Making a 10cc Whippet pattern

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This came out better than I had hoped. Two out of the three head covers came out with a very nice fine finish and the bad one is still useable but has some pitting. Not much difference between the first two and I don’t think the knife gate made any difference in a pattern this small. The venting on the other hand I think did the most with the last picture being the one that had the least.

All in all a good day. Learned something, got to melt stuff ;D and now have 2/3 good castings that I’ll clean up and this time keep.

Hope you enjoyed this as much as I did. And thank you for your comments



I thought it was time for the family photo even if one member missing.

This last family member has been the red haired bastard step son. I don’t know how long I’ve been looking at this drawing and I don’t know if I will ever use it but seeing as it is a casting in the kit I thought I’d try. The contact breaker is not very big and has a lot of convoluted little corners so the only thing I could come up with was to attempt to make a split pattern for it.

Contact Breaker.jpg
I started with the round part at the bottom that mounts over the upper boss on the timing case. This section makes up the lower half of the body but is only 5/8” in diameter and a total 1/4” thick. With the pattern being split this means that I need two pieces at 1/8”. There is no way I could keep a square edge on these and keep all my fingers so I trued up the end of a dowel, cut off a disk a little long, glue the disk back onto the dowel to sand them to the 1/8” I needed.

To make the tapered top part I picked through my pile of paint stir sticks and picked out the one with the straightest grain I could find and planed down to 3/32”. Rough cut it and glued two of the pieces together with a 1 to 1 print of the pattern. Then I drilled holes to match the radius of the 5/8” bottom disk and the ¼” boss at the top, sanded it to shape and then split it.


The arm that the blade mounts onto is 1 ½” long, ¼” wide and needed to overlap the 5/8” button so I clamped it to a piece of scrap and drilled an offset recess about 3/32” deep then added the two bosses for the blade mount and push rod bushing.
To make the round bolt (little screw) boss at the bottom I just sanded off half of some ¼” dowel and used a round file to form the recess for it to sit in. With newspaper between the two halves I got everything glued up, put in some alignment pins and gave it a quick shot of primer.




This is definitely the smallest pattern I’ve tried, and I don’t know if I’ll use it but after some fiddling and sanding I got it to where it would pull from the sand. The tapered top part is not very thick so I wanted to see if it would cast.


This was a fun little piece to do and all in all it didn’t come out half bad. It has a lot of flash but a quick cleanup with a file and it’s not terrible at all.

Hum. I don’t remember turning on the date in that camera.
Actually I’m not sure how to turn on the date. scratch.gif




Hi bmac2

Given it looks like this thread has come to it's end, I just wanted to say thanks very much for sharing this with us. It's been extremely interesting, informative and motivational!

Looking forward to the build thread for this engine.

Thanks James.
The thread isn’t quite dead yet it’s just been on sabbatical for a bit. Between work and getting ready for winter (We usually get our first snow in Oct.) I haven’t had much free time. I hope to get the castings done in the next week or two and post a few videos.
I needed to make up some more cores before I could go any further so I’ve been messing around trying a few different setups. The biggest problem I have is the Co2. I’d like to use a paint ball cylinder but a new 20oz. one is around $50.00 and I’m too cheap to lay out the cash for something I’m just not sure I’d use that much so I’m on the scrounge for a used one.

Until then this is my latest incarnation of “Budget Sodium Silicate Cores”. If you only are working with a small core, the one for the Whippet takes 130g of sand so it’s pretty small. Or if you don’t think you’ll make a lot of cores, or just want to try it this could be a viable way to go with minimal cash outlay.

Small quantities of foundry grade sodium silicate are hard to come by but you can get wood stove gasket cement in almost any hardware store in a 2oz bottle for around $3.00 ($2.99 Can Tire). According to the MSDS its 47% sodium silicate and water. With 1 bottle I made 3 cores and have a bit left over.

The standard Crosman 12g Co2 cartridges work out to be about $0.85 each and it took one for each of the cores. I don’t know what they cost but a buddy of mine gave me this bicycle tire inflator that was leaking. A rubber grommet, quick and dirty mod with a piece of tubing and a dollar store funnel and it’s a Co2 dispenser. Now this thing REALLY NEEDS a regulator. You can control the Co2 with the trigger but I wore one of my cores when I squeezed it just a bit too much.:fan:

The sand I used was a mix of HD play sand and 50/100 blasting media. My thinking was that the larger partials in the play sand would allow the Co2 to penetrate the core better and that any surface’s that need a good finish are machined anyway.
I did the cores open filling each half of the mold and setting it with the Co2 before putting them in the foundry toaster oven at around 250f for half an hour to dry them out. One advantage to doing it this way is I can cut in venting that would be impossible any other way.
I’ve tried a couple of things as release agents and what I did this time was put on a thin film of Vaseline followed by a good dusting of talcum powder. It sounds like a weird mix but the cores just dropped out of the mold when I took them out of the oven. That’s right my manly-man foundry smells like a baby’s bum. ;D
Following Dougie’s (fourstroke) suggestion I put a nail through the core print before gluing the two halves tougher, hopefully this will keep it from going walkabout on me. I think I may have used too much SS in the mix because these are hard as a rock. It might be a ***** to clean them out but if I soak them for a day or so it shouldn’t be that bad.


Así que el fin de semana pasado me puse en marcha en el intento número 3. Volví a repasar la construcción de Dougies y miré las fotos de sus patrones. También volví y miré el hilo Making a set of Wallaby castings de jasonh ( Vi que ambos se construyen más como un pastel de capas. Nunca he hecho un pastel de capas, pero me he comido uno. Pasé un tiempo de calidad con mi CAD cortándolo en rodajas y ahora tenía un plan que creo que funcionará.

So this past weekend I got going on attempt No 3. Went back over Dougies build and looked at the pictures of his patterns. Also went back and looked at the thread Making a set of Wallaby castings by jasonh ( I saw both are built up more like a layer cake. Ive never made a layer cake, but I have eaten one. Spend some quality time with my CAD slicing it up and I now had a plan I think will work.

View attachment 77485

View attachment 77486
hello can you pass me the right leaf
In CAD this was easy a few round bits on a basically square bit. Now Ive made the jump from the cyber space onto the meat world and things got difficult. I need to make a negative mold to get a positive cast of the sand core so Ill have the correct negative (hollow) in the engine casting. This is what I want to end up with.

View attachment 77576
and this cad
I missed this thread when it got posted back in 2015.

Some interesting pattern work and backyard casting.

I recall the days of trying to find the right sand.
First it was the Home Depot playsand, and then the Northern Tool sandblasting sand.
Finally ended up with OK85, which is commercial foundry sand.

The sand and associated mold will make or break a good casting.

The washing soda as a degasser thing mentioned again.
I am not sure if this will ever go away, since it got popularized on youtube.
If you bake the washing soda completely dry before you use it, you will see it has no reaction with molten aluminum at all.

Turbulence causes some of the problems with his castings.
Abrupt changes in the flow of metal are not good.

I like making patterns from wood, but it is hard to beat the accuracty of a 3D printed pattern and corebox.

Some decent casting work in this thread.

I wonder if he got it completed.

hola este motor me gustaria fabricarlo
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