Engine block casting for boxer twin

[Lakc]

Had a semi sucessful casting experiance tonight, casting engine block halves for a twin I am building. Took a few pictures and decided to share them.

The forms were 3d printing in nylon, another first for myself in this project. There are a lot of things I would do differently next time around but what I have is functional, and the education is well worth the $45 spent. I am a horrible patternmaker, and this saved me months of work, even as I have to rework it slightly.

I used the larger of my two crucibles, and made several mistakes due to the rush to finish in one night after work. I tried to cast two sets but only one turned out useable. I need the crucible completely full to attempt two casts at once, but I rushed the pour as my daughter and her boyfriend had just arrived and I had an audience. At least I had someone to take pictures of the pour for a change.

These are the forms getting the first coat of primer. I finished them with white enamel but they are so bright the pictures wouldnt come out.

Followed by a few pics of the making of the mold. The forms are hollow, so I backfilled them with sand first to keep the stress down

I lit off the burner and proceeded to ram the second mold.

Both molds ready to go and crucible is cooking. The furnace is about 14 years old and converted from a charcoal Gingery to propane with a modified Reil angle burner

And the skim and pours. Boots, gloves, jacket, hat, faceshield in 75 degree F weather. Playing with molten metal is fun, but only if you stay scared enough to stay safe.

Daughters boyfriend and I examining all my mistakes.

And a look at the mainly unsucessful cast. One gate choked off by freezing early and not enough metal for the pour. I still learn things every time I screw up.

And here is another pic of the forms, the unsucessful sprue, along with the semi successful pieces, already cut out.

 

[kustomkb]

Looks like an evening well spent. nice work!

 

[xlchainsaw]

lol i hate on lookers....last time i did a bit.....showing the grandkids and answering questions.... left the pattern in the mold!!!!and it was a wooden one too!!!

 

[Lakc]

lol i hate on lookers....last time i did a bit.....showing the grandkids and answering questions.... left the pattern in the mold!!!!and it was a wooden one too!!!

I have been doing this for years and thats the first time I had an audience. That will change soon, however, as grandson just turned 2. By next year he will only want to play in grandpa's sandbox. ;D

 

[Dan Rowe]

Hi Jeff,
Nice photo spread. :bow: I like the smoke and choice of beer.

I have a charcoal Gingery not getting much use, could you give me a bit more info about your propane burner? Is Reil a type or company? I have some larger bronze pours comming up so I will have move up from the hand held cruciable I usually use for lost wax casting.

Dan

 

[Lakc]

Thanks Dan.

Ron Reil is/was the guru of homemade propane burners. Although he does more forging then casting, they are just as applicable. I dont have the exact link anymore but here is his current page(s) on burners.

http://ronreil.abana.org/design1.shtml

Its been so long, I dont remember if mine is actually one of his designs or somebody else's modification. Its simply a (1 1/4"?) pipe union with an .035 mig tip for a jet. You position the jet relative to the opening and when you get it perfect it sucks in its own air.
I have a small venturi on the end of the pipe but I dont think its necessary when used in a furnace, only if you want to use it in a non-confined place. I dropped those two notepad sheets into the furnace and turned the gas on at 7psi, by the time the sheets had burned up the fire was self sustaining. I will look for some better pics when I get home.

EDIT:
I did a little digging and found the sidearm burner design.
http://zoellerforge.com/sidearm.html
I did not have any luck finding the actual brand he referenced, but with a little lathe clean up on the interior I am satisfied with my burners performance.

 

[doubleboost]

Nice to see you are taking safety seriously
I had a nasty scare with bronze and a damp ingot mould

Regards
John

 

[Lakc]

Ouch, thats why we wear those faceguards.
Scare is probably the best word, if your scared of what could go wrong you tend to keep to the proper precautions.
Embarassment is also another good one. After 11 years in the automotive repair trenches without major injury, I would laugh myself out of town if I managed to hurt myself in my shop.

 

[Artie]

Mate, excellent project! You bloody beat me... its the very next thing on my list.... a bmw style boxer bike engine. Ill be watching this with interest.

Good luck, great start...
Cheers

Rob T

 

[Lakc]

Mate, excellent project! You bloody beat me... its the very next thing on my list.... a bmw style boxer bike engine. Ill be watching this with interest.

Good luck, great start...
Cheers

Rob T

Thanks Rob!

Working with hollow forms has become a bit of a problem. The good pieces from this cast were a little undercut in the center, and their flexibility as I removed them from the sand tweaked the parallel sides a bit askew, making a good starting datum for squaring and cleanup fairly difficult.

