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-   -   New Mechmate build soon in Spain (http://www.mechmate.com/forums/showthread.php?t=6409)

baltaran Mon 10 February 2020 15:02

New Mechmate build soon in Spain
 
Hi,

Just call me Balta.

I have been reading this forum for more than 3 years and I have followed many builds that came to life with success. I am really fascinated with the results that a lot of builders could achieve with Mechmate.

I have been interested in building one of these machines but due to the lack of space and time I have been postponing it until now.

My intention is to start with the kitchen table and as I am not a specialist in electronics I have some doubts which I hope you would help me out to clarify before I place my order.

My main doubt so far is with the motors. I have seen many of you using different motors and as I can not afford those excellent OM steppers or Clearpath servos I would just stick with Chinese steppers for now. I have found these closed loop motors which can be purchased for a good price, however as I am not an expert in the field I would like te get your feed and advice. Are these motors good enough to drive a 3300mm x 2200mm MM.

I have also found these Transformers and I wonder if they are suitable to power 4 of the steppers mentioned above.

I would also be grateful if you could tell me where I could buy the laser cut parts in Europe. I contacted the guys listed in the forum from Portugal, Italy, Macedonia, etc. two weeks ago but I have not recieves a reply so far.

I have already ordered some parts and tools to start my project. As I start getting them I will be posting fotos and updates.

This is all for now. I am very excited to start my build and I am quite sure that I am gonna need more of your help in the future.

Thanks a lot in advance.

bradm Wed 12 February 2020 09:39

I don't have a strong perspective either way on the motors; if they meet the specs given, and the torque curve is appropriate for the acceleration you want, they seem otherwise fine.

The transformer link is to an 80vA, which on the order of five times too small. In general, you want the highest voltage you can reasonably engineer for the best power and response, and as you can see from the torque curve, it's better at the 60v example than at the 48v example. I'd be aiming for 60-70 volts in this system.

6 Amps x 60 Volts = 360 VA peak for one motor. Peaks on all four motors simultaneously are rare to non-existent, and the capacitors are there to deal with that eventuality, but you still want a transformer in the 400VA range, not the 80VA range.

And make sure you're planning for the capacitors needed as part of the power supply as well; the voltage and number of caps in parallel will have a big impact on the price.

baltaran Wed 12 February 2020 13:34

Thanks a lot Bradm.

Your clarifications have been of great help to me because I did not really know what does (VA) refer to and how it is calculated. Thanks to the easy way you explained everything, now I understand the maths behind it and I can calculate correctly the amount of VA needed to power a given stepper motor. I have also learnt that capacitors are necessary to deal with unusual situations where all motores are simultaneously under full load.

I am an IT specialist and my knowledge of electronics and electricity is almost null. With that said I would consider buying a ready made transformer from antekinc.com though the final cost to have it received in Spain would be more than twice its price.

I contacted omc-stepperonline.com and they advised me to buy 4 of S-350-48 power supplies. One for each Stepper motor. However, I am more inclined to using a torroidal transformer than using an individual power supply for each motor. Moreover I have noticed that most MM builders use torroidal transformer and I guess that should be the best decision.

In relation to the motors, I chose, I would really appreciate if someone else could guide me to make the right choice before placing my order. By the way omc-stepperonline.com has a wide range of nema 34 motors but I am not sure which one would be powerful enough to drive a 3300mm x 2200mm MM. I just thought that the ones I mentioned in my first post are better, but I could be wrong.

I would really appreciate you help.

danilom Sat 15 February 2020 19:14

These I use for almost all machines now , affordable and powerful

https://vallder.com/en/c/292/38/step...r-8-5nm-detail


...but looking at the stepperonline offer they seem competitive too, so no matter where from you order, these closed loop steppers are way to go, only gear them, and they will be happy

baltaran Mon 17 February 2020 07:45

Quote:
Originally Posted by danilom View Post
These I use for almost all machines now , affordable and powerful

https://vallder.com/en/c/292/38/step...r-8-5nm-detail


...but looking at the stepperonline offer they seem competitive too, so no matter where from you order, these closed loop steppers are way to go, only gear them, and they will be happy
Thanks a lot Danilom,

I can see that the stepper motor and driver kit you use is almost identical to the one in omc-stepperonline.com so I prefer to order them from Germany or Belgium to avoid extra customs charges.

By the way which power supply would you recommend? I know that most MM builders use Antekinc PS solutions but as I prefer to source out most parts from Europe I wonder if you know of any other good alternative in EU.

Thanks again!

danilom Mon 17 February 2020 15:09

I use 60V 350w ones they supply with motor and drive kit

baltaran Mon 17 February 2020 15:55

Thanks Danilom for your quick reply.
Your answer has been of agreat help to me.


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