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Rostock Mini Pro Issues

Posted by andychang28 
Rostock Mini Pro Issues
February 20, 2015 09:33PM
Hi everyone,
Before I begin, this is my first post, so please correct me in any violation of protocols. I am building a Rostock Mini Pro, which I purchased several weeks ago from 3dPrinterCzar. I have finished the mechanical and electrical parts, and the only issues that remain are in the software.

My priority target for now is the fact that my printer does not seem to know when its hot end has reached the print bed. I have tried lowering the z axis length in my Configuration.h file, even going so far as to set it at 114 mm, but nothing seems to work. I have checked the EEPROM settings as well, and they are all set to 114 mm. However, the motors keep on pushing the hot end down into the print bed.

Aside from that problem, whenever I try to home my printer, the carriages move up as they are supposed to, but once they have all reached the top endstops, they suddenly turn around and move down slowly for a centimeter or two. Then, they come back up at the same slow speed, and this time they stop when they hit the tops.

Finally, whenever the motors stop, (this includes homing, moving through manual control in Repetier, etc) they make a very high-pitched whining noise. I feel like they're still running but stopped at the same time.
confused smiley

Please help!
Thanks, Andrew
Re: Rostock Mini Pro Issues
February 21, 2015 07:16AM
I bought a Rostock Mini Pro from 3d Printer Czar last month too. Getting it working well has been a fun adventure. That I've... almost finished! In order from easy to hard: smiling smiley

Quote
andychang28
Aside from that problem, whenever I try to home my printer, the carriages move up as they are supposed to, but once they have all reached the top endstops, they suddenly turn around and move down slowly for a centimeter or two. Then, they come back up at the same slow speed, and this time they stop when they hit the tops.

That's normal. It's just the Repetier firmware backing off and then rehoming. I kind of like it.

Quote

Finally, whenever the motors stop, (this includes homing, moving through manual control in Repetier, etc) they make a very high-pitched whining noise. I feel like they're still running but stopped at the same time.

You're probably supplying too much current to your stepper motors. The Mini Pro build instructions are a bit weak when it comes to setting that. You'll probably also notice the stepper motors under the build platform getting very very warm.

I fixed that by following the motor calibration guide in http://reprap.org/wiki/Calibration. It should be a lot quieter afterwards.

Quote

My priority target for now is the fact that my printer does not seem to know when its hot end has reached the print bed. I have tried lowering the z axis length in my Configuration.h file, even going so far as to set it at 114 mm, but nothing seems to work. I have checked the EEPROM settings as well, and they are all set to 114 mm. However, the motors keep on pushing the hot end down into the print bed.

I disabled EEPROM settings while calibrating (set EEPROM_MODE to 0), to make sure the printer was running with the settings I'd entered in Configuration.h.

But I'm not too sure what might be wrong in your case. Are you homing the print head first? If so, running a command like G0 F8000 X0 Y0 Z0 will send the head to where it thinks the 0 point is. With your Z height still set at 114mm that should put the head roughly centred, something like 60-70mm above the build platform.
Re: Rostock Mini Pro Issues
February 21, 2015 12:38PM
Thanks for the reply stibbons, I'm away from home right now but I should be able to try changing the current soon. As for the G0 F8000 X0 Y0 Z0 command, how exactly do you give the printer the command?
Andrew
Re: Rostock Mini Pro Issues
February 21, 2015 05:36PM
By the way, if your configuration.h file is working well, can you send me a copy of it? It would be a great help.
Re: Rostock Mini Pro Issues
February 22, 2015 02:54AM
Bought my Rostock 9 months ago but got frustrated and took a break. I think deltas are just a lot harder to calibrate.

Not sure I understand your bed issue. My height is around 160mm, so if you are moving from your max height down 114mm, the hotend should be around 25mm from the bed. If you are hitting the bed, my guess is you steps per mm values are off. What process have you gone through so far to calibrate your firmware? Have you seen minow's calibration steps?
Re: Rostock Mini Pro Issues
February 22, 2015 10:40AM
Maybe this helps ?

I have also built the Czar mini pro.
It took me quit some time (and help) to have all tuning done. Now, with this config, it works almost fine :-)
I only sometimes have a strange missed step so some objects end-up misaligned from that point.

