How much power at the cutting tool?


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    Default How much power at the cutting tool?

    I apologise if this question has been ask before but I have been unable to find the answer.

    What I need to know is how much power an X2 mill has at the spindle? I know the motor is rated 350W or 0.47hp but what is actually getting to the cutting tool? Does anyone have or know of a source for this information? I know with the two mechanical and then the electronic speed control it will vary to a large extent. I would like this information to help me with feed, speed and depth of cut calculations using ME Consultant 2.0. As a side note does anyone know how well this program works? I will not be taking the figures as gospel just a good starting point.

    This could be the wrong forum for this question and maybe it should have been posted in at least two other possible places but as this is the “bench top mill” forum it seems to be the right place to start.

    As always any help or advice is very much appreciated,

    John

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    Just in case anyone is interested in the answer.

    http://www.cnczone.com/forums/showthread.php?t=38120

    John



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    Hi again,

    I am bouncing this question back to this forum as the answers I need now are more likely to come from you guys.

    From the link I gave in the last post the answer for “power to the cutter” is at this time 175Watts or 0.2346789 hp (it may be revised so check there) . So looking at the figures from ME Consultant for cutting Steel-low carbon (1020) in the attached picture it gives a figure of 0.182 hp at the cutter. Working with the figure we have that is within the power range of the X2 mill.

    So my question to the experienced users is; does this sound about right for a mill of about the size of an X2?

    My next question is as there is excess power available how would you go about utilising it; would you increase cutting depth, feed speed, rpm and feed speed or a combination of these?

    Just so everybody knows I am a complete beginner with a mill so any helpful advice or links for where to start will be very much appreciated. I am hoping to be able to use ME Consultant to get me going and hoping its figures will be a good place to start when it comes to doing my first cuts.

    John

    Attached Thumbnails Attached Thumbnails How much power at the cutting tool?-mec1-jpg  


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    Quote Originally Posted by Oldmanandhistoy View Post
    Hi again,

    I am bouncing this question back to this forum as the answers I need now are more likely to come from you guys.

    From the link I gave in the last post the answer for “power to the cutter” is at this time 175Watts or 0.2346789 hp (it may be revised so check there) . So looking at the figures from ME Consultant for cutting Steel-low carbon (1020) in the attached picture it gives a figure of 0.182 hp at the cutter. Working with the figure we have that is within the power range of the X2 mill.

    So my question to the experienced users is; does this sound about right for a mill of about the size of an X2?

    My next question is as there is excess power available how would you go about utilising it; would you increase cutting depth, feed speed, rpm and feed speed or a combination of these?

    Just so everybody knows I am a complete beginner with a mill so any helpful advice or links for where to start will be very much appreciated. I am hoping to be able to use ME Consultant to get me going and hoping its figures will be a good place to start when it comes to doing my first cuts.

    John
    If you have 'excess' power, presumably you aren't using your mill efficiently, so you want to put that power to work removing metal, right? Well, firstly, IMHO you are probably better off not running the spindle at 100% rated power - e.g. if you are drilling through something and the drill tip pops out of the material, the drill tends to bog-down, so you'd want a bit of power left in reserve.

    Anyway, power seems to be proportional to material removal rate, but cutting force seems to be roughly proportional to chip-volume (depth of cut x chip-load). Therefore, on a light mill like the X-2, I would be tempted to increase the RPM and the IPM as this will increase the removal rate without massively increasing the cutting force.

    If that doesn't seem to make sense, imagine eating ice-cream very,very fast with a teaspoon, vs the same removal rate with a shovel - which cut takes more force?

    That said, with small endmills, you'll probably find you'll run out of RPM pretty fast on an X-2 - which is why I'm keen to hit 6,000 rpm on my next mill.

    Cheers.



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    Thank you digits for going to the trouble of replying and your advice/experiences are very welcome.

    I kind of liked the idea of increasing the depth of cut as this would make better use of an end mill (tool life) as you would be using more of the tools length. Also deeper cuts would require less passes so could workout the same job time as increasing feeds. Is this faulty thinking and if yes would you mind explaining why?

    John



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    Quote Originally Posted by Oldmanandhistoy View Post
    Thank you digits for going to the trouble of replying and your advice/experiences are very welcome.

    I kind of liked the idea of increasing the depth of cut as this would make better use of an end mill (tool life) as you would be using more of the tools length. Also deeper cuts would require less passes so could workout the same job time as increasing feeds. Is this faulty thinking and if yes would you mind explaining why?

    John
    Well, I really am no expert - really you should put your saftey specs on, bung some stock in a vice and attack it and see what happens!

