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  1. #41
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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    I agree with Handlewanker on most of these points. It is the intended purpose that should drive all the other decisions though (including setting the budget). It is better to buy nothing than to buy something that can't do the intended job...

    Most of my (many) purchasing mistakes came from me putting the cart before the horse. If you want to cut steel, that should be the basis for all aspects of the design, not just the spindle. i.e. build a machine base with the weight and other features necessary instead of trying to figure out later how to mount a 300lb Bridgeport on a Chinese 6060 aluminum gantry.

    btw, For a machine that only needs to cut steel, I found that it is cheaper to buy a used Bridgeport and do a cnc conversion than it is to do any sort of comparable diy build. working mills start at $1800 near where I live. It costs $700 for a 500 watt high torque mini mill head alone these days. Even the Tormach R8 and BT30 cartridges cost $800... (without a motor or mount).



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Well, even if you acquired a completely CNC converted Bridgeport without a spindle as a gift you still then wouldn't fit a HSS to it which is the whole argument, unless you only wanted to cut aluminium, wood and plastics etc, but the argument holds if you wanted to cut steel with the HSS which would be impractical.

    It doesn't matter what else you want to do, a HSS has no place on a milling machine if steel is in the picture.

    It is possible to cut steel with a HSS, as I said, but the whole point of going to a CNC solution is to be efficient, and dropping the speed and feed rates to cater for the inadequacies of a HSS won't put pennies in the bank or allow you to compete on any platform......for DIY and hobby work.....yes it could work if you had the stuff laying around and you're that desperate, but in the end I think you'd get more out of an SX3...whatever.... with CNC mods.
    Ian.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Hi, just found an interesting concept mill amongst my file collection that...………...wait for it...…….has a High Speed Water Cooled spindle on it...…….yes, isn't it a small World.

    Perhaps the table could be made 48" square.
    Ian.

    Attached Thumbnails Attached Thumbnails Why most (non-router) milling machines don't use self-contained spindle?-cncfun-games-bridge-mill-jpg  


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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Quote Originally Posted by handlewanker View Post
    Well, even if you acquired a completely CNC converted Bridgeport without a spindle as a gift you still then wouldn't fit a HSS to it which is the whole argument, unless you only wanted to cut aluminium, wood and plastics etc, but the argument holds if you wanted to cut steel with the HSS which would be impractical.

    It doesn't matter what else you want to do, a HSS has no place on a milling machine if steel is in the picture.

    It is possible to cut steel with a HSS, as I said, but the whole point of going to a CNC solution is to be efficient, and dropping the speed and feed rates to cater for the inadequacies of a HSS won't put pennies in the bank or allow you to compete on any platform......for DIY and hobby work.....yes it could work if you had the stuff laying around and you're that desperate, but in the end I think you'd get more out of an SX3...whatever.... with CNC mods.
    Ian.
    The Datron machines mill steel with high speed spindles. As do many other large 5 axis maching centers. There are a number of brands that specialize in making high speed direct drive spindles for milling hard metals like steel. e.g.

    https://www.ibagnorthamerica.com/iba...large-spindles


    Electrospindle HSK-A63 EVO | Products | Omlat - High quality Electrospindles

    https://www.setco.com/products/spind...motorized/206/


    If money is no object and you have access to the appropriate power source, these are a superior option to the older belt drive designs.

    The advantage with belt drive spindles is only that gearing can be used to increase low speed torque. This was helpful when you were using a 1hp motor on a Bridgeport with HSS end mills. This is less of an issue with the 20hp or 40hp motors used in modern high speed machining centers.

    Some of those IBag and Omlat high speed milling spindles (with built in motors) produce more than 100nm of torque without gearing.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    I have to wonder what the originator of this thread had in mind when he titled it "most (non router) milling machines"...…….probably with an SX3 or Grizzly whatevers in mind.

    Going to a higher spec mills, and to industry expectations construction wise, then I suppose the spindles mentioned would be practical even if bank balance busting.

    I doubt anyone would go out and buy an industrial quality mill and then retrofit it to use one of those exotic spindles.....the spindle and VFD rated for it would probably cost more than the machine itself.....you're definitely into the big league when you go down that path, that being said, you would most likely be buying a machine that already had such a spindle as part of it's design for the work you intended.....and the tooling.....and the infrastructure to support it.
    Ian.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Quote Originally Posted by handlewanker View Post
    I have to wonder what the originator of this thread had in mind when he titled it "most (non router) milling machines"...…….probably with an SX3 or Grizzly whatevers in mind.

    Going to a higher spec mills, and to industry expectations construction wise, then I suppose the spindles mentioned would be practical even if bank balance busting.

    I doubt anyone would go out and buy an industrial quality mill and then retrofit it to use one of those exotic spindles.....the spindle and VFD rated for it would probably cost more than the machine itself.....you're definitely into the big league when you go down that path, that being said, you would most likely be buying a machine that already had such a spindle as part of it's design for the work you intended.....and the tooling.....and the infrastructure to support it.
    Ian.

