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  1. #11
    Ah right. I see a lot of them have mostly down flute and a small up flute, that explains how I got confused because people were talking about them pushing the work down.

    I've cut a few small pieces of MFC on my little 6040 using my standard manual tools, 1/4" with 2 straight flutes. They haven't damaged the melamine edge.

    I was hoping to use the same tool for cutting the 19mm edge and for grooves which are about 6mm deep. It looks like I might be lucky and that the melamine will still be on the down flute for grooving.

  2. #12
    You can ask 1000 people and they will all tell you a differant feed n speed, WHY.? . . . Because every machine is differant.

    No one tell you exact speed N feeds you'll get away with unless they have the exact same machine and even then material and tool grades play some part.
    They can only guide you to small degree based on machine spec which is what I did on the phone, the fact you have removed the machine spec makes this harder for folks to help. (And giving attitude when spec is questioned isn't endering)

    Now if it was the same you told me with single 32mm ballscrew using steppers then 3500mm/min will be close to rapid speeds which is differant to what you'll get cutting making things worse. Hence why I told you it would be too slow for cutting MFC or MDF and maintain any decent tool life. The spec you told me was IME mixed up and wrong for any decent machine for cutting wood.

    By your own searching you can see that average feeds are much higher so what do you want to hear.? . . Best advise in the world isn't worth a cracker if it's ignored, like wise all the sweet words you'd like to hear don't mean a thing if there wrong. They won't make the machine any better suited.!!

  3. #13
    As I've said, I'm trying to get away with a slower machine than what is recommended for tool life and productivity. And I'm hoping I can because my requirements are very different to a cnc shop.

    And I wanted this thread to be about minimal requirements for a machine, not about any particular machine I'm looking at.

    I'd be happy to hear about what machine design WILL fit my needs though, if anyone wants to make suggestions.

    I've got another thread about designing a machine, it's still at the stage of choosing steel frame or aluminium extrusion. I got a bit hung up with straightness of rails I think after reading all Sylvaskis epoxy endeavours. So it hasn't got on to drive system yet.

  4. #14
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 13 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.
    Forgetting about tool life and cut quality for a minute.
    3500mm/min is painfully slow, and will get old very quickly. Imo, there's really no excuse for a machine to be designed to have a maximum speed of 3.5m/min.

    Now, yes, you can cut at 3m/min with a 2 flute cutter, at 10,000-12,000 rpm, and get good results.

    Fwiw, I cut 19mm melamine at about 25m/min every day - on a $100,000 machine.
    Gerry
    ______________________________________________
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  5. #15
    It was my mistake to originallly say I only needed a slow machine, that's why I was offered 3500mm/min. When I know what speed I need (not what I want!) I can get a faster spec.

    OK, here's the machine (1500mm version).
    http://www.alibaba.com/product-detai...981060776.html

    The advert for the 1500mm bed machine states up to 8000mm/min working speed. Seller has said 6000mm/min is fine, maybe 7000 for my machine. But as Jazz noted, seller has suggested it will mean going up to 32mm ballscrew.

    I'm having a 3kW spindle and square rails at the moment.


    edit:
    I've forgotten one of my principles: always think about resale value. So an abnormally slow machine doesn't make sense there.

    So, I will up the speed to 6000 ish. I need to understand the performance disadvantages of 32mm ballscrew, in case seller offers eg only 5000mm/min with 25mm screw, or 6500 with 32mm.

    I guess I'm going to have to download octave unless there's an excel spreadsheet calculator around?
    Last edited by jimbo_cnc; 05-03-2015 at 03:01 AM.

  6. #16
    Clive S's Avatar
    Lives in Marple   Stockport, United Kingdom. Last Activity: 11 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 5-6 years. Has a total post count of 2,308. Received thanks 402 times, giving thanks to others 35 times. Made a monetary donation to the upkeep of the community. Is a beta tester for Machinists Network features.
    I think you might need to ask if it has two screws on the x and what pitch and what is on y and z ..Clive

  7. #17
    Quote Originally Posted by jimbo_cnc View Post
    OK, here's the machine (1500mm version).
    http://www.alibaba.com/product-detai...981060776.html
    Remember what I said on phone about the Chinese chasing profit which means only one thing, something has to give.!! . . . Look closely at that machine and see if you can spot what is jumping out at me.!! . . (Clue) Sloppy and Baggy needing maintenance ounce a month.! (No it's not a Women) . . . . And that cost cutting can be seen from out side just imagine what's lurking under those covers and in that control box.??

  8. #18
    Don't worry Jazz, I'm having square profiled rails on mine.

    Seller will build to what I want, but his opinion is 32mm screw rather than 25mm. He says 10000mm/min will vibrate with 25mm screw. Thisimplies 2510 ballscrew to me. There is no belt on the drive, so that rules out the simple double the pitch and use pulleys to keep the same motor speeds.

    He also susgests that 3kW spindle is not powerful enough for 10000mm/min at 19mm depth anyway.

  9. #19
    Quote Originally Posted by jimbo_cnc View Post
    Seller will build to what I want, but his opinion is 32mm screw rather than 25mm. He says 10000mm/min will vibrate with 25mm screw. Thisimplies 2510 ballscrew to me.
    Argh Probably because he's got a pile of 32mm screws he wants shut of.!! . . . You won't find many other reputable builders recommending 32mm screws with a single central screw at this width and using steppers.!! . . . . . However You will find many machines this size running 20 and 25mm screws without any trouble.

    Also 3Kw will easily push cutter thru MFC at 19mm with correct cutter/size but if your in no rush what does it matter if it's done in 2 passes.? Proper spec'd machine will do 2 passes quicker than one only capable of 3500mm/min.!

    By the sounds your sold on the machine anyway, so no point saying anymore really other than good luck.!

  10. #20
    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 :)

    Those machines you mention are running 2525 or 2020 I assume ?

    ...and 1 pass at 6000 is quicker than 2 at 10000 :)
    Again, this could be my mistake for mentioning cutting at full depth when that might not be an actual requirement.

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