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Cherry Pi III Is Available

Posted by AndyCart 
Re: Cherry Pi III Is Available
March 27, 2015 02:04AM
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Zzyzxx71
Quote
AndyCart
Your tower designations and I assume your stepper and limit switch RAMPS connections are incorrect. X is front left, Y is front right, Z is the rear tower. If you get those correctly connected it may just spring into life!

Awesome - Fixed!

Edit #2: It appears I only have access to the forward left portion of the "cylinder", X only goes left of center, it refuses to go right, same with the rear (regarding the Y axis), it only goes to the front.

Edit#3 - video of the issue can be found here. - [www.youtube.com]

Edit#4 - Ugh - OK I've completely swapped out for a spare ramps shield and replaced the second Y axis end stop, and the behavior is the same. This has to be something in the firmware, I have new end stops, new shield, new connectors, etc. Z axis motion is working as expected, but homing isn't, but only for the Y tower.

Kinda stumped now. Additionally still haven't resolved the "front left quadrant" issue either.

Sounds more like a host program issue to me. Which host are you using? Have you told it your bed centre is 0,0?

Edit: just looked at your video. I would guess it's limit switch problems. If you move the carriages away from the top what do you see on screen if you send an M119 command?

Edited 1 time(s). Last edit at 03/27/2015 02:08AM by AndyCart.
Re: Cherry Pi III Is Available
March 27, 2015 05:38AM
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AndyCart
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David J
Andy,

Am I right in thinking that you recommend doing the mod on the StepStick motor drivers - shorting out R4, I think? I'll be starting off by using your configuration.h file, so I'll need to match your setup as much as possible. I will be using the 3 links under each driver board.

I have the right soldering kit to make this mod, but I only want to do it if it's a real benefit. smiling smiley

Absolutely, it make a big difference to how quiet the motors run and how much current they draw. Recently the A4988 boards I have been getting have the mod already done. What looks like a SMD resistor at R4 is actually a link

Is there an easy way to tell? Multimeter across R4? Originally it was a 10k resistor, but I don't know if there are any other conductive paths to confuse a meter reading.

It doesn't help that my Chinese-made stepsticks have a different PCB layout to the ones shown in the RepRap wiki - I'm not sure where R4 is on the board (I know roughly where it should be - hanging off pin 13 of the 4988 chip - but the traces go under the chip so it's hard to follow).

Edited 2 time(s). Last edit at 03/27/2015 06:23AM by David J.
Re: Cherry Pi III Is Available
March 27, 2015 06:47AM
The links normally have a 0 on them ie zero ohms you may need a magnifying glass to see it though
Re: Cherry Pi III Is Available
March 27, 2015 07:28AM
I've finally worked out where R4 is on mine - and it is 10k ohms. Reasonably easy to short out though (hopefully!) as it's on the edge of the board.

Edited 2 time(s). Last edit at 03/27/2015 07:35AM by David J.
Re: Cherry Pi III Is Available
March 27, 2015 10:34AM
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gowen
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David J
I've decided to experiment with the power input - I'm planning to use a 203W Xbox PSU to power the printer, so I've decided to take the obvious route and try to fit an Xbox power socket to match. This will have numerous advantages:

  • I won't need to modify the PSU lead.
  • It's built to take all the power the PSU can offer.
  • I will probably be able to fit a switch to turn the PSU on and off remotely.
  • I have the choice of powering the Arduino directly with 5v, rather than use the linear voltage regulator built into the Arduino/RAMPS, thus reducing heat output.

Of course, this means that I will have to build a nice enclosure to house the socket and switch (an enjoyable task) and I may have to design a PCB to keep it tidy (should also be fun).

I have ordered the socket on ebay, so watch this space! smiling smiley

Make sure you order the right socket. I had the same idea, but the power socket I ordered was for an Xbox 360 Slim and the PSU I had was for an Xbox ONE. The socket looks the same but the sizes are ever so slightly different. Just enough to mean I couldn't use it.

