Firmware

[Brad Stansell]

Thanks for all the help guys, I've pretty much got the mechanical part of my printer up and running, the software to run it is somewhat of a different story. 

In the past I've used repetier, to run things from my PC, linked to an Arduino Mega 2560 with a Ramps 1.4 shield on top of it.  I've been attempting to compile and upload different firmwares with differing degrees of success.  Some will work with the z-axis just fine but the Y axis won't move.  Others allow for y axis movement but the x axis moves at less than a crawl. 

Honestly, a lot of the terminology in the code is confusing to me.  Xmax, Ymax, width, height, etc.  So many variables to examine when a lot of this stuff seems like it should be implied. 

Does anyone have some experience configuring firmware?  I'm going to read up on it but most of the tutorials I've found are fairly cryptic. 

[Bill Schwanitz]

Brad,

Yea Marlin can be fun to set up. The biggest things to do:

1. Get the direction of movement correct. You always home to 0 in a cartesian printer

  * either invert the direction in firmware or ( powered off ) flip the stepper wire the opposite direction

1. steps per mm on x/y/Z axis, get it right - http://prusaprinters.org/calculator/

1. esteps - depends entirely on your extruder setup

I always read through http://reprap.org/wiki/Triffid_Hunter's_Calibration_Guide and then go back to take a pass at config / calibration. The doc does a great job of explaining everything including the fine tuning steps. I suggest estep calibration with PLA as you can iterate way faster ( no waiting for the bed to get back up to temp )

Assuming your printer is transportable bring it tomorrow and me / others can help you out. The above should get you going

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[jesse...@gmx.com]

If you bring it to the meetup I can help you get it setup.

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[jesse...@gmx.com]

Joy, now it looks like I will not able yo make it.

[Brad Stansell]

I think I went to the wrong place, lol (thanks, Siri).  When I got there it was some dark loading dock with no cars around.  The kind of place you would imagine being shot in a movie.  I was actually pretty excited to meet you guys and show you my machine but I was too scared to get out of the car. 

Anyhoo, I've been studying and finally have my machine oozing out what could vaguely be called 'prints.'  I definitely need some calibration to say the least.  If anyone would want to hang out at my place for an hour or two and give me a hand I wouldn't turn them away (We could play PS4 when we were done!).  You could give me a hand hooking up my Bowden kit also! 

I'm not having much luck with my extruder/hotend either.  I purchased some ABS parts designed for a Prusa i3 and when I connected the geared extruder for the first time.... it melted the assembly.  I shouldn't be THAT surprised, since it's not the first time it's happened.  I don't even know how many thermistors/ hotends/ extruders I've been through so far. 

I'm getting closer, but just far enough away from workable that I want to throw the thing out the window sometimes.  And I've spent more than I like to admit.  I could probably have afforded a fully assembled machine had I just saved my money... one of the high end ones too!   Any help I can get would be incredible. 

[Ethan Dicks]

On Thu, Mar 17, 2016 at 9:37 AM, Brad Stansell <stan...@gmail.com> wrote:
> I think I went to the wrong place, lol (thanks, Siri). When I got there it
> was some dark loading dock with no cars around. The kind of place you would
> imagine being shot in a movie. I was actually pretty excited to meet you
> guys and show you my machine but I was too scared to get out of the car.

The address is 421 W State St. The back side isn't what I'd call
"dark", but right across the alley/street is Land Grant Brewing. If
you didn't see a large white overhead door with that on it, you were
in the wrong place.

The front entrance is on State St. Glass doors.

Starting in April, because of construction, the front entrance will be
closed for demolition and reconstruction, so we'll be using the
"member entrance" on the SW corner. There should be signs to direct
folks around the corner, and I'll be mentioning that in the meeting
reminders.

-ethan

[Brad Stansell]

Since we both didn't make it to the previous meeting and it appears I won't make it to any future meetings (shift change at work) and that guide seems to be from 4 years ago, I'm still looking for help with the fine tuning of my settings. 

The calculators helped quite a bit and I think I've nailed down the tweaking of steps/mm, but there's not a lot of info on how to tweak acceleration/speeds so my machine doesn't tear itself apart or drag my prints from the surface.  I feel like I'm missing some magic ratio between travel speed, extrusion rate, temperature, layer height, and acceleration that causes me to consistently get messy prints.  Sometimes it seems like my extruder is moving too fast, so do I slow it down in the firmware or in slicer?  Sometimes it feels like it's not extruding enough filament, or the filament isn't viscous enough... so should I compensate by increasing the temperature or increasing the flow rate?  Too hot and my print will warp as it cools, which causes the nozzle to bump into it, pushing it out of position. 

