[SEL] Falk piston core box and pattern update.

[Judge Tommy Turner]

Thanks Curt.  I have a better idea of what you're talking about now.

Tommy Turner
Magnolia, KY


> Tommy,
> Consider a piston (or any hollow casting) that is perfectly 
> symmetrical on the inside. You make a core box that is essentially 1/2 
> of the core and you ram 2 of these core halves up and glue them 
> together. But in the case of Dave's Falk piston or my 3HP Herc piston 
> the inside is not symmetric. In Dave's piston there is a bottom that 
> sticks down from the top that drips oil on the wrist pin. On the Herc 
> piston there is a web across the top that supports the copper tube 
> that oils the wrist pin. Because of this you have 2 choices. Make 2 
> separate core boxes with this feature on the right on one half and 
> with this feature on the left on the other half.
> Or you can make a single core box and make the feature removable and 
> swappable (word?) to the other side. You also make a blank. By 
> swapping the blank and the feature, you are able to ram right and left 
> core halves with the same core box. For small volumes of casting this 
> is the most economical method, as making core boxes is labor intensive.
>
> As to the patterns and separating them. I spot glue mine and then 
> split with a 2" chisel. The paper method works too, but the spot glue 
> method works so well that's all I do now. Maybe 10 little drops spread 
> around in a pattern and the drop about 1/8" diameter. When you clamp 
> them to dry the spots will grow to about a 1/4" diameter. I also run a 
> thin bead at each end. That solid glued section either gets cut away 
> during the lathe work or you may have to saw into the end with a 
> hacksaw for a 1/4" or so. Then it will split easily. The glued end is 
> to add strength to the spreading forces the center tend to impose. 
> Having a pattern fly apart in the lathe wouldn't be too fun!
> Curt Holland
> Gastonia, NC
>
>
>
> Judge Tommy Turner wrote:
>
>> Dave or Curt,
>>    I have "loosely" followed the pattern making thread but wished I 
>> had paid more attention. Here are a couple of questions.  Can you 
>> give me some additional info. on the removable insert?  How's it held 
>> in, removed, etc.  Second, is it simply paper you put between the two 
>> halves before glueing so that you can separate them later?  I had a 
>> guy once tell me he glued newspaper between the halves then took a 
>> sharp chisel and with a blow of the mallet they would pop apart.  
>> This pattern work is beginning to interest me and I admire the work 
>> you've done.  Thanks.
>>
>
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