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    Default Doosan DVF 5000

    I have been a long-time reader, but this is my first post. I am seriously considering buying a Doosan DVF 5000. I will be doing a mix of job shop work with a mix of materials. Most of the parts will be 3+2 with an occasional 5-axis toolpath. Some of the work will be reasonably tight, and I don't want to constantly chase offsets from the machine moving around.

    I was wondering if anyone has any direct experience with this machine that could offer some feedback. How thermally stable and accurate is the machine? How rigid is it, and how are the clearances? Anything I should be concerned about in particular?

    There are not many other machines with this size capacity in my price range, but open to recommendations. I have some experience with the Mazak VC-500A/5x, and that is another option. I also have experience with many of the more premium European brands, but those machines are outside what I can afford to spend at the moment.

    Thank you for your help!

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    Quote Originally Posted by Trevor360 View Post
    I have been a long-time reader, but this is my first post. I am seriously considering buying a Doosan DVF 5000. I will be doing a mix of job shop work with a mix of materials. Most of the parts will be 3+2 with an occasional 5-axis toolpath. Some of the work will be reasonably tight, and I don't want to constantly chase offsets from the machine moving around.

    I was wondering if anyone has any direct experience with this machine that could offer some feedback. How thermally stable and accurate is the machine? How rigid is it, and how are the clearances? Anything I should be concerned about in particular?

    There are not many other machines with this size capacity in my price range, but open to recommendations. I have some experience with the Mazak VC-500A/5x, and that is another option. I also have experience with many of the more premium European brands, but those machines are outside what I can afford to spend at the moment.

    Thank you for your help!
    it'll be lightyears ahead of haas umc's. but not quite like a GF/hermle etc. should be reasonably fine.

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    Mazak VC-500A/5x

    I think folks found out the hard way that the x-travel is not really sufficient for fixturing work off the center of the table when tilted over. Seems to do OK on larger impellers i.e. the table is tilted at 30, 45, 60 degrees ish - most of the time.

    VC-500A/5x was a noble attempt to provide a more affordable 5 axis machine - designed and cobbled together in Kentucky from Yamasaki Mazak (Japan) components. A number of problems to iron out over time that some customers took a bit of a hit on.

    There are some good machines from MAZAK (for sure) but feedback on the VC line has not been great or "Glowing".

    Going more up market / spendy with the (various) Variaxis series of 5 axis machines it's really important to check the work envelope esp. for your parts , with the table in different positions + reach and space occupied by the spindle/ spindle head. Sometimes there is a counter intuitive use of the volume - narrow in x also but nice and deep in y - artifact of gantry design.

    Seems the UK MAZAK branch did a good job (design wise) on the CV5-500 - (through the bridge trunnion ) layout / made affordable , but not available in the USA.

    __________

    I believe the Doosan DVF 5000 can be optioned with direct read scales (linear) - not sure about how direct read the rotary scales are ? Looks beefy / can take a pounding + smooth moves.

    __________


    How does a DVF 5000 price out as compared to a Hermle C 250 (for example ) ?

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    That has been my experience with the Mazak VC-500A/5x. Not very ergonomic in terms of clearances and needed some very long gauge length tool holders to make things work.

    I am hoping to get a copy of the Doosan model into Camplete TruePath and try out some different setups on the computer to see what kind of fixturing and gauge lengths I could get away with on the machine. I am hoping it will be better than the Mazak.

    I believe the Doosan has scales on all axis as standard now, but need to double-check.

    I would love a Hermle C250, but I think it's just out of my price range. I can get out the door with the DVF for a good bit less than 250k. I assume the Hermle would be around 100k more?

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    Quote Originally Posted by Trevor360 View Post
    That has been my experience with the Mazak VC-500A/5x. Not very ergonomic in terms of clearances and needed some very long gauge length tool holders to make things work.

    I am hoping to get a copy of the Doosan model into Camplete TruePath and try out some different setups on the computer to see what kind of fixturing and gauge lengths I could get away with on the machine. I am hoping it will be better than the Mazak.

    I believe the Doosan has scales on all axis as standard now, but need to double-check.

    I would love a Hermle C250, but I think it's just out of my price range. I can get out the door with the DVF for a good bit less than 250k. I assume the Hermle would be around 100k more?



    ^^^ I don't know if you saw this video or not; (second time I've posted reference to this vid. ).

    Barry (originally) from General Atomics devised this demo.

