HLV-H Tool Post Slide seems loose
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  1. #1
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    Default HLV-H Tool Post Slide seems loose

    I was doing a profile face cut on my HLV-H this evening. These put a good bit of pressure on the tool, and so I tend to take it pretty easy with them. I felt like the tool post was rocking back slightly under the pressure. Also, it had vibration in it that seemed like too much for the relatively easy cut I was making. The vibration stopped between the tool slide assembly and the cross slide: the cross slide did not vibrate much.

    I checked the tool slide's ways, and they were correctly adjusted and lubed. I then squirted some way oil around the base of the tool post slide, and noticed that when I took another cut the slide assembly tilted back enough so that I could actually see the puddle of lube suck under the slide assembly slightly.

    The problem definitely seems to be on the interface between the top of the cross slide, and the bottom of the tool post slide assembly. As you know, this is held together by the eccentric rod with the hex socket head. Something is not right, but I can't see what.

    Removing the tool slide assembly off the mount is really difficult. The eccentric comes out easily enough, and the tool slide assembly can be raised up about 5/8" without problem, but it's very hard to get totally disengaged from the mounting rod (the one that's drilled for the eccentric).

    Once the tool slide assembly is off the mounting rod, it becomes clear that the mounting rod has a lot of vertical play, and can be rocked back and forth without really finding a seat against the inside-top of the cross slide.

    I've cleaned everything (really, it wasn't dirty & no chips in the way) and put it back together, and turned pretty hard on that eccentric. No luck, the performance is unchanged.

    I've looked at the eccentric, and it is not bent at all or worn very much. It seats up nicely.

    Can someone please help me with a suggestion as to what might be wrong?

    Thanks very much!
    Dave

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    Hi Dave did you try the excentric bolt in the mating hole without the compound slide the cam might be jaming in the hole before it has pulled the compound and cross slide together
    I will strip mine down in about 2 hrs and get back to you
    mabe make a new cam bolt with more throw
    Kevin

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    Quote Originally Posted by keebo View Post
    Hi Dave did you try the excentric bolt in the mating hole without the compound slide the cam might be jaming in the hole before it has pulled the compound and cross slide together
    Keebo, as far as I can see this is working correctly. As you suggest, I tried just the eccentric and the mating hole (no tool post slide). As far as I can see, the parts mate and turn as designed.

    Quote Originally Posted by keebo View Post
    I will strip mine down in about 2 hrs and get back to you
    mabe make a new cam bolt with more throw
    Kevin
    I really appreciate that, thanks! I've looked again carefully at the eccentric bolt, and I just don't think it's the problem. There is very little wear on it, and no marks or bulges where some Hercules might have turned it too hard.

    Don't get me wrong, the tool slide does lock down. It just seems to be slightly wiggly under moderate cutting force, really, a good bit more wiggly than I think is OK. But, you cannot just spin the tool slide around by hand, it definitely binds down much harder than that.

    When you lift off your tool slide, I'd be very curious to know if it comes off the mounting rod (the one drilled for the eccentric cam) easily. Mine lets me lift of the tool slide about 5/8", but then it's extremely difficult to get it free of the last tiny bit of the mounting rod. Also, after the tool slide is off, the mounting rod has an enormous amount of play: even when you pull upwards on it to seat it it does not seem to have a "favored" center position.

    Thanks very much for the help!
    Dave

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    Hi Dave I'm back with a picture
    Is your cam bolt the same as mine also do you have the location ring that fits to the bottom of the compound slide (2 screws)
    My center post is pretty loose it will rock around (not the clock) but about 2mm
    Also have you got the woodruff key in your center post
    Second picture any cracks to the compound slide base see green area
    Kevin
    Attached Thumbnails Attached Thumbnails ebay-new-213.jpg   ebay-new-213a.jpg  
    Last edited by keebo; 01-11-2008 at 01:51 PM.

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    I suspect the center post, through which the eccentric passes, has yielded. It is hard to pull off the compound because of burrs at the top of the cross hole in that part. It is easy to file off the burrs. If you remove the cross slide, the post can be removed and examined. I think the head on the bottom of the post has been deformed, effectively making the post longer, so that the compound does not get tight.

    Larry

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    Kevin,

    Many thanks for the excellent pictures and the time and trouble you spent! My cam eccentric looks exactly like yours, and this evening I confirmed that it was straight. I've got the locating ring you mention as well, and it seems to be alright but after looking at it I don't think it actually comes into contact in the horizontal plane; I think it is simply a guide to locate the tool slide assembly when the eccentric is loose and the assembly is being moved to a new radial position. There is a somewhat scruffy looking woodruff key in the center post; it has seen better days but seems adequate for its job.

    Regarding your second picture; I cleaned the bottom of the tool slide assembly and looked it over very carefully for cracks. I have to admit I did not see any, but if swapping out the center post doesn't cure the problem I'll bring the slide out for magnafluxing.

