Has anyone installed a Variable speed thingamajig on their Step pulley head?
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  1. #1
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    Default Has anyone installed a Variable speed thingamajig on their Step pulley head?

    I have a VFD I run my mill from and
    its really nice being able to adjust
    the speed on the fly with it.

    Now that I have my HLVH, and Im
    going to want to get a Surface grinder,
    I think Id rather have a
    Rotary Phase Converter instead of a
    VFD on each machine?

    Anyway Id like to be able to adjust
    the speed on my step pulley head
    without changing belt positions.
    Just curious if anyone has done this?
    Thanks.

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    So you refer to a VFD as a thingamajig.
    Is that a diminutive comment about VFDs?
    If it is, why are you so interested in them anyways
    if you have a bias against them as something inferior?

    -Doozer

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    I think maybe you misunderstood my question
    or what I’m wanting to do because I said NOTHING
    about having a bias against VFD’s

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    Quote Originally Posted by Doozer View Post
    So you refer to a VFD as a thingamajig.
    Is that a diminutive comment about VFDs?
    Damn straight....we "in the know" types refer to them as variable speed doohickes....

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    Variable speed heads exists and would certainly be the easiest thing to swap in or mimic, but you've already got the VFD on the mill. Run the lathe and grinder and any other future equipment on the rotary but why make work for yourself when the mill is already done.

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    It depends. I have both a phase converter that I run a bunch of stuff on and I have installed VFD's on a number of things. VFD's add some benefits like soft start and stop, start stop controls, variable speed, and protection. I installed two on my cutter grinder, one for the grinder and one for the work head. It's really nice to just be able to flip it from forward to reverse and it slows down to zero then reverses. I did the same on my 13" lathe. I have not installed one on my bridgeport, which does have step pulleys. It does not really eliminate belt changes but does give some more speed range.

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    Quote Originally Posted by Hephaestus29 View Post

    Anyway I’d like to be able to adjust
    the speed on my step pulley head
    without changing belt positions.
    Just curious if anyone has done this?
    Thanks.
    You mean that the adjustment is to occur while using a RPC instead of a VFD?

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    Quote Originally Posted by JCByrd24 View Post
    Variable speed heads exists and would certainly be the easiest thing to swap in or mimic, but you've already got the VFD on the mill. Run the lathe and grinder and any other future equipment on the rotary but why make work for yourself when the mill is already done.
    The reason I don’t want a variable speed head is because
    my step pulley head is SUPER QUIET.

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    I get that, hence leave VFD on mill and get a rotary for other equipment.

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    Quote Originally Posted by rons View Post
    You mean that the adjustment is to occur while using a RPC instead of a VFD?
    Yes, I’d like to power the mill through
    a rotary phase converter, but keep the
    Variable frequency drive to change the
    spindle speeds.
    I was already told this could be done
    by Craig Chamberlin of Precision Electric
    that this could be done but I still
    don’t know how to do it because he
    fails to admit apparently that I bought
    the unit from him even after I heard
    what good customer support they had.
    The very first time I called for support
    he questioned whether or not I bought the
    unit there, I’m like how would you not
    know? You’ve got my Name, wouldn’t it
    be connected to the serial number.
    Anyway that’s beside the point.

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    I'm sympathetic to your situation but have to wonder why an RPC and a VFD. Either would do the trick. There are relatively inexpensive VFD's (single phase in, 3phase out) that'll power a bport easily, as would a 2 hp RPC.

    Changing belt position is pretty fast and I do sometimes wish I had a speed between steps, once every 5 years or so. But if that's what you want, that's what you want. A VFD is the only way to do it. Teco is a popular brand.

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    I have an old Boss type head with the pneumatic speed control for the pulley adjuster. Normally I just use the VFD for speed and leave the head at the max speed setting. That works great for most aluminum work or steel work with smaller tooling. The down side is there is a loss of torque using large tools at slower speeds through steels. It is nice having the option to spin down the head for large tooling, to get the torque back up, while still using the VFD for primary speed control.

    Is this kina' what you're talking about, as I am still fuzzy what your objective is...

