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  1. #21
    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    I think it is a matter of preference for each customer. All 5 of my machines run under Windows. It's what I know and is cheap and easy to replace upon a failure. In fact I have two stand by laptops ready to take over a machine when one fails or faults. 3 of them use IBM R40 laptops with XP.

    The new Pulsar is different in that it has an on board computer with an SSD and Win7. Fast boots. It also has Smooth Stepper Ethernet. That makes it very stable. I have not had it lock up like some have in the past using a PP. Still waiting on a new Arduino BOB. It has a proprietary BOB now, but the Arduino should prove nicer and even more stable. This is the direction I would probably go.

    Now it does have a Servo spindle and I gotta tell you, once you go rigid tapping, you won't look back. For that reason alone, I would probably source some of my electronics from Novakon.
    I like and have plenty of tooling for R8. That is already an investment.
    I would not invest in something else. R8 does fine in even a little larger machine, so it is fine for one this small.
    Like Defeng, I think you should design possibly two heads or offer two spindle cartridges. R8 being one of them. You are trying to bridge the gap between hobby and pro. That would help.

    Lee


  2. #22
    Member Tkamsker's Avatar
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    Default Re: VMC Mill Discussion

    Hi,
    G59

    My world is metric so it will be metric in my case
    my spindle is 2,3kw at 230 V but can do 400 as well
    I aim for 230 240 Volts because not everybody has 400V avail
    About servor or steppers will be my next post i basically i have to work it out now i have steppers on it
    i will only work on windows if i get heavily payed for so in my case it is linuxcnc but everyone can choose his control how it suits them if a small factory has all in fanuc i guess they insist on fanuc -

    i already have ISO 30 in my shop so i stay with it but about 10.000 rpm i have to see
    i ordered an ISO 30 ATC Spindle from an german i have to check what the ball bearings are supposed to survive -

    but i am here really more about to understand the average pro / con and requirements and see what is key aspect of dfengs design ,..



  3. #23
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    Default Re: VMC Mill Discussion

    It might be worth looking at some of the high performance designs for inspiration. Say a bridge mill like a Datron or a moving head like a Chiron. The interesting thing about those designs is that while they move a lot of mass, they are largely independent of the weight of the workpiece and you can calculate all of your dynamics up front.

    Whether those designs can be built DIY in a space-efficient and cost-efficient manner is another question altogether.

    bob



  4. #24
    Member Tkamsker's Avatar
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    Default Re: VMC Mill Discussion

    Hi
    so i will skip the control software and as i wrote everyone should be able to choose (only if have to support it i choose )-

    About servos and steppers there is a good white paper of tormach why they have choosen steppers. I worked with steppers and servos (for newbies there is a good link for info Comparing Stepper, Servo and Direct Drive Technologies | Motion Technology Blog )
    the work envelope will be comparable to BF46 so like y200mm and x 450mm
    so if i have an spindle with 5mm pitch we have 90 revolutions to go from max to min in x axis which if we would have zero mass and no ramp will translate to 1,8 seconds if 3000 rpm

    so the tables might have some weight the vice and piece as well
    so lets anticipate that with 50kg (or should i take less ? )
    ( Newton (unit) - Wikipedia, the free encyclopedia )
    force should be (50kg *0,45m) / 1,8 square on my calculator it shows 6,94444 newton

    we can see the 5mm per revolution as ramp (in german "schiefe ebene") so a fith will be the actual force on the stepper. i know i have forgotten the friction and mass inertia.

    So if we have an stepper of 3 nm (required 1,388 ) we would be fine.
    My question i have the impression that steppers break much better than servos do is that right ?

    Is someone who can verify my calculation ?

    i right now look into 2 configs
    one config is the DIY cheap region where i have 5A Steppers a tripple beast (because it is quiet and working ) control and 48V or an servo (i looked at komotec) which then requires 100 to 200 v and an controller per servo.
    where i look into ( Drive electronics | Granite Devices Online Shop ) the vdd series can work in Dual mode (and i have now experience with them ) so i would only need 2 of them for an 4 axis machine

    thomas



  5. #25
    Activation process G59's Avatar
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    Default Re: VMC Mill Discussion

    Is this thread already dead?