    As with any other type of spindle, there are budget options. For example, this 6000 rpm 2.2kw spindle with a usable range from 0-6000rpm:

    GMT Air Cooled CNC Spindle 2.2 kW 220V / 380V 6000RPM S | Air Cooled Spindles

    If I was building a smaller cnc machine specifically for making steel parts, I would def consider one like that (although I would prefer water cooled for metalwork).

    For cnc machines, I would rather have that 6000rpm spindle than one of the .5kw 2000rpm R8 milling heads they sell for those benchtop mini mills.

    It all comes down to what size (and strength) machine base it is going on. It is probably not possible and certainly not advisable to bolt a 300lb 1.5hp Bridgeport head to a diy benchtop machine or any sort of 5 axis head.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Hi, it may be a good price and could be considered self contained, but you're stuck with an ER25 collet on the end...……..anyone constantly changing an ER collet chuck will know what I mean......give me an R8 or ISO30 any day over an ER solution......but I suppose the fact that R8 and ISO 30 both need to have a drawbar and the power draw bar mechanism to clamp them too, that makes it a too hard basket item to manufacture for the same price range.

    The original basic design model for the Skyfire SVM-0 mill I bought came out with an ER32 spindle end and a 1 HP BLDC motor etc etc, but I pushed for the ISO 20 spindle option with an additional option to have a self contained water cooled High Speed spindle change over capability for carving etc ......and paid accordingly...….. but it did give me interchangeable tooling and a power draw bar which is the main reason I went ahead and bought it.

    If you were designing the ideal mill...….. size whatever...... the main aspect would be it's milling capacity as opposed to the economy, but if it was for a sale item then you'd have to cut many corners just to compete in a very tight market......the market is saturated with mill options from the very cheap and retrofittable to the exotic high end commercial stuff., it just depends on what you intend to use it for...…..hobby work is a totally different ball game.

    BTW, the specs for the spindle you linked showed a usable rev range from 2,000 to 6,000 not 0 to 6,000, that is a big limiter.
    Ian.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Quote Originally Posted by handlewanker View Post
    Hi, it may be a good price and could be considered self contained, but you're stuck with an ER25 collet on the end...……..anyone constantly changing an ER collet chuck will know what I mean......give me an R8 or ISO30 any day over an ER solution......but I suppose the fact that R8 and ISO 30 both need to have a drawbar and the power draw bar mechanism to clamp them too, that makes it a too hard basket item to manufacture for the same price range.

    The original basic design model for the Skyfire SVM-0 mill I bought came out with an ER32 spindle end and a 1 HP BLDC motor etc etc, but I pushed for the ISO 20 spindle option with an additional option to have a self contained water cooled High Speed spindle change over capability for carving etc ......and paid accordingly...….. but it did give me interchangeable tooling and a power draw bar which is the main reason I went ahead and bought it.

    If you were designing the ideal mill...….. size whatever...... the main aspect would be it's milling capacity as opposed to the economy, but if it was for a sale item then you'd have to cut many corners just to compete in a very tight market......the market is saturated with mill options from the very cheap and retrofittable to the exotic high end commercial stuff., it just depends on what you intend to use it for...…..hobby work is a totally different ball game.

    BTW, the specs for the spindle you linked showed a usable rev range from 2,000 to 6,000 not 0 to 6,000, that is a big limiter.
    Ian.
    It says 0-6000 range but it says the manufacturer recommended range is 2000-6000. This is due to the shaft fan cooling. If the main purpose was metal milling, you'd want to order a water cooled or electric fan (or compressed air) variant. Then you'd get 0-6000.

    On the type of tool holder, anyone considering a manual spindle like that would be on a limited budget. My main spindle is a 7.5hp er25 cooled by electric fan. It can do all the work I need it to. Obviously if money was no object, I would have gone for the $12000/ATC variant. For my needs, I chose to invest in a high quality mtc spindle instead of a Chinese ATC option. Either is a compromise though.

    I also have a 2000rpm R8 spindle belt drive cartridge with a 1hp motor but the weight and size of the combo makes it completely unsuitable for a benchtop Gecko G540 build.

    You could buy a Tormach BT30 cartridge with a 1.5hp motor plus a power drawbar and tool changer but then you get out of the hobby-level pricing. If it is for commercial manufacturing, I would avoid all these diy options.

    For diy hobby-level builds, it is cheaper, safer and easier to use an all in one spindle even if it's for making occasional steel parts. My spindle can easily mill steel with smaller tooling and I am 100% positive it would do a better job than a LMS benchtop hobby mill.

    Ironically, it is easier to copy a Datron mill than it is to build a diy Bridgeport...



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Now what diam and at what low speed could you use such a spindle that is rated to go down to 0 rpm?

