upgrading steppers

upgrading steppers

Postby powair7s » Sat Nov 04, 2017 12:59 am

I am currently running a pibot board and controllers but would like to upgrade my steppers to some NEMA 34s that require 5A. Does anyone know a similar setup that would accommodate a larger current? I run GRBL and use Universal Gcode Sender and would like to continue with this setup. Any help would be appreciated.

Thanks,

Ben
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Re: upgrading steppers

Postby martin54 » Sat Nov 04, 2017 1:57 am

What steppers are you using just now & what do you hope to achieve by replacing with nema 34's ? What voltage are you currently running, is it regulated or unregulated & will you need to look at increased voltage as well as current ?
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Re: upgrading steppers

Postby powair7s » Sat Nov 04, 2017 4:14 am

Thanks for the reply Martin.

I am going to run thru everything for you because it's not just one thing that is pushing me to this and not everything is arising from the stepper issue.

1. I want to use a probing block to set my 0,0,0. (this is what started my search). My board accepts a G38.2 command but the router does not move. I verified I was in inches and not mm. After doing some research online it looks like there is a firmware issue with the pibot board. I sent the pibot technical help a question about the probing, havent heard back yet.

2. I want to be able to do deeper, faster passes. I think I am limited by my steppers (mostly x) and my trim router. In most woods I am only able to cut about .125" at 60 ipm. I notice it struggles more in x than in y. If it is a hardwood I have to slow down to 40 ipm.

on to my setup.

-I have a home built 4'x8' table.
-porter cable trim router
-x-axis - 1 425 oz.in stepper
-y-axis - 2 425 oz.in steppers
-z-axis - 1 313 oz in stepper (plan on adding a gas spring)

I run on a pibot board, I am including pictures
-it looks like the controllers go up to 4.3 amps - so perhaps I could jump up to a 5 amp nema 34 and run it at 4.3 amps.
-12v 10 amp power supply
-I will have to check how many amps I currently have going to each stepper, there is a dial to set the amps. I know as I increase the amps, I start to hear a high pitch sound so I turn it down a little.
Screenshot_20171103-221754.png

Screenshot_20171103-225645.png

Screenshot_20171103-230832.png


go easy on my home build haha
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Re: upgrading steppers

Postby Adrian » Sat Nov 04, 2017 10:44 am

I wouldn't think that the steppers are the limiting factor in that setup. It's not far removed from the first machine I used and the steppers on that were capable of far more than the router and assembly could ever cope with. Yes it bogged down and stalled when pushing bigger cuts but that was a sympton of the router not being able to keep up. When I upgraded that the was so much flex in the wooden assembly that I couldn't push to what the new router was capable of.
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Re: upgrading steppers

Postby NormanAlbert » Sat Nov 04, 2017 12:38 pm

Hi: I agree. Your router and bits, especially the bits, have more to do with what your steppers can do. The bits have to be sharp and the load factor
accounted for. The hardness of the wood makes a big difference. One saying I live with is, Let the tool do the work! My routers finally have given up
and I switched to DC spindles. What a difference! Now able to dial in the correct rpm, no guessing, and with quality bits ( I use 2L Inc.) have made a huge difference in speed and quality of cut. Norm
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Re: upgrading steppers

Postby powair7s » Sat Nov 04, 2017 12:56 pm

Thanks for the information. I was planning on upgrading my router to a spindle but then considered upgrading steppers first. Your comments make that decision a little easier.

So I guess now I am just back to finding a board and controllers that will allow me to do z-probing. Any suggestions? I want to stick with a USB connection, no serial ports.

I buy most of my bits from toolstoday.com
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Re: upgrading steppers

Postby ger21 » Sat Nov 04, 2017 1:14 pm

The 12V is probably your biggest issue. Most 425oz steppers need about 70V (or even more) to really take advantage of them. Speed is proportional to voltage. You really need a minimum of 36V to get good performacne from any steppers. Actually, you'd probably get better performance going with slightly smaller motors, with less inductance.
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Re: upgrading steppers

Postby powair7s » Sat Nov 04, 2017 1:56 pm

so my board says it can handle a max of 24 volts. what are you guys using to get higher voltage to your steppers?

