New Build - PM30/AMA30/VM32 Type Milling Machine


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Thread: New Build - PM30/AMA30/VM32 Type Milling Machine

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    Default New Build - PM30/AMA30/VM32 Type Milling Machine

    Based on this machine.

    VM32 Variable Speed Milling Machine | Belt Drive Milling Machine | Bench Mill | Quality Metalworking Mills

    Justification - in the UK the 80kg lighter AMA20 style machine is £1200, this machine is bigger, heavier and stifffer for £1450. The next bigger machine is an RF45 type but that is £2100 - with CNC parts that makes it too expensive, also the weight may be too much to dissemble and rebuild in my garage. I am tempted by a RF45 type though for the extra stiffness..

    This is the list of parts
    Mounting Hardware - price of alloy maybe expensive due to some large parts, end plates will be alloy, I may use steel for the saddle mount, will have to wait and see. I strongly considered some of the kits available but I wanted to use different (better grade) ballscrews, also they are in the USA and my machine may well be different to say a PM30 so the parts (or some of them) may not actually fit, and I'd have to pay for shipping to the UK (for parts that may not fit) so I will make my own. I have a small manual mill at the moment so can make parts on that.

    Mach 4 £160 - Just because I use windows..
    3 Nema 34 4nm closed loop and drivers £400 Justification - quite a lot of thought gone into this. I don't want cheap drivers and believe steppers are still on par or better for accuracy (I want the machine to be accurate), I used the motorcalcs excel spreadsheet to try and estimate max torque and figures come out very low - 0.26Nm cutting with 150mm/sec and 75Nm force 5mm pitch ballscrews. Most torque appears to be needed for acceleration at high speed - this set-up can reach 3000mm/min in the spreadsheet, it may be a lot better than that because of the use of closed loop steppers.. I may also consider some lower Nm steppers but I wanted plenty of reserve if I want tight gibs and ballscrews to improve accuracy...

    3 power supplies 120 - just std switched 60v supplies
    C5+ ballscrews For me I'm not happy with C7 accuracy so will pay a bit more and go for C5 (new parts) or better than C5 (2nd hand parts)
    Ballscrew machining TBC
    Double preload balnuts 90 This is based on the quote from Fred at BST on Alibaba I think - no name ballscrews but they are double with adjustable preload. I'm expecting I may have to reball if they are too tight on the shafts I have and also adjust the preload (any info on how to do this is welcome)
    Electronic Case 30 - planning to use a computer case from the electronics
    Toolco VM32 1450 Mill
    Breakout Board (smoothstepper) ethernet 160 I need to understand what this does, if it's necessary or if cheaper alternatives will work well..
    £36 for Dunlop 3 double sets of angular contact bearings.
    £?? unknown for a spindle speed control - can I tap into the machines spindle speed controller and do this easily/cheaply?

    Total is around £2540 at the moment.

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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Quote Originally Posted by men8ifr View Post
    Based on this machine.

    VM32 Variable Speed Milling Machine | Belt Drive Milling Machine | Bench Mill | Quality Metalworking Mills

    Justification - in the UK the 80kg lighter AMA20 style machine is £1200, this machine is bigger, heavier and stifffer for £1450. The next bigger machine is an RF45 type but that is £2100 - with CNC parts that makes it too expensive, also the weight may be too much to dissemble and rebuild in my garage. I am tempted by a RF45 type though for the extra stiffness..

    This is the list of parts
    Mounting Hardware - price of alloy maybe expensive due to some large parts, end plates will be alloy, I may use steel for the saddle mount, will have to wait and see. I strongly considered some of the kits available but I wanted to use different (better grade) ballscrews, also they are in the USA and my machine may well be different to say a PM30 so the parts (or some of them) may not actually fit, and I'd have to pay for shipping to the UK (for parts that may not fit) so I will make my own. I have a small manual mill at the moment so can make parts on that.