    Larry,

    Thank you very much for your help! On removing the center post it appears that it has elongated slightly. I don't know how long the shaft was originally, or how much elongation it can reasonably tolerate, but I'm going to change it out with a new one and see if that solves the problem.

    It will take a few days to get the part, but I'll report results back on this thread.

    Thank you both again very much for your thoughtful analyses and help. I appreciate it very much!

    Best regards,
    Dave

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    In my humble opinion, I will venture to guess that your slide is snug with the eccentric lock down bolt and the rocking action that you have is due to the bottom slide being "bowed".
    Due to the design of the compound slide single eccentric lock bolt, over time some small chips accumulate under the slide and while locking down the slide, these small particles "hold up" the lower slide slightly while the center eccentric lock bolt draws down the middle area only.
    You will see a shiney area on the bottom of the slide directly beside the post opening.
    I suggest removing the ring,
    Stone the bottom and place the whole compound on a granite plate or similar. You will probably get .003" rocking motion.
    Eliminate the "raised shiney" area, and you will help flaten the bottom of the slide.
    Of course, the best way is to dismantle and grind and scrape properly, but eliminating the raised area or the curve of the bow, should help.
    Good luck.

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    Paul, I've often wondered, does the compund ride and seat on the small ring screwed to the bottom, or does it bear on the whole "metal to metal" contact patch of the compound? If so, what is the purpose of the smaller ring?

    Thanks.

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    The ring is just a sheet steel stamping, so the top and bottom surfaces are not precise. It provides a rotating locator for the swivel action of the compound. The large diameter of the ring locates better than the center post, which is left free to float in an oversized hole. The contact between the bottom of the compound and the top of the cross slide is several square inches of hand scraped cast iron.

    This design, with the ring, dates back to the 1946 slide rest for the DV-59.

    Larry

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    What Larry said.
    The cutting forces are transferred to the cross slide due to direct contact of the compound and the top of the cross slide.
    Your compound, if I am correct, is "rocking" or pivoting due to the high point caused by a slight bow in the base.
    The high point is the pivot point.
    If the eccentric was worn, you would be able to continue around during tightening.
    Good luck,
    PJB

  11. #11
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    Quote Originally Posted by Paul Babin View Post
    You will see a shiney area on the bottom of the slide directly beside the post opening. ..... You will probably get .003" rocking motion.
    Correct on all counts. Man, it's like you were there.

    The bottom of that compound is going to have an intimate exchange of views with a surface grinder tomorrow evening.

    Many thanks!
    Dave

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    Smile

    You are welcome.
    I have seem many compounds during 30 years of rebuilding HLVs and Bridgeports.

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    Hello,
    I know this is an old post, but I hope people can still react. My HLV-H suffers the exact same problem. When using a cutting blade i can hear/feel the compound slide moving resulting in a lot of vibrations and noises. I noticed the "shiney area" as mentioned in here and took the compound slide to a grinder to grind it flat again. It seems a bit improved but the problem is not 100% solved. If i put some oil on the surface of the cross slide where it meets the compound slide and i take a heavy cut, i can see that the compound slide move, because the oil is "sucked" under the compound slide.
    Is it common to also grind the cross slide surface? Since I have no knowledge of scraping that would be my only solution, but I am afraid that the "degrees reading" will also be grinded off then?

    Sorry for my bad english, and thanks for an answer,
    Regards, Melle in Holland

    Verstuurd vanaf mijn Nexus 7 met Tapatalk

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    I dug up this old thread while searching for fixes for the distorted area under my compound. Figured I'd post a picture of the affected area (which is raised about .002").
    I'll scrape the areas lightly and verify with honing stones.

    Paul Babin's explanation of why it probably happens seems very likely.

    2019-08-09_1253.jpg

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    Whatever the reason it's seems like a problem endemic to the design. I'm currently fixing the same issue on my machine by scraping it all flat.

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    Quote Originally Posted by Peter. View Post
    ...I'm currently fixing the same issue on my machine by scraping it all flat.
    Wow, that's alot of distortion you have there.

    Tonight, I scraped my high spots until a straight edge didn't rock and a stone showed spot contact.
    Then indicated the whole bottom surface, as an assembly, to show approx. .0005" deviation from planar.

    My, new to me, lathe worked fine before, but I was setting up to turn some accurate 2 deg. tapers and noticed some rocking.

    I still have the slightest hint of rocking but the tapers turned out great, I think I will call it good...for now.

  17. #17
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    Yep, this seems to be a well known feature on HVHs. I had to work the base of the compound slide exensively to get it to work well, It was worn by a lot.

    I suspect that the assembly has always been problematic for anyone to uses the lathe as other than a precision tiny part machine. The assembly there
    is basically pretty delicate.

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    Paul pointed me to the same problem last year when I was having problems turning. Paul point me to the same spot. The retractable slide makes internal threading simpler.


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