Oil pockets or grooves on cylindrical grinder swivel table?
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    Default Oil pockets or grooves on cylindrical grinder swivel table?

    I have a question for Richard or anyone else here who has some hands on experience with fixing up cylindrical grinders.

    The swivel table on top is used for grinding tapers. On my grinder you tweak it to get your part cylindrical/parallel and then you set over the swivel table using gage blocks, to get a specific taper. There is a nice screw feed handle for doing this.

    In practice, when the time comes to swivel it, the table is a bit stuck/glued in position. After it breaks free it moves OK, but the reason for this is that both the underside of the swivel table and the top of the moving slide table have ground pads where they meet. So they tend to wring together.

    The geometry is perfect, nothing to fix there, but I was wondering if it made sense to scrape some half-moons on one of the faces, or just break it up with the crosses using the Biax, making sure to leave enough original surface to preserve the geometry.

    But this might also be a bad idea, because this is an area quite exposed to grit and coolant, and by design, when you slide the swivel table, it will expose part of the top and bottom pads. Also, those pads are different sizes, the top ones are larger than on the bottom, so if I follow the rule of thumb to put oil pockets in the top part, those will be exposed to air/grit.

    Another approach would be to make some oil grooves which can not be exposed and add oil ports and nipples.

    Which brings me to my question for Richard: do you put oil grooves or oil pockets on swivel tables? Where??

    Thanks!

    Bruce

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    Bruce

    It's midnight here. I used to 1/2 moon the bottom of it and then squirted Vactra 2 so there is always some lube in the little puddles. When many of those machines were made, they planned the tables and the planning left minute holes in the casting that held the oil. I used to guarantee my work for a year as long as proper maintenance was used. Your parts are ground and have stick slip like you said if you do nothing. 6 of one 1/2 dozen to the other. So you could do both, square cut the table top and also 1/2 moon the bottom of plate. But if your smart pull it apart in a year and see what it looks like

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    My Abene cylindrical grinder's swivel is scraped both top and bottom. It gets "gunked" up. I think removing the top part of the table for cleaning is regular maintenance. FWIW

    Bill

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    Quote Originally Posted by Bill in PA View Post
    My Abene cylindrical grinder's swivel is scraped both top and bottom.
    Do you know if it's jsut scraped for flatness/contact? Or does it also have deeper oil pockets (half moons, typically) scraped in?

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    It's midnight here.
    Thanks for replying quickly!

    I used to 1/2 moon the bottom of it and then squirted Vactra 2 so there is always some lube in the little puddles.
    Do you mean "1/2 moon the bottom of the upper (swivel) table" or do you mean "1/2 moon the bottom sliding table"? I think you mean the first but am not sure.

    When many of those machines were made, they planned the tables and the planning left minute holes in the casting that held the oil.
    On my machine those surfaces are ground not planed.

    So you could do both, square cut the table top and also 1/2 moon the bottom of plate.
    Here I am pretty sure you you mean "square cut the lower part (sliding table) and 1/2 moon the upper part (swivel plate)". Is that right?

    But if your smart pull it apart in a year and see what it looks like
    Which is also what Bill said. Makes sense.

    Thanks again!

    Cheers,
    Bruce

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    Square cutting means the same as "Crosses" or equally spaced and length scape marks and the comeback 180 degrees so you get the checkerboard look or design pattern. As you said it does not change the geometry, just adds oil pockets that looks super. I meant to 1/2 moon the bottom of the swivel plate and square cut the top of sliding table. Or you could just square cut the bottom of the table. I don't remember if you own a BIAX 1/2 moon flaker BL-10. If you don't just square cut it. Your not doing this for geometry and no one will ever see it. 1/2 moon flaking the top of slide table is also possible as it is not exposed to the air so grit will lay in the .002" deep flake marks. You should be able to figure this out on your own.

    Your looking for a way to help the swivel table to move easier when you adjust the taper and one way or the other will work and make it better then having gauge block stick slip super flat surfaces. After you squirt the oil under there you could wipe it or squeegee off the top and only have the oil in the pockets. Tell us how does it grind now? After taking the scraping class in Austria has your knowledge of scraping changed? I will be teaching again in Austria again in October thru BIAX again. Come on over and tell your friends. I hope to go fishing on the Lake this time :-)

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    The Jones and Shipman 1310 I ran in school (didn't finish the apprentice training but that's another story) didn't have much for contacting surfaces between top swivelling table and sub table. I'm pretty sure, from memory, the bottom surface of top table was flaked. It didn't get much maintenance (or use) being a school machine, but it was no problem to nudge the top table into place. Bruce, how much contact surface area does your machine have between top plate and sub table?

    Lucky7

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    It's a common problem on universal grinding machine swivel tables. The are normally set in the optimum position for parallel grinding and are only moved to produce tapered work now and again. Coolant can get between the two surfaces and gum up the works.

    As said by other posters, regular cleaning and maintenance are the only real solutions.

    Regards Tyrone.

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    Quote Originally Posted by lucky7 View Post
    How much contact surface area does your machine have between top plate and sub table?
    It's a few hundred square centimeters, or a few dozen square inches.

    Here is a old photo of the swivel table before I had it reground. From memory it's about 18 x 100cm (7x40"). The numbers in black are microns away from planar, it was really screwed up in that top left corner, which was under the workhead. The factory would not have let it out the door like this, so that means it was (badly) reworked in the past. That means it might have looked different (ie, scraped and/or pocketed) when it was new.


