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  1. #1
    Join Date
    Feb 2012
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    Tamworth, NSW
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    35

    Default Bridgeport mill and VFD advice please

    I have had a look as best I can through old posts and have come out a little confused so I am hoping for some advice please.

    I have been on the search for a mill and a Bridgeport has come up that may fit my needs. I have not a lot of detail yet and will view it on Tuesday. It seems to be one with the variable speed head via cone pulleys. I believe there is also old power feed (looks to be geared and quite a large looking unit compared to modern power feeds). There may also be y axis power feed but that is unconfirmed.

    So so my question relates to power - the spindle motor is 3 phase and I expect that the power feed and lube pump is as well. The mill has a three phase plug. My shed doesn’t have three phase power although there is three phase to the house close by ( the air con is 3 phase). I currently run two other 3 phase motors off a vfd for a belt and a disc grinder. The grinders have same spec motors and the vfd is changed between the two using 3 phase plugs (female plug on the output side of vfd and male plugs on each of the two grinders).

    I had assumed if I bought a 3 phase mill I could similarly just connect my vfd via 3 phase plug and away I would go (assuming motors are relatively matched). However now that I have been thinking about other motors like the power feeds etc I have become quite unsure. Can anyone who has a vfd setup with a similar style mill please give some advice on what my options and expectations are please? If I need another dedicated vfd I could do this although I am pushing my budget very hard here. My other option is to admit defeat on a decent mill and revert to a Chinese hobby mill - single phase and will likely do all I need cheaper but will always feel that much lesser of a machine to a decent Bridgeport or similar.

    i don’t have long to make a decision - speedy advice please!

  2. #2
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    Sep 2012
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    North Yorkshire UK
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    Default

    Hi Danger Mouse, Sounds like a cartoon mouse

    Anyway you will likely need a separate VFD for the main motor and another one for the coolant pump if you decide to use it, you may also need one for the table drive motors.

    You could be better off with a direct to three phase supply or a phase converter.
    Best Regards:
    Baron J.

  3. #3
    Join Date
    Aug 2011
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    Melbourne
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    Default

    Hi there,

    It would be a shame to have to settle for a Chinese mill over a bridgeport purely because of the cost of the VFD!

    As Bob said, you will need a seperate VFD for your mill. Realistically, a VFD should be set up and be dedicated to drive one motor and only one motor. However, me being a tight , I have a VFD that runs up to three motors at once. My surface grinder has three 3PH motors, spindle, coolant pump and hydraulic pump. I have a single VFD that runs all of them in any combination without a problem. Being doing it for about 5 years now.

    Having said that, if you look on eBay these days you can find 2.2Kw VFD's for around $110. Not too expensive in comparison to the cost you must be paying for your bridgeport, especially if it's in reasonable condition.

    Simon
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  4. #4
    Join Date
    Jun 2007
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    Vic
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    Default

    Hi Danger Mouse. The table feed is likely to run off 110v single phase. Have have a Bridgeport clone and the conjunction box on the side where it plugged in has a transformer inside, you just need to connect 240v single phase to that transformer and that is it. As for flood coolant pump, it is quite messy, get a spray bottle. I have portable pump for the lathe and I just use that if I need flood coolant.

  5. #5
    Join Date
    Jul 2006
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    Athelstone, SA 5076
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    Default

    if you have or get 3 phase in the shed, then just use 3 phase.

    If you want to use a VFD for speed control of spindle you will need to use 3ph input to 3ph output VFD. This would be connected only to the spindle motor. Leave all other wiring as is.

    If you want to use a single ph input to 3ph output VFD you will need to modify motor to delta. This may mean having to take it to rewinders to alter motor from star to delta...unless you can do it yourself.

    If it were me I just connect to 3 phase and leave it alone..ie no VFD.....as its easy to change the speed on that type...(not like mine where I need to change pulley ratio's)

  6. #6
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by simonl View Post
    Hi there,

    It would be a shame to have to settle for a Chinese mill over a bridgeport purely because of the cost of the VFD!

    As Bob said, you will need a seperate VFD for your mill. Realistically, a VFD should be set up and be dedicated to drive one motor and only one motor. However, me being a tight , I have a VFD that runs up to three motors at once. My surface grinder has three 3PH motors, spindle, coolant pump and hydraulic pump. I have a single VFD that runs all of them in any combination without a problem. Being doing it for about 5 years now.
    It depends if you want to use the VFD for differential speed control - on a surface grinder presumably it's all one speed. On a mill you don't want the table speed to depend on the spindle speed.