    What's clever about this - (at least to me) -is that the blade is way off center forcing the X Y and particularly the Z axis to reciprocate through long travels and still achieve very good surface finish on titanium - constant engagement + really contiguous surfaces generated by genuine high precision smooth moves in cut. [+ everything else, tool poise / engagement / tool selection / feeds and speeds and programming. + rigidity / amount or iron in the right places + pretty nice approach to fixturing. ~ Obvi. ].

    [Easier to do more centered on a table with smaller work volume and smaller ranges of movement from each axis (particularly on machines with a different layout more suited to this type of work) but to demo that blade on the near extremes of travel - including far out on the rotary table - on the DVF 5000 is never the less really impressive.]. ~ Never seen a blade done that way on a universal before.

    For me that was a really compelling demo of what the machine could do.

    + I believe BARRY will be showing the other end of how that was programmed so use of the volume / collision avoidance will be nice to see. [MasterCam - I believe.].


    __________________________________________________ _____________________________________


    Yeah Hermle C250 with standard collection of nice-ish options in the $350K ball park.

    Doosan DVF 5000 for under $250K (depending options) sounds promising. [I wager though that with more equivalent options might creep towards or nudge over $300K.]. OTOH there may be some options on the DVF 5000 that the Hermle can't close in on.

    I think Methods (machine tools) tried or are trying to roll out a custom machine specc'd by them from Litz that's a universal [MB-650u ] that is 5 arc second direct read encoders (Heidenhain) and direct read linear scales for just under $300K.

    MB 650U | Methods Machine Tools

    __

    DMG mori DMU 50 3rd gen - more expensive all round. Scales all axes linear and rotary + pretty serious attempt at thermal management + Speed-master + other spindles.
    __



    ~ personally for this type of work esp. on a universal positional (rotational) accuracy needs to be of the order of 5 arc seconds + decent bandwidth mechatronically on the control / servo drives and encoders etc. working in concert in a "harmonious" / well tuned way. + dependable build geometry/alignment + good foundation. + any adjustments / tweaks after settling in beyond just various on-machine calibration routines to munge everything together.

    @Trevor360 I hear you on the 3+2 principal requirement + work volume provided by the DVF5000 or it's bigger sister DVF 6500 ~ looks like the ergonomics might be easier on the 6500 ? .




    __________________________________________________ _________________________________

    * Welcome to General Atomics | General Atomics

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    Thanks. I have seen that demo and was thinking the same thing. Also seems like a good sign for a lot of Z travel.

    Stated Accuracy for the machine:

    Positioning accuracy (full stroke) +/- .0002"
    B and C axes accuracy B(+/- 10) C(+/-6) seconds
    Least command increment .0001"
    Repeatability +/- .000080"

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    Quote Originally Posted by Trevor360 View Post
    Thanks. I have seen that demo and was thinking the same thing. Also seems like a good sign for a lot of Z travel.

    Stated Accuracy for the machine:

    Positioning accuracy (full stroke) +/- .0002"
    B and C axes accuracy B(+/- 10) C(+/-6) seconds
    Least command increment .0001"
    Repeatability +/- .000080"
    That ^^^ would (probably) be without rotary direct-read scales; but looks like linear scales could be in play ? [at least for that set of options.]. +/- 5 micron full stroke - maybe not. but positional repeatability +/- 2 micron ?

    Actual in-factory (runoff) test sheets and plots usually test tighter / much tighter to account for long term wear and basic machine dynamics when under real cutting conditions / loads.


    OTOH some MTBs are not that far inside of "brochure tolerances" in all cases.

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    So basically in the first 60 seconds "They" - Titan- group say / state,

    (sim) 5 axis , 60 tools, 18,000 rpm Dual contact Big Plus, SCALES ALL AX[E]S LINEAR and ROTARY.

    So "scales" on rotaries can be open to interpretation , but maybe it's legit ?

    I believe that's the machine that BARRY is running the Titanium blade demo on. in post # 5.
    Last edited by cameraman; 07-25-2021 at 05:40 PM.

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    Info I have here says:
    "absolute rotary encoders on B and C axes and absolute glass scales on XYZ axes"

    "The X, Y and Z-axes have absolute type, linear glass scales that do not require referencing at power on. These
    virtually eliminate the impact of slides, ball screw thermal expansion, and help to enhance repeatability. This
    improves the ability to hold tight part tolerances with fewer offset changes."

    Pretty Interesting....

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    Quote Originally Posted by Trevor360 View Post
    Info I have here says:
    "absolute rotary encoders on B and C axes and absolute glass scales on XYZ axes"

    "The X, Y and Z-axes have absolute type, linear glass scales that do not require referencing at power on. These
    virtually eliminate the impact of slides, ball screw thermal expansion, and help to enhance repeatability. This
    improves the ability to hold tight part tolerances with fewer offset changes."