It fits - it's the right socket! Whoopee! smiling smiley
Re: Cherry Pi III Is Available
March 27, 2015 11:25AM
Quote
gowen
With this added it compiled and installed fine although I did get these messages.
Sketch uses 121,982 bytes (48%) of program storage space. Maximum is 253,952 bytes.
Global variables use 6,386 bytes (77%) of dynamic memory, leaving 1,806 bytes for local variables. Maximum is 8,192 bytes.
Low memory available, stability problems may occur.
It appears this warning appeared because I was compiling using version 1.6 of Arduino. I've now switched to 1.0.6 and it compiles without any warnings.

Using the latest version of Rich Cattell's Marlin I have finally had some success with auto-calibration. I went through the printer with a 2 foot digital vernier I borrowed from the company inspection department. I found there was a 1mm height difference between top column head brackets so I evened that up. I also found a little slop in the carriages which I removed and tightened one of the belts which was a bit looser than the others.

I found this post in the New Testing Branch of RC's Autocalbration firmware thread on google groups. Following this I ran the auto-calibration with the following results.

0.1mm precision (G30 A0.1), completion in 23 minutes after 9 iterations.
Save (M500)
0.07mm precision (G30 A0.07), completion in 20 minutes after 18 iterations.
Save (M500)
0.05mm precision (G30 A0.05), completion in 20 minutes after 15 iterations.
Save (M500)
0.03mm precision (G30 A0.03), Still going at 19 minutes and 9 iterations.

I shall run a manual calibration on Monday and then be ready to print.

My missing filament from 3DFilaPrint turned up 15 days after ordering and a couple of hours after the replacement filament I'd ordered from a Hobbyking. So now I have 3 kg of filament ready to print.

I'm just waiting for the Kapton Tape which should arrive early next week.
Re: Cherry Pi III Is Available
March 27, 2015 11:30AM
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gowen
Quote
gowen
With this added it compiled and installed fine although I did get these messages.
Sketch uses 121,982 bytes (48%) of program storage space. Maximum is 253,952 bytes.
Global variables use 6,386 bytes (77%) of dynamic memory, leaving 1,806 bytes for local variables. Maximum is 8,192 bytes.
Low memory available, stability problems may occur.
It appears this warning appeared because I was compiling using version 1.6 of Arduino. I've now switched to 1.0.6 and it compiles without any warnings.

I totally failed to compile it under version 1.6 - version 1.0.6 works for me too.

Edited 1 time(s). Last edit at 03/27/2015 11:49AM by David J.
Re: Cherry Pi III Is Available
March 27, 2015 03:17PM
Since upgrading to all metal hotend I am having trouble with print head hitting the print sometimes and making the rods pop out,Any suggestions on how I can stop this.
Re: Cherry Pi III Is Available
March 27, 2015 11:29PM
Quote
AndyCart
Quote
Zzyzxx71
Quote
AndyCart
Your tower designations and I assume your stepper and limit switch RAMPS connections are incorrect. X is front left, Y is front right, Z is the rear tower. If you get those correctly connected it may just spring into life!

Awesome - Fixed!

Edit #2: It appears I only have access to the forward left portion of the "cylinder", X only goes left of center, it refuses to go right, same with the rear (regarding the Y axis), it only goes to the front.

Edit#3 - video of the issue can be found here. - [www.youtube.com]

Edit#4 - Ugh - OK I've completely swapped out for a spare ramps shield and replaced the second Y axis end stop, and the behavior is the same. This has to be something in the firmware, I have new end stops, new shield, new connectors, etc. Z axis motion is working as expected, but homing isn't, but only for the Y tower.

Kinda stumped now. Additionally still haven't resolved the "front left quadrant" issue either.

Sounds more like a host program issue to me. Which host are you using? Have you told it your bed centre is 0,0?

Edit: just looked at your video. I would guess it's limit switch problems. If you move the carriages away from the top what do you see on screen if you send an M119 command?

M119 is showing intermittent activation of the Y end stop, even after swapping out the end stop and the ramps shield. I'm starting to think I might have an issue with the arduino.
Re: Cherry Pi III Is Available
March 28, 2015 04:30AM
That intermittent activation of the Y endstop suggests to me that you have a bad crimp connection in the endstop cable.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Cherry Pi III Is Available
March 28, 2015 05:53AM
Noted, but I've rebuilt that end stop twice. (using both new switches, and existing working switches). If I screwed this up, I've screwed it up 4+ times.
Re: Cherry Pi III Is Available
March 28, 2015 06:37AM
Quote
Zzyzxx71
Noted, but I've rebuilt that end stop twice. (using both new switches, and existing working switches). If I screwed this up, I've screwed it up 4+ times.

