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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Spindle Regrinding Service for Benchtop Machines
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  1. #25
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    Re: Spindle Regrinding Service for Benchtop Machines

    I do not have a picture BUT I know where there is a Kneemill type CNC machine that runs every day and he simply reground teh taper to match a stock BT30 tool holder and installed a ball type pull stud drawbar. There is room inside of a R8 spindle to do it. It also has an ATC. It has been running for years now. There is only a sqeak of difference between teh R8 and BT30 tapers.

    Dave C did teh other option and had CT30 type tool holders ground to teh R8 taper. And then later made his own tool holder Cat30/R8 . Much simpler/Cheaper to just have teh spindle ground ONCE and use stock tool holders.

    (;-) TP

  2. #26
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    Re: Spindle Regrinding Service for Benchtop Machines

    Quote Originally Posted by cncuser1 View Post
    Vmax, do you have an example to show?
    The BT30 and R8 have the same 1.25" large diameter, and the taper on the R8 is a little "steeper", so to grind for a BT30 only requires taking out about 0.080" from the back end of the R8 taper going to 0 at the fat end. Very doable but there is no going back from it.

  3. #27
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    Re: Spindle Regrinding Service for Benchtop Machines

    IF you are woried about going BACK then you should not consider this option but I am not sure WHY you would want to go back. But replacement spindles in this machine range are fairly cheap to replace.

    Your option would be to have BT30 tool holders reground to teh R8 taper. A lot more expensive to have to grind every tool holder. OR you could contact a tool holder manf and ask to have some custom made. Maybe a group buy.

    (;-) TP

  4. #28

    Re: Spindle Regrinding Service for Benchtop Machines

    Somebody needs to offer a G0704/PM25/[insert R8 mill here] spindle regrinding service. I would pay pretty good money to be able to use BT30 on my G0704. I'm not a huge fan of TTS so i've just continued to bang my R8's on and off with a butterfly impact wrench. TTS would probably be faster but i don't want to invest $1000 in tts to replace my R8 stuff. Bt30 seems like a better investment in the long run.

    Has anybody ever used a pull stud on a R8 set screw holder? Seems like it might be doable.

  5. #29
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    Re: Spindle Regrinding Service for Benchtop Machines

    YEP it has been done Pull stud R8. By a company called mach1

    (;-) TP

  6. #30

    Re: Spindle Regrinding Service for Benchtop Machines

    As i recall R8 doesn't need all that much tension. Seems like that might be a decent option.

  7. #31
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    Re: Spindle Regrinding Service for Benchtop Machines

    R8 solid tooling does not require as much tension BUT a R8 collet DOES require a lot more tension.

    The way to go is to buy a BT30 spindle cartridge that will fit your G704 head casting. The fellow that did teh spindle regrind mentioned above ALSO redid a Bridgeport by installing a new BT30 cartridge (10K rpm POSA manf). He did have to cast a new head assy but in teh end it was VERY smooth, quiet and cool running. It also has an ATC installed.

    (;-) TP

  8. #32
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    Re: Spindle Regrinding Service for Benchtop Machines

    Handlwanker

    If your just trying to use the mt2 to hold tools you can always buy something like this. https://www.ebay.com/itm/ER32-Collet...pe!27012!US!-1
    It would be a lot easier then modifying the machine.

    Ben

    Sent from my E6810 using Tapatalk

  9. #33
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    Re: Spindle Regrinding Service for Benchtop Machines

    What SIZE spindle cartridge does a G0704 use ??

    (;-) TP

  10. #34
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    Re: Spindle Regrinding Service for Benchtop Machines

    IF you are woried about going BACK then you should not consider this option but I am not sure WHY you would want to go back. But replacement spindles in this machine range are fairly cheap to replace.
    Because the original post wasn't about changing tapers. It was about dusting the taper to reduce runout.

  11. #35
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    Re: Spindle Regrinding Service for Benchtop Machines

    And teh same warning applies there as well IF when grinding teh spindle it gets muffed up ( And I have seen many muffed up) there is usually no going back as well.

    Most postings seem to Morph a bit as they grow older.

    Just a thought, (;-) TP

  12. #36
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    Re: Spindle Regrinding Service for Benchtop Machines

    Quote Originally Posted by bhurts View Post
    Handlwanker

    If your just trying to use the mt2 to hold tools you can always buy something like this. https://www.ebay.com/itm/ER32-Collet...pe!27012!US!-1
    It would be a lot easier then modifying the machine.

    Ben

    Sent from my E6810 using Tapatalk
    Hi, well into that "look see" option.....the problem I have with the spindle I'm modifying is originally it did not have a draw bar through the solid upper drive shaft and nobody with sense mills with just the grip of a Morse taper and no draw bar...…...the M2 tooling is/was held in like a bench drill press spindle as this machine is/was originally a jig borer per se.

    The mod I'm going to do entails major surgery to the existing spindle by cutting off the Morse end section and welding on the ER32 long shank chuck then re-machining the spindle to make it run true.

    Welding is not a problem as I'll be using a plasma welder and the weld zone will be approx. 100mm up the 25mm diam. spindle and well away from the ER end.

    Having just an ER32 chuck on the business end is not a problem as this machine will only be used in the manual mode...…….to replace a big mill I have to sell as I'm downsizing.

    Meanwhile back at the ranch, the R8 spindle run out problem is similar and parallel to a problem I also have on my Skyfire SVM-0 CNC mill, not in the spindle which runs dead true but in the ten ISO 20 tool holders I bought with the mill that all run out, some as much as .004"...…..I kid thee not.....the best one has only .001" run out.

    So, first option was to mount the tool holders in the spindle cartridge off the mill and on the table of my big mill and use a short slide with a die grinder etc to touch up the ER tapers, but as it requires power to rotate the spindle it would be simpler and less labour intensive to do the work on the CNC mill with the spindle insitu and a die grinder mounted vertically on a short slide.

    It's only a small amount of grinding...….004" or .002" off one side in the worst case, and as the tooling is held in the spindle at least they will all run dead true afterwards......……..cheap collet run out is a different kettle of fish.
    Ian.

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