    Pretty Interesting....
    Just to be clear or clearer,

    Stated Accuracy for the machine:

    Positioning accuracy (full stroke) +/- .0002"
    B and C axes accuracy B(+/- 10) C(+/-6) seconds
    Least command increment .0001"
    Repeatability +/- .000080"
    from above;

    B axis - B(+/- 10) arc seconds so probably a 20 arc second positional spread or uncertainty - but not actually being stated to any confidence limits is pretty meaningless, nor describing the scheme of plots or measurements - uni-directionally or bi-directionally.

    One would assume that would be without direct read scales.

    Same for +/- 6 arc seconds on C - that's pretty damn broad 12 arc second spread. So maybe bi directional 3 sigma value -

    ^^^ That would be very atypical for a machine that has proper rotary scales of the class / bracket that would be appropriate for a Doosan DVF 5000.

    Least command increment .0001" ~ that's more about the resolution of the control not what the machine's sensitivity of positioning is,

    but .0001" one "tenth" or 2.5 micron. ~ that one is a little odd , maybe they mixed and mashed up units there.

    Repeatability +/- .000080" <---- That's a linear repeatability but could be from a sequence over 100 mm / 4" (unidirectionally) +/- 80 millionths ---> +/- 2 micron. 4 micron spread.


    The problem is such statements and sometimes in brochures are fragmentary, incomplete and without context.

    So seems team Titan got their DVF5000 optioned out with extra scales rotary and linear + other ?

    ______________

    Also worth paying attention to is the positioning error / mis-match brake on and brake off on the rotary axes for higher torque (in cut) positional work. [not relevant to everybody / style of work.].

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    Quote Originally Posted by empwoer View Post
    it'll be lightyears ahead of haas umc's. but not quite like a GF/hermle etc. should be reasonably fine.
    Light years ahead of Haas but also light years behind the Germans.

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    Quote Originally Posted by Trevor360 View Post
    Info I have here says:
    "absolute rotary encoders on B and C axes and absolute glass scales on XYZ axes"

    "The X, Y and Z-axes have absolute type, linear glass scales that do not require referencing at power on. These
    virtually eliminate the impact of slides, ball screw thermal expansion, and help to enhance repeatability. This
    improves the ability to hold tight part tolerances with fewer offset changes."

    Pretty Interesting....
    These
    virtually eliminate the impact of slides, ball screw thermal expansion, and help to enhance repeatability
    More ^^^ over generalized brochure-like statements (perhaps);

    So Slides or linear rolling element slides and trucks etc. ~ basic build straightness should not be affected by reading scales. [even when talking about Abbé errors ]. Some machine builders will claim a true "geometric" accuracy and others are a little sketchy or vague as to whether they correct orthogonal "squareness" digitally and dynamically. A machine should be able to cut straight and square without any scales or corrections unless a given machine is especially asymmetric for a given set of applications / good reasons.

    That's why laser plots that indicate straightness or at least videos of DTI against a granite test bar / plate can be useful.

    So scales will thermally expand and contract and so will the frame of the machine and so will the ball screws unless some attempt is made to thermally regulate those - like - core cooled ball screws.

    Some machines fair quite well without scales up to a point depending on thermal management strategies and quality of build geometry.

    Most good machines have laser calibrated pitch error compensation (+ tables) for ball screws. [In some cases pre-tensioned ball screws can be an advantage.].

    Some MTBs will have scales that have temperature sensors built in to monitor / measure the anticipated thermal expansion of a given linear scale and will even have cooling points within the machine such as critical bearings and parts of various castings and spindle / spindle housings and other sources of heat.

    Each MTB has their own style and way of closing in on all that.

    Scales are helpful when integrated properly into a larger scheme of overall "metrological" management of the machine.

    Usually process reliability can be improved by linear- scales -part to part- accuracy but the individual part accuracy might not be improved that much. Card carrying mold machines with long cycle time precision work need every trick in the book to keep everything on course, different need / approach.


    __________________________________________________ _____________________________


    Rough mental mnemonic for arc seconds,/ getting a handle on this " Arc second " business...

    Roughly speaking, (1° degree of arc) divided by 3600 = 1/3600 = 0.00027777° ... or = 1 arc second or written (confusingly) as 1")

    One arc minute being 1/60 = 0.0166666° so 60 arc seconds in one arc minute. 1 arc minute being written as 1'


    In terms of practical tilt,


    1 arc second is 1 micron (40- "Millionths" [0.00004" ]) tilt over 8.0" (roughly).