Thomas


www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)
Attachments:
open | download - Configuration.h (54.2 KB)
Re: Rostock Mini Pro Issues
February 22, 2015 11:09AM
Thanks everyone, I found out why the hot end was crashing into the print bed. It turns out my steps per mm was way too high, and for every 10mm I told the printer to move it actually moved about 23mm. eye popping smiley
Anyway, now I'm trying to get the extruder to push the plastic out the nozzle. I can make plastic melt and come out of the hot end by manually pushing it through, but if the extruder motor tries to do so it doesn't work. The extruder motor runs fine, so the problem must be somewhere between the motor and the hot end. I think calibrating the extruder motor might help this. Any advice?
Andrew smiling smiley
BTW Here's my config file
Attachments:
open | download - Configuration.h (21.6 KB)
Re: Rostock Mini Pro Issues
February 22, 2015 01:43PM
Quote
andychang28
I can make plastic melt and come out of the hot end by manually pushing it through, but if the extruder motor tries to do so it doesn't work. The extruder motor runs fine, so the problem must be somewhere between the motor and the hot end. I think calibrating the extruder motor might help this. Any advice?

Does the extruder motor turn smoothly when it is trying to extrude? If yes, then the hobbed part is not gripping the filament. Many extruder designs have a screw for adjusting the pressure on the idler bearing that pushes the filament against the hobbed part, and you may need to increase the pressure.

If instead the motor is not turning smoothly but is skipping steps, then you may need to increase the extruder motor current.



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: Rostock Mini Pro Issues
March 01, 2015 11:34AM
Sorry for the week-long wait guys, I've been cramming for schoolwork recently. The extruder motor turns and pushes the plastic fine, the problem is that once it gets to the hotend the plastic stops moving. Then the extruder starts skipping steps. Hope I get some time to poke around with the printer soon. Thanks!
Re: Rostock Mini Pro Issues
March 01, 2015 11:43AM
Unless the extruder motor is already getting warm, try increasing the extruder motor current.



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: Rostock Mini Pro Issues
March 05, 2015 01:40PM
Lots of snow here today. I can't open my door...
Anyway, I've found yet another issue with my printer-when I use manual control to move the print end on the x and y axis, it moves a bit on the z axis as well. Basically, whenever I move the hotend away from the center, it moves up.
Assuming I have to calibrate the x-y axes, but I haven't figured out how to do so yet. Any advice?
Thanks, and fingers crossed for another snow day tomorrow!
Re: Rostock Mini Pro Issues
March 05, 2015 03:49PM
To fix that problem, decrease the delta radius setting in whatever firmware you are using. A good starting point is to decrease the delta radius by twice the excess height at the centre of the bed compared to the edges.



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: Rostock Mini Pro Issues
March 05, 2015 04:43PM
Quote
dc42
To fix that problem, decrease the delta radius setting in whatever firmware you are using. A good starting point is to decrease the delta radius by twice the excess height at the centre of the bed compared to the edges.

Does it matter if the print head rises near the edge and almost touches it at the centre?
PS I got the motors to stop whining. Thanks!
Re: Rostock Mini Pro Issues
March 05, 2015 04:54PM
Sorry, as your height is lower at the centre than at the edges, you need to increase the delta radius, by about twice the height error.



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: Rostock Mini Pro Issues
March 05, 2015 05:18PM
Just to clarify, I should be changing the parameter "DELTA_RADIUS", not "DELTA_MAX_RADIUS", correct?
Re: Rostock Mini Pro Issues
March 05, 2015 07:15PM
Quote
andychang28
Just to clarify, I should be changing the parameter "DELTA_RADIUS", not "DELTA_MAX_RADIUS", correct?

I've no idea, because you haven't said what firmware you are using.



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: Rostock Mini Pro Issues
March 05, 2015 08:36PM
Sorry about that, I'm on Repetier Firmware and Host. grinning smiley

I increased both by double the error measure, and I see major improvement, but there's still a one or two millimeter gap. Is that normal?

Edited 1 time(s). Last edit at 03/05/2015 08:42PM by andychang28.
Re: Rostock Mini Pro Issues
March 06, 2015 03:19AM
I don't know how Repetier is configured. The factor of 2 is only approximate. I suggest you increase the delta radius again, try by 2.2 times the remaining error. Iterate as needed.