What about where it connects to the electronics board - do you have a crimp connection there?

But it's also possible that the problem is caused by a poor joint on the RAMPS or the Arduino, or in the connector between them.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Cherry Pi III Is Available
March 29, 2015 04:49PM
Andy

Could I request a top bracket with bearing mount for the cherry pi III with a M5 hole in the outer side like the bottom bracket. I would like to tighten the top brackets a bit more as I have a bit of play and am reluctant to over tighten the bearing one bolts as last time I did that it bent the part.

Thanks

Matt
Re: Cherry Pi III Is Available
March 29, 2015 05:41PM
Hi Matt. I'll see what I can do. Pushing holes through a curved surface in Sketchup isn't as easy as it should be though so it may take me a while to hand ball it.
Re: Cherry Pi III Is Available
March 29, 2015 05:55PM
Thanks Andy

Trying to get any play out the system as I am having some issues calibrating. The tower offsets appear to change every time the carriage moves.. I could play a tune using the belts and have gone through everything else, just looking into the play in the frame now. The carriages appear nice and tight, no play as far as I can tell.
Re: Cherry Pi III Is Available
March 30, 2015 05:03AM
Hi Matt

Give this a whirl. It wasn't as difficult as I thought.

Andy
Attachments:
open | download - Top Bracket With Extra Mounting Bolt.stl (222.8 KB)
Re: Cherry Pi III Is Available
March 30, 2015 05:08AM
Andy,

That's perfect, thanks a lot. I will get these printed tonight smiling smiley

Matt
Re: Cherry Pi III Is Available
March 30, 2015 10:07AM
Is trying to auto-calibrate to 0.03 wishful thinking? I've successfully calibrated to 0.05.
Re: Cherry Pi III Is Available
March 30, 2015 11:10AM
How far does the Z carriage travel down the extrusion in use? Or, to look at it the other way round, how close does the bottom of the Z carriage get to the bottom of the extrusion where it sticks out of the bottom corner bracket?

I'm trying to tidy up the wiring from the extruder and hot-end after it's passed through the Z upright, and I'd like to know how far up I can put clips! The slot in the extrusion is now a bit full of wires on the print-bed side...
Re: Cherry Pi III Is Available
March 30, 2015 11:43AM
Oh - one more question - I'm a bit puzzled about the end-stop wiring on the RAMPS board: do the wires go from S to -, or S to + in this configuration?

I've seen instructions on web pages that contradict each other.
Re: Cherry Pi III Is Available
March 30, 2015 01:05PM
Quote
gowen
Is trying to auto-calibrate to 0.03 wishful thinking? I've successfully calibrated to 0.05.

I auto calibrate my Mini Kossel to 0.02mm before each print. By that, I mean that further auto calibration cycles adjust the endstops and delta radius by no more than 0.02mm. I think that's about the limit of the mechanics. To get this reproducibility, I have to discard the first reading from the mechanical Z probe after deploying it. I plan to try an IR Z probe soon, which will avoid the deploy/retract time and make auto calibration faster. I'm also looking at using a 7-point auto calibration routine, which will also implement bed compensation for the parts of the bed furthest from the towers and centre.

Edited 4 time(s). Last edit at 03/30/2015 01:09PM by dc42.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Cherry Pi III Is Available
March 30, 2015 06:31PM
Quote
David J
Oh - one more question - I'm a bit puzzled about the end-stop wiring on the RAMPS board: do the wires go from S to -, or S to + in this configuration?

I've seen instructions on web pages that contradict each other.

