Harbor Freight Carbide Grinder

[bemader]

I just noticed adding the draft to my pattern increased the diameter.



This won't matter for my own use and probably won't really matter if used on the actual grinder but isn't an exact copy of the one I was trying to copy. At over 7 hours of print time I'm not going to remake it.



The height looks pretty close.

I'm still painting the 3d printed pattern and will need to smooth it up before I can try using it to cast my own. I started digging up some boards to build the taller flask to make the sand mold. I have a limited amount of green sand so I don't want to make the box bigger than it needs to be and don't know exactly how I will ram it up yet. I'm guessing the "core" will need to be on the bottom (drag) half of the flask so this could be a bit harder than I first imagined.

 

[GeneT45]

I think you're going to want to ram up the pattern on its side (the draft not really being necessary since the lip would make a vertical setup extremely difficult). Then you'll need a core and core prints, and a way to close off the top.

Alternately, you can do it any which way if you used the pattern as an investment, but the priming and painting might muddle that up - I'm really not sure how it would react.

GsT

 

[bemader]

My smaller flask isn't really big enough for even the half scale model and that one isn't smoothed up very good.



The "sand castle core" didn't come out clean and the sand was just now dampened but this is what I was thinking I would need to do.

 

[GeneT45]

Did you preserve the "button" in the bottom? That's a difficult lift. If you have some sodium silicate you could make a CO2 hardened core with just sand inside the cup. Harden by setting it out, or with gas from your kegarator or welder. You used to be able to get Sodium Silicate (isinglass) from the drug store. Ceramic supplies are another source.

GsT

 

[yota]

that hole in the bottom center is only to allow the cup to be pegged on the pin on top of the tool grinder. if you are just dipping and have another way to mount the cup, then you don't need the hole or the reverse of it on the inside. do you have the tool grinder with the peg or just planning to use this on a bench grinder?

 

[bemader]

Did you preserve the "button" in the bottom? That's a difficult lift. If you have some sodium silicate you could make a CO2 hardened core with just sand inside the cup. Harden by setting it out, or with gas from your kegarator or welder. You used to be able to get Sodium Silicate (isinglass) from the drug store. Ceramic supplies are another source.

GsT

My quick test did look like the "button" impression did come out or would if I spent more time ramming up the mold with sifted and better tempered green sand. I designed the pattern with draft on the "button" specifically so it would release from the sand cleanly and the full size pattern is being sanded much smoother than the half scale test. I think I have a can of sodium silicate at my other shop if it is still good but I never tried it to make cores.

Another option that I never tried myself is the baked cores using 90% sand, 10% flour, and dampened with water containing about 10% molasses. I don't know if those need to be baked in the mold though. My 3d printed pattern wouldn't work if it needed heated.

I only NEED 1 or possibly 2 of these for my own use. I don't have a Baldor type grinder and my plastic jar has been working fine to dip my cutters and bits into to keep them cool. I have other ideas that a cool, home-cast dripper pot might be useful for but this project is mostly just to see if I can do it. I have other projects that I'd like to cast so this seems like a good excuse to get my foundry set up better.

that hole in the bottom center is only to allow the cup to be pegged on the pin on top of the tool grinder. if you are just dipping and have another way to mount the cup, then you don't need the hole or the reverse of it on the inside. do you have the tool grinder with the peg or just planning to use this on a bench grinder?

As I wrote above, I don't have a tool grinder with the peg and I am just planning to use this on a normal bench grinder without the dripper. I might still want to mount it using a pin or have that option if I do need it. I did find a needle valve I had from another project that I could add to this but that wouldn't be used on the bench grinder.

 

[yota]

a number of pedestal mounts come with cast iron dipping cups that mount to the column.

 

[bemader]

My pattern isn't ready yet and I still need to build the other "half" of my flask box.



The other box shouldn't need to be very deep which is good. This took a lot of sand and is pretty heavy when full but I should have enough sand left if I don't make the other side as deep.

Inside dimension is only around 8x9 inches but the depth is 6-1/4" and it is just made out of a rough cut piece of wood I had laying around. I'll need to hunt around and see if I have another piece of the same thickness that is narrower so I don't need to clean off and change the blade on the table saw. I have a 4" wide board sitting here that is a little thinner but it is softwood of some kind.

I have other projects I need to get back to and this isn't something I NEED but it should be pretty close to melting some metal assuming I can get a promising looking sand mold rammed up.

 

[bemader]

I built the other part of my flask and am waiting for the glue to dry on the locating tabs before messing with it.



The smaller end is around 3-3/4" deep which should be enough considering no part of the pattern will be in that section.

Being curious and impatient, I wanted to see if the smaller pattern would work.



No, it didn't fill. I don't think I had enough height to force the metal into the mold. The flask I used was just barely deep enough to hold the height of that pattern.



I can see the mark for the center hole and the one for the valve might be where a bit of burnt sand is stuck but I noticed the pattern still has sand stuck in that pocket so that mark probably didn't cast.



The "button" on the inside kind of formed. It was probably not enough pressure to get the metal to that section fast enough or maybe the sand was a bit too wet or the aluminum wasn't hot enough.

I didn't expect this one to work but I wanted to try it anyway. The rim didn't come out very good but part of that was likely from damage to the sand when I took the pattern out and trying to line it back up to reassemble the mold for pouring. That pattern was just roughly sanded. The full size pattern I'm spending a lot more time to get it smooth. I'll also be more careful to get the sand packed around that pattern and it might need a vent.

 

[GeneT45]

Add a 1" dia. riser, fairly close to the casting to help feed it. Although that looks like you poured a bit cold.

GsT