Casting a windmill gear in grey iron

Ok, blog time is over.
Its out to the shop for molding.

Man I wish they had that F.I.R.E. event more than once a year.
That was crazy fun to be around 50 people all doing iron castings at the same time.

Edit:
We need a backyard metal casting exhibit.
I bet the metal museum would let us host it there.
We would have to find a sponsor (I think David would be a good sponsor, so I volunteer him in his behalf).


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So how did the gear come out? I'm on my second bag of popcorn waiting.

 

Slowly making progress.

Make the core print, and the core box.

Working on the sprue/runner/gate/riser arrangement, and figuring out what is in the cope/drag, etc.

I want to be able to put a round block of wood on the blank end of the gear to hammer it out of the sand, and so that will cause me to have to make a 1" cap to cover the hole in the sand.

Also shown is the test block of resin-bound sand I made last night.
Hard as a rock (its hard to measure very small amounts of resin/hardener/catalyst).

The gate will actually be in the cope, not in the drag as shown in the photo.

We are getting close to tea time.

 

I use a triple beam scale like this one. It is accurate to tenths of a gram and very robust.

https://www.ebay.com/itm/OHAUS-2610...741151&hash=item546db5bb4e:g:tvcAAOSwa9dcrejL

The electronic 10-pound scales are pretty accurate to 10 grams but I do not really trust them for a few grams to be accurate. The triple beam is dead simple and reliable and precise.

I don't see any coal in that core. That may be ok though finish will suffer, but if there is no sugar, get your chisel out and set aside some time. 15% sugar per weight of silicate will solve that hardness problem..

Denis

 

I've made a few castings lately where the runner is the only thing in the drag. Seems kind of funny to ram up a single runner.

So is the picture the drag upside down?

 

FWIW:For small amounts of sand like a half pound or so those flat blade plastic drill stirrers work pretty well. For a few pounds, one of these below run in REVERSE does a great job. Forward works, but in reverse it pulls itself into the sand.

 

I've been doing that too. 3-part flask/mold. Cope and cheek have 99% of the mold in them and then there is the drag with literally a few grams of sand removed for a runner coursing from the bottom of the sprue to riser to main mold cavity.

 

Hah, Mr. Ed can get out his chisel, my work is going to be done once the metal goes in the mold.
Nope, no sugar.
I don't use that stuff (yet), not with resin binder.

I am going to spray on an alcohol-based mold coat, which is suppose to help with surface finish.
Resin binder by itself with OK-85 sand gives a pretty decent finish.
Should be better with the mold coat.

I am sort of making this up as I go, and the cope/drag thing is fluid at this time.
I guess since I put the runner in this piece, then it is officially the drag.

The sand is mixed and rammed.
Waiting about 30 minutes for strip time, and then we will have our answer about how deep a pattern can be stripped out of bound sand with no draft.
Could work ok, or it could be a total bust, but we will soon find out.

There is nothing under the gear right now once I remove the plywood bottom, so the idea is to pound it down and out of the sand.

 

For mixing, I use this bad boy.
275 lbs I think, Hobart.
I bought it used.
I told then guy I did not need any help carrying it out to the car.
He said "Yeah......right".
It took five of his guys to get it in my car.

I have a small kitchen size of the same style for small batches.

Scale is a small electronic one.

 

Ok, I am going out.
Moment of truth.

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Strike 1.

The sand seemed a bit dry.
Its a little difficult to accurately measure small quantities.

With nothing to lose, I decided to try heavy grease on the gear.

Here we go with round #2.
I may try a support behind the sand this time.

 

Bingo.
Now I just have to clean off the grease.

 

Staying with it! I assume you smoothed off the grease from the photo of the gear.

Great you got it out. When do you cast it?

 

Persistence pays off! Way to go.

Denis

 

I see you have the supplies for lost foam. when do you do some lost foam casting?

 

Somehow the grease has to come off.
I will probably start by wiping it, then a little alcohol (for the grease removal), and then a light flame, followed by a mold coat.

Rather tedious process, but the best I can do with zero draft.

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Clarke bought some of the slurry, and is going to try some lost whatever stuff, but I have too many other irons in the fire right now (3D printed patterns) to try lost foam.
I would probably try lost PLA or lost was before I tried lost foam.

I don't really want to change processes right now, since it can take a long time to master a process, and I have the bound sand process down pretty well.

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If I can get the other pieces of the mold made today and cemented together, then perhaps tonight.

I have to put the gear back in the hole in order to make the remainder of the mold, but I think it will go in ok.
The mold should be quite hard today.

I guess this is going to be a 3-piece mold, with the piece made last night being in the center.

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Can you drill it to put in a sprue?