    +/- 2.5 arc second (5 arc second spread) ≈ 5micron tilt over 8.0" (inches) ≈ to a "two tenths" - spread over 8.0 "

    +/- 5 arc second (rotational error/ positional uncertainty) ≈ +/- 0.0002" or 0.0004" spread over 8.0"

    +/- 10 arc second positional uncertainty (like the quoted B axis on a universal 5 axis machine ) +/- 0.0004" or 0.0008"

    ^^^ basically edging in on a "thou" for positional uncertainty (on only one rotational axis) when referenced to the spindle which is about as good as tramming a head in on a 50 year old manual Bridgeport.


    It's a lot of money to pay for something when the "Universal" 5 axis machine idea is that it can function as a good 3 axis machine and can do more demanding positional work.

    All errors are additive so smash in your other 22 or more errors beyond tilt errors.

    That's why I feel that 5 arc second rotational tolerance +/- 2.5 arc seconds to 2 or 3 sigma confidence level + genuine machine sensitivity of movement to near sub arc second adjustment would really serve a lot better to actually obtain the mythical 'Two tenths" with a machine that has tilted axes. [The idea is (perhaps) to eliminate surface grinders and specialized jig borers and multiple set ups, scrapped parts and too much time in inspection etc. ? + precision fixtures ].
    Last edited by cameraman; 07-26-2021 at 11:55 AM. Reason: handle on counterintuitive angles

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    Quote Originally Posted by Radar987 View Post
    Light years ahead of Haas but also light years behind the Germans.
    no doubt, agreed.

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    No experience with Doosan, but the first thing I see when I watch some videos on line is the placement of the laser. I could see that thing getting wiped out if your not careful.

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    Quote Originally Posted by Trevor360 View Post

    I am hoping to get a copy of the Doosan model
    Good luck, I had to sign my life away just to get the models AFTER I had bought the machines. They don't like giving out their models for some reason.

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    Quote Originally Posted by lastrada View Post
    Good luck, I had to sign my life away just to get the models AFTER I had bought the machines. They don't like giving out their models for some reason.

    This is absolutely not true. We do require you to sign an NDA, formality really. But we have no issue whatsoever giving models to customers to have machine simulation handled properly.

    Paul

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    Quote Originally Posted by LockNut View Post
    This is absolutely not true. We do require you to sign an NDA, formality really. But we have no issue whatsoever giving models to customers to have machine simulation handled properly.

    Paul
    GF gave me a cad model of their machine way before we even committed to it without any paperwork BS attached...

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    Quote Originally Posted by empwoer View Post
    GF gave me a cad model of their machine way before we even committed to it without any paperwork BS attached...

    That's great. We would most likely do the same. But what good is a CAD model without a machine? And what harm is an NDA?

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    Quote Originally Posted by LockNut View Post
    That's great. We would most likely do the same. But what good is a CAD model without a machine? And what harm is an NDA?
    shop layout. figuring out what goes where and how to set the machines up for max efficiency in CAD, making sure you can fit the machine(s) in etc.

    as far as NDA, more bullshit and headaches for me to deal with.

    wtf do you need an NDA for anyway? what could someone possibly do with a gutted CAD model of a machine that would hurt the company?
    fucking archaic bullshit that needs to die.

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    Quote Originally Posted by LockNut View Post
    That's great. We would most likely do the same. But what good is a CAD model without a machine? And what harm is an NDA?
    I have never had a problem signing NDAs (various) and quite often I will offer to sign an NDA.

    Generally I ALWAYS try to be very careful to not let any materials migrate into the hands of "Others" be they friends colleagues or perceived competitors. [I think that's really important.]. Even if someone is point blank asking me for a runoff factory test sheet , I say NO. and NO in no uncertain terms but re-direct them to approach the company directly if they want that kind of deeper info.

    Personally ( I think ) it's really important to be discrete when handling other people's internal data no matter what.

    But that's deeper related engineering info, not so much CAD models of machines.

    IME best not to share sensitive info even when "Secured" by an NDA.

    I.e. Don't trust 2nd and 3rd parties with data that's important/ mission critical or consequential (to you, or your company) if it falls into the wrong hands.

    There are ways to handle spatial / CAD data in other non-infringing / non-sensitive ways, just an extra layer that someone has to deal with to produce. ~ I think HAAS do that pretty well as I understand.

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