    The way I'd do it is, VFD for the spindle, SP for the table, and a misting system for cool/lube.

  7. #7
    Join Date
    Feb 2012
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    Tamworth, NSW
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    Thank you to all that have posted. Looks like a dedicated VFD for spindle and go single phase for power feed. If mill is in decent condition and I can procure it I will have lots of questions....

  8. #8
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    Jun 2011
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    Quote Originally Posted by jackaroo View Post
    Hi Danger Mouse. The table feed is likely to run off 110v single phase.
    It *might* but also might not - my genuine old B/port most definitely has a 415V motor for table feed gearbox. Not sure if it's star/delta but likely is as the spindle drive motor is. Never cared as I have 415V 3 phase power.

    Need pix to determine what sort of power feed unit is fitted.

    PDW

  9. #9
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    Jun 2011
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    Quote Originally Posted by BobL View Post
    It depends if you want to use the VFD for differential speed control - on a surface grinder presumably it's all one speed. On a mill you don't want the table speed to depend on the spindle speed.
    This. A previous owner of one of my mills 'cleverly' converted it from a 2 speed motor to a single speed 240V 3 phase motor with a VFD. Really helpful when a) he didn't fit a frequency display or anything so you're guessing on the spindle rpm (it's actually a geared head) and b) the same motor drives the feeds gearbox so now the lovely dials telling you the feed rates are also meaningless.

    He also *threw out* the original 2 speed motor! That cost him a lot when he on-sold the mill.

    It's on the list of things to convert *back* again as soon as I lay my hands on a suitable 2 speed motor and the time.......

    Personally, with 3 phase to the main board, I'd be getting a line run to the shop and being done with the VFD caper. They're great for speed control and OK for avoiding highly expensive/unobtainable true 3 phase power runs. But if you can get 415V 3 phase, you're mad not to do it IMO.

    PDW

  10. #10
    Join Date
    Aug 2011
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    Melbourne
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    Hi Bob,

    I guess it depends if you want to use the mechanical speed control or not.

    My pacific mill has the same variable speed head. I pretty much just run that at 50hz and use the existing variable speed in the head. The speed range is more than I need at 50 - 4000 rpm without the need to deviate from 50hz.

    Simon

    Sent from my SM-G970F using Tapatalk
    Girl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.

  11. #11
    BobL is online now Member: Blue and white apron brigade
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    Quote Originally Posted by PDW View Post
    Personally, with 3 phase to the main board, I'd be getting a line run to the shop and being done with the VFD caper. They're great for speed control and OK for avoiding highly expensive/unobtainable true 3 phase power runs. But if you can get 415V 3 phase, you're mad not to do it IMO.
    While I agree 3P is definitely the best way to go. However, given the OP is seriously balking at spending $100 for a second VFD it sounds like he's on a really tight budget . Running 3P even if it's just from his house to his shed is gonna cost a lot more than this. Yes BIG money can be saved by going with used breaker boxes and power points but that's when you do it yourself or can find a compliant sparky. My experience is the average sparky is far less likely to do this sort of thing.

  12. #12
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    Feb 2012
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    Quote Originally Posted by BobL View Post
    While I agree 3P is definitely the best way to go. However, given the OP is seriously balking at spending $100 for a second VFD it sounds like he's on a really tight budget . Running 3P even if it's just from his house to his shed is gonna cost a lot more than this. Yes BIG money can be saved by going with used breaker boxes and power points but that's when you do it yourself or can find a compliant sparky. My experience is the average sparky is far less likely to do this sort of thing.
    Thanks Guys

    A cheap VFD can be done, I will get a quote for running the 3 phase to shed and make a call then. Iím very thankful for the advice given so now I understand the options and some pros and cons. Next step is to check the mill out.

  13. #13
    Join Date
    Oct 2010
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    melbourne, laverton
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    Default 3 phase in shed

    Hi mate if its your house.
    Than i think the best option is take advantage of having 3ph allready conected to the property and get it in the shed to. I wont suggest
    Doing it your self but with out a doubt thats what i would do.
    Besides this i think the bridge port depending on condition is a good option.
    All though ive never used one. Ive spent pleanty of time using a kaonda. Mill.. If the bridge port is as good then your laughing .
    Aaron

    Diy or die

  14. #14
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    dont forget if that if dont get 3ph to shed you will need a 1phase input to 3PH output VFD
    and you will need to get motor converted to delta.

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