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  1. #141
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    Another issue is you have to clean the coolant tank sooner if you don't have a fiber coolant cleaner...I couldn't afford one back when I had my Thompson...man could she hog :-) I can't wait to see your base scraping. Your a great student...is your friend who ground the stones Stefan G? He told me he is grinding stones and giving (and selling them) to people in Europe? Rich

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    Hi Richard,

    Quote Originally Posted by Richard King View Post
    I can't wait to see your base scraping. Your a great student.
    Thank you, but here I think the teacher deserves the credit! (By the way, you're mixing up this thread with this other one.)

    ..is your friend who ground the stones Stefan G?
    No, it's a different Stefan, and the ground stones also come from a different source. But I am probably going to purchase a pair of these stones myself from Stefan G.

    He told me he is grinding stones and giving (and selling them) to people in Europe?
    Yes, that's right. Perhaps it's overkill for removing scraping burrs. But I like the way that it polishes the high spots so you can see what sort of coverage you are getting.

    Cheers,
    Bruce

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  4. #143
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    Quote Originally Posted by ballen View Post
    Thanks for all the helpful replies!

    Ewlsey: based on some of the other comments here, I'm going to go cautiously at first. Yeah, I think they used one of those paint-eating synthetic clear lubricants, which leaves an almost impossible-to-remove sticky coating on paint. (I remove it by wet sanding with soap and water followed by some polishing compound.) The deflection I am worried about is not deflection of the chuck, which is about 3" thick, but deflection of the table underneath it which is thinner. If that is deformed by clamping forces, it will make the machine inaccurate.

    Peter: I'll do what you suggest. I've got a surface plate that's the right size for the chuck, so I can verify the chuck on that, or scrape it if needed. Then I can use this as a master for the top of the table.Regarding table wear, I have now looked at the scraping marks underneath the table and they are perfect and pristine. So whatever might have happened with the rust, I don't think it wore the table in the middle.

    Cash: I would use Never-Seize but I don't know where to get it in Germany or in Europe. I am hoping that the bottom of the chuck will clean up with the Evaporust to leave the original pre-rust flat surface. Likewise for the table. So this way I can avoid the bowing.

    Stephen: thanks for the step-by-step. I'm a fan of LPS products, and Boeing T9, so will see if those can be had in Europe. I'm going to try and avoid the humping x 2, because I suspect that the machine as I have it is basically pristine. So I'll go slowly and do some measuring before anything else. (All the evidence indicates that this machine was used for some months in 1987, enough to wear/dress about 10mm off a 200mm x 20mm wheel, and then hardly ever used after that. The chuck controller had some problems that I repaired, it might have been that when that went south the owners stuck it in a corner and never got around to getting it fixed.

    Cheers,
    Bruce
    [Quote]

    “Regarding table wear, I have now looked at the scraping marks underneath the table and they are perfect and pristine. So whatever might have happened with the rust, I don't think it wore the table in the middle.”

    That is a great break and likely eliminates a lot of work. It basically looks to be a fine grinder. Using good coolant and taking some extra time to keep up the maintenance you will be served well. I appreciate the pictures as that makes it easy to understand what you have and where you are going.

  7. #145
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    I used to use Never Seize thinned out with spindle oil for years. Then my journeyman machine tool rebuilder made the comment that never seize has very small balls/pebbles in it, maybe we are talking a couple thou diameter.

    He felt this could be enough to allow coolant to start to get in, I agreed with this.

    So we have switched to grease. I use Mobil EP0 as we get this in 5 gal pails so we just scoop in on the tables.

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    At my first real job Cutmore Tool the common method was to cut a sheet of mylar to the size on the chuck and use it as an underlay, with putting a note at the machine back "chuck replaced-date."

    Qt Cash; [switched to grease.] seems a good method.

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    I thought I would follow up after 2 1/2 years, when I ground the table top and the bottom of the chuck.

    This morning I needed to grind a large part, almost as big as the chuck. I haven't done any really big parts for a while, so I measured the chuck to see if I should dust it and discovered that it was tilted about 35 microns (0.035mm = 0.0014") over the 450mm (18") length. That seemed like too much, so I took it off.

    Here's the table:



    And here's the chuck (compare with this, 3 years ago).



    I scrubbed them both off with a brass brush and WD40, then stoned them lightly. After I was done the bottom of the chuck was much smoother than the table.