I guess I am confused on the stepper drivers...they get the larger V in, does that come directly from the power supply or does that come from the board and if it comes from the board the board needs to be capable of that voltage. Using the pibot kinda took all this out of the equation for me. I guess I am trying to figure out if I can still use the pibot board with larger stepper drivers but bipass the pibot board with the 70v's. Not sure if this makes sense.

really appreciate the help.
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Re: upgrading steppers

Postby ger21 » Sat Nov 04, 2017 4:28 pm

so my board says it can handle a max of 24 volts. what are you guys using to get higher voltage to your steppers?


Better stepper drives. :D

Yes, you use a higher voltage DC stepper supply. I'm using a 60V toroidal power supply and Leadshine AM882 stepper drives.

Those cheaper, all in one boards that run open source software tend to be lower powered systems. I don't really have any experience with those, so can't suggest the best way to upgrade from it.
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Re: upgrading steppers

Postby PaulRowntree » Sat Nov 04, 2017 4:50 pm

Are you familiar with the Gecko 540?
http://www.geckodrive.com/geckodrive-st ... /g540.html
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Re: upgrading steppers

Postby martin54 » Sat Nov 04, 2017 7:49 pm

Looks like you have had some good advice while I have been out working :lol: :lol: :lol:

Difficult to know what to suggest because if you do upgrade a part of the machine then you find the next weakest link so you may only achieve a very slight increase in performance if any at all :lol: :lol: I certainly wouldn't look at changing your stepper motors with your current set up, your current stepper motors are running way under what they are capable of just now :lol:
Stepping up to 24V will obviously give you an increase in performance but it might not be quite what you are hoping for, really depends where you see yourself going with this & how big a budget you have :lol: :lol: :lol:
Once you start to upgrade it can be a real drain on your finances lol

Adrian & ger21 have pretty much summed it up, would have thought your board was really designed more for 3D printers than CNC routers if your running 12v dc & max is 24v.

Like ger21 I am running Leadshine AM882 drivers with a 70v power supply, motion control is via Ethernet rather than USB, Gecko that Paul has mentioned seem to have a good name but what put me off the 540 was that I wanted individual drivers rather than one board for all 3 axis on my machine, that's just personal choice though. Gecko drives were also not as easy to come by in the UK when I rebuilt my machine.
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Re: upgrading steppers

Postby powair7s » Sat Nov 04, 2017 7:50 pm

I have heard of the Gecko stepper drivers but I really want to stick with USB. If I am understanding this correctly I could run an arduino uno and from there go to 4 larger stepper drivers. Is the arduino capable of running a 4th stepper as a slave and can it handle 70v? Is there a 4+ axis BOB that will run grbl and accept USB? All the boards I am seeing want you to run Mach3/4.

THanks again.
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Re: upgrading steppers

Postby powair7s » Sat Nov 04, 2017 7:55 pm

I was just thinking I could probably run my pibot board with larger stepper drivers but bump down the Vs going into my pibot board. I really don't want to use this board anymore because it can't run the G38.2 command and apparently my eyes are not very good at depth perception.

Martin, which break out board are you using with an ethernet connection?
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Re: upgrading steppers

Postby ger21 » Sun Nov 05, 2017 2:44 am

I have heard of the Gecko stepper drivers but I really want to stick with USB.


Geckos, and all other stepper drives, accept step and direction signals. These come from either a parallel port (with Mach3 or LinuxCNC), or a motion controller. There are plenty of people using Gecko drives with USB motion controllers.

The issue is the hardware/software combination that you use.
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Re: upgrading steppers

Postby powair7s » Sun Nov 05, 2017 3:00 am

I get that part (now)....I guess I need to know what people are using for USB motion controllers?
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