Page 1 of 2 12 LastLast
Results 1 to 10 of 12

Thread: Vertical milling machine

  1. #1
    Join Date
    Mar 2001
    Posts
    3

    Question Vertical milling machine

    Hello all, I'm contemplating on buying a JET JVM836. Does anyone out there own one and is happy with it or should I avoid it. I'm a hobbyist and will not use it for commercial production work. Would like to hear pros and cons or alternate recommendations. Thanks.
    Noel

  2. #2
    Join Date
    Apr 2001
    Posts
    22

    Post

    noel

    I'm going to buy a jet myself. but your
    numbers are different than mine. I am going
    to get 2hp 3phase. The only thing i know is
    there made in Tiwain,most "knee" vertical
    mills are pretty much the same. You can't do any havey machining on thoughs light machines. but you can do light work on a 2hp or 3hp. also 3phase is cheaper to operate.

    doug

  3. #3
    Join Date
    Mar 2001
    Posts
    3

    Post

    After reading your reply, I think I'll avoid the JVM836 Doug. My next coice is the JTM-1. I already have 3 phase power for my lathe. What are your thoughts on the JTM-1? Noel

  4. #4
    Join Date
    Apr 2001
    Posts
    22

    Post

    Noel

    I have looked at them in person. There is
    a Jet Outlet where I live. The real question
    is how long will the bearings hold out. For
    a home workshop I think you would want less
    gagets. Its expensive to get anything fixed.
    As to your question,I am going to buy a
    jtm-1. I would like a 3 hp but can't afford
    it. I would'nt worry,most machines are run
    16 to 20 hours aday. Your not going to do
    that.

    Doug

  5. #5
    Join Date
    Apr 2001
    Location
    Maine
    Posts
    6,626

    Post

    I saw a JVM-836 a couple of weeks ago. It looks pretty good.

    I have the JVM-840, which I bought about 16 years ago. It's no longer offered; the 830 or 836 seems to be the replacement.
    The only complaint I have, after 16 years, is that the table is pretty soft and dents easily. Otherwise, it's been a very good machine. I think you'd be happy with the 836.

    I might suggest that you get the 3-phase motor and a variable-frequency-drive for speed control. Even though my 840 has a two-speed motor (like the 836), lowest standard spindle speed is 192 rpm. With a decent-sized slitting saw that works out to 200 fpm cutting speed, which is pretty lively (about 2x what it ought to be, in fact). I got a surplus TECO-Westinghouse VFD a couple of months ago, and it's great. I can now get down to as low as 30 rpm.

    See http://www.dealerselectric.com/ or http://www.vfds.com/vfdprice.htm, for instance.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields

  6. #6
    Join Date
    Apr 2001
    Location
    Maine
    Posts
    6,626

    Post

    P.S. I serioulsy doubt if you could possibly need more than a 1 hp motor on the JVM-836. It just isn't that big a machine.

    Even a 1/2hp motor would probably be enough for anything you'd put on an 836. The motor on my JVM-840 is rated 1/2 hp at its lower speed, and I've never felt the need for more power.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields

  7. #7
    Join Date
    May 2001
    Location
    Utah
    Posts
    175

    Post

    I have the JVM-836. I am very happy with it, given it does not have a quill power downfeed and is limited to 5 speeds (with a max of 1550). Mine has the 1.5 HP motor (11/220 single phase). In a conversation with Jet they will void warrenty if a static phase converter (VFD) is used. The motor is not inverter rated.
    I have had the motor go out on it (for unknown reason) and Jet had a replacement at my door in 2 days. (I won't go into what FedEx did to the replacement motor, as Jet had to send me a second replacement, again in 2 days).
    I am currently considering a new lathe (to replace my Atlas Clausing) and Jet is at the top of my list. I suggest talking to Alley Supply Co in Nevada (look in HSM for ad). They have good prices, including shipping. They also like to talk about machines, features, and trade offs.
    Jim

  8. #8
    Join Date
    Apr 2001
    Location
    Maine
    Posts
    6,626

    Post

    You can't use a VFD with a single-phase motor anyway.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields

  9. #9
    Join Date
    Mar 2001
    Posts
    3

    Post

    JimH, do you know what caused the motor to burn up? Also, you got me curious now. What did Fedex do to your replacement motor?
    SGW, thanks for you input. I was not aware that you couldn't use VFDs on single phase motors. While I already have a rotary phase converter for my lathe which I sized to also accomodate a mill in the future, I was planning to use a VFD to vary the speed of a three phase step pulley mill. I now wonder if Jet will allow this.

  10. #10
    Join Date
    Apr 2001
    Location
    Maine
    Posts
    6,626

    Post

    No, a single phase motor and a VFD wouldn't get along very well because of the starting circuit required in a single phase motor. Typically, the starting circuit drops out when the motor gets up to 80% of its full speed or something, so if you slowed down a single phase motor by any significant amount the starting circuit would stay engaged, not likely to be a good thing for longevity.

    A three phase motor doesn't have that problem because the phase shift among the three phases makes the motor self-starting.

    I see no reason why you couldn't use a VFD on your mill if it has a three phase motor. I've got one on my Jet mill; it works fine. Friends have VFDs on an assortment of machinery and have had no problems. I'm well past any warranty period so I don't have that to think about, but as best I can tell there is no particular reason why using a VFD on a three phase motor should be a problem, anyway. I imagine if you ran the motor bog-slow for an extended period, heavily loaded, it might complain, but you're not going to do that. Or if you cranked it up to some outrageously high speed well past its design limits you might have problems, but I can't imagine you're going to do that either.
    ----------
    Try to make a living, not a killing. -- Utah Phillips
    Don't believe everything you know. -- Bumper sticker
    Everybody is ignorant, only on different subjects. -- Will Rogers
    Law of Logical Argument - Anything is possible if you don't know what you are talking about.
    If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •