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  1. #1
    Join Date
    Jul 2021
    Posts
    44

    New build mini Mill

    Hello everyone,
    I've been reading this forum for a month and decided to build my own milling machine. The machines you built inspired me a lot. Unfortunately I don't have any experience with cnc machines, but my hobby is electronics (repairing amplifiers, power supplies and inverters). I even applied at Techinical Univercity (Mechatronics) in my country, so if they accept me I will start on January(wish me luck). I want the machine to be small and rigid with good precision of 0.01mm or close enough. I want to cut aluminum and steel. I don't care how much it will weight, but i want to fit on a table like 1000-1200x800mm. Maybe I will make enclosure. I made a mistake buying the lineal rails, ball screws and nuts before making any 3d model, so I must design my project for them. Before I buy anything else, I want to consider my design with you. I've been learning Fusion 360 for about 2 weeks(no previous exp with other softwares) and I made a model which I want you to see. The base of the machine is now 800x500x150mm and the column is a structural steel tube 300x200mm with 10mm wall thickness(is this a good choice or should I weld plates 15-25mm as a rectangular?) with 25mm welded plate on the bottom. The whole base will be welded together, but the column will be bolted down to the base after stress relief and machining. The table on the drawing is 300x570mm with the working zone of 180x450mm (the green area).
    In the future i may add 4th axis if everything is ok.

    The parts I have:
    2x 420mm 35mm HGR rail
    2x 1300mm 35mm HGR rail which ill cut by 2x 530mm and 2x 770mm
    12x 35mm HGH Tanks
    1x 360mm x 20mm Ball Screw with Double Ball Nut
    1x 450mm x 20mm Ball Screw with Double Ball Nut
    1x 650mm x 20mm Ball Screw with Double Ball Nut
    3xBK15
    3xBF15
    3xNut Holders

    With those parts the working dimensions are X=450mm, Y=180mm, Z=260mm
    All the plates in the drawings are 20-25mm C45 Steel. I'm also thinking to fill the column and the base, with concrete or epoxy. Z axis with epoxy. I will add counter weights for Z axis when I complete the drawings. Now the project is around 600kg and will reach 1000kg or more with the filling.

    For the motors I chose Ac Servo DMM 750w nema 34 version for XYZ (haven't bought them). Is there anything better and cheaper than that? Do I need Z motor with a brake since it will be counterweighted?

    Spindle?
    I have no idea but I read in the forum that most of you guys use BT30? And the Spindle Motor I want something big like 2.6-3.8kw? What is your opinion about that?

    CNC controller?
    Can you recommend something for a beginner?
    DDCS V3.1 is this good? Or should I use mach3-4. What CNC controller?
    I want to work with fusion 360.

    Before going any further i want share my work and see your opinions.
    Any help, advice or feedback is appreciated.

  2. #2
    Join Date
    Jan 2018
    Posts
    1516

    Re: New build mini Mill

    First off.
    What mains power supply do you have available?.
    single phase 120v or 220v
    Or
    3phase 220v+
    ?.

  3. #3
    Join Date
    Jul 2021
    Posts
    44
    Quote Originally Posted by dazp1976 View Post
    First off.
    What mains power supply do you have available?.
    single phase 120v or 220v
    Or
    3phase 220v+
    ?.
    Single phase 220v. I have also 3 phase, but it is not in the same room that the machine will be, I prefer to use single phase 220v. The power consumption of the machine is not a problem. I can connect it direct to the circuit breaker.

  4. #4
    Join Date
    Jan 2018
    Posts
    1516

    Re: New build mini Mill

    Quote Originally Posted by Vilyoo View Post
    Single phase 220v. I have also 3 phase, but it is not in the same room that the machine will be, I prefer to use single phase 220v. The power consumption of the machine is not a problem. I can connect it direct to the circuit breaker.

    Technically it is a slight problem. You'll be restricted to the size of spindle motor you can fit.
    For instance, if you use a servo you'll probarbly be limited to 2.2kw or less.
    A 2.6kw and above servo motor/drive can peak above 50A.
    You'll want to look into it a little further before commiting to anything.

    An example:
    https://www.aliexpress.com/item/4000...59247987%22%7D

    That's why some people are dissappointed with the Tormach 1100MX.
    That is built with single phase users in mind.


    I have a 1.8kw for a PM25 type machine.

  5. #5
    Join Date
    Jul 2021
    Posts
    44
    Quote Originally Posted by dazp1976 View Post
    Technically it is a slight problem. You'll be restricted to the size of spindle motor you can fit.
    For instance, if you use a servo you'll probarbly be limited to 2.2kw or less.
    A 2.6kw and above servo motor/drive can peak above 50A.
    You'll want to look into it a little further before commiting to anything.

    An example:
    https://www.aliexpress.com/item/4000...59247987%22%7D

    That's why some people are dissappointed with the Tormach 1100MX.
    That is built with single phase users in mind.


    I have a 1.8kw for a PM25 type machine.
    I think 50A peak is not a problem for my installation. The circuit breaker is 63A and the cable to it is 6mm2 copper. But if there are any problems I'll plug it to 3 phase. I think the drivers for the motors work both for single and 3 phase?

  6. #6
    Join Date
    Jan 2018
    Posts
    1516

    Re: New build mini Mill

    Quote Originally Posted by Vilyoo View Post
    I think 50A peak is not a problem for my installation. The circuit breaker is 63A and the cable to it is 6mm2 copper. But if there are any problems I'll plug it to 3 phase. I think the drivers for the motors work both for single and 3 phase?

    Many do work on both but it's highly likely they will supply you a 3 phase only if you go for 2.6kw & above. A wiring regulation thing.

  7. #7
    Join Date
    Jul 2021
    Posts
    44

    Re: New build mini Mill

    Okay, I will consider moving 3phase to my work room if needed. I really want strong motors.

  8. #8
    Quote Originally Posted by dazp1976 View Post
    Technically it is a slight problem. You'll be restricted to the size of spindle motor you can fit.
    For instance, if you use a servo you'll probarbly be limited to 2.2kw or less.
    A 2.6kw and above servo motor/drive can peak above 50A.
    You'll want to look into it a little further before commiting to anything.

    An example:
    https://www.aliexpress.com/item/4000...59247987%22%7D

    That's why some people are dissappointed with the Tormach 1100MX.
    That is built with single phase users in mind.


    I have a 1.8kw for a PM25 type machine.
    If a 2.2kW drive is peaking over 10kW then something is wrong in that spec! Can you confirm the 50A peak is on the INPUT side? You can drive 50A on the motor three phase, the inverter is a DC-AC device with a rectifier AC-DC and DC link capacitor bank. If it's limited to 2.2kW it shouldn't pass ~10Aac on the input side regardless of the current on the output. Power is power is power, even with a power factor of 0.7 and an efficiency of 80% you'd only be drawing 2.75kW average and 3.93kW peak (1.18kW ripple). That's still under 20Aac.

  9. #9
    Join Date
    Jan 2018
    Posts
    1516

    Re: New build mini Mill

    Quote Originally Posted by StrawberryBoi View Post
    If a 2.2kW drive is peaking over 10kW then something is wrong in that spec! Can you confirm the 50A peak is on the INPUT side? You can drive 50A on the motor three phase, the inverter is a DC-AC device with a rectifier AC-DC and DC link capacitor bank. If it's limited to 2.2kW it shouldn't pass ~10Aac on the input side regardless of the current on the output. Power is power is power, even with a power factor of 0.7 and an efficiency of 80% you'd only be drawing 2.75kW average and 3.93kW peak (1.18kW ripple). That's still under 20Aac.
    Well. There's a reason why once you get up to 2.2kw in servo motor, single phase drives start to vanish in favour of 3 phase.
    You'll be constantly tripping the breaker on startup bursts for a start.
    My lowly little 1.8kw servo alone requires a 30A breaker.

  10. #10
    Join Date
    Apr 2004
    Posts
    5728

    Re: New build mini Mill

    "For the motors I chose Ac Servo DMM 750w nema 34 version for XYZ (haven't bought them). Is there anything better and cheaper than that? Do I need Z motor with a brake since it will be counterweighted?"

    If you're using AC servos, make sure to get compatible drivers at the same time. They are all different - even some made by the same company can be different from others they also make.

