Need check on location of piston to crank disc connecting pin

[student123]

Doing my first engine, Dave Goodfellows brassy babe:
http://www.davegoodfellow.com/plans.pdf

Mine's been rechristened brassy madam. New to engines also.

I've followed the plans & located the pin linking piston to crank 1.05" from base of piston. If you do the algebra on the plans , the hole on the crank disc (which the pin goes into) should be 0.2" from the centre

Above is a pic of where the brassy madam build is at - the piston is at its lowest.
However , in the pic the link pin is virtually at to the centre of the crank disc

Am I right in assuming at the bottom end of the stroke, the piston wil be vertical & the conncing pin at its lowest point?

If yes, it looks like I need to relocate the connecting pin. Theres a pencilmark in the pic 0.2" from the centre of the crank disc -am I right in relocating the pin to align with that pencil mark (ie move the pin approx 0.2" down?

Thanks in advance

 

[kvom]

Am I right in assuming at the bottom end of the stroke, the piston wil be vertical & the conncing pin at its lowest point?

That assumption is correct. But comparing your parts to the plans something is not correct if the pistion is at the low point in your photo. Check all your measurements.

 

[PaulG]

Student123, The print shows .2375 from crank disk center.

Paul

 

[bearcar1]

Student123, the drawings are a bit confusing at best but given the dimensions of the crank disc diameter at .550" and the center reference of the pin hole being .075" from it's outer edge, then the hole should locate up at .195" from the disc center. (.200" being pretty close) At any rate, what you are displaying in your photo image there appears to be something "not right" and I suspect it to be your measurement of the distance from the very end of the piston rod/face to where the pin is physically located at this time. Double check all of your measurements once again and report back to us your findings. I'm sure it is nothing that can not be corrected easily enough. The old carpenter's adage of "measure twice and cut once" holds quite true. I know I've certainly made my share of those mistakes :


BC1
Jim

 

[student123]

Guys,

Thanks for the help. I had checked all the measurements before posting, & they all seem OK. But I think I've located the problem - the piston is not going all the way down into the cylinder bore. I need to take a little more metal off the cylinder.

As an aside, the calc I did for the location of the pin on the crank was diameter = 0.55 / 2 = (radius of) 0.275 - 0.075 (edge to connecting hole in the diagram) = 0.2in.

Mike

 

[bearcar1]

Student 123, you are correct in your calculations (unlike some of us *ahem*) That is how I make 90% of my mistakes but you seem to have found the problem. Good luck with fixing your problem, I'm going back to the blackboard now and practice my math skill some more. Now let's see, 4-2=2......6-4=2...8-4=4...... This is going to take a while. :big:

BC1
Jim

 

[tony_m_baker]

Do you still have the plans for this? I'm trying to build it and only have a partial plan and the website is gone.