Page 1 of 3 123 LastLast
Results 1 to 10 of 21

Thread: Trepan a big washer?

  1. #1
    Join Date
    Nov 2015
    Location
    Sydney
    Posts
    1,245

    Default Trepan a big washer?

    I need to make seven large washer-like disks. About 230mm (9") OD and 150mm (6") ID. Material is 3mm (1/8") 316 stainless.

    I was thinking of using the lathe faceplate or a rotary table, but then I thought about trepanning it on the mill as it would be easier to set up. I've got a slightly overbuilt indicator holder for a fly cutter head that I could use. The indicator holder is 1" square.

    So what do you suggest? Faceplate, rotary table or trepan? Carbide or HSS? I've got a carbide face grooving tool that I could use.


  2. #2
    Join Date
    Jul 2006
    Location
    Germany
    Posts
    178

    Default

    Faceplate.
    Using measurement instrument holders for machining is a total no-go, even if it's overbuilt. Just the idea!

  3. #3
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
    Posts
    3,322

    Default

    Second vote for faceplate. Would consider trepanning 230mm stainless disk on a mill only if your mill is super heavy monster(at least the tool taper is promising)

  4. #4
    Join Date
    Nov 2015
    Location
    Sydney
    Posts
    1,245

    Default

    Mill is one of these https://www.machineryhouse.com.au/M585D

    Not a super heavy monster, but probably more rigid than a BP as the head doesn't nod. Weighs 1.7 tonnes.


  5. #5
    Join Date
    Jan 2007
    Location
    Minnesoa
    Posts
    1,383

    Default

    Hi,

    Yeah, I would do a face plate too. Your mill is a bit better than a Bridgeport, but it's still going to be pissed at you.
    If you think you understand what is going on, you haven't been paying attention.

  6. #6
    Join Date
    Jan 2003
    Location
    Chilliwack, B.C.
    Posts
    11,692

    Default

    No, I don't think that machine is going to be good enough Seriously, I'd have some reservations about trepanning at that size in stainless to begin with. I'm in the faceplate camp- I'd probably band saw them out roughly, then mount on a faceplate and turn out the center disc, then re-mount using the center hole so you can turn the OD. Just my thoughts on it-
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  7. #7
    Join Date
    Oct 2002
    Location
    Kirkland, Washington
    Posts
    2,088

    Default

    I would rough it out first with a plasma cutter and use the mill to drill a center hole. Then I'd put on the lathe faceplate and put the part against a piece of MDF against the faceplate with pieces of kraft paper between. Hold it there with a live center in the tailstock. Now you can either turn it to size or trepan, your choice. Either way you can dig the cutter right into the MDF, no damage to the faceplate or part.

    After you get the OD finished you can put the part in a 4-jaw carefully and trepan the inner hole.

    metalmagpie

  8. #8
    Join Date
    Nov 2015
    Location
    Sydney
    Posts
    1,245

    Default

    Thanks all. No bandsaw or plasma cutter here. Any concerns about only clamping it from the outside, cutting the ID, then cutting the OD? The minimum distance between slots is about 200 mm (bigger than the ID of the part).


  9. #9
    Join Date
    Sep 2015
    Location
    NW Illinois
    Posts
    729

    Default

    I would go with the faceplate. Clamp the blank with some sacrificial material behind it. Grind a narrow trepanning tool.You want a lead angle on the tip of the tool so the side facing the part breaks through first. Cut the hole first, then the OD. Be prepared for some excitement when the tip of the tool breaks through.

    You might consider fastening the blank to the sacrificial material with glue or double sided tape. That could prevent material from shifting when the tool breaks through. Less excitement that way.

    edit
    Better yet screw the sheet to the backing inside the 6" dia. Several screws. Cut the outside first, then the inside. You might want to consider drilling and tapping some holes in the faceplate inside thr 6" dia. to better grip the sheet.
    Last edited by Illinoyance; 03-28-2019 at 11:54 AM.

  10. #10
    Join Date
    Mar 2012
    Posts
    165

    Default

    Why not rotab on the mill with a backer board? Sounds real boring to me compared to the potential "excitement" of the other methods.

Posting Permissions

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