Tuesday, January 15, 2013

Error on page 3 of Farmboy plans?

Below is a "thread" of e-mails between me and "EngineMaker" - builder of Farmboy #003 on Jan 15th and 16th, 2013:


Me --> EngineMaker

I trust all is well with you and your family this New Year.

A customer has a question that I'm not sure about.  On page 3 of the Farmboy plans, in the upper-right "rearward view" it shows a dimension of .325 as the thickness of the side frame INCLUDING the cam shaft protrusion support.  So, .325 minus .250 (thickness of frame wall) should equal a protrusion thickness of .075.  However, the lower right "bottom view" it shows a protrusion thickness of .105 --- this is a .030 inch difference.  I can't quite get my cheapo caliper in there to measure the actual dimension on Dad's Farmboy (flywheels are in the way), and I was wondering if you could provide some insight.  If I were to make a guess, I'd say the .105 is correct, and the "rearward view" dimension is incorrect.

Please advise...


EngineMaker --> Me

I see what you mean on the drawings. I can't remember what dimension I used when I made mine in January of 09.

Looking at the drawing, the pad already has a 1/32 inch radius at the frame and the pad looks to be 2 times that in height than that which would put it about .094" high (all very inaccurate). If I had to guess I'd say I made it to the .105" number and if it was incorrect I could always mill it back down to .075" and I don't remember doing that.

Another way is to get the placement of the gears and then work backwards to see how high the pad has to be from the frame.

That being said I'll get in about 7 tonight and measure mine and get back to you.  I remember also your Dad told me that when he made the plans from the original engine that he made a few changes to parts to make them easier to make.


EngineMaker --> Me

I just got home and checked my Farmboy. The best that I can measure mine it looks like .375". Now if you take .250" for the frame and .105" for the pad you get .355". That's a difference of .020" which I'd say are the layers of paint on the inside of the frame and the outside of the pad on mine.  I'd say .105" is correct.

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