( some of the rocker arm covers are magnesium so be careful about them),and pistons. I don't process transfer cases because many of them are magnesium. Wheels are also a good source for aluminum. The castings are 356 alloy or very close. this is what the cast parts are mostly made out of. 356 has between 6 and 11% silicon added to the aluminum and the silicon changes the flow characteristics of the aluminum and also removes the tendency for the aluminum to stick to the cutting tools when machining. Pop cans are almost pure aluminum, extruded aluminum as well as plate aluminum have very little silicon.

Art B

 

[jimsshop1]

for quality casting you want to use something that was previously a casting, automotive or marine engine parts such as intake manifolds, cylinder heads, engine blocks, rocker arm covers( some of the rocker arm covers are magnesium so be careful about them),and pistons. I don't process transfer cases because many of them are magnesium. Wheels are also a good source for aluminum. The castings are 356 alloy or very close. this is what the cast parts are mostly made out of. 356 has between 6 and 11% silicon added to the aluminum and the silicon changes the flow characteristics of the aluminum and also removes the tendency for the aluminum to stick to the cutting tools when machining. Pop cans are almost pure aluminum, extruded aluminum as well as plate aluminum have very little silicon.

Art B

Thank you for all that information. It will be helpful the next time I do some aluminum. I did not know about the silicon in 356.

You never know what you can learn on here!

Jim in Pa

 

[nel2lar]

Jim
I just seen this thread and if I might suggest something try bumping your bentonite clay up to double what your recipe calls for. Bentonite is what make the sand hold together and it looks like your sand is quite crumble. If you can not do the fist full of sand compressed and get a good rock hard clump or if the edges are just loose and falling off, it your mix.What you can do is take a half gallon of your sand and add about a pint of bentonite and see what happens. Green sand always works better the day after mixing it or it has for me. Green sand is the only thing I will use unless I go to something hotter like iron.
Good luck and Happy Casting
Nelson

 

[Aerostar55]

I am building the Atkinson Differential Engine with my own aluminum castings. This is my first time at casting and so far have all the parts cast except the flywheel. The castings are not the best I've seen but they are usable. My problem is with the 6 spoke flywheel. I have cast it 3 times but am having problems with the mold when I take the patterns out of each half. The sand edges of the spokes keep breaking off so my impression seems to deteriorate as I try to clean it up. I can not get the sand to hold it's form. I am using fine play sand and ground up kitty litter as my green sand and I know that is not the best way to go but it's all I have. I can form a turd shape in my hand and it breaks clean without crumbling so I think I have the mix close to correct. One thing I noticed when using talc for parting agent is it dries out the sand around the pattern so I am only using it between the 2 flasks so they separate better. I have watched myford but he uses oil base sand. Can anyone please give me some tips to get good crisp edges around the impressions? I'm sick of playing in the sand>:wall:

Thank you,

Jim in Pa

Jim:
I can recommend using sand from Budget Casting supply. I buy 50 pound boxes online. It is an oil sand works great with aluminum. I used it to cast my Atkinson engine flywheel. Other than that you could try adding a little extra water to your sand then after you pull the pattern out and assemble the flask to the cope let it sit overnight before you pour in order to let it dry. Additionally you might try rapping your pattern quite a bit in all directions before you pull it out. This helps break the surface tension with the sand before the pull.

 

[SmithDoor]

I am building the Atkinson Differential Engine with my own aluminum castings. This is my first time at casting and so far have all the parts cast except the flywheel. The castings are not the best I've seen but they are usable. My problem is with the 6 spoke flywheel. I have cast it 3 times but am having problems with the mold when I take the patterns out of each half. The sand edges of the spokes keep breaking off so my impression seems to deteriorate as I try to clean it up. I can not get the sand to hold it's form. I am using fine play sand and ground up kitty litter as my green sand and I know that is not the best way to go but it's all I have. I can form a turd shape in my hand and it breaks clean without crumbling so I think I have the mix close to correct. One thing I noticed when using talc for parting agent is it dries out the sand around the pattern so I am only using it between the 2 flasks so they separate better. I have watched myford but he uses oil base sand. Can anyone please give me some tips to get good crisp edges around the impressions? I'm sick of playing in the sand>:wall:

Thank you,

Jim in Pa

Look at other casting you will see flash but they had some grind off the flash
It also may be the sand is to dry
I have use oil base sand and works good but you need a muller to keep sand up

Dave

 

[nel2lar]

Jim
Casting is a real learning curve and if you do it for 50 years you will still have thing to learn. When I read your messages on your sand, it might not be your sand. The pattern can hold a lot of answers and one thing I have learned is the smoother the pattern is, it will much easier to pull from sand mold. The second thing about the pattern is the draft, If it does not have sufficient draft it will not come out of the best sand. I've played with sand for over 25 years and I am learning every project. My advice would be watch as many U-Tube video on casting and try to get the results they are getting. There are many trick the old hands use and the only way to get the,m is to watch. Good luck and just hang in there.
Nelson