    My understanding of this project is to build a modern machine. So no steppers please.
    I don't care much for the Tormach "whitepaper", as it is obvious they biased their findings, favoring their configurations.
    I want speed with accuracy. Emphasis on speed. Accuracy is equally important.
    Steppers have better braking? It's funny as my old milling machine can go 200ipm and stop on a dime with servos. When it stops like that, you feel it right through the floor of the shop with a loud audible sound.(not good).
    No Mach software whatsoever. Let people choose.
    Just the mechanical would be great.
    10,000 RPM / 3hp is my preference so small cutters can be used.
    Metric is the only way to go.

    That's what I would like to see in a 'new' machine. Now I'm sure others have different requirements.



  6. #26
    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    Okay. You and I need two completely different machines. That said, they can look and even be the very same base machine.
    I would use Mach. I would use AC steppers. An AC servo for spindle. I am comfortable with what I know. That setup can be made to run fast and reliable. No Metric. No please about it. It can be a metric made machine, but it's gonna be cutting in inches. That is why this discussion should focus only on the machine. The bones, drive train and ways. Spindle cartridges as well. I think two different heads might be needed. One R-8. The other whatever G59 wants. You know it has to be different.

    Lee


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    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    Now on spindles. The prebuilt spindle are nice and would be easy to mount, but they are ER collets on the ends. The ones I have looked at. That makes for difficult tool changes. That means we rule those all in ones out, correct?
    It needs to have spindle cartridges that are timing belt driven. Then various motors can be used. Users choice. Have R-8 and BT30 heads available that can even swap out if needed.

    A couple of universal alignment pins and 4 to 6 bolts through the head into the Z carriage would make short work of head installation.

    Lee


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    Default Re: VMC Mill Discussion

    Hi the tread is Not Dead but we are all busy i guess ,
    About Steppers and servos i think it is mainly a cost and which material do you Cut at which Speed. I See on that bridgeport if it is on Speed and the z axis is more than 300 kg you can Tell the fore it Needs to decellerate
    So i will do that optimal like standard and pro Model.
    I have Spöken Last days to several Shop owners to find Out what they think.
    One of them says atc possibility is Not important power draw Bar sufficient
    I learned from another owner that dh has Seen that rail Systems Tend to collect Steel dust under the Balls and hardened rail. He Thinks that dovetails are superior ,..
    I havent looked at that from that Angel ,..
    And next week i get an iso 30 atc spindle the Guy WHO Build it used high Quality ballbearings but they are specified for max 7000 rpm
    I guess that 10000 will be some hurdle the question is if it pays off ,.. Leeway what do you Cut that You Need 10k ? So when i get the spindle i will do an Test setup



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  9. #29
    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    I don't cut anything that needs that kind of speed.
    If I do, I cut it on the router. My little home made mill turns 6600 RPM and the Pulsar mill 4500 RPM. That takes are of my requirements.
    I do have an attachment that I can put on the side of my small mill head that holds a trim router. It worked great as a high speed spindle when I needed it.
    I think that is the way it should be done in this case as well. Not everyone would want or need one. Those that do, could easily attach one.

    The cost of a large high speed spindle is much more than a small step higher once you hit the 10,000 RPM mark.

    Lee


  10. #30
    Activation process G59's Avatar
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    Default Re: VMC Mill Discussion

    Have R-8 and BT30 heads available that can even swap out if needed.
    Now there is an original idea. I would love to see that. A++++

    what do you Cut that You Need 10k ?
    Molds. Small radius corners, small engravings of company logos in the molds and small drilling.
    Many things I do require less than <0.0625 tools.
    I machine both steel and aluminum.
    Belt driven BT30 spindles that go 10K are $250-300 more than a 6000RPM one. I would gladly pay the extra cash.
    Must have PDB. No ifs and or buts.
    ATC for myself is a must and the design of the mill should consider built in mounts ready to adapt such appenditures. Make it an option.