    However, as far as I understand it, taking deeper cuts will increase the cutting force which will cause your endmill to deflect more, and it will also put more strain on your mill. If your X-2 doesn't sound like it's about to stall, or shake itself to bits, go for it - though I believe the rule of thumb is that the depth should not to exceed 1/3-1/2 of the cutter diameter. A rule to which there is obviously an exception - check out the amazing vids at http://www.freesteel.co.uk/ (the .wmv one is best IMHO) - they're doing very deep cuts but across very little of the tool's diameter - it does need some serious CAM magic though!

    On my little X-1, I simply can't take deep cuts without the head deflecting from vertical, and the whole machine making nasty noises, so I usually cut at 0.1-0.25mm deep and 600mm/min - and yes, everything takes ages hence my crazy DIY build!

    Hope that helps - or better still someone else comes on to confirm or deny all of the above!

    Cheers.



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    I have a few things to buy before I start cutting and then I will do some test cuts to work out the limits of the mill and cutting tools. At the moment I am looking for a good place to work from. Also if I sort getting some useful figures out of “ME Consultant” it will save me quite a bit of time doing the calculation. I will customise the program to suit the mill when I start cutting. I am a qualified wood machinist by trade so have a good idea about speed, feeds and depth of cuts also maximising job profitability (time over cost). Having said all of this I have almost no experience with metals and cutting metal could be very different to cutting wood.

    Thanks again for all your help

    John

    EDIT: nice link; we will be seeing videos of your new machine cutting like that? Or maybe not quite as fast as that



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    Quote Originally Posted by Oldmanandhistoy View Post
    I have a few things to buy before I start cutting and then I will do some test cuts to work out the limits of the mill and cutting tools. At the moment I am looking for a good place to work from. Also if I sort getting some useful figures out of “ME Consultant” it will save me quite a bit of time doing the calculation. I will customise the program to suit the mill when I start cutting. I am a qualified wood machinist by trade so have a good idea about speed, feeds and depth of cuts also maximising job profitability (time over cost). Having said all of this I have almost no experience with metals and cutting metal could be very different to cutting wood.

    Thanks again for all your help

    John

    EDIT: nice link; we will be seeing videos of your new machine cutting like that? Or maybe not quite as fast as that
    Well, to make things even more complicated, I have no experience of cutting steel, which unlike aluminium is supposed to work harden, so as far as I understand it, gentle cuts may actually cause a hardened skin to form on the uncut metal!

    I did have a play with Machinist's Toolbox - which is very similar to ME consultant, but at the end of the day, you have to start off from a sensible surface-feet-per-minute number, and actually finding that for my X-1 took a lot of trial and error. For these little mills, I don't think one can just go from the motor power to the ideal cutting rate - in theory an X-1 should be able to remove 0.5cu in of aluminium a minute - if I could do it in half an hour, I'd be impressed!

    Another problem is the non-calibrated motor speed control dials, and the fact that you have to reset them to zero to restart the motor. Most of my milling runs involve setting an approximate speed, listening for 5s and then tuning it to avoid chatter. I am hoping to use electronic speed control on the new machine though, so that might make ME consultant worthwhile. Until then, I am going to use a note pad to take down the speeds/feeds/DOC's that seem to work for me.

    As for the new machine - it was designed with a 200N cutting load in mind - which if I remember correctly, I calculated from 2.5mm DOC @ 600mm/min on a full width cut with a 6mm, 4-flute end mill. It was also designed for 3-D work, so it should be capable of high speed work with very light cuts on its second 1kW, 10,000-30,000 rpm spindle - the servos are good for 20,000 mm/min, but I doubt my nerves are!



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    Just a couple of clarifications:

    Carbon steels generally do not work harden, and definitely not low carbon steel. Some stainless steels do.

    The ideal surface feet per minute is dictated by the type of material you are cutting and the material your cutter is made of. It has nothing to do with the machine you are using. The feed rate and depth of cut may be dictated by the machine or by the cutter, whichever one reaches its limit first.

    Regards
    Phil


    Quote Originally Posted by digits View Post
    ......I have no experience of cutting steel, which unlike aluminium is supposed to work harden, so as far as I understand it, gentle cuts may actually cause a hardened skin to form on the uncut metal!

    ........but at the end of the day, you have to start off from a sensible surface-feet-per-minute number, and actually finding that for my X-1 took a lot of trial and error.




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    Quote Originally Posted by philbur View Post
    Just a couple of clarifications:

    Carbon steels generally do not work harden, and definitely not low carbon steel. Some stainless steels do.

    The ideal surface feet per minute is dictated by the type of material you are cutting and the material your cutter is made of. It has nothing to do with the machine you are using. The feed rate and depth of cut may be dictated by the machine or by the cutter, whichever one reaches its limit first.

    Regards
    Phil
    Thank you philbur, much appreciated

    Regards,
    John



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How much power at the cutting tool?

How much power at the cutting tool?