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    Quote Originally Posted by Tyrone Shoelaces View Post
    As said by other posters, regular cleaning and maintenance are the only real solutions.
    Tyrone, you must have repaired at least a few J&S cylindrical grinders. How did they come from the factory? Were these surfaces ground or scraped or pocketed or ???

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    Quote Originally Posted by ballen View Post
    It's a few hundred square centimeters, or a few dozen square inches.

    Here is a old photo of the swivel table before I had it reground. From memory it's about 18 x 100cm (7x40"). The numbers in black are microns away from planar, it was really screwed up in that top left corner, which was under the workhead. The factory would not have let it out the door like this, so that means it was (badly) reworked in the past. That means it might have looked different (ie, scraped and/or pocketed) when it was new.

    The top of the photo it looks like it is ground or shinier then the bottom and it's marked - 130 ?? or lower then the bottom side of the photo?

    Did you have it ground? Did you scrape it flat prior to sending it to the surface grinder? Many make the mistake by ASSUMING a ground surface is perfect and ASSUME the grinder company knows what the heck is going on. If they are machine rebuilders like Cash and yours-truly they scrape one side prior to grinding so when the grinding company can mag down a flat surface and not mag down to a twisted surface that looks shiny and perfect, but it's not and it gets ground cockeyed.

    I am not scolding anyone, just making a point to all the readers that you can not ASSUME anything when it comes to rebuilding you have to PROVE it. That is why I tell everyone to be a detective and measure and test everything prior to scraping and grinding everything. It may take extra time in the beginning, but will save tons of time and money afterwards if they screw it up. If I had sent the swivel plate out to be ground, I would have first stoned everything, wiped it off, set it on a granite plate and checked the swivel and tried to slide in feeler gages, tapped the up side with a dead blow hammer. Miked the parallelism or indicated it like your doing.

    Then flip it over and do the same thing. Keeping in mind I am looking for the flattest side and I will rough scrape the best side before sending it out. I would always mark on the part "grind this side first (the bad side) then flip it over and grind the rough scraped side. No need to scrape more then 2 to 5 PPI and no need to worry about the looks as your just looking for contact with-out a twist when it is magged down. Then when your finished it will be parallel and flat as long as you scraped the table top parallel to the bed. Like building a house. Good foundation and straight and level as you build up. :-)
    Last edited by Richard King; 04-01-2019 at 11:23 AM.

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    Quote Originally Posted by ballen View Post
    Tyrone, you must have repaired at least a few J&S cylindrical grinders. How did they come from the factory? Were these surfaces ground or scraped or pocketed or ???
    I can't remember what I had for my tea last night ! The bigger " Churchill " machines weren't scraped there if that bit of my memory still functions. Do you plan on adjusting it regularly ?

    I remember a pal of mine buying a very expensive hi fi system back in the day. The guy invited me around to his house to listen to it. Without any music playing at all he cranked the pre amp and power amp up to the max. It was really quiet. He said to me " Listen to that Tyrone, not a murmur ".

    Regards Tyrone.

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    Quote Originally Posted by Tyrone Shoelaces View Post
    Do you plan on adjusting it regularly ?
    In production use suppose you might tune in the swivel table and then not touch it for weeks or months or years. But that's not my situation. I'm using it for one-offs and repairs and always seem to be adjusting the swivel table back and forth. For example I am still in the process of making tooling for the machine, so grinding lots of short MT5 tapers.

    I remember a pal of mine buying a very expensive hi fi system back in the day. <SNIP> He said to me " Listen to that Tyrone, not a murmur ".
    I am using the machine, and the swivel table. Not every day all day, but at least a couple of times a month.

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    The top of the photo it looks like it is ground or shinier then the bottom and it's marked - 130 ?? or lower then the bottom side of the photo?
    It's been about a year since I had this ground, but as I recall there was no difference in the finish on that bum corner and the rest. So I think you are just seeing an effect of bad photo lighting.

    I did spend many hours checking out this table before it was ground. The remarkable thing was that the other side (top side) was flat to within 5 microns (0.0002"). Just that one corner on the bottom was messed up. The guy who ground it did not magnetise the chuck, he just lay it on top, the weight held it down. After he had finished the underside and we checked the top, it was so close to perfect that he told me it was better just to leave it, he would not be able to make it better. (FWIW that was before I had your scraping class.)

    I've carefully checked the geometry with the swivel table assembled onto the slide table, and it within a few microns of perfect. So all that I might do is some oil pockets/square cutting as discussed earlier in this thread, just to make it easier to swivel. Still trying to decide if it makes sense.

    Note that before I had this swivel table ground the grinder geometry was horribly off at the left end. When I tightened down the swivel table it twisted that corner around 100 microns = 0.004". But it took me a long time to track down the cause. I definitely agree with your point about being a detective. You need to figure out what is wrong and have a plan, before you can fix it.

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    Quote Originally Posted by ballen View Post
    Do you know if it's jsut scraped for flatness/contact? Or does it also have deeper oil pockets (half moons, typically) scraped in?
    Scrapped for flatness no oil pockets. I just had it apart for cleaning last month. You'll have to wait until next year for pictures. Sorry.

    Bill

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