    If you wanted to drill with a 10mm drill the rpm for HSS is approx. 300rpm...….go up to 20 mm and it gets worse....150rpm...…..now we're getting less torque than ever, but that ER25 collet chuck only holds 15mm at most so no problem.

    I suppose the lower rpm could be used for fly cutting with large sweep diams but that is just for a surface clean up at .25mm at most...…...tapping, forget it, the torque is non existent unless you
    re doing 5mm diam fine threads.

    The point is it's not practical for most uses to have a self contained all in one spindle on a mill.....it "could" be done, but for various reasons it's not.

    The other point is, no manufacturer would consider marketing a mill with a high speed spindle, water cooled or not, unless it was a high end cost a bomb special purpose or reason option, as the market would not consider it practical, so it wouldn't be part of an inventory in any tool catalogue...….....it's horses for courses in the end.
    Ian.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    Quote Originally Posted by handlewanker View Post
    Now what diam and at what low speed could you use such a spindle that is rated to go down to 0 rpm?

    If you wanted to drill with a 10mm drill the rpm for HSS is approx. 300rpm...….go up to 20 mm and it gets worse....150rpm...…..now we're getting less torque than ever, but that ER25 collet chuck only holds 15mm at most so no problem.

    I suppose the lower rpm could be used for fly cutting with large sweep diams but that is just for a surface clean up at .25mm at most...…...tapping, forget it, the torque is non existent unless you
    re doing 5mm diam fine threads.

    The point is it's not practical for most uses to have a self contained all in one spindle on a mill.....it "could" be done, but for various reasons it's not.

    The other point is, no manufacturer would consider marketing a mill with a high speed spindle, water cooled or not, unless it was a high end cost a bomb special purpose or reason option, as the market would not consider it practical, so it wouldn't be part of an inventory in any tool catalogue...….....it's horses for courses in the end.
    Ian.
    All small mills and cnc routers are limited to smaller tool sizes. The R8 spindles found on most bench mills can technically hold larger diameter end mills but most brands state a suggested max of 1/2" to 3/4" (for end mills).

    The limiting factor (for use of larger end mills) is not the spindles torque or the type of toolholder. It is the machine stiffness, weight and resultant vibration damping capability. It would do you no good to mount a 40 taper spindle on a bench mill or a Chinese 6040.

    I obsessed a little over being able to hold larger end mills when spindle shopping until I realized the above info and that it only really matters on manual mills. With cnc machines, there is not much (or maybe nothing) that you can do with a 1" HSS end mill that you can't do just as well (or better) with a 1/4" carbide end mill.

    Datron machines are limited to very small tools but you could make a better steel part and a lot faster than you could with your average Bridgeport.

    Obviously if you have a high speed spindle, you would never choose a HSS end mill. You would go with carbide and, according to my speed /feed Calc, any carbide end mill you could use to mill stainless steel has a suggested spindle speed of more than 2000rpm. For 1/8" carbide it suggests more than 4500 rpm. Even if you were using a 4 pole 1725 milling motor, gearing would be of little help.



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    Default Re: Why most (non-router) milling machines don't use self-contained spindle?

    If I were reducing a 25mm thick block of steel 100mm X 100mm down to 20mm I would rather mill with a 20mm diam HSS cutter and take less cuts at a shallow depth than use an 8mml carbide cutter and take lots of deeper cuts.....the 8mm diam carbide cutter will have a tendency to flex whereas the 20mm diam HSS one won't.

    There is a difference in the mode of production you are using...…...if it's a business or commercial venture than you'd be applying the best solution for metal removal to be competitive as opposed to just cutting metal to get down to the size you want if you were a hobby person doing it for fun.

    You could go on at great lengths applying the specs for various cutters...... and machines you cannot afford…….. that would shave seconds and minutes off a machining cycle, but that would only apply if you were in a production scenario and time being money etc.

    What is 10 minutes extra on a job when it would probably sit on the bench overnight to be delivered sometime the next day or when the customer picks it up.

    I doubt anyone cranks a mill up to the max for a one off job just to save a few minutes on a work cycle, but if the work piece is in a queue and other work is pending then I suppose the time taken to do that piece at it's best production time would reflect on the profitability when you get more out of the door today instead of tomorrow sometime.

    Once you get into the race of speeds and feeds to make money, then the machine itself is the critical factor...….a wrong machine for the job does not make money to buy exotic cutters that will make more chips in less time...…...that is one good reason many people have a CNC mill in their workshop just to be able to let it do the setting and resetting to get to size that takes so much time with a manual mill......but having a mill that only came with a high speed spindle does limit your options and selection of tooling if the total set-up is not on par.
    Ian.



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Why most (non-router) milling machines don't use self-contained spindle?

Why most (non-router) milling machines don't use self-contained spindle?

Why most (non-router) milling machines don't use self-contained spindle?