    Mach 4 £160 - Just because I use windows..
    3 Nema 34 4nm closed loop and drivers £400 Justification - quite a lot of thought gone into this. I don't want cheap drivers and believe steppers are still on par or better for accuracy (I want the machine to be accurate), I used the motorcalcs excel spreadsheet to try and estimate max torque and figures come out very low - 0.26Nm cutting with 150mm/sec and 75Nm force 5mm pitch ballscrews. Most torque appears to be needed for acceleration at high speed - this set-up can reach 3000mm/min in the spreadsheet, it may be a lot better than that because of the use of closed loop steppers.. I may also consider some lower Nm steppers but I wanted plenty of reserve if I want tight gibs and ballscrews to improve accuracy...

    3 power supplies 120 - just std switched 60v supplies
    C5+ ballscrews For me I'm not happy with C7 accuracy so will pay a bit more and go for C5 (new parts) or better than C5 (2nd hand parts)
    Ballscrew machining TBC
    Double preload balnuts 90 This is based on the quote from Fred at BST on Alibaba I think - no name ballscrews but they are double with adjustable preload. I'm expecting I may have to reball if they are too tight on the shafts I have and also adjust the preload (any info on how to do this is welcome)
    Electronic Case 30 - planning to use a computer case from the electronics
    Toolco VM32 1450 Mill
    Breakout Board (smoothstepper) ethernet 160 I need to understand what this does, if it's necessary or if cheaper alternatives will work well..
    £36 for Dunlop 3 double sets of angular contact bearings.
    £?? unknown for a spindle speed control - can I tap into the machines spindle speed controller and do this easily/cheaply?

    Total is around £2540 at the moment.
    I found the u.k. sucks for availability Been after something with R8 that's bigger than my poxy X2 for 6 months.
    Don't rule out the Amadeal AMAT30LV machine as well (prefer the blue). Supposedly due in soon and apparently a R8 version available too. Much better than MT3 I found.
    I think Toolco put extra on top for shipping.
    I've put a deposit down on the 25LV R8 package 2. I couldn't budget the 30 as yet and I use a lot of 6mm atm so the 2800rpm speed should suit better..
    I hope it's in sooner rather than later!.
    https://www.amadeal.co.uk/acatalog/A...8.html#SID=380

    1 thing I noticed you mention is a speed of 3000mm/min. Don't get your hopes up too much because dovetail ways may be the one thing that restricts you. Most machines of those speeds and more generally have Linear rails.
    For example:
    The Tormach 1100 has dovetails and is only rated to max out at 2800mm/min rapids and that's an expensive good bit of kit.
    https://www.tormach.com/1100m/#techspecs
    The Syil X7 has linear rails and can rapid at 5000mm/min and more depending on motor system.
    https://www.syil.com/small-cnc-mill
    Big difference.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    I never understand why dovetails restricts your speed, they will require more force to move but that is true at any speed - not just high, if the motors have enough torque why can't the speed be high...

    Maybe the extra drag means steppers struggle to provide enough torque at higher speed.. but even then it appears acceleration of the mass is what limits speed the most....