    A brake on the Z axis servo motor is one way to avoid having a heavy spindle drop to the table when power is turned off. But if you've got counterweights or gas struts to hold it up, it's probably not going to be necessary.
    Andrew Werby
    Website

  11. #11

    Re: New build mini Mill

    Quote Originally Posted by dazp1976 View Post
    Well. There's a reason why once you get up to 2.2kw in servo motor, single phase drives start to vanish in favour of 3 phase.
    You'll be constantly tripping the breaker on startup bursts for a start.
    My lowly little 1.8kw servo alone requires a 30A breaker.
    I see, we're talking different specs here. You are talking about a 1.8kW continuous servo, with a peak in the range of 3.8kW-4.2kW at the servo. I'll adjust my understanding here, in the motor design side we would call that a 4.2kW motor, since the continuous rating can be highly variable depending on the final housed thermals, cooling, and even the controller. Even with the same housed motor, environment and controller can make big changes to motor power, so designers usually design around peak torque and peak voltage (knee point, maximum power) and then back out to the (hopefully conservative) continuous rating, which then feeds back into the design if the continuous rating is not achieving spec.


    So his 2.2kW continuous servo is what, ~6.5kW peak? Is that the estimate we're going with? Machining basically never uses the motor continuous rating fully and if you're drawing peak power at startup there should be a soft start option in your drive to eliminate that issue. Better safe than sorry, but I'm trying to grasp the apple here when I'm coming up oranges.

  12. #12
    Join Date
    Jan 2008
    Posts
    1523

    Re: New build mini Mill

    Servos sold for CNC use are all marketed based on their continuous output.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  13. #13
    Join Date
    Jul 2021
    Posts
    44

    Re: New build mini Mill

    can you recommend servos 750w-1000w for xyz, DMM are a bit expensive for me.
    Maybe something like this?
    https://www.ebay.com/itm/32424632673...gAAOSwdUJcHGPp

  14. #14
    Join Date
    Jan 2005
    Posts
    15362

    Re: New build mini Mill

    Quote Originally Posted by Vilyoo View Post
    Hello everyone,
    I've been reading this forum for a month and decided to build my own milling machine. The machines you built inspired me a lot. Unfortunately I don't have any experience with cnc machines, but my hobby is electronics (repairing amplifiers, power supplies and inverters). I even applied at Techinical Univercity (Mechatronics) in my country, so if they accept me I will start on January(wish me luck). I want the machine to be small and rigid with good precision of 0.01mm or close enough. I want to cut aluminum and steel. I don't care how much it will weight, but i want to fit on a table like 1000-1200x800mm. Maybe I will make enclosure. I made a mistake buying the lineal rails, ball screws and nuts before making any 3d model, so I must design my project for them. Before I buy anything else, I want to consider my design with you. I've been learning Fusion 360 for about 2 weeks(no previous exp with other softwares) and I made a model which I want you to see. The base of the machine is now 800x500x150mm and the column is a structural steel tube 300x200mm with 10mm wall thickness(is this a good choice or should I weld plates 15-25mm as a rectangular?) with 25mm welded plate on the bottom. The whole base will be welded together, but the column will be bolted down to the base after stress relief and machining. The table on the drawing is 300x570mm with the working zone of 180x450mm (the green area).
    In the future i may add 4th axis if everything is ok.

    The parts I have:
    2x 420mm 35mm HGR rail
    2x 1300mm 35mm HGR rail which ill cut by 2x 530mm and 2x 770mm
    12x 35mm HGH Tanks
    1x 360mm x 20mm Ball Screw with Double Ball Nut
    1x 450mm x 20mm Ball Screw with Double Ball Nut
    1x 650mm x 20mm Ball Screw with Double Ball Nut
    3xBK15
    3xBF15
    3xNut Holders

    With those parts the working dimensions are X=450mm, Y=180mm, Z=260mm
    All the plates in the drawings are 20-25mm C45 Steel. I'm also thinking to fill the column and the base, with concrete or epoxy. Z axis with epoxy. I will add counter weights for Z axis when I complete the drawings. Now the project is around 600kg and will reach 1000kg or more with the filling.

    For the motors I chose Ac Servo DMM 750w nema 34 version for XYZ (haven't bought them). Is there anything better and cheaper than that? Do I need Z motor with a brake since it will be counterweighted?

    Spindle?
    I have no idea but I read in the forum that most of you guys use BT30? And the Spindle Motor I want something big like 2.6-3.8kw? What is your opinion about that?

