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The following 2 users Like dallen's post:
oldgoaly (08-18-2013), Mayhem (08-19-2013)
08-18-2013, 07:23 PM
(This post was last modified: 08-18-2013, 07:26 PM by dallen.)
I throwed together a short video on how I do a Sand and Sodium Silicate Core when I need them like for the Leadscrew Support casting I have been working on.
Not mentioned in the video is that the needle I have on the gas hose if from one of the injector needle you get at the grocery store normally they come with that injectable marinade, but they can be bought by themselves.
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The following 1 user Likes doubleboost's post:
oldgoaly (08-19-2013)
Thanks for that
I have had very limited success with sodium cores
They have been to hard (not collapsing) when the job is poured
I may have been using to much sodium silicate
John
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I haven't tried this yet but I was told it works fine, if you have some cores and put them in a closed container, then feed CO2 slowly in to the container, leave them over night they will get hard just fine. I'm thinking a small plastic bag may work too. I always seem to need 3 hands when holding a core, the hose for the CO2, then the valve....... I do like the smell of molasses baking in the oven! better than it does when de-rusting!
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(08-19-2013, 04:05 PM)doubleboost Wrote: Thanks for that
I have had very limited success with sodium cores
They have been to hard (not collapsing) when the job is poured
I may have been using to much sodium silicate
John
It takes a lot less SS then a lot of people think, all you want is enough to make the sand stick together, the core that I made in that video came out pretty easy actually a lot easier then I figured it would, but it still had too much SS in it, the one I made today when I repoured the part I used even less but a different brand and I had to knock it out with a hammer also, but I'm using a really fine grain sand to make them out of too. a little courser sand would probably let them break down easier.
(08-19-2013, 05:10 PM)oldgoaly Wrote: I haven't tried this yet but I was told it works fine, if you have some cores and put them in a closed container, then feed CO2 slowly in to the container, leave them over night they will get hard just fine. I'm thinking a small plastic bag may work too. I always seem to need 3 hands when holding a core, the hose for the CO2, then the valve....... I do like the smell of molasses baking in the oven! better than it does when de-rusting!
Goaly use a tank with a regulator on it and a blow gun for and air hose. the big thing is to make your cores so you only need two hands, but then I also like the smell of molasses cookies baking in the oven just don't like the extra heat in the house in the summer time
David
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One of the guys on Madmodder (ironman) makes his out of cement, with good results, from what I have read.
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you can make molds with cement bonded sand also you just have to make sure you don't have to much water in them, but the process is usually reserved for extremely large molds that need the strength of the cement.
Me I'll stick with the SS and sand to make cores with, I've even done complete molds with it because I didn't want to make a special flask so I use a 3 gallon bucket to mold in then sunk it in a cardboard box full of sand to keep it from floating.
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08-25-2013, 02:37 PM
(This post was last modified: 08-25-2013, 02:37 PM by the artfull-codger.)
Well here's my two penneth worth!!
No1, 5ml boiled linseed oil,8 dessert spoons of dry fine sand [windblown beach or kiddies play sand], about 15ml water & 1 teaspoon of dextrin,I usually put a teaspoon of bentonite in to give it green strength[not essential] then bake in the oven@200c till solid. strong cores!!
No2,1x raised teaspoon of cereal binder [standard stuff from john winters foundry supplies uk] 5x level tablespoons of dry sand & water to suit then bake as usual [dead easy to make!!]
No3,co2, injected with a fine hollow needle from ''pub gas'' bottle,or you can leave it in the workshop for a few days & it'll harden itself.
my preference??? well it depends on my mood,they all work well.
Graham.
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Graham sounds like you got a pretty good handle on what you like for cores, only problem I have with the first two is that there is a standing rule that NO ONE turns on the oven during the summer months in my house.
we what baked goods have to buy em.
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(08-25-2013, 02:47 PM)dallen Wrote: Graham sounds like you got a pretty good handle on what you like for cores, only problem I have with the first two is that there is a standing rule that NO ONE turns on the oven during the summer months in my house.
we what baked goods have to buy em.
Hi Dallen,
btw I like the video, wish I could make 'em myself!!,I've just learnt how to do pictures!! I love John's video's too [he only lives a few miles north of where I live] I can forgive him for being a geordie though,we've not met but it's just a matter of time,you wouldn't like our house then, we have a rayburn cooker & it's on 24/7 in the winter but in the summer[we actually got one this year!!] I light it to cook the dinner & get the water hot for domestic use[& cores of course] & it's out by 11.00pm but the radiators come on too, if mrs artfull comes in 1st & it's sunny she often cooks on the electric & puts the immersion heater on much to my annoyance!! 'cos electric costs money & woods generally nothing!! I expect you have solid fuel central heating cookers over there as well??
Regards Graham.
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Graham the taking the video is the easy part its the cutting out all the stuff you feel that you don't need or know you don't want in it thats the hard part.
I don't run my cookstove because then I have to wash dishes and pay for getting rid of the the heat, this time of the year the old thermometer hangs up around the three digit mark most of the time.
I would say that yes I could get the same type of setup that you have but why when my gas bill during the winter doesn't really run that much. and with wood I would have to go find someplace to cut the stuff.
Glad you liked the video, I made a core tonight for a pour that I hope to do tomorrow took all of 5 minutes after I split the PVC pipe for a mold.
I like Johns video's can't understand half of what he says thou
DA
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