There are a lot of things I would do differently, that's the benefit of learning from your mistakes. I will make another attempt this weekend with the forms I have, and hope for better results. Once I have the casting part done, I will start another thread in the build forum, where I can show the rest of the parts I have already made. If all goes successful and I am happy with the engines performance, I will have a MkII version of the forms made and possibly supply castings.

 

[Lakc]

Well, this weekend I did get round two accomplished. Again, not perfect results but I did get one usable form. The 3d printed plastic hollow forms wont take heavy ramming, so the idea here is to get solid production forms finished that can withstand a proper ramming. I also goofed on one 3d object and I needed to flip the cam and crank gear bosses around, so this attempt uses both forms but I only intended to retrieve one usable hard form from this cast.

To begin, I set the two forms with the faces adjacent that I needed to transfer. I also will be backing the hollow forms up with a flat board on the cope to avoid them shifting in plane. I sift loose sand approx to the top of the forms and start packing the corners with hand pressure first. Then I begin to firm up the sand around the forms, and cover with another 1" of sand before ramming.



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Drags flipped over and ready for the board and cope.


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Board laid on top, packing the sides and corners by hand first, then the ramming commences.



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All packed and ready to pull the forms.


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I tried to use a little thin oil to slick the sand near the corners that tend to break out, that did not work well, and I do not recommend it. Not sure what would work in this case with petrobond oil sand. I did a little freehand sand digging to scoop up the sand where the form was too small for the cam gear, using the mating surface of the other form for a guide.



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As to the pour, I did not have any help to take pictures. The board I backed the forms with was thicker then I thought and I didnt have enough metal to fill the sprue, but the boards thickness filled in any shrinkage in the forms quite well. I cut this in half with the bandsaw leaving the gear bosses from the good form attached to the hand cut one.



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I used the proper contour from the attached section to mill away the excess cam gear boss and squared the new form up. I spent a considerable time with a file smoothing and adding better draft angles, and the new form sits quite a bit higher on its own plate now.



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Sorry the photographs are not very good. I suspect this camera is ready to fail, as it has some issues with contrast and white balance that becomes very obvious at times for unexplained reasons. I will have to put another camera on my Christmas list.

 

[Artie]

Im watching.... updates? Any news? If there IS nothing to report...MAKE SOMETHING UP!

Its sad we are so far apart.... Id like to borrow the forms or plugs for this one.....

No RT dont do it! Dont start a new project til you finish the current one..... (sadly I usually lose arguements when I argue with myself...) 8)

Keep it up mate... you are my testing ground.....

 

[Lakc]

There are some updates, but as I have been without computer for most of the weekend, I didnt get a chance.

First update, was last weekend, I finished the form off and was ready for heavy ramming. I did a lot of hand filing the draft angles, some body filler and a few courses of primer/sanding and back to the foundry.

But what I got was full of sand inclusions.

So, we obviously needed some change of technique here. ???

I had been casting face down. This was to allow the shrinkage cavity in the backside that was to be milled eventually anyway. What I needed to do was cast it face up to avoid any loose sand ruining my day, which I think would be time for a chill in the mould. I will look into that later, but for now, I deceided to use double runners to increase the head pressure, and a rather deep channel across the bottom to feed from the bottom up. Not ideal, but quick and dirty.

Success!

And the sand ramming seems to have been the problem all along. While my sand passed the squeeze test, it seems rather shock sensitive. Bad rams allowed the sand to seperate in layers, and sand breakout around the mould edges were rather problematic. I thought and read a little about it over the week, and quite by chance I tried adding some rubbing alcohol to the mix. With barely 3 ounces of alcohol into approx 70 pounds of sand it improved greatly. I mixxed this petrobond up about 13 years ago, and havent changed a thing since, so why it worked now, I dont have a clue, but it really worked. I made a bigger rammer, almost cartoonish in its size. which also helped spread the blows from ramming out, as the sand was squirting out the edges of my ram and not really compacting itself. This sand, with the alcohol wetting it out, behaved beautifully. Instead of ramming each small half for 30 minutes it was perfectly rammed in 10 minutes for the whole mould.

The other half of the case went identical to this one, and I now have passed the casting portion for now. Next is making a few jigs to hold the castings, and then machining them. Once I have some ideas and some progress to report, I plan on starting a build thread and cross linking the two. So I would like to thank everyone for their interest and support, this saga will continue!

 

[Lakc]

Ok, build thread started, you can find it here http://www.homemodelenginemachinist.com/index.php?topic=11215.0