Thread: Kopal Milling Clamps

Page 1 of 2 12 LastLast
  1. #1
    Has anyone else here discovered Kopal milling clamps?
    My local tool shop had some second hand ones in and I bought a pair, stripped & cleaned them and tried them out.
    Then I bought another pair, then a larger pair for clamping tool plates on my fly press, I've started calling them Frosties 'cos They're Gr-r-reat!

    - Nick

  2. #2
    No idea where I would get em around here, but they look nice. They clamp good enough for metal milling?

  3. #3
    Quote Originally Posted by magicniner View Post
    Has anyone else here discovered Kopal milling clamps?
    My local tool shop had some second hand ones in and I bought a pair, stripped & cleaned them and tried them out.
    Then I bought another pair, then a larger pair for clamping tool plates on my fly press, I've started calling them Frosties 'cos They're Gr-r-reat!

    - Nick
    You must be rich, Nick. I have looked at the price of these things !
    Sent from my clunky old Windows 7 Machine

  4. #4
    Quote Originally Posted by sinnsvak View Post
    No idea where I would get em around here, but they look nice. They clamp good enough for metal milling?
    Oh yes, you can apply some serious clamping force with relative ease.

    Quote Originally Posted by cropwell View Post
    You must be rich, Nick. I have looked at the price of these things !
    Not really, they were second hand, had sat for many years unsold, and needed a good strip and clean, I got them for a song and I can't sing very loud ;-)

  5. #5
    Jay's Avatar
    Lives in Chesterfield, United Kingdom. Last Activity: 07-11-2016 Has been a member for 9-10 years. Has a total post count of 19.
    We used Kopal clamps on a Hmc at work to hold 350x350x25mm plates for machining and they gave great clamping force but I would recommend making some steel bushes that you can knock on the knurled part of the screw to increase the strength of the Allen socket because they are prone to breakage if you over torque the screw so the coller stopes it ripping apart and becoming useless. They will be a pain to get off if you want to service the clamp but it's doable.

  6. #6
    Quote Originally Posted by Jay View Post
    We used Kopal clamps on a Hmc at work to hold 350x350x25mm plates for machining and they gave great clamping force but I would recommend making some steel bushes that you can knock on the knurled part of the screw to increase the strength of the Allen socket because they are prone to breakage if you over torque the screw so the coller stopes it ripping apart and becoming useless. They will be a pain to get off if you want to service the clamp but it's doable.
    I've milled the hold-down bolt hole on two of mine out to a slot to take M10 custom bolts but it's a common misconception that the hold down bolts need high torque, they don't.
    Kopal clamp hold down screws should be hand tight and not swung on, they only need to be tight enough to stop the clamp easily moving out of position before any clamping force is applied, the tool provided has the right dimensions to stop the uninformed swinging on the screw and applying excessive torque ;-)
    The whole point of the design is that applying the clamp uses the hold down bolt as the pivot point of a lever with the work contact and the back end of the clamp as the pressure points.
    If you break the screws you're not understanding the correct usage of the clamps :D

    - Nick
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  7. #7
    Jay's Avatar
    Lives in Chesterfield, United Kingdom. Last Activity: 07-11-2016 Has been a member for 9-10 years. Has a total post count of 19.
    I fully understand how the Kopal clamps work and worked very close with Kopal along with a few work colleagues 19 years ago when we found that although the clamps where good on material with a clean edge they where pretty crap when it came to a flame cut edge or rough edge.
    The problem we found was that the foot of the clamp wasn't in full contact with the edge of the plates we where using because they where flame cut so after having a few plates come flying off our HMC (one littereley taking the enclosed doors off the runner and bending the frame) we had talks with Kopal to look in to the problem. After we looked at the job and found what was happening and Kopals rep having seen what was happening the answer we got and only solution was to dog them down as much as possible until all the clamp was in contact with the edge of the plate which worked apart from blowing the heads of the screws out which is where we had to fit collets to the screw head. In all they are pretty good clamps but you have to torque them up more on anything than a good clean edge especially on a HMC.

  8. #8
    Quote Originally Posted by Jay View Post
    In all they are pretty good clamps but you have to torque them up more on anything than a good clean edge especially on a HMC.
    It's common in industry to misuse and abuse equipment that is used outside it's design parameters but to describe that as a fault of the equipment rather than operator error is unfair on the product.
    The correct solution to your problem would have been custom feet for the clamp noses which incorporated spherical contact surfaces to allow free alignment of a lower section with 3 distinct high points allowing clean 3 point contact on uneven surfaces, the rep sounds like he had no engineering background or problem solving capabilities beyond "big spanners" and when all you have is a hammer, every problem looks like a nail ;-)
    Last edited by magicniner; 23-08-2016 at 09:03 AM.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  9. #9
    Jay's Avatar
    Lives in Chesterfield, United Kingdom. Last Activity: 07-11-2016 Has been a member for 9-10 years. Has a total post count of 19.
    No body blamed the equipment. What I said was that they where only designed for clamping on a good clean edge or otherwise you would need more force if the edge was slightly out or serrated for instance. The idea of havin clamps made as you describe would not have worked at all and would have offered even less clamping force as flame cut plates can come out with all manner of edge shapes. I hope I'm coming across ok as I sometimes hate this where you try to describe something over the Internet but it's so much easier face to face.
    By all accounts as uv said above they are good clamps and I liked them even to the point where I suggested the use of them to a few companies uv worked for but as always cost played a part and if you know Kopal then you know they where not cheap. In fact while I write this I seem to remember I bought a few sets home after my brother did a management buy out of the company and sold the machines off and they where sat in the tooling locker so I grabbed them before someone else did.
    I'll have to have a rummage around and see if I can't find them and if I can then I'll stick them on here if their of use to someone as iv packed in due to terminal cancer so they are no use to me and never will be now. Got an old emco compact 5 Cnc gathering dust with loads of stuff and tapes with it to if their still being used by people or is it a case of scrapping because people are not interested in them anymore? ( been out the game a while so no idea what's the in thing these days you see...lol)
    Last edited by Jay; 23-08-2016 at 10:20 AM.

  10. #10
    Quote Originally Posted by Jay View Post
    Got an old emco compact 5 Cnc gathering dust with loads of stuff and tapes with it to if their still being used by people or is it a case of scrapping because people are not interested in them anymore? ( been out the game a while so no idea what's the in thing these days you see...lol)
    The EMCO stuff is still cutting chips, most now use MACH3 or LinuxCNC, some use parallel port & break out board, others USB or Ethernet and an external motion controller. Some use the old steppers, some replace them but the base hardware is good and is still worth having,

    - Nick
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

Page 1 of 2 12 LastLast

Similar Threads

  1. Lenzkes Tooling Clamps Qty2 - CNC Milling/Drilling
    By mekanik in forum Workshop & Equipment
    Replies: 2
    Last Post: 02-02-2015, 05:47 PM
  2. MOD 1 rack clamps
    By charlieuk in forum Marketplace Discussion
    Replies: 3
    Last Post: 31-01-2014, 08:07 PM
  3. Hold down clamps, what do you use?
    By Web Goblin in forum Machine Discussion
    Replies: 16
    Last Post: 14-04-2012, 11:45 PM
  4. Clamps
    By p1lts in forum General Discussion
    Replies: 3
    Last Post: 27-10-2011, 06:55 PM
  5. FOR SALE: Pneumatic Clamps
    By compfranon in forum Items For Sale
    Replies: 5
    Last Post: 07-04-2010, 07:33 PM

Bookmarks

Posting Permissions

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