    Thinks that dovetails are superior ,..
    Not true. If you want absolute best rigidity, you have boxed ways, but we are not building a "hogger" now are we?
    Linear rails only require proper lubrication, Oil preferably, and your machine can weigh less for the same accuracy.

    I am in the process of making my own machine which is twice the size requirements of this one, and my forecast budget has been blown out of the water already by trying to keep it modern.
    I know it's not easy. As an engineer, you have to look at different angles to every problem or different customer needs.

    Leeway is right, let's settle on a good base that can be modified later with the potential of reaching the extremes of more demanding owners such as my self.



  11. #31
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    Default Re: VMC Mill Discussion

    I think the whole thread is about different angles to have clear Engineer view ,..
    You are right about dovetails Design but the Guy has 40 years plus machine design and use experience he Build an Company which döes sausage packaging incl net and his Hobby is fixing real size steam machines and doing Big size Modell steam machines ,.. Thats whY i mentioned it
    But i am sure that because of reduced Weight ball Bearing systems are superior ,..


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  12. #32
    Activation process G59's Avatar
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    Default Re: VMC Mill Discussion

    Well, what can I say. Just look at what today's machines are made of, and you see that linear rails are not just a trend, but a norm. Proven more efficient with good rigidity for most applications.
    Ultimately, it's your machine and if you want dovetails on it, then that's what you get.
    I personally think it is a step backwards.
    I also believe my machine is of a different design with different requirements, than yours.
    Don't let me discourage you, go with what you think is best.
    Secondly, and I'm sure this won't fly either with most people, I would have the workpiece stationary.



  13. #33
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    Default Re: VMC Mill Discussion

    G59 i agree it will be on Rails simply because of table weight which I have to accelerate and decellerate but it Shows How also experienced People think ...



  14. #34
    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    There are a few benefits with profile rails and trucks over dovetails. Most come from being able to replace them quickly. Once you do that once, you then have the extra set to load new bearings into. Stock parts. Since this will not be cast iron, the obvious choice is the profile rails. There are no adjustments on them, so no gibs to adjust. Smaller motors could be used, though I doubt that many will use smaller ones. Speed is useful in some types of machining while it is possible to run a dovetailed machine at high speeds, it makes more sense to put that speed on rollers.
    For a welded frame machine, I don't really think we have a choice. Not one that makes more sense than the profile rails.

    You can argue with old timers till blue in the face. You get the same results arguing with a surface plate.

    Lee


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    Default Re: VMC Mill Discussion

    I agree about the old-timers -

    i am thinking of what you are mentioning of that speed. i also do molds and light stuff on the router ( i have an Heiz 400 T german quality ) the spindle is an kress 1050 which can do up to 25k
    and i also have one with an ATC on it but ,.. in that config i did some molds ( air wing profile in my case ) but the bearings of the ATC get verry hot and from time to time the release did not work.
    the spindle issue i have to think of because it might be of sense to have different spindle package

    for instance one of the young timers says in his view he need 80 % CNC but he also likes the Quill ( in German called PINOLE) feture where he can drill or cut big holes in steel

    and i think not everyone needs an ATC feature and not everyone needs the > 6k speed but they who need really need them

    So i will now be quiet because of thinking -
    have a nice weekend



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    Activation process G59's Avatar
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    Default Re: VMC Mill Discussion

    Quill? Another no for me. (Yes, it's just me I know,.) Circular interpolation just as good if not better(depends how deep).
    I think the old timers got a hold of your young timer.
    Leeway, once you start using the HSM toolpaths, you'll quickly like the features of it and you'll kick yourself in the butt that you didn't go for a higher RPM spindle. Once you get the feel for cutting at a true average speed of 250 ipm even with circular motions and 3D surfacing, you'll never go back to 4500~6000RPM.
    I know I'm expecting alot. But if I can't get it here, my larger build will definitely go there. I'm following this thread to mostly see what everyone else is looking for in a machine.
    As for the ATC, I'm fine with a Static one like Datron.
    It's unfortunate more people haven't chimed in.



