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  1. #21
    Your going to need a beefy machine to do 19mm in one pass at 6m. I wouldn't fancy doing that with 6mm tool either! Cut quality would be shite with all the chatter and that's if it didn't snap. 10mm would be where I'd want to be at really.

  2. #22
    OK, so that was a bad thing for me to mention as a requirement to the supplier, I'm correcting that now.

    I have some 6mm wide grooves, and 19mm wide grooves, both about 6mm deep. I was hoping to cut the whole thing with one cutter but swapping is no biggy either.

    What do you recommend if I had 3kW spindle and 6000mm/min ?

    The whole job with 6mm cutter and DOC= 6mm?
    or 6mm cutter for narrow grooves, 10mm for wide grooves and multi-pass for cutting the profile?

    Multipass rough cut the profile, then a full depth finish pass with compression cutter?


    I will be hot glue edgebanding the cut edge, and I've got a choice of chipboard or mdf for the core of the melamine board.
    Last edited by jimbo_cnc; 05-03-2015 at 04:50 PM.

  3. #23
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 9 Hours Ago Has been a member for 5-6 years. Has a total post count of 508. Received thanks 68 times, giving thanks to others 0 times. Referred 1 members to the community.
    If you need both the top and bottom edges clean, then you want to cut the profile with a compression bit.
    If you can, I'd try to go up to a 4-5Kw spindle, which should let you cut the profile in one pass with a 10mm compression bit. Machine rigidity will dictate how fast you can go, but I've cut 19mm board in one pass at ~17m/min with a 10mm compression bit.

    If your limited to 3Kw, then I'd probably try using a 1/4" compression bit for everything. Cut the profiles slightly oversize in 3 passes, with a final cleanup pass at full depth, removing about .5mm.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  4. #24
    Thanks for that.

    I'm not limited to anything. I'm just looking for the most economic way to cut 200 boards per year.

  5. #25
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 9 Hours Ago Has been a member for 5-6 years. Has a total post count of 508. Received thanks 68 times, giving thanks to others 0 times. Referred 1 members to the community.
    The most economical would probably be to pay someone else to cut them.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  6. #26
    Quote Originally Posted by Ger21 View Post
    The most economical would probably be to pay someone else to cut them.

    It might be close if they were all the same, but say I have 10 model options. That would mean liasing and travelling to the cnc shop everytime someone orders one. That's $50 of my time IF it all goes well, plus the $100 machining fee x 50 visits = $7500 per year.

    If I damage a panel later in the build process the costs and delay are horrendous if I can't just run another one off myself.

    Obviously there are also many other advantages to having my own machine too, outside of the main 200 board requirement.

  7. #27
    Quote Originally Posted by jimbo_cnc View Post
    Don't be like that Jazz,

    I'm here for help to get what I want. Although all I seem to be doing is pissing of all my potential suppliers :)
    I'm not being or have been anything other than helpful with sound advise.!! You on the other hand appear not to be listening and hell bent on that particular machine so I wished you good luck. Nothing more than that.! . . . . I still wish you good luck.

  8. #28
    I'm listening and using the advice I get.

    I'm not hell bent on that machine, but no one has suggested any alternative yet. That's not a criticism, just a
    fact.

    And it appears to meet my needs. Even if it doesn't meet your idea of how fast I should cut wood. (I'm up to about 6000mm/min now, just in case you think I'm still at 3500)

    As to ballscrew size, I've asked for 2 proposals from the seller, 25mm ballscrew and 32mm ballscrew, with details of motors and drivers. When I get that info, I will try to analyse the overall performance of the options. Apart from acceleration, what else is there to consider?
    Last edited by jimbo_cnc; 05-03-2015 at 10:58 PM. Reason: added 6000mm/min

  9. #29
    as anticipated, next question is acceleration.

    I've got some specs:

    Motor: 85BHX450B current:4.0A resistance: 0.5Ω, inductance:3.0mH, torque:6 Nm
    can't find that on google, but I can just use the values given.

    Driver: Leadshine MA860H


    I've plugged the values, along with some guesses on gantry weight into the motorcalc spreadsheet, and for 25mm ballscrew it all looks good.

    I deconstructed the spreadsheet so I can see the acceleration being used is based on time to achieve feed rate. This results in 0.57g requirement for my cutting.

    Is that an appropriate value for this machine?

    I'd also like to use this machine for my small plastic parts. I haven't paid any attention to acceleration settings on my 6040, although I might have followed some advice without remembering it. I'm going to run some of my cutting jobs in Mach3 with different motor tuning to see what difference it makes.


    32mm ballscrew:
    When I plug in the 32mm ballscrew, it's clear the ballscrew dominates. I can get about 0.3g from the motor above. Or I can ask for a larger motor. I was quoted +$100 for 32mm ballscrew, but wasn't given a price for a bigger stepper.


    Attached Files Attached Files

  10. #30
    Quote Originally Posted by jimbo_cnc View Post
    32mm ballscrew:
    When I plug in the 32mm ballscrew, it's clear the ballscrew dominates. I can get about 0.3g from the motor above. Or I can ask for a larger motor. [SIZE=2][COLOR=#000000][FONT=&] I was quoted +$100 for 32mm ballscrew, but wasn't given a price for a bigger stepper.
    It'a not just as simple going Bigger on stepper motor. The drives they are providing now only just about cuts it for that size stepper so going bigger only makes things worse.
    It's a Classic mistake often made thinking bigger is better when reality is it's often the worst thing to do. Bigger motors spin slower and require much more power and those drives won't handle larger steppers and give great performance from them.

    You Get the performance thru correctly matching screws and motors to rest of machine. Just going LARGE only leads to COSTLY under performing Mistake.!!

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