    The table was rougher feeling (forgot to take a picture).

    I have the impression that at least some of the rust is because the cast iron has a different electrochemical potential than the steel of the chuck. So this time, when I put them back together, in addition to the German-LP3 I put a layer of 150 micron (0.006") mylar in between the chuck and the table. That will prevent metal-to-metal contact, so should avoid creating a corrosion cell. I'll check back in here in a few more years to report if it worked.

    PS: a nice surprise, after I had cleaned everything off and reinstalled the chuck, it was flat to about 5 microns (0.0002") which was good enough for the part I needed to grind. The cleanup removed the tilt.

    Cheers,
    Bruce
    Last edited by ballen; 02-17-2020 at 10:58 AM.

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  12. #148
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    A very interesting thread Bruce and some very enlightening replies ...

    I'm taking delivery of a 1972 J&S540 this week ... first job will be the chuck off!

    just wonder what I'll find??

    John

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    I have heard that you must not put oil between the chuck
    and the table because it lifts the chuck. Now it seems
    that not oiling the mating surfaces also causes problems.

    What is the best thing to do?

  14. #150
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    Quote Originally Posted by ballen View Post
    I thought I would follow up after 2 1/2 years, when I ground the table top and the bottom of the chuck.

    This morning I needed to grind a large part, almost as big as the chuck. I haven't done any really big parts for a while, so I measured the chuck to see if I should dust it and discovered that it was tilted about 35 microns (0.035mm = 0.0014") over the 450mm (18") length. That seemed like too much, so I took it off.

    Here's the table:



    And here's the chuck (compare with this, 2 1/2 years ago).



    I scrubbed them both off with a brass brush and WD40, then stoned them lightly. After I was done the bottom of the chuck was much smoother than the table.



    The table was rougher feeling (forgot to take a picture).

    I have the impression that at least some of the rust is because the cast iron has a different electrochemical potential than the steel of the chuck. So this time, when I put them back together, in addition to the German-LP3 I put a layer of 150 micron (0.006") mylar in between the chuck and the table. That will prevent metal-to-metal contact, so should avoid creating a corrosion cell. I'll check back in here in a few more years to report if it worked.

    PS: a nice surprise, after I had cleaned everything off and reinstalled the chuck, it was flat to about 5 microns (0.0002") which was good enough for the part I needed to grind. The cleanup removed the tilt.

    Cheers,
    Bruce
    That's only what I would expect to see under a chuck and you say that one only gets occasional use. Imagine what a well used chuck would look like. Even with copper grease and a bead of silicon all the way around you still get a mess after a year or two of heavy use.

    Regards Tyrone/

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    Hi Tyrone,

    have you come across Permatex Form-A-Gasket No. 2 Sealant? It's a sticky smelly black goo: a slow-drying non-hardening sealant. If I put a bead of that between the chuck and the table, no air or water or coolant would get into the gap, so no corrosion. But I am afraid that the chuck might be nearly impossible to remove from the table. Has anyone out there tried this?

    Cheers,
    Bruce

  17. #152
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    Quote Originally Posted by ballen View Post
    Hi Tyrone,

    have you come across Permatex Form-A-Gasket No. 2 Sealant? It's a sticky smelly black goo: a slow-drying non-hardening sealant. If I put a bead of that between the chuck and the table, no air or water or coolant would get into the gap, so no corrosion. But I am afraid that the chuck might be nearly impossible to remove from the table. Has anyone out there tried this?

    Cheers,
    Bruce
    That's not something I've come across but it sounds like " Hylomar " jointing paste that was made over here initially for " Rolls-Royce ". That was like a toothpaste style product but blue in colour. It was mainly used for sealing gearbox lids, end caps etc. It stayed " plastic " in nature. What it would be like between a cast iron work table and a magnetic chuck I wouldn't know.

    Regards Tyrone.

  18. #153
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    MolyKote 111 compound has been recommended for use between the magnetic chuck and the table. I've got a tube of it, but haven't used it yet. At the moment, the chuck is resting on a layer of zinc-rich paint that I sprayed on the table and allowed to nearly dry before replacing the chuck.

  19. #154
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    Has anyone tried the Kendall SHP grease? It really does work. Honest,.

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  21. #155
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    molycote 111 seems to be silicone grease. thats what i use, its fairly cheap and you can get it where they sell/service grass robots.


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