  17. #37
    Gold Member LeeWay's Avatar
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    Default Re: VMC Mill Discussion

    I do intend to see what HSM is about.
    I just got SolidWorks installed and will be able to check out HSMXpress soon. I have had zero time for training on either yet.
    Soon hopefully.

    An ATC is not a must for me, but to truly modernize and automate a machine, it would need ATC. PDB at least. My pulsar has a lever draw bar and it is pretty nice as well. The draw back with it is that it can't be or it isn't automated. Non issue without an ATC.

    Lee


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    Default Re: VMC Mill Discussion

    G59 "'m following this thread to mostly see what everyone else is looking for in a machine. "
    exactly that is what the thread is all about.
    i was under the impression that is why people followed dfengs thread

    and i also think it is unfortunate that not more people share their vision with it.

    and i also think there are a lot of people (like the old-timers) who know that and this better
    but i think there are a lot of different needs out there so an perfect machine for everyone doesn't exist.
    it is always a compromise.

    and now where i do all the maths myself i also better understand why other manufacturers have done which decisions

    and i think only if you really tried it yourself you will know

    and i also have to accept the fact that i live in an extreme over regulated part of the world. it is like an bureaucracy dictatorship.
    so coming week i get the ATC Spindle and then we see if it gets hot if it needs redesign

    beside i also understand that a lot people are happy with manual changes
    sp
    thx
    thomas



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    Activation process G59's Avatar
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    Default Re: VMC Mill Discussion

    and now where i do all the maths myself i also better understand why other manufacturers have done which decisions

    and i think only if you really tried it yourself you will know
    I have, but for a larger, heavier machine. My machine is a welded steel plate unit with strategically placed vibration dampening material.
    I'm still gathering some parts. My software is mostly done thanks to two software engineers that I work with, and the best part is they did it for free. It is only 3 axis at the moment but it works well with Fanuc standard G Code, using a PC and Galil card and it can do complex 3D contouring and surfacing.
    I had to confirm where the motors were manufactured and now that I have my answer, we'll be using DMM motors and drives. Expected axis velocity of 300ipm average. Work envelope is X 24", Y 15", Z 14". BT30 spindle 8000 RPM. 3~5hp. PDB and soon after an ATC. The total shop foot print is 6' wide x 6' deep x 7' tall. The footprint includes completely enclosed machining work area, coolant tank, chip tray and of course, the built in control panel.
    Next week, the first steel parts for the base will be cut and welded. I figure it will take me a year to get it ready and machining steel.
    I will be selling my machine once it is fully assembled.
    Now the trick is how to keep costs down.
    I would send you my 3D assembly file, but I fear many would copy it and make their own.
    My software will be made available (open source) once i have tested and I have run it on my machine.

    But enough of my build.
    I want to know what the real world wants.



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    Default Re: VMC Mill Discussion

    Since you're looking for more input, here are my thoughts.

    - Supply a basic machine, to which the buyer can fit whatever motors/controllers they see suitable for thier needs. I know personally I'd prefer brushless servos, along with a KFlop motion controller, but some will be happy with steppers and a simple BOB.
    - PDB is a must using some form of recognised standard toolholders, which are capable of ATC operation i.e. BT/ISO30
    - Spindle should be belt drive, that way users can select their own motor. Again I'd prefer a servo spindle for positioning capability, but others may prefer a more standard induction motor/VFD.
    - Work area, something similar to a X3 would suit me, but I'd be reasonably flexible on that.
    - Have things like limit switches already fitted, or provide mountings that use standard components.



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