The calculators are great but there are some things they don't seem to cover, like ideal Slic3r settings, or layer height, etc.  I'm slowly working my way towards a solution but it's just trial and error at this point.  But, I suppose that's how we learn. 

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[bill]

Brad,

You replied to the group but I think you intended me?

Assuming so I could probably help you out Sunday afternoon. Reply privately if you want to meet up or chat. Could also do a Google hangout and I can walk you through a few things 

Bill Schwanitz

If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut. - Albert Einstein.

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[Brad Stansell]

Anyone, really, but I definitely appreciate the offer.  I'm up for a Google hangout, Skype, Facetime (with screen sharing)... whatever works.

Tomorrow I'll probably spend most of my time trying to find a way for my new Tungsten Disulphide hotend/nozzle to mount securely.  I've got all the parts, it's just that none of them want to work together. 

I think my wife is correct when she says this project will be the death of me. 

[Brad Stansell]

I'll start up a Google Hangout tomorrow morning once I wake up (probably around 9 or 10... or 11).  Anyone's free to join in.  I'll take all the help I can get.  I posted some pictures so you have a general idea of what I'm working with.  I've been flip-flopping between Repetier's firmware and Marlin.  Mostly because Marlin seems to have issues compiling with the U8G library and I like the direct access to the EEPROM that Repetier provides. 

[Brad Stansell]

Just wanted to say that I appreciate all the help you guys have given me.  I think I may have finally gotten my calibration issues solved. 

I finally figured out (after a lot of research) that one of my main issues was with my extruder steps.  I found a fairly simple math equation that (now that I found it) made me feel very stupid that I didn't figure it out sooner.  I'll post it here for any other lost soul who may be having issues. 

Some other sites have suggested calibrating the extruder by measuring a 10mm length of filament, telling your program or whatever to extrude 10mm, and then seeing how much it actually extrudes and doing a bunch of ratio calculations with the number of teeth on the gear and blah blah blah.  While this sounds like it works in theory, I found it to be more than a little difficult with the measuring before and after.  I stumbled upon this simpler equation that uses very rudimentary math that anyone past 5th grade should understand. 

We essentially need the following:  How many steps does it take for our motor to make one revolution / how far does one revolution of our motor take us.

The second is easy enough to find since it's essentially the circumference of a circle.  This circle is the gear attached to our motor.

- Measure the diameter of your extruder gear using calipers (in mm, since our firmware thinks in mm) and multiply times pi (pi * diameter = circumference, which is how far the filament will travel in one revolution)

The second part is a bit trickier but it all makes sense if you keep track of what you're measuring. 

- Figure out how far your motor travels in one step.  A NEMA 17 travels 1.8deg, other motors may be different. 

- 360deg is a revolution so divide 360 by the above value to get the number of steps it takes to turn 360deg.  NEMA 17 comes out to 200steps

- Now we need to figure out how many microsteps you have your stepper drivers set to.  This will either be 1/16 or 1/32.  This is a hardware setting/limitation and is critical to get right as I found out.  We're interested in the bottom number since we really need to know how many signals sent to the driver will complete one step.  16 for 1/16 or 32 for 1/32. 

Now comes the fun part.  I'll use my experience for an example.  I had NEMA 17 motors so I got 200steps/rev and I multiply it by 16signals/step to get 3200 signals per revolution.  Then I divide that by my gear diameter (12) * pi which is roughly 37.699mm/revolution (another way of saying circumference).  Just cancelling out the units, you see where I'm going... 3200signals/37.699mm.  This equates to around 84.882signals/mm. 

Obviously my nomenclature isn't correct here.  The firmware asks for steps per unit and I'm giving you signals (or electrical pulses/mm) which is what the firmware is really asking for.  And it's not precise and works best for extruders where the motor isn't geared (MK8, not tested on Wade), but the science is sound and I've found it's much easier than making marks with markers on filament and calculating ratios ad nauseum. 

Now that I've bored you all to death, let me bore you all with death.  In closing, I present my best print yet...

[bill]

Very nice!

 e_steps_per_mm = (motor_steps_per_rev * driver_microstep) * (big_gear_teeth / small_gear_teeth) / (hob_effective_diameter * pi)

From http://reprap.org/wiki/Triffid_Hunter's_Calibration_Guide#Calculate

That print looks very nice BTW well done!

Bill Schwanitz

If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut. - Albert Einstein.

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