Big Scrapper

[Harry]

My lil' Scrapper gave up the ghost during my last run. Once the hotface started breaking away around the top it quickly went south. It really took a beating from sitting wheels on it and of course knocking on them when they were hot short to hurry their progress down into the bore. It just wasnt really up to task with the bore being smaller than a wheel.

So lil' Scrapper will get a makeover as a #20 crucible furnace, getting a couple of SiC crucibles this size soon because I have a new project coming together that will have some castings that are too big for #10. Will be sizing the bore to the #20 and adding a flame trainer to it with a nice combustion chamber in the bottom. Will also be going with a 1" plus hotface because I dont want to be rebuilding this furnace any time soon.

This means I am going to need some means of making ingots when I run out of metal from the last run. I did 30 wheels so I have some time on this but have to start thinking about it now and getting the parts together.

The Big Scrapper is going to be a two burner monster with a 30" bore. Filled to the drain hole capacity will be just over 200 lbs and the pool will be 4 1/2" deep.



The tuyeres are 3" and the hotface will be ~1 1/4", the spout hole is 1 1/2".

The shelf there has a 10" diameter hole where the lip is formed and 3 rows of 1/2" holes out to a 18" diameter. The shelf is removable in case I want to be able to drop an engine block in there

The empty space between the hotface and shell will get a foam/refractory insulating layer.



Considering rolling rings out of angle iron and a shell from sheet steel. All these posts on ring rollers has me wanting to build one The tilt will be set up so that it rotates about the spout for consistent pouring through the arc, this will be nice pouring ingots but invaluable if I ever decide to do a really big casting. Will probably use an electric trailer tongue jack for the actuator because this thing is going to be real heavy.

Not real sure what will end up on top if anything. I was thinking if I ever end up doing engine blocks then a riser section would be good and have not given a lot of thout to a lid. On the lil scrapper I never did use the lid while scrapping.

[ian b6]

i like the ever increasing size i thought it was just me who had got this far from just playing.
i use a blower of a bounce castle a 3"pipe and a lot of oil in a not dissimilar set up it burns below i sort of crucible container for the melted metel but as a insulated containing area to heat up wheals and blocks and run the melt to the pot

Ian

[Harry]

Hehe... yeah bigger has always been a component of my OCD When I made my yard I had paced off a nice sized area and show my wife then when I was setting posts it ended up about twice as big.

Would love to see some pictures of your scrapper. This one I am working on will hopefully do all I need and last a good long time. Certainly not cheap to put together but then a heck of a lot less than buying a commercial unit. I am figuring it will be able to go up to around 3 GPH or about half a million btu. That should make lots of liquid wheels in short order.

[Nudge]

That should make lots of liquid wheels in short order.

Like yup

[Harry]

Stopped in at the country hardware/feed store that is on the way to Home Depot today. I love that store because they have everything and many things like hot water heaters they beat the big stores on. Anyhow I wanted to find out how much those 4' diameter and 2' deep galvanized stock tanks were... lets just say if my wife would have let me tie one on top of the car I would have it here now. Will have to wait until I get back out there in the pickup but $99 sounds to me like a pretty hard to beat shell for the big scrapper and it will even make the walls a little taller than I had originally planned which should not hurt anything at all.

pipe-top-round-tank[1].jpg (12 KiB) Viewed 5329 times

I also see that they make these in a 24" diameter 24" tall which might be a good option for a crucible furnace shell, here is one website with this size at $85.

Now I have to get busy collecting up all the other stuff I need and make a trip to get half a dozen or so bags of refractory so this baby can start coming together. I figure I have less than two months with my current aluminum stockpile before I am going to need to scrap again so its time for this furnace to get started. Have plenty of steel for the tilting frame but need to order a heavy duty actuator, probably this one from Surplus Center for $139.

p28-1746E1[1].jpg (22.8 KiB) Viewed 5329 times

[Harry]

that big a diameter what you gonna make the lid out of????, surely your not going to leave it open that would be a waste of a lot of heat.

What type of refactory are you using, high strength or high temp 3000 degree insulating????

Man thats going to be a lot of refactory are you planing on putting any of the stainless steel slivers is what I call em, they have a trade name. but are nothing more then chopped up stainless steel for reinforcing the refactory in the mix.

I hope you got a concrete mixer for that much mixing.

I measured it earlier and it is 44" so with 5-6" walls it will have a 32-34" bore. I have no intention of making a lid but if I did it would simply have plenty of rebar in it to support it and hold it together. That dense castable is some pretty amazing strong stuff after it is fired. I have thought about possibly making a center section that is removable making the bore deeper which would hold more heat, this was along the thinking of melting whole blocks in it but I would probably be afraid the shelf would not hold up an engine block.

I am planning about 4" of an insulating layer that will be 2 foam to 1 castable. I have done 3:1 in the past and it has held up well but I want this thing to be just as tough as possible and it is going to have 1 1/2" solid castable hotface so it will take a little while to warm up anyhow.

With two burners on this I figure it is going to make more than enough heat to waste some. The idea is that the shelf in there will heat up and transfer by contact to a wheel laying on it. Also the heat will be directed to the center of the wheel through the holes in that shelf. The outer rim is usually pretty thin so I am hoping that will keep up with the rest. The plan is to stack two wheels in at a time so that as one is melting the next is preheating so by the time it gets down to the shelf it will be ready to push over the temperature and putting the next wheel on wont slow it down too much.

Hadnt really thought about the stainless needles though that might be a good idea just to make the shelf stronger if nothing else. I do have a mixer and might use it for this though more likely will use a hoe in a wheel barrow because it will be a pretty dry mix and would tend to stick in the mixer.

My one concern about this design is the potential for overheating the pool in the bottom by the time it is filled. I am thinking that the just melted cooler metal running in will help keep it down along with shedding heat through the bottom as the pool gets deeper keeping it from going way too hot. This isnt such a big concern for pouring ingots but if I get to pour some big molds it might become more important.

[Harry]

Well I am about to make an incremental advance in this project. Seems this whole thing is going to cost me considerably more than I had anticipated so it has been dragging on some. Tomorrow I am going to purchase the insulating castable for this and for rebuilding the Lil' scrapper and enough 3K* dense castable to finish the Lil' scrapper.

The insulating castable is Kast-O-Lite 20-45 and is 28 lbs per cu ft. I was shocked to see that it takes 4 gallons of water to mix a 25 lb bag, we will see how that works out but it sounds like it swells up like a sponge. It will take about 10 bags of this then another 8 bags or so of the dense to do the Big scrapper do all together about 700 lbs of refractory at 85 to 90 cents a pound.

Still need to buy the 12v trailer jack for tilting and get all of the parts to set up the two burners. I really wanted this together by now because I need to do another scrapping run. I am having a helper over next week and plan on casting 200 lbs of aluminum while he is here and only have 100 lbs or so of ingots left from the last run. Looks like Lil' scrapper is going to get one more run but probably a small one of 300 lbs or less. This should get me through the next couple of months and hopefully I will have the material for the hotface and the rest of big scrapper complete and ready for its inaugural session.

[4cylndrfury]

Ive been looking forward to progress on this thread ever since you came up with that solidworks pic...It seems like its gonna be a great tool in your business. I hope it all goes as planned!