I connect to the outboard two pins so S and -VE. As long as you don't short out the 5V rail (inboard two pins) you should be fine
Re: Cherry Pi III Is Available
March 31, 2015 02:05AM
Does anyone (in Brisbane, Australia?) want to buy an almost-there Cherry Pi IIIS? I've spent probably more than 20 hours after "completing" the build to try and get it working but can't, and I'm kind of over it. Still having issues extruding and I'm sick of taking apart the effector and hot end to clear it out and try something else. It's probably a stupid fault that any idiot could pick up and fix, but I can't, so if anyone wants to buy it I'm willing to sell cheap.
Re: Cherry Pi III Is Available
March 31, 2015 03:17AM
Quote
David J
How far does the Z carriage travel down the extrusion in use? Or, to look at it the other way round, how close does the bottom of the Z carriage get to the bottom of the extrusion where it sticks out of the bottom corner bracket?

I'm trying to tidy up the wiring from the extruder and hot-end after it's passed through the Z upright, and I'd like to know how far up I can put clips! The slot in the extrusion is now a bit full of wires on the print-bed side...

Not quite sure what you are asking here! Maybe a picture? I normally fit the filament spool and set the bottom of the extruder with about 5mm clearance to the top of the spool. This sets the height of the hole from the rear of the Z tower to the front (print bed) side. All the cables from the hot end and the extruder motor then go through the hole (normally two 6mm holes close enough to form an oval with a bit of filing) and then down the front 'T' slot to the under side of the machine. There's normally plenty of room and I finish off with a length of coverstrip or tape
Re: Cherry Pi III Is Available
March 31, 2015 03:54AM
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AndyCart
Quote
David J
Oh - one more question - I'm a bit puzzled about the end-stop wiring on the RAMPS board: do the wires go from S to -, or S to + in this configuration?

I've seen instructions on web pages that contradict each other.

I connect to the outboard two pins so S and -VE. As long as you don't short out the 5V rail (inboard two pins) you should be fine

Excellent - I guessed correctly!

As for the wiring/carriage travel, my wiring flaps around in the inside groove below the hole and there's a risk of getting caught up when the carriage passes over - I was thinking about putting a clip over it, but tape or coverstrip should do the trick. I wish I'd picked up on the "two holes filed into one" before I started - those wires are VERY snug in the single hole! winking smiley

Thanks,
David

Edited 1 time(s). Last edit at 03/31/2015 03:55AM by David J.
Re: Cherry Pi III Is Available
March 31, 2015 05:29AM
Andy, out of interest, how have you checked the temperature of your hot ends in the past? I got an IR thermometer but it's not effective... I think this is mostly because the emissivity of the hot end is super low.

Quick physics lesson why: IR based temperature measurement is largely dependent on the type of surface. A perfectly black surface with no shine to it at all (matte), has an emissivity of probably 0.990. Most cheap remote thermometers are calibrated to 0.95. Materials like polished metal, glass, etc have emissivity values ~0.05 to 0.1. Long story short, they'll appear to have the temperature of objects around them which has 'bounced' off the surface you're trying to measure. Oh, they usually have a conical measurement area too (the particular one I have has a ratio of 1:12... being if I'm 12m away from something it'll have a measurement area with a 1m diameter.

So there's no real easy way to measure the temperature of my hot end.

Would it just be easiest if I got a new thermister and tried that?

I'm pretty fricken frustrated at the moment. I don't know why it's not feeding filament.
Re: Cherry Pi III Is Available
March 31, 2015 05:42AM
Pugzor, I have had hot end issues in the past also, what I found was that with some of the hotends, they appear to need the ptfe tube feeding all the way into it, I have had one that only went into the gas joint, and others that went through the gas join all the way down. When I didn't put the ptfe all the way down the filament would bunch up inside the hot end and block the nozzle. The filament needs to be snugish all the way down or when it gets hot it just fills up the space. Not sure this is the issue your having, just something I have had issues with.
Re: Cherry Pi III Is Available
March 31, 2015 06:01AM
Quote
pugzor
Andy, out of interest, how have you checked the temperature of your hot ends in the past? I got an IR thermometer but it's not effective... I think this is mostly because the emissivity of the hot end is super low.

