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Moulding flasks

Posted: Sun Oct 03, 2010 3:46 am
by RobWilson
Hi All .

This is my first post here ,, i apologize if there are too many photos ,,,, i am not the best with words :roll:

One thing has always bugged me about my foundry set up and that was the moulding flasks made from wood ,, they burn when you spill molten metal on them , warp and generally fall to bits after a wile ,,,,,,,,,, so time for some steel flasks   ,, last week i had eight  lengths of 1/8" x 4"  steel given ,, all about 110" long ,,,,,,, just the job me thinks to make some flasks from .
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Then i thought i need a bead up the lengths of steel ,so that the sand would grip to ,  as this it a one off job i knocked up a ruff and ready press tool from bit of off cuts .
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dragged my shop built press into the middle of the shop and fed the lengths of steel through the press 6" at a time
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When all were done ,, they were cut into 65" lengths , then all the off cuts were welded together and cut to 65" ,, this gave me enough for 6 set of flasks 12"x16".
next came the bending ,, so i removed the large vice from my welding bench and tac welded 4 lengths of round bar to it ,  for the bending jig .
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The lengths were then bent round the jig ,heating the bends with oxy gear
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Then after they were all bent up , the over lap was trimmed off and welded up
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Due to the welding and bending they had a bit of a warp in them .
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easy fix , stuck a shim under the one of the high corners , this is to allow for the bit spring back ,
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plonk a bit weight on the offending corners , and heat the other to .
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Next was to make sure they are truly flat , as some metal on the corners get raised due to hammering on the bends , a bit grinding took care of that using one of my ally core plates as a reference.
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Then they were paired up ,cos they aint all the same ,,,,,,,,,,, the ones i did with a hangover are slightly different  
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Made the handles from some re-bar i had scrounged ,, nice and grippy ,, my #25 vice was just the job to use as a bending jig ,,,,, heat, bend , bash
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Then the pins and handles were then  welded to the flasks , using the mark one eye ball and my least squished thumb to get them in ruffly the right place  

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They still need a bit of tweaking here and there ,,,,,,,,,, nowt to major ,,,,,,,,,,,, well that's another job off the list .
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Rob

Re: Moulding flasks

Posted: Sun Oct 03, 2010 12:29 pm
by steamin10
If a picture is worth a thousand words, you have quite a lot to say! Dang that is a nice way of creating needed flasks. Crystal clear process.

I have some commercial flasks, and find them very cumbersome for fist sized and smaller work, so I have made some flasks that are shoebox and half shoebox sized for smaller parts, as many of mine are. It saves the back and moving a lot of uneeded sand.

My compliments on your efforts and pics. Thanks

Re: Moulding flasks

Posted: Sun Oct 03, 2010 2:13 pm
by mechanicalmagic
RobWilson wrote: i am not the best with words :roll:
Rob
Welcome Rob.
The pictures told the story.
You can come back anytime and just tutor me with fine photos.
Dave J.

Re: Moulding flasks

Posted: Sun Oct 03, 2010 7:25 pm
by Russ Hanscom
Good looking results. You are innovative.

Re: Moulding flasks

Posted: Sun Oct 03, 2010 7:30 pm
by norman
Very nice heavy duty flasks! You must be planning on casting some large parts. I had to laugh at the comment of hangovers, those can be a problem. some of this casting and machining will almost make you want to take a nip.
Wait until you loose an eye lash or eyebrow and not know
how it happened when firing the furnace and no other burns except no eyelashes on one side?!
Even wearing a face shield with safety glasses????
Looks like your having fun.
Don't mash your good thumb. doing something like that can make wet spots on your pants..
Norman

Re: Moulding flasks

Posted: Sun Oct 03, 2010 7:37 pm
by dly31
That is some really good design of both the flasks and the process/tooling to make them. They also look very professional. If you hadn't shown them being made I would think they were factory built.

Thanks for the photos and write-up.

Don Young

Re: Moulding flasks

Posted: Mon Oct 04, 2010 6:46 pm
by Big B
Hi Rob and thanks for the post.

I especially like the way you made a die to form the sides.

I'm sure there are many of us who would like to see more posts as you begin to use your new flasks.

Big B

Re: Moulding flasks

Posted: Tue Oct 05, 2010 10:30 am
by RobWilson
Hi Lads ,,, thanks for the comments and interest :D


steamin10 ,,, My thoughts are to cast a few parts in each set of flasks ,,, or have a good session casting with all the flasks full ,,, just to save on fuel .

Norman ,,,, i have a thing for big-ish model engines :D

Some of my work so far ,,, bed plate for a gas engine ,, shown on the table of a 626 mill
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and a Rider Ericsson hot air engine
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Thanks for looking Rob

Re: Moulding flasks

Posted: Wed Oct 06, 2010 11:13 am
by steamin10
Great pic of the patterns and corebox for engine parts all in red, with teh traditional black interferance reference. Some foundries used this for years, such that a glance from a floorworker would confirm the patterns needed. The black areas signifying the need for overlaps with cores and various bonding setups. A kind of mental braille method of guidance.

I never fire up a furnace for just 1 part or two. Since a furnace warmup may take and hour or so to keep from spalling the lining, yo waste at least that much fuel, everytime. So for pure economics and wear factors, I usually run to the end of feedstock on hand, the parts and spares for a coupla hours, or change and go from aluminum to bronzes, making molds all the way. As stated before, the fist sized or less onesy twoseys, are a problem, but with smaller parts I have boards that run 5 small sets at a time. With larger pieces, it comes to how much material do you wnat to hold in semifinshed castings, unavailable for any other use. You dont want to get in the postion of having to melt made castings that are unwanted to fill a diferent order.

I too like the larger engines, larger than desk top paper weights. The engine base is a good start. Do you have the gearing and all worked out? Or is this built to another plan, like a Hired Man ?