I will be scraping some bronze bearings that are located in the wrist pin end on a connecting rod in a old, slow speed compressor. The bearing is an adjustable 'wedge type'. My understanding is that I will need to:<br>1. put the assembly together in a vice<br>2. coat the bearing id with prussion blue<br>3. install the wrist pin, tighten the bearing adjustment bolt, and rotate the wrist pin<br>4. remove the wrist pin and locate high spots on the bearing surface<br>5. remove the high spots on the bearing via a halh round scraper<br>6. repeat the above procedure until a nominal 60% contact is obtained<p>The pin has tapered ends and I have lapped it true to the crossead. I had the bearing surface of the wrist pin chrome plated and ground. <p>Any advise would be appreciated, i.e. do's and dont's. I am 32 and I have meet few machinists/millwrights/mechanics that have been able to tell and/or show me how to accomplish this task.<p>Any help will be appreciated.<p>rchandy@gulfcoastcompression.com<br>



rchandy@gulfcoastcompression.com

From your description you have a newly machined wrist pin and worn brasses? If so, or if your brasses have been machined also, it is easier to read the bluing if you coat the outside of the wristpin thinly with blue. High spots on the bearing would be indicated by the presence of blue wiped off onto the brasses. This is easier to see than if the brasses were coated and the wristpin inserted and rubbed , as you would have to locate areas where the blue had been wiped-off the brasses. It is easier to see the deposit of blue that the absence of blue wiped off. If your pin is new and your brasses bored with proper clearance, there should be no nood to blue and scrape. You should, however, check the accuracy of the machining to make sure that the edges of the brasses (where they touch coming together) are not scraping the wrist pin as clearance here is good. You want the brass bearing to have contact from the crown toward the edge but not touching at the edge. If freshly machined and not touching on the edges, leave it alone and run it.<br>



steamrr@mashell.com