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IndustryArena Forum > MetalWorking Machines > Bridgeport Machines > Non standard ISO30 on Bridgeport Interact 1 Mk 2
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  1. #1
    Join Date
    Jan 2022
    Posts
    6

    Non standard ISO30 on Bridgeport Interact 1 Mk 2

    So I have gotten a old (1989) Bridgeport Interact 1 Mk 2 CNC
    Mostly hobby. It works well with the tooling that came with it.

    It is supposed to use ISO30, using not a drawbar, but it's ... what to call it ... collar? to connect and hold on. With a special nut that grabs its collar.
    In fact, there is no hole in the spindle to even hold a drawbar, so it is not an option

    Recently I bought a new ER32 collet adapted, and it does not fit.
    Checking why, and checking the "ISO30" that came with it, I found the reason is the distance from the collar to the start of the taper is 2mm to far

    (see attachment)

    According to DIN2080, a+L2 should be 9.6mm and the one I bought is exactly that.
    But all the (working) ISO30 I have have a+L2 of 11.6mm

    Also D1 seems to officially be 50, but my Bridgeport accepts max 46
    I only discovered the a+L2 problem after I had already turned down D1


    Questions:
    - Anyone else ever run into this?
    - And if so, how did you fix it
    - There is not, perchance, some place that sells modified nuts for Bridgeport

  2. #2
    Join Date
    Jan 2022
    Posts
    6

    Re: Non standard ISO30 on Bridgeport Interact 1 Mk 2

    Hmm, suddenly I find some "alternate" to ISO 30 which seems to match what I have:

    NMTB 30 (Erickson Quick-Change) Shank

    Ok, extra question, anyone know of a conversion nut from NMTB 30 to ISO 30 DIN 2080?
    Attached Thumbnails Attached Thumbnails NMTB 30 (Ericson Quick Change).PNG  

  3. #3
    Join Date
    Jan 2022
    Posts
    6

    Re: Non standard ISO30 on Bridgeport Interact 1 Mk 2

    Ok, so I read a lot:
    Writing it down as much for myself as for others, take with caution so far it is only armchair study, not practical.


    Bridgeport was definitely supplied with Erickson QC30 spindle

    The critical dimensions in which it deviates from common other ISO30 tapers are:
    - indeed the flange diameter D1, which is 46.06mm instead of the common 50
    - The distance from the flange surface to the taper start (a+L1), which seems to be 10.67mm officially

    Erickson themselves provided a guideline on how to grind down other tapers to fit in their QC holders (see attachment)
    Grinding is preferred of course, as turning is not as precise. However, the actually precision surface is the taper, which remains untouched.
    A modified flange, when rough or incorrect, will wear down the QC holders inner ring needlessly.


    NMTB30
    - Most NMTB holders, though by design held by drawbar, are purposely manufactured to be compatible with QC spindles. Some may not be, especially/specifically the ones that have no flange at all.

    BT30 BBT30 MAS403 ISO7388 JIS6339
    - Users report that this can be made compatible by turning/grinding down the outer D1 to 46mm and by turning/grinding its V groove to a U groove with 10.7mm (a+L1) distance, but some of the V groove will remain making it held by only the tip of the QC30 inner ring lips, possibly causing the latter to wear out more quickly
    - I read of one user who rebuild the inner ring of the QC holder to directly hold the BT30 V groove properly. He still still needs to turn down the outer diameter D1, and his holder is now incompatible with original QC

    NT30 DIN2080
    - Can be made compatible by turning/grinding down the outer D1 to 46
    - Has a (a+L1) of 11mm, slightly oversize, but will fit directly into the QC holder

    SK30 ISO7388
    - Very similar to BT30 with a V groove, but in the centre so not enough material to leave a 10.7mm distance

    ISO30 DIN2080 (I think. ISO30 seems used a lot for the other variants too)
    - Has a (a+L1) of 9.6mm, which will not fit and is not easily modifiable to fit into the QC holder
    - Mind you, one of my "working" holders, on better inspections, shows signs of having been welded and then turned to thicken the 9.6 to 10.7mm

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