    CNC controller?
    Can you recommend something for a beginner?
    DDCS V3.1 is this good? Or should I use mach3-4. What CNC controller?
    I want to work with fusion 360.

    Before going any further i want share my work and see your opinions.
    Any help, advice or feedback is appreciated.
    With the Dmm Servos get the new 20Bit encoder

    What grade is the Ballscrews
    Mactec54

  15. #15
    Join Date
    Jan 2005
    Posts
    15362

    Re: New build mini Mill

    Quote Originally Posted by Vilyoo View Post
    can you recommend servos 750w-1000w for xyz, DMM are a bit expensive for me.
    Maybe something like this?
    https://www.ebay.com/itm/32424632673...gAAOSwdUJcHGPp
    You get what you pay for the eBay servo your link is to there encoder PPR is too low for CNC machines
    Mactec54

  16. #16
    Join Date
    Jul 2021
    Posts
    44

    Re: New build mini Mill

    I dont know what grade are the ballscrews it is not written in the site i bought them......
    I bought them from here, im very dissapointed from this supplier but in my country is the only one. They always make mistakes with the order and their product's quality is poor.

    https://exallto.com/sachmeno-vintovi...t-sfu1605.html
    https://exallto.com/sachmeno-vintovi...-sfu-2005.html

    actually my ball nut is different from those in the site

    you mean to wait for DYN5 release?

  17. #17
    Join Date
    Jul 2021
    Posts
    44

    Re: New build mini Mill

    A little upgrade on the drawins. Added counter weight steel box with 20mm walls, which i will fill with Lead, it will fit around 80k of lead. The working table will be with m16 holes since i dont have T slot table.

  18. #18
    Join Date
    Jan 2005
    Posts
    15362

    Re: New build mini Mill

    Quote Originally Posted by Vilyoo View Post
    I dont know what grade are the ballscrews it is not written in the site i bought them......
    I bought them from here, im very dissapointed from this supplier but in my country is the only one. They always make mistakes with the order and their product's quality is poor.

    https://exallto.com/sachmeno-vintovi...t-sfu1605.html
    https://exallto.com/sachmeno-vintovi...-sfu-2005.html

    actually my ball nut is different from those in the site

    you mean to wait for DYN5 release?
    They are Rolled Ballscrews so will never be that great no matter who you buy them from, the double nut will help a little but they won't be as smooth running as a Ground Ballscrew

    I thought they had released the Dyna 5, Yes I would wait 16Bit is ok but 20Bit is much better, always go for the highest Encoder PPR you can get for any axis movements if for a spindle then it does not matter what the PPR is
    Mactec54

  19. #19
    Join Date
    Nov 2013
    Posts
    4280

    Re: New build mini Mill

    Hi,
    I bought and use three 750W Delta B2 series (160,000 count per rev) servos and drives for my new build mill, one of them braked.
    They are Taiwanese but made in China are good quality and well supported and have the all-important set-up and tuning software with which to program the drive.

    https://www.fasttobuy.com/flange-80m...er_p28084.html

    $438USD plus shipping from China for the 750W B2 servo, drive and cables is fair value. They are very similar in terms of quality and support and cost to DMM.

    I paid $80USD each for shipping to New Zealand via DHL and I tracked them from Schenzen to my workplace in Christchurch New Zealand in two days 14 hours....I got what I paid for.

    There are cheaper Chinese brands and while the quality seems reasonable the documentation is crap, support questionable and most importantly no set-up
    and tuning software, you have to program the drive by pushing buttons like a microwave, very tedious and error prone. Avoid like the plague.

    If this is your first experience with servos I would avoid the cheapest Chinese stuff and get at least Delta's or DMM's. Once you got a few servo installs under your
    belt THEN perhaps the el-cheapo Chinese made brands make sense.

    Craig

  20. #20
    Join Date
    Jul 2021
    Posts
    44

    Re: New build mini Mill

    Thanks everyone for your comments. So I will buy dmm or delta motors with high PPR. About the ballscrews I will see how my ballscrews will operate and if I'm not satisfied with the result i will change them to ground ballscrews.

    My Z axis will be around 150kg, is 750w servo with a brake enough for it, cuz I see it is cheaper to buy a motor with a brake instead of making counterweight.

    Any words about the design? How do you find it. Should I change anything there.

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