TinyG vs GrblShield

Discussion of tinyG control platform
Pseudo
Posts: 15
Joined: Thu Jun 21, 2012 10:30 am

TinyG vs GrblShield

Post by Pseudo » Thu Jun 21, 2012 10:38 am

Currently waiting on the new Inventables pre order to finish, and I was wondering how much of an effect the more advanced motion systems in the TinyG will have when compared to the grblshield? I already have a grblshield in another project but I'm mesmerised by this youtube video and I'm ordering Nem 23s for X/Y as a result, and still working out if a tinyG is worth the expense.

What's the community's thoughts on the matter?

alpha
Posts: 174
Joined: Thu Apr 12, 2012 2:49 pm

Re: TinyG vs GrblShield

Post by alpha » Thu Jun 21, 2012 1:52 pm

I had an Aduino so I thought the GrblShield should be good enough. But now I would go with the TinyG or build something my self. To me it looks like the Y backlash it to great so I think you will need 4 axis (2 Y axis), or a drive shaft. I think the second stepper may be better. Looks like the TinyG has a lot more firmware options and the development looks a lot more active. Maybe this will change with so many ShapeOkos in the wild (I do hope so).

aldenhart
Posts: 132
Joined: Tue Apr 10, 2012 2:17 pm

Re: TinyG vs GrblShield

Post by aldenhart » Mon Jul 16, 2012 9:58 pm

Here's a wiki page about the differences between the two. Hopefully this answers some questions.
http://www.shapeoko.com/wiki/index.php/ ... grblShield

Pseudo
Posts: 15
Joined: Thu Jun 21, 2012 10:30 am

Re: TinyG vs GrblShield

Post by Pseudo » Tue Jul 17, 2012 8:28 am

Thanks Alden :)
I read the wiki page and I decided to order a TinyG, but I also had another idea:
With the tinyG's 4 axis capability could you use it to run a 3d printer? As far as I understand an extruder is just a 4th axis from a gcode point of view, but would the acceleration calcs throw off the plastic extrusion?
I know there's a bunch of 3d printer electronics already out there, but I'm waiting on orduino/azteeg x3 to materialise for dual extruder support and I figure a control board that would allow me to run both shapeoko and my printer in the mean time would be awesome.

aldenhart
Posts: 132
Joined: Tue Apr 10, 2012 2:17 pm

Re: TinyG vs GrblShield

Post by aldenhart » Tue Jul 17, 2012 11:10 am

It's possible to extend TinyG to run a 3d printer but there are some important hardware and software components that need to be provided.

- The extruder is actually a tuned system that needs the temperature, back-pressure and extrusion rate to be coordinated with the X/Y head movement. I think the simplest way to get up and running would be to use the RS-485 port (which uses the Makerbot RJ45 pinouts) to drive an external extruder system such as the makerbot extruder or one of the alternatives. Extending the Gcode interpreter to recognize the "E" axis and the M100 commands and pass data through to the RS-485 port should be relatively straightforward.

- Doing a fully integrated native extruder controller in the firmware would involve the following. Grab one of the ADC ports on the Xmega A port for a temperature sense line. The A port controls the X axis (motor #1), and the Xmin/Xmax limit pins should be able to feed one of the two ADCs on the xmega (Xmin/max can be re-mapped to other available pins). Next use the spindle PWM (output bit 2 - which is reserved for the PWM function - in development) to control the extruder heater. Next add a new axis mode for the Extruder and map motor #4 to it. This should use a stubbed out section of code that does an inverse kinematic transformation down in the bowels of the planner. Currently it just does a cartesian pass-through - coordinates that come in are what go out. This code is executed after acceleration planning, so the number of steps needed to drive the E axis can be computed from the X/Y movements at this point and Extruder pressure coordinated with the X/Y motion.

External electronics would probably be required to do some conditioning on the extruder thermistor or thermocouple and an FET or some other power circuit to drive the extruder heater(s), and another for a heated bed - to be complete.

I'd love it if someone felt like taking this on. I've been focused on CNC, not 3d printing - but I can see the utility of having both. The code base is written in plain C, GPL v3 open and heavily commented. Look for github/synthetos.

- Alden

Pseudo
Posts: 15
Joined: Thu Jun 21, 2012 10:30 am

Re: TinyG vs GrblShield

Post by Pseudo » Wed Jul 18, 2012 12:18 am

Thanks again for the reply Alden :)

Yeah I thought of TinyG as a temp 3d printer board after a 13 hour shift and I'd completely forgotten about thermal control etc.

It's probably more hassle than it's worth, dual extruder boards will become available soon enough :(

aldenhart
Posts: 132
Joined: Tue Apr 10, 2012 2:17 pm

Re: TinyG vs GrblShield

Post by aldenhart » Wed Jul 18, 2012 11:09 am

Yes, there are some interesting things going on with extruders. I like the peripheral approach as well. It's always a trade-off between modularity and cost - do you want an expandable system that bears the cost of connectors, packaging, power, or do you want an all-in-one board purpose built for a specific application? I'm interested to hear what people think is the best approach to add extruders, heated beds, laser controllers, coolant flood systems and other capabilities to a base CNC platform (TinyG or anything else).

DanMc
Posts: 257
Joined: Fri Apr 13, 2012 3:34 am

Re: TinyG vs GrblShield

Post by DanMc » Sat Jul 21, 2012 6:02 pm

I agree with the peripheral approach. By keeping things modular, it allows for more experimentation and innovation. By starting with a core 3-4 axis board and adding the modules specific to ones needs, the possibilities are endless. If the idea is to innovate and expand capabilities, one could always add or remove the drivers/relays needed whereas with a single purpose-built board, you would have to start all over at the beginning. I'm really not an electronics person, but that's my 2 cents.

RicSo
Posts: 1
Joined: Sat Jun 21, 2014 1:13 am

Re: TinyG vs GrblShield

Post by RicSo » Sat Jun 21, 2014 1:26 am

I am also an advocate of modularity, however, if you want to get going quickly and easily, you may want check this board:

http://store.quintessentialuniversalbui ... roduct=129

briankb
Posts: 7
Joined: Fri Apr 18, 2014 10:47 pm

Re: TinyG vs GrblShield

Post by briankb » Sun Apr 26, 2015 5:50 pm

Just wondering if there are any updates on using the TinyG to control an extruder, no other hardware or min hardware but not an extra board. I just got my Shapeoko 2 setup and working with TinyG and want to use it for CNC, Laser, and 3D printing. It's a great small XYZ platform especially with TinyG handling the motion.

I do have several Printrboards and one Smoothieboard too. I thought about using the Printrbot board when using it for 3D printing until I can figure out how to use the TinyG.

Thanks!

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