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    I think your writing style is causing confusion as you mix statements about customer support with your desired configuration in the same sentence.

    But I did parse out that you wish to have an RPC and a VFD. So what is the issue? Power the VFD with the RPC and power the mill with the VFD. Done.

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    Once you get into having multiple machines the RPC makes sense. You are now making semi three phase power for all.
    The VFD thingiee on the B-port gives you nifty speed control but it's ability is not the same as changing belts and pulleys.
    Yes I have done it, moving more than 30-50% off of the base speed does not produce great results no matter how much time and effort you put into tuning the VFD.
    Make no mistake, it will run even way outside this range. There is a practical limit to high end and spinning a 60hz motor at 400hz is not advisable although some VFDs will let you try.

    I do like the "thingamajig" as a term in this question.
    Bob

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    I too enjoy the peace and quiet of a step pulley, and if I ever owned a manual mill for personal use, I would almost certainly have a short table short knee step pulley machine

    A VFD is nice for drilling of small holes with high speed, or slowing spindle down for less than max capacity milling.

    A RPC probably makes as much noise as a vari speed head, tho it is not 6 inches from your skull.

    You will only be running on machine at a time, so one could run multiple machines from the single VFD, and if your memory is not good enough to remember to set the VFD back to 100% a little cleverness in low voltage wiring could solve the problem I would think

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    I really like having the VFD on my surface grinder. I can convince a wheel it's something it's not and the gentle ramp start and stop insure nothing ever shifts.

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    For a shop having only single-phase mains, having an RPC to drive constant speed machines is a fine thing.

    Having VFDs on variable spindles is a wonderful thing.

    They need not be used together in order to reap the benefits of either.

    IF you're powering a spindle off a VFD, then just use a VFD that will accept single-phase input.

    If you have other machines that don't benefit from variable speed operation, then hook 'em to the RPC, and only start the RPC when you need those tools.

    I have both. I ran a home-built 10hp rotary for 20 years, and over the course, installed VFDs on all the spindles of the mills, drills, and lathes. I even installed them on odd applications including, but not limited to table saws, exhaust fans, air compressors, and concrete power trowels. They have their drawbacks, but in terms of operational performance, if they're not performing well, the usual issue is improper programming or an inappropriate selection of drive components and drive ratio.

    The simplest VFD conversion I have, is on my J-head bridgport knee mill. I removed the direction switch, wired the VFD direct to the motor, hung the electronics on the side of the column and put a control pendant on a hook on the front of the table. I still use the original V-belt step pulley, but it's not for any particular advantage aside from the fact that it still works fine. I have the ability to use it to change drive ratios, and the J-head backgear still works, but the belt is more or less parked on the center sheaves (1:1 ratio) because that point is where belt contact maximum occurs (any ratio other side yields a smaller contact on either the motor or the spindle). I mill everything from wax to steel, and have no problem with operational limitations. The only thing I DIDN'T do, which I probably should have, is put a constant-speed cooling fan on the motor, so that it'd cool well at substantially slow speed, but I haven't experienced any heating issues with the big pancake motor.

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    The reason Bridgeport variable speed heads suck so bad
    is the Reeves drive uses a spring on the one pulley to
    pinch the belt, while the other pulley provides the
    adjustment. This spring pulley constantly pinching the
    belt leads to huge power loss and heat generation.
    A Reeves drive that does NOT have the spring pinch pulley
    is on a DoAll bandsaw or a Hardinge lathe. They have 2
    belts that shuffle for position, without the need for a
    spring loaded pulley that pinches. I really hate variable
    speed Bridgeport heads. Some people just don't understand
    enough to care.

    -Doozer

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    Quote Originally Posted by Doozer View Post
    The reason Bridgeport variable speed heads suck so bad
    is the Reeves drive uses a spring on the one pulley to
    pinch the belt, while the other pulley provides the
    adjustment. This spring pulley constantly pinching the
    belt leads to huge power loss and heat generation.
    Does it have anything to do with the orientation of the Reeves drive?

    On a Bridgeport the shaft is vertical.
    On a Hardinge lathe the shaft is horizontal.

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    No.

    -Doozer


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