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    I've read of maximum speeds for dovetails (which iirc are all over the board at 2-5m/min,) but I'm not sure where the numbers come from. With the extra friction, there will of course be more heating as well, which maybe can end up causing binding?
    I think generally max usable speed of dovetails is just due to the steppers having to work harder to overcome the friction.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Quote Originally Posted by skrubol View Post
    I've read of maximum speeds for dovetails (which iirc are all over the board at 2-5m/min,) but I'm not sure where the numbers come from. With the extra friction, there will of course be more heating as well, which maybe can end up causing binding?
    I think generally max usable speed of dovetails is just due to the steppers having to work harder to overcome the friction.
    Whether it's an issue with my machine or not is unclear but I got a high amount of wear on my gibs at 1500mm/min.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Planning a machine build you need to take into consideration all aspects of the build otherwise you can end up with the equivalent of drag race car - good at going fast but not much else!
    If you are planning on having it capable of 3000 mm/min when is it going to be able to use that speed? As an example of cutter for that size of machine, 6mm diameter 2 flute is representative, running it at 1400 mm/min in aluminum means it needs a 10000 rpm spindle (and that's a HSS tool, carbide could do 2400 mm/min at 20000 rpm!)
    Also - closed loop steppers don't change the laws of physics and make steppers better at high rpms - they'll just either fault or play catch up if they miss steps (neither one of those is a good thing!) The stepper motor itself has a torque curve that drops off as rpm rises and the closed loop doesn't help with that at all.
    Lastly - a dovetail machine can have greater friction than you think and that will impact your top speeds. Usually the gibbs are run tight on a cnc machine to reduce slop or backlash when trying to climb mill. Dovetails also require lubrication to minimize wear - the faster you run them the faster that lube is worked away and needs to be replaced, or you're going to wear your machine. Running a dovetail machine fast is going to dictate an automatic oiler.
    Good luck on your build.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Nine finger I think you have words of wisdom there. I'm looking at both how to get accuracy (most important) and speed. A lot of this is developing understanding. I have a manual mill which helps understand machine basics. For stepper specification I used a spread sheet someone else has constructed to look at cutting and rapid speeds. Your comments make me think I need to look more at cutting speeds. I had just put in some slow value at 150mm/min and a high 75N cutting force and then pick a stepper e.g 4nm NEMA 34 and see what max speed would be for that set-up. My initial data showed an 8nm stepper is very limited in top speed but a 4nm unit could reach 3000mm/min so I see 4nm as more likely to be the right size i.e other considerations will probably limit speed. Next step is to understand accuracy so I'm looking at torque available at microstrip positions which is very poor. So 8 microstepping may cut torque to 30percent.... I can't really tell how much better the closed loop steppers will be here as there is not much info on this. I was going to work on the principal that get the performance ok as per open loop steppers and the closed loop should only be better but I don't know how much or where yet there is very little info on them.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    I'm also considering if a belt drive would end up more accurate. I.e a little error due to the belt but a motor could run at actual step positions and avoid the (great) torque loss probably leading to in accuracy at microstepping.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    And then there's the fact that the leadscrews will expand upto 0.13mm as they get warm, interestingly someone mentioned their machine is not accurate until warmed up, maybe this is why.



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    I don't think torque loss due to microstepping is that significant. https://openbuilds.com/threads/torqu...stepping.9235/
    You'll lose half your torque going from full-step to microstepping if you use the same peak current, but you can just program your driver with 40% higher peak current (the RMS current will be the same,) and most all drivers these days are smart enough to reduce the static current so you don't overheat a coil by having that extra 40% current on it for any amount of time. Microstepping generally runs much smoother (quieter,) and usually damps oscillations a bit better, so you can end up with more effective torque than without it (undamped oscillations can drive stepper torque to near 0 in the worst case.)
    I don't have any real numbers, but I think generally microstepping is a worthwhile tradeoff. It may help to get better surface finish as well. Just don't expect any accuracy improvement from it.
    Having a reduction will get you better accuracy/precision with steppers if it's implemented correctly.

    I think a big reason machines get more accurate as they warm up is the oil and grease get warmed up and spread around better, reducing stiction. My mill has fairly soft spring-loaded double nuts (with quite a bit of play without the second nut,) and my Y axis had quite a lot of backlash when cold that dropped way down when warmed up. (I've since increased the preload, so there's much less difference now.)



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Expanding drive screws on machines like this is very unlikely to be of concern. I wouldn't worry about it. I have measured noticeable changes when warmed up, in the 30LV class machine I have. It's all in the spindle length, which is easy to compensate for if needed. The head gets warm, the XY system never leaves room temperature, and I have done loads of long multi-hour engraving jobs running over 1000mm/min.

    LongRat
    www.fulloption.co.uk


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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Been told I should have mine from Amadeal next Thursday (I'll believe it when I see it)
    A couple of thoughts:
    Been getting a few bits in through the post and I may have to bite the bullet when it comes to shaft couplings.
    The 14/10 plum couplings I got seem good but the 8/10 ones that came have awful play in them.
    I ordered 9 more from a different place in China for £17 in the hope I can get 3 good ones out of it.

