The first part of this submission is how to make the press. The second is my adventures in making it work. This is the first time I have ever baked a Pie.
Step 1: Stuff You Need
Vector drawing program (http://www.freecad.com/CAM_Programs/)
Cam generator (http://www.freecad.com/CAM_Programs/)
Mach3, EMC or similar (http://www.machsupport.com/) (http://www.linuxcnc.org/)
CNC Router or contract fabricator (www.100Kgarages.com)
¾ “ Maple or other hardwood
All purpose Flour
Step 2: Skills I Need!
Not necessarily in that order
Step 3: CAD – (Computer Aided Design)
There are so many design programs out there (http://www.freecad.com). Some are free, some are not. Try the free ones, or the trial downloads, and spend some time assessing their capabilities. Make sure you look at what they can import and export. This will be important in moving your drawing files to the CAM generator (more about that later). The higher end ones, have a steep learning curve and take a while to be comfortable with. The lower end and free are getting better all the time. Check out Sketchup (free) with the ruby script that allows output in .stl and .dxf formats. Sweet! (http://www.guitar-list.com/download-software/convert-sketchup-skp-files-dxf-or-stl)
I use several CAD programs depending on my mood and how complex the design will be. This time I used Vectric as the output would ready for the CNC Router.
Starting with a 5" and 6" circle from the same origin, and bisecting it in half, I then separated the two halves with a gap of .5". To round the corners, I created .75" circles and placed them over the sharp parts of the two haves of the larger design, then clipped out the extra vectors. With .5" circles, I repeated the process on the inner 5" diameter halves. Now I had two symetrical parts that had .5" border on the curved portion and .125" at the hinged (straight) edge. For the second version (the first had triangles) I selected a .25" circle, to fill in the wider border. I copied it 34 times and placed them equidistant from each other within the .5" border section. Vectric allows one to covert a 2D vector drawing to 3D, so using their modeling features, I made divots of the small .25" circles and a concave shape of the center section. Lastly I took a pi symbol bitmap, converted it to vectors, placed it in the center of each half of the mold and created a raised (convex) shape.
This sounds difficult , but you can see the result easier than I can describe it.
Step 4: Tooling Bits
Our router only goes one speed in rotation and maxes out at 25 linear inches per minute, so the only control we have is how deep it cuts per pass, and the inches-per-minute speed it travels through the material. As I was to cut maple, a fairly hard wood, and didn’t want to break those expensive bits, I set the toolpath depth to cut just .1” deep on each pass. Also I slowed the feed rate to 12 inches per minute.
Before any machinery is turned on, install the bit into the router you have. Be VERY careful, they are quite sharp. I don’t know anything about bleeding on my project (hah!), but there are a wide range of band-aids and compresses readily available in our shop, just in case.
Step 5: Material
Make sure that the piece you load on the machine is bigger than the project. Additionally I place a sheet of cardboard under the material to protect the bed of the machine. Seems obvious, doesn’t it? Right. Also, make sure that it is oriented correctly in the X and Y plane. I never make those mistakes.
Stabilize the wood. Many treacherous opportunities lie here. Cut the wood larger than the project -- just a reminder). You want extra room for clamping down the outer edges with screws, cam locking devices, or even double-sided tape. In this case I used screws around the outer edges. Regardless of the method, one wouldn’t want the highly rotating router bit or the router itself crashing into something hard and unyielding. Some very interesting results WILL occur and you really don’t want that experience. The least is you may lose some steps in the g-code and get the remainder of the cut all cockety-wampuss, and the worst is flying bits of high speed steel flying around. Which brings us to the all-time favorite subject of OSHA -- Ta-da: SAFETY!
Step 6: Safety
Ok, the condensed version:
-Ears - CNC machines are loud. I like to put on noise cancelling earphones with my favorite music playing in the background. Not too loud as you want to lightly hear the machine as it runs, giving you a heads-up to any problems.
-Eyes and face – Flying objects do sometimes come from the machine, best to protect them. I use a face shield.
-Breathing – All materials have some dust created during the cut. Use at least a filter mask for non-toxic woods and cardboard something better for MDF and plastics.
(If at all possible make or buy a dust collection system to keep the fumes and dust to a minimum. That’s the next project for us after this contest. Wish I had done it earlier.)
Step 7: Power
Step 8: Zero, Zero, Zero
Step 9: Magic
When the cycle ends, and the router comes back to zero, turn it off. Then remove all the screws, or what-have-you that is holding the material firmly. Pick up the piece and be amazed. Remove the waste sections, and vacuum or blow off the dust so the machine is ready for the next fabulous project.
Step 10: Check and Re-do
Most of the time, it takes several iterations and tests to get it right. This one took four tries to achieve the high standards I aspire to. Something like approaching infinity, I’m never quite there.
If yours is perfect, move on down to finishing.
Step 11: Finish
Then apply Mineral oil (food safe) to all surfaces and let dry completely. Just an hour or two will do.
Last the hinges must be attached to the two parts. I clamped the parts with about a 1/8” gap (the thickness of a file I had) between them. Then laying the hinges in what looked good to me position, I drilled the holes with a self-centering hinge bit (if you haven’t tried them they are wonderful). I was careful to aim the drill a bit to the side so as not to cut into the cavity. Put the screws in and you are ready to go baking.
Step 12: Baking Adventures
None of them, at first, could figure what to do when the first trials failed. What happened, was that I got a beautiful impression in the dough, but when cooked, all those clear impressions just disappeared. Bummer!
Turns out that as the fats melt, any shape in them or the dough tends to go away, little did I know.
So after checking with those more knowledgeable, a possible solution was tested.
Step 13: Dough
Mix together in a large bowl:
4 cups all purpouse flour
1 Tbs sugar
2 tsp salt
Add and mix with a fork or pastry cutter till crumbly
1 3/4 cups Crisco or lard or butter (room temperature)
In a small bowl beat together:
1/2 cup cold water
1 Tbs white or cider vinegar
1 large egg
Mix the wet into the dry ingredients with a fork until it just holds together.
Turn out onto the counter and divide into four equal pieces.
Smush each portion into 1" thick patties and wrap with plastic wrap.
Refrigerate until stiff (at least 1/2 hour).
Makes 2 double crust or 4 single crusts.
Can be frozen indefinitely.
Step 14: Using the Mold
Step 15: Filling
Step 16: Baking
This is when another chef gave me the idea to cut the symbol into the dough and place another thin piece of dough on the back (inside) as a sort of band-aid. Well this seemed a bit too fiddly, so being a shop guy not a baker, I went back and re-cut the mold twice more at different depths to see if thicker dough would hold the impression better. No joy, that approach was no better and made a lousy tasting pie.
Step 17: Voila!
I went back to the original mold and figured out how to use a spoon to squish the dough down to expose the symbol and carefully cut the dough around it using a knife, then place a band-aid on the inside before filling ( you will see this in Step 14). Way fiddly, but the result was what I was looking for. The last improvement was suggested by my lovely wife. Mixing egg and milk together and brushing it on the dough before cooking gave them a pleasant golden sheen rather than pasty white.
Step 18: Conclusion
The press worked extremely well, but trying to emboss images into dough (either positive or negative) was not at all successful.
I think next time, I will make a cookie cutter like device from sheet metal to cut the pi symbol. It might work as well, probably better.
And the band-aid idea---brilliant!
Another Instructable maybe?