Quick physics lesson why: IR based temperature measurement is largely dependent on the type of surface. A perfectly black surface with no shine to it at all (matte), has an emissivity of probably 0.990. Most cheap remote thermometers are calibrated to 0.95. Materials like polished metal, glass, etc have emissivity values ~0.05 to 0.1. Long story short, they'll appear to have the temperature of objects around them which has 'bounced' off the surface you're trying to measure. Oh, they usually have a conical measurement area too (the particular one I have has a ratio of 1:12... being if I'm 12m away from something it'll have a measurement area with a 1m diameter.

So there's no real easy way to measure the temperature of my hot end.

Would it just be easiest if I got a new thermister and tried that?

I'm pretty fricken frustrated at the moment. I don't know why it's not feeding filament.

Hi Andrew

I had the exact same problem with IR thermometers. I solved it, mostly, by just sticking a piece of kapton tape onto the heater block and then pointing my thermometer at that. It certainly seems to be within a degree or two. In the end though I just gave up on the numbers and did it this way :-

Unscrew the hinge on the extruder so you can manually push filament into the bowden. Get the hotend to temp (I normally start at about 190 on my display) try to push filament through, then increase by 5 degrees and try again, repeat. There is a definite point where it becomes much easier to feed filament through the system. At that point make a note of the displayed temperature and, moving forward, use that temperature for that filament. I've had very few issues with filament feed since adopting that approach.

The main reason I moved away from the JHead in favour of an E3D type all metal design was due to the hassle of unclogging a JHead. It's so much easier just unscrewing a brass nozzle and popping a new, clean one, in. I have two. One in the hot end and one I clear and keep in reserve. The clones from China are cheap as chips and I really like them once a few simple mods are carried out (as in the current thread in this forum - [forums.reprap.org]). I've found silver and black PLA particularly bad for nozzle clogs for some reason.

Andy

Edited 1 time(s). Last edit at 03/31/2015 06:42AM by AndyCart.
Re: Cherry Pi III Is Available
March 31, 2015 06:22AM
Thanks for the response guys.

Yeah, I didn't bother with the Kapton tape because I thought it was too shiny. Still might give it a go.

I don't know where it's getting stuck but there's definitely something wrong in the hotend. It very well could be the PTFE lining. Even when I try to feed it in manually (removing the Bowden tube, inserting another length of tube and feeding in filament by hand) it's jamming on something. I'm quite sure it's not debris in the nozzle itself because it's slowly 'dripping', and usually just after I've cleaned it out it'll extrude a little bit... but then clog up again. I've been running at 210°C so maybe it's melting too far up, but with that in mind I've tried pushing filament onto the nozzle from the outside and I don't think it's melting anywhere near as fast as it probably would need to for the feed rates I've seen. I'd imagine it should almost turn into liquid, similar to pushing solder into a soldering iron? Okay, maybe not that extreme but pretty close.

Long story short it'd be super handy to know the actual temp of the hot end to rule that out. I'd hate to go to the effort of replacing the entire effector assembly if it's just a dodgy thermistor causing my woes.

Agreed, it'd be super cool to get an E3D (or clone). I'm hoping though that maybe the upgrade will be to a Cyclops though. Can't be that many dual extruding deltas out there...
Re: Cherry Pi III Is Available
March 31, 2015 06:35AM
Be a little bit wary of the Cyclops. Don't get me wrong it is a superb piece of kit for dual extrusion and works flawlessly. But that's the rub. As it's a dual extruder that relies on mixing it requires both filaments to be present in the hotend. If most of your printing is single colour then the filament that is unused sits there for hours and cooks. When you come to want to use it it is normally jammed in the heatblock. No big problem to clear it but it's a pain. You also can't retract the unused filament out of the hotend to stop it cooking as then the colour you are using finds it's way back through the hotend and lodges, cooled in the feed tube for the unused colour. Another blockage! I am contemplating building a separate machine for dual extrusion and going back to a single, all metal, extruder for my production machine. A better option for mostly single colour printing with infrequent dual use is probably the E3D Chimera as it has two, individual hotends. This also makes it suitable for printing with two differing filaments (which the Cyclops can't do) but then you may have the common dual nozzle issue of drips, etc from the unused nozzle. I have no experience of the Chimera though as I purchased the Cyclops (which I do love despite all of the above)
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