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: Rostock Mini Pro Issues
March 07, 2015 09:17PM
K, Thanks anyway dc42. I think all i had to do was increase it by more, if any more problems come up i'll post again. smileys with beer
Re: Rostock Mini Pro Issues
March 16, 2015 08:39PM
ugh. another problem.
The hot end seems jammed whenever the extruder motor tries to push the filament through. The plastic just gets stuck right near the hot end. A little bit comes out at first, but after that nothing. If I turn the exto motor some more with manual control, the tube thing holding the filament pops right out of place. When I push it through manually, it's fine.
Any suggestions?
Re: Rostock Mini Pro Issues
March 17, 2015 06:07AM
Do you have a working hot end cooling fan, to keep the top of the nozzle assembly cool so that the plastic doesn't melt too high up?



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: Rostock Mini Pro Issues
March 18, 2015 04:19PM
My kit from 3D Printer Czar came with a J-head clone and only had a fan for cooling the print, not the hot end.

During some of my first extrusion attempts, I managed to rip the bowden adapter out of my extruder because I was attempting to extrude at too cool of a temperature. I just super-glued the hell out of it and got it limping along again.
Re: Rostock Mini Pro Issues
March 18, 2015 09:39PM
I've got a small fan that came with the printer, but I don't see any way that it could cool down the hot end. Why would plastic melting too high up be a problem?
Re: Rostock Mini Pro Issues
March 19, 2015 07:20AM
Quote
andychang28
I've got a small fan that came with the printer, but I don't see any way that it could cool down the hot end. Why would plastic melting too high up be a problem?

When plastic melts, it first turns into a rubbery substance before it goes totally liquid. That rubbery substance pushes out against the side walls of the hotend bore, causing a huge resistance that some extruders cannot overcome. Hotend science (or black magic) has generally concluded that keeping the transition/melt zone as short as possible keeps this plug from developing. Without the fan, an E3D will let that plug creep above the heat break and into the cooling fins. Hence, no fan on an E3D is bad. A real J-head with a PEEK body does not benefit from a fan, and I have never seen one used to cool the PEEK.....
Re: Rostock Mini Pro Issues
March 23, 2015 08:34AM
What I gather from these comments is that I need a fan for my hot end, or at least the gray area with vents above it. How much would this fan cost, and would there be any other way to keep the plastic cool?
P.S. Is it possible that defective filament could be causing the white tube thing holding the plastic to pop out of the extruder motor housing?
Re: Rostock Mini Pro Issues
March 23, 2015 08:49AM
Quote
andychang28
What I gather from these comments is that I need a fan for my hot end, or at least the gray area with vents above it. How much would this fan cost, and would there be any other way to keep the plastic cool?

If you are using an all-metal hot end such as the E3D, then you do need a fan. The usual choice is a 40mm square x 10mm thick 12V PC fan. These are cheap, for example GBP4 from my local Maplin store, or GBP2 on eBay.

Quote
andychang28
P.S. Is it possible that defective filament could be causing the white tube thing holding the plastic to pop out of the extruder motor housing?

Normally, the extruder motor skips steps rather than forcing the tube out. So the pneumatic connector (or whatever else is holding the end of the Bowden tube) may need to be replaced, to hold the tube more securely.



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: Rostock Mini Pro Issues
March 23, 2015 09:59AM
Quote
dc42
Normally, the extruder motor skips steps rather than forcing the tube out. So the pneumatic connector (or whatever else is holding the end of the Bowden tube) may need to be replaced, to hold the tube more securely.

Many people consider the Bowden tube pneumatic connectors to be consumables, like filament, kapton/blue tape, and glue sticks. If they will no longer hold the tube inside, replace them.....
Re: Rostock Mini Pro Issues
March 25, 2015 07:41PM
I have a J-head mk v clone with a plastic vented shroud around the upper half, does that mean I don't need a fan? If the absence of a fan isn't the problem, what else could be causing the hot end to become jammed constantly?
Thanks, andy
Re: Rostock Mini Pro Issues
March 26, 2015 07:30AM
Your hotend shroud is made of PEEK, like a genuine J-head. It does not require a fan.

However, some of the J-head clones have been reported to omit the teflon liner inside that runs through the PEEK and down to the heater block. There's a web page that I saw with different J-head clones and their differences from the real part, and it had several pictures you might want to reference.....
Re: Rostock Mini Pro Issues
March 26, 2015 08:45PM
Hi again,
I took apart my hotend, and I have visual confirmation that the teflon liner is present. It is a small, roughly one inch long white cylinder with a small hole going down the middle. My hotend seems to be working fine whenever I push plastic through manually, but it won't print squat when the extruder motor tries. What is going on with my printer?!
Thanks, Andy
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