    If not:
    Most quotes from the u.k. so far work out to be around £40 each. Which to go for though, the Jaw type, the Oldham or something else?
    Also would a 2005 ballscrew be better for the Z? (considering the motor I've got is 1600oz/in - 11.3nm).
    Need to measure the machine and plan the parts before I order.

    Thinking of going straight through the base with the Y screw and putting a floating bearing block on the back rather than have it free hanging if I can so it's more stiff. Should be fairly easy beings the column is apparently bolted to the top on these 25LV versions.
    Thoughts?



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    New Build - PM30/AMA30/VM32 Type Milling Machine-oldham_couplers-jpg

    Home made Oldham couplers, done on the mill before conversion.
    I think I bought the plastic sliders as a pack of spares from RS, they were extremely cheap. 10 years later they are still going strong with no play, even though I never got round to making any protective covers! Definitely a big fan of Oldhams for this application.

    New Build - PM30/AMA30/VM32 Type Milling Machine-img_20181026_145050865-jpg

    If you can I would have a go at this, way cheaper option and no waiting.

    LongRat
    www.fulloption.co.uk


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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Quote Originally Posted by LongRat View Post

    Home made Oldham couplers, done on the mill before conversion.
    I think I bought the plastic sliders as a pack of spares from RS, they were extremely cheap. 10 years later they are still going strong with no play, even though I never got round to making any protective covers! Definitely a big fan of Oldhams for this application.


    If you can I would have a go at this, way cheaper option and no waiting.
    Thanks for the idea matey.
    That's a plan. I'll have a crack at that
    I'll get some round ally billet to make it easier if I can get a close diameter.
    X2 needs rebuilding first. A few issues have cropped up and it isn't good enough to be making bits for the new one in it's current state.

    I would have a go manually on the new one so I can verify it is totally sound but it will need dismantling to get it on the bench. Have no way of lifting it in one go. I could always mill with it whilst lying on the floor i suppose
    Thanks again.

    Just had an email saying it'll definitely be here the end of next week. Fingers crossed



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    Just an update, just like Daz, I'm waiting to be able to buy my machine, hopefully Monday I may hear more... Just got to be patient.

    In the meantime I've worked out I can have closed loop control to a Dynomotion Kflop board and would then need to use their (free) software for motion control... I'm tempted we will see.

    Ball screws/ballnuts is a difficult decision I think I will go for C5 screws and chinese double ballnuts and set the preload myself... IF it works..IF they fit together (i.e. ballnuts are in tolerance) etc etc I don't think the burget would stretch to TBI double ballnuts at £145 each...

    I'm liking everything I hear about the leadshine(or copy) closed loop steppers so far, I've not prices servo's up I'm just assuming they would be a lot more expensive and I'm also not sure they are more accurate than closed loop steppers but I don't have all the info..

    The other possibility is to save money and get cheaper ballscrews and cheaper (basic) steppers and rely on closed loop feedback from glass encoder scales.. but I'm not sure I'd be happy with a not great mechanical system and rely on getting closed loop working to glass encoders to fix everything..



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    Default Re: New Build - PM30/AMA30/VM32 Type Milling Machine

    I agree with you! CNC parts always make machines expensive because they help the machine to work more accurately and this makes them royal and different from all cheap machines.
    I usually wonder most of the time What's So Special About Milling Machines? Why they are so expensive? But if we think about its features accuracy and the part that is used in it make them valuable and perfect, These machines last long just because CNC parts are used in them. While working for a company that makes amazing machines if I compare them with other milling machines there's a huge difference I can find in them. But we can't say that only the CNC part makes them accurate there other different factors involved in it (like the idea of the machine, maintaining the machine greasing them with a good quality product.

    In CNC machining, the MCU is the most important component. Electronic components are used in their construction. After reading the milling machine program's instructions, the MCU interprets them and translates them into mechanical behavior for the specific machine tools. As a result, the control unit serves as a necessary connection between the software and the milling machine tool. There is much helpful information related to CNC machines available across the internet which can help us in understanding their importance!



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