Parker surface grinder table ways
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  1. #1
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    Default Parker surface grinder table ways

    I have a Parker surface grinder that has Rulon on the table ways. I have had the table off and cleaned everything. It all looks good but the table does not slide freely. I have replaced the hand crank bearings.No change in stiffness. Have tried thick and thin way oil. No difference. Alot of my other Parkers have a teflon liner on the ways. Is the Rulon liner incorrect for this application? It feels like I have too much friction. Possibly too much surface to surface contact? Any advise would be appreciated.

  2. #2
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    Even with Turcite / Rulon material you can get stick slip. When I taught classes in Taiwan the machine builders were seeing stick-slip on Vertical Machining Centers especially under the saddle or Y axis. PTFE materials are soft and compress so if they only ground it or did not scrape it deep enough it would get stick slip.

    Most folks apply it wrong too, when I contacted Tri-Star Plastic who sell it, they told me that machine builders do not understand the application principles of the plastic. I saw this on the ways of a Drake Thread grinder when I pulled the table off the bed on a rebuild I did a few years ago at Minnesota Grinding. The original Excello thread grinder base that Drake rebuilt and adding their software to make their machine. The original machine was cast on cast ways. The original V and Flat ways were about 2 1/2 wide, but the strip of Rulon they glued to it was about 3/4" wide. I called Tri-Star and asked an application Engineer and he told me that rulon does not achieve it best mechanical wear factor unless it is compressed. I will write them and ask to get a letter from them again explaining this.

    As far as the question. Next time you have the table off take some pictures and post them here. What your going to have to do is scrape in some oil pockets so they oil can adhere to the material. Another thing to think about is how the oil spreads out of the oil grooves. Think about that Rulon or Turcite compresses and if the material is 100% contact it is like a gasket and the oil can not flow out of the grove.

    With out a picture this is a educated guess. Scrape the Rulon with a hand scraper with the blade ground and then lapped to a negative 12 deg rake and a 20 mm radius tip. The scraped pockets should be a minimum of .002" deep. You could also scrape the cast iron opposite side to break up the surface again so the oil can adhere to the iron. If it is worn smooth or ground it is like rubbing gage blocks together and you get stick slip.
    Picture is from PMC a Research center in Taiwan where we teach scraping. See the 50% contact and 40 PPI on 1st pic and 20 PPI on the other.
    Rich.

    dsc00534.jpgimg_1407.jpgimg_0572-1-.jpgimag0613-1-.jpg

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