Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Quartz tube cutting in a lathe

  1. #1
    Join Date
    Nov 2018
    Location
    Estonia
    Posts
    153

    Default Quartz tube cutting in a lathe

    Have an interesting project at hand: a reflux column head for a brewhouse pilot production still. 304 stainless with a quartz sight glass section inbetween to monitor operation.
    I need to cut a section from a hefty walled section of tube to make the sight glass. After some meditation as how to make that happen I chose to use the lathe for the purpose:



    A fine diamond cutting wheel was secured into the toolpost and the tube fixed on PTFE supports between the chuck and a live center. Water was brushed over the cutting area and very slowly the disc ground away on the rotating tube.



    After literally several hours of careful tinkering I managed to part a section of needed length from the tube stock.



    Since the tube was far from being uniformly round I could not really get a totally clean break...bits were chowdered away from the internal surface, but it is good enough for the purpose.
    Last edited by markx; 07-22-2019 at 06:30 PM.

  2. #2
    Join Date
    Nov 2018
    Location
    Estonia
    Posts
    153

    Default

    Further the support rings were machined from 304 stainless sheet and PTFE gaskets to accommodate the sight glass section.



    The sight glass was test fitted into the reflux head:



    Seems to fit like a glove, just tight enough to seal, but still enough clearance to allow for thermal expansion forces to relax.

    Five special screws were machined to secure the flange section together and tighten the gaskets.





    Last edited by markx; 07-22-2019 at 07:31 PM.

  3. #3
    Join Date
    Dec 2015
    Location
    Chilliwack, BC, Canada
    Posts
    5,572

    Default

    Now that's a nice bit of work. And big kudos on thinking outside the box and using the diamond blade.

  4. #4
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    2,445

    Default

    I presume you stopped grinding just before it finally parted.

  5. #5
    Join Date
    Nov 2018
    Location
    Estonia
    Posts
    153

    Default

    Quote Originally Posted by old mart View Post
    I presume you stopped grinding just before it finally parted.
    Lord knows I tried ! But it would not part off as such and I was afraid to break it completely by forcing, so i kept grinding very slowly to further weaken the system. Of course it broke through, caught on the shards, parted in the turning lathe and shred the internal corner before I could slam on the stop button. Well at least it remained in one piece and functional. The cutoff disk separated the pieces and would not allow them to catch too bad on each other.

  6. #6
    Join Date
    Mar 2013
    Posts
    1,638

    Default

    When I saw your first pictures my first thought was fill the tube with wax in the area of the cut to keep it from dropping off as you finish.

  7. #7
    Join Date
    May 2015
    Location
    Somerset UK
    Posts
    2,445

    Default

    If you have to make another, a liner could be made to keep the ends supported. A length of rolled corrugated cardboard might suffice.

  8. #8
    Join Date
    Oct 2012
    Location
    San Antonio TX, USA
    Posts
    2,769

    Default

    very cool! I hope you get some samplers as part of your payment! Cutting glass without chipping on break through is a major PITA. The only thing that's helped me is supporting the exit with wood or plastic. I'd further the comments above, but suggest a piece of PVC or delrin machined to the tube ID and slid down to where the cut is. You'd still have to cross your fingers and turn around on the spot three times to be in with a chance though

  9. #9
    Join Date
    Nov 2018
    Location
    Estonia
    Posts
    153

    Default

    Yea....quartz glass can be a treacherous beast! The problem with machining an internal support is the fact that the tubes are.....well how to say it, "crooked" at best.....and it seems to be a universal characteristic void of significance towards time or space of production. Hence machining a functional central support that actually contacts the internal surface of the tube in more than a few spots without splitting it apart upon installation is quite a challenge. And the wall thickness is not uniform, so one is going to break through at some point and inevitably a more or less unclean break is the result.
    I've worked with the material a lot in my past days as a high temperature chlorination reactor maintenance engineer and really the only option to have a really clean contact surface is to cut off an ovesized lump and grind off the chowdered edges afterwards on a diamond grit surface. To be honest, for practical purposes it rarely makes a difference if there are a few bits missing from the edge.

    I remember a rather humorous episode from the days when I was still young and beautiful and had the motivation to work an occasional late night shift welding quartz reactor cores or mixers in the lab workshop. I had just finished welding together a rotating bed reactor mixer from quartz....it was sitting on graphite blocks secured in vice. I turned off the oxy acetylene torch and took my welding mask off.....the task was completed. Off and away for the night....right? No!! The next moment the vice gave rise to a slight "tick" sound caused by thermal expansion from the heat of the welding process.....released the graphite block and dropped all of my hard work on to the workshop floor, shattering it into a thousand shards. As I floated there about two inches above the floor from just the pure horror of what just had happened, the clock struck midnight. At midnight the automatic alarm system of the premises armed itself and went off silently at the same time because of my presence in the workshop. About two minutes later the security patrol guys arrived, rushed in and were about to cuff me to the radiator. It took some explaining from my side to let them leave me be and mourn my heavy losses

  10. #10
    Join Date
    Aug 2009
    Posts
    6,566

    Default

    It looked like it worked out well for you. A bit time consuming on the cutting. You basically filed your way through it. I think the job would have went faster if you could have spun the diamond blade as well as the quarts tube like in a tool & cutter grinder and motorized work head. Might have been a cleaner cut especially when you start to break through.

    JL...........

Posting Permissions

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