Question On Cutting A Piston

[mike silvia]

Hi Guys
I need to machine valve clearance on some pistons. I'm using a Goodson UPV-35 UNIVERSAL PISTON VISE. Does anybody have experience with this vise? Or does anybody have any tips for me? Thanks for any input

 

[JimDawson]

I have never seen one of those before so I had to look it up. It doesn't look like anything I would want to hold a piston with for flycutting, at least not without substantial modification. Not enough beef there.

I also found this write up. http://www.speedtalk.com/forum/viewtopic.php?p=99322

The last time I needed to flycut pistons, I built a fixture to hold them in a mill vice. That was about 40 or so years ago

If I were going to buy or build a piston vice it would look something like this: http://www.jegs.com/p/Proform/Proform-Heavy-Duty-Multiple-Angle-Piston-Vise/2106721/10002/-1

 

[kd4gij]

Is this what you have?

 

[JimDawson]

Goodson UPV-35 UNIVERSAL PISTON VISE

 

[mike silvia]

I would prefer the red one...lol
but I have the other one

 

[kd4gij]

In that case I would use one of the jaws as a v-block in my mill vise.

 

[Andre]

I would take a big chunk of wood and bore out a center hole just the right size to fit the piston base (that hollow section, whatever you call it) then a cross-hole through the block for the wrist pin to aid in alignment. Then clamp the wood and piston in the vise.

You could also use a lathe chuck bolted down to the mill table and use that to gently grab the piston, and indicate each side of the wrist pin for alignment.

 

[chips&more]

The round bar goes through the wrist pin hole. Make a sleeve if necessary for a good fit. This process aligns the piston to the fixture. Put the loose V block thing on the end of the rod. Adjust the De-Sta-Co clamp for a good hold on the piston. Now you can mount this assembly on your mill for machining and repeat set-ups. Maybe even put the fixture in a vise for angle machining…Good Luck…Dave.

NOTE: the piston can be mounted on this fixture in one of two ways. Make sure you have proper orientation.

 

[mike silvia]

set it up on a sine bare and bypassed the quick clamp for a better hold on the piston
worked pretty good
Thanks for all the info