Newbie setup

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sparx
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Joined: Thu Feb 16, 2017 4:48 pm

Newbie setup

Post by sparx » Thu Feb 16, 2017 5:18 pm

Hi guys,
I've been drooling over machines like the Shapeoko, Stepcraft, etc. for quite some time now, however their price tags are not within my hobby spending range. When i saw the Rpi CNC hat i knew this is my chance to build something cheaper and upgrade it over time as my budget allows so i ordered one and started digging.
So far i have the Rpi3 and the v2.58 CNC hat (and a dremel), from here on, i was thinking about getting pololu drv8825 stepper drivers and a power supply (24 or 45 volts).
Now as i have a few sets of rack mountable server slides (they are sturdy and fairly well made, image below), i was wondering what steppers would you recommend, having in mind that the drv8825 support up to 2.2A at the most ? I know i need as much torque as i can get, but i really struggle to find an advice about what to get.
I'll do my best to get at least 60 by 50cm of working area, so it might be a heavy beast. Also, i'm thinking of using screws, seems like they get more support than belts, any advices on that ?

I dont have a lot of experience building this kind of stuff, so there is a steep learning curve with this project, so any advice is welcome. By the way, i got the Rpi CNC hat as i fell in love with the fact that it has a web interface and doesnt need a PC connected to it, also looks really thought out and simple to assemble.

Thanks in advance :)

Rails:
Image

Bertus Kruger
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Re: Newbie setup

Post by Bertus Kruger » Thu Feb 16, 2017 10:18 pm

Screw will be strong and slower.

I would start with some 2Amp steppers. You can always upgrade to larger external driver if needed but that will cost more.

I agree on the RPi's they are so versatile!!

sparx
Posts: 3
Joined: Thu Feb 16, 2017 4:48 pm

Re: Newbie setup

Post by sparx » Fri Feb 17, 2017 9:22 am

Sound advice :) Thank you.
By the way, regarding the stepper drivers, found these - http://www.ebay.co.uk/itm/5x-DRV8825-St ... Swal5YKNUB , i would go with original pololu ones, but they are quite expensive here and i can get this lot for the price of one original pololu stepper (locally). Is it worth paying more and getting the original pololu ones ? What damage can the stepper make if its not quality made ? These are also rated to 2.5A (instead of 2.2A for the pololu ones) ... or is that just Chinese marketing ? :)
Thanks.

Bertus Kruger
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Re: Newbie setup

Post by Bertus Kruger » Mon Feb 20, 2017 6:39 pm

The Pololu versions seems to be stronger and closer to the Ratings they give.

The link you sent is a good start. I prefer the A4988 drivers over the DRV8825 because
they deal better with heat and stress.

sparx
Posts: 3
Joined: Thu Feb 16, 2017 4:48 pm

Re: Newbie setup

Post by sparx » Tue Feb 21, 2017 5:40 pm

Ah, i already ordered the ebay ones ... hope they can manage until i finish assembly.
I was checking DRV8825, because it has a better power rating (2.2A), than the A4988 (2A at the most), i should have waited for your reply. Ah well ... :D
A friend gave me a few old printers, so i'll be scavenging their steppers and see what i can use from their mechanics. Will keep you posted here on my progress.
By the way, after i posted this thread i noticed there is a Member Projects forum, if you consider my thread more suitable for that forum, please go ahead and move it :) Sorry for the trouble and thanks for the help.

Bertus Kruger
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Re: Newbie setup

Post by Bertus Kruger » Wed Feb 22, 2017 6:22 pm

Thanks, I have moved it.

Keep us up to date. ;)

azijoe90
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Joined: Sat Mar 18, 2017 2:50 am

Re: Newbie setup

Post by azijoe90 » Sat Mar 18, 2017 4:07 am

hi.. im newbie.. i have some problem with driver Stepper motor DRV8825 (i buy from China) .. i already assembled rpi2 b+, preload image tu sd card like at website, my Stepper Step Motor 1.8Deg 17HD48004-22B so 1 rotation 200 step. i use full step selection.. i mean no pin is high i plug.. my problem is why my stepper motor don't move x,y,z axis.. all same. in bCNC all port connected.. led TX n RX blinking if run G-code program.. do i missing some step somewhere..

Bertus Kruger
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Re: Newbie setup

Post by Bertus Kruger » Sun Mar 19, 2017 6:56 pm

azijoe90 wrote:hi.. im newbie.. i have some problem with driver Stepper motor DRV8825 (i buy from China) .. i already assembled rpi2 b+, preload image tu sd card like at website, my Stepper Step Motor 1.8Deg 17HD48004-22B so 1 rotation 200 step. i use full step selection.. i mean no pin is high i plug.. my problem is why my stepper motor don't move x,y,z axis.. all same. in bCNC all port connected.. led TX n RX blinking if run G-code program.. do i missing some step somewhere..
Did you connect power for the Stepper Motor Drivers?

azijoe90
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Joined: Sat Mar 18, 2017 2:50 am

Re: Newbie setup

Post by azijoe90 » Mon Mar 20, 2017 1:37 am

hi. tq for your feedback.. i already connected power supply 12vdc to incoming supply for stepper motor. but what i missing is.. my power supply drop voltage to 10.33v when running G-code program.. after i change new power supply ATX.. my voltage is maintain 12vdc now. but new problem is if run rapid speed.. my stepper motor is stuck.. i already calibrate Vref for driver motor.. the problem is same. i thing my 4-wire Stepper Step Motor 1.8Deg 17HD48004-22B not support for fast moving.. or i have missing some adjustment again..

Bertus Kruger
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Re: Newbie setup

Post by Bertus Kruger » Mon Mar 20, 2017 6:52 pm

azijoe90 wrote:hi. tq for your feedback.. i already connected power supply 12vdc to incoming supply for stepper motor. but what i missing is.. my power supply drop voltage to 10.33v when running G-code program.. after i change new power supply ATX.. my voltage is maintain 12vdc now. but new problem is if run rapid speed.. my stepper motor is stuck.. i already calibrate Vref for driver motor.. the problem is same. i thing my 4-wire Stepper Step Motor 1.8Deg 17HD48004-22B not support for fast moving.. or i have missing some adjustment again..
You will need to slow down the speed or increase the micro stepping.

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