VN 16 leaking knee
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  1. #1
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    Default VN 16 leaking knee

    Hi All: Have a new to me VN 16 with oil leak from knee at threaded shaft which controls z axis. I have downloaded manual from the french website but I can't tell what I'm going to need to do to replace seal. Can I simply lift knee and remove 4 cap screws at upper end of shaft and pull shaft from below or will more tear apart of knee be necessary. I have searched web but don't see any threads talking about this. I'm not interested in a huge teardown as I see those threads often started and rarely finished. Plus, every truck I own leaks oil, so why shouldn't my mill!


    Sam

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    I will caveat what I'm about to say with the disclaimer that I've never had a VN 16 apart. However I have been inside the knee of my 22L and I'll say it looks far more complicated from the diagrams that it really is. If I had to guess I'd bet money you can probably service the screw from below. I would run the knew up, block it up and run some straps around the block(s) and mill body to hold them in place and lock the gibs. Then you can take the tension off the knee screw and start to dig into it and see how it goes. Worse case you get stuck and stop.

    Second part is what kind of oil are using? I believe VN called for oil with a viscosity 300 SUS @ 100F which would translate to a modern ISO 68 machine oil (Mobil DTE Heavy Medium). That said when I talked to RPI when they were still in business a few years ago they highly recommended a heavier oil like ISO-100 Mobile DTE Heavy in the old Van Normans.

    Good luck
    Mike

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    Mike: Thanks for encouragement. It sure does look complicated in the diagrams.

    I am using ISO 68 and will refill with something thicker. Sam

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    Is this a No. 16, or a later model such as a 16L or 16M?

    The No. 16/16L/16M/16S all had the X-axis feed motor in the knee, but no feeds for Y or Z. (The No. 22 has power feed on all three axes and has a much more complicated knee gearbox.) The No. 16 et al. elevation mechanism is fairly simple: the elevation handwheel drives the elevation screw via a pair of bevel gears. None of the complicated stuff in the knee is involved. I've not had mine apart, but it looks like you should be able to block the knee up at the top of travel, pull the bolts that secure the round bearing support (part number 16-1162) and then rotate the screw by hand to draw the top end of the elevation mechanism down out of the knee. (See page 19 of the No. 16 manual, "Knee Details Plate No. 8", upper left corner; or page 26 of the No. 16L/M/S manual, "Knee Details" Plate No. 12, upper left corner.) Some Permatex on the flange of 16-1162 should do the trick.

    Cal

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    This is a 16 plain. I looked at seal yesterday, "Garlock Klozure part 346" So I changed to new designation 0346 and went to garlock website. Came up with three different seal types with 0346 but only 1 is standard seal. 21158-0436 which crossed to skf 12545. 1 1/4 id and 2 1/8 od. Confirmed measurements on machine and it looks like a match. $9 delivered from Amazon. Will know more on Tuesday when they arrive (bought 2). Sam

  6. Likes Paolo_MD, Mike C., Ohio Mike liked this post
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    kimg0469.jpg
    Quick Followup. skf 12545 did fit but is not as robust of a seal as the original which was a multipart seal but was cracked and worn. New seal probably wont last as many decades as the last one.....

    As Mike and Cal suggested, pulling apart was not difficult. Blocked knee in place with 2x4s strapped to knee slide and loosed flanges at both ends of screw. Screwed in bottom flange to allow clearance and tapped shaft out without minimal fuss. There were shims under (above) upper flange to control gear mesh. Seal came out easily without disassembly of gears, just slid it down the screw and off bottom end. I did use permatex since there was no gasket at upper flange (probably also contributing to leak) but squashed permatex after about 10 minutes so as to not change gear mating. While apart, I did take chance to wipe out 6 decades of sludge from bottom of knee gearbox.

    Thanks for everyone's help with this little project. Sam kimg0471.jpg


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