Another newbie's Smarcore build

After continuously flopping back and forth between building a Prusa i3 and the Smartcore I have finally settled on the Smarcore. I kept looking for other options in an attempt to find more readily available printed parts but finally found an ebay seller that will print a full set of the v.1.24 printed parts for me for $40. I haven't pulled the trigger on the parts yet but soon! Now that I know I can get the printed parts I can finally move forward on bulding the box and sourcing the other bits!

Getting excited,

Michael

I have ordered the printed parts for my smartcore (I never heard back from emails to smartfriendz regarding the parts they had for sale) and now i'm shopping for the rest of the parts. In the BOM at youmagine they list, at the bottom:

GT2 pulleys : 3 x 20 teeth.
pressfit : 2 x 4mm with M6 thread.

Is that "pressfit" listed there in reference to the GT2 pulleys?

The press fit are for the bowden tube. My e3d-lite6 doesn't need a pressfit connector, so I only needed the one. You are looking for something like the following: [www.ebay.com]

Ahh, that makes sense. I'm going to do the rework of the cheap aliexpress hot-end rcjoseb uses and it comes with the fitting:

[smartrapbuild.files.wordpress.com]

That hot end has been awesome so far. Have only had to take it apart and clean it up once.

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rcjoseb
That hot end has been awesome so far. Have only had to take it apart and clean it up once.

I look forward to trying it! I am slowly accumulating pieces, my stepper motors and smooth rods arrived today, but I have a while to wait for the things from Aliexpress to get here.

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rcjoseb
That hot end has been awesome so far. Have only had to take it apart and clean it up once.

I forgot to ask: You indicated that you used a screw-in thermistor, did you have to tap the hole or does it come ready to fit for the ebay thermistor?


thanks,

Mike

I purchased another heatsink that had the hole already tapped but you could easily tap it.

The person I ordered the printed parts for my SmartCore (through his ebay store originally, via messaging) now has a page up on his store site for the parts;

[makercoast.com]

I haven't received them yet, so no review on the parts, but communication with him has been very quick and considered so far. And the reviews for his SmartRap parts he sells on Ebay have been good. I have high hopes!


Michael

I have ordered printed parts for my smartrap from MakerCoast and the parts are very good quality. Just be aware that since he is printing the parts from gitgub you will need to use wood/rods that are set for the dimensions of the parts.

That's good to hear! I specifically asked him about resizing for 19mm walls and 8mm rods on all axes and he assured me that it wouldn't be an issue (and I keep reminding him )

He's a nice guy to deal with.

I finally have the printed pieces in hand and I'm starting assembly. These are versin 1.2.4 pieces. However, i'm having an issue with the xy head assembly. The bearings are sliding very well on the smooth rod when not in the mount but when put into the head assembly they are slightly out of alignment and grab. For the bottom pair of bearings I managed to loosen up the mount enough (by prying open the "clamp" a bit") that the two bearings are able to align themselves and now they move well. However, this approach isn't an option with the top pair. My plan now is to use a dremel to carve out the bearing mount area a bit so that the two bearings are able to align themselves. Of course, not having the option of being able to print a replacement, I'm a bit hesitant.

Any suggestions, perhaps a better way to loosen things up, before I jump in and start making modifications?

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MichaelBrock
I finally have the printed pieces in hand and I'm starting assembly. These are versin 1.2.4 pieces. However, i'm having an issue with the xy head assembly. The bearings are sliding very well on the smooth rod when not in the mount but when put into the head assembly they are slightly out of alignment and grab. For the bottom pair of bearings I managed to loosen up the mount enough (by prying open the "clamp" a bit") that the two bearings are able to align themselves and now they move well. However, this approach isn't an option with the top pair. My plan now is to use a dremel to carve out the bearing mount area a bit so that the two bearings are able to align themselves. Of course, not having the option of being able to print a replacement, I'm a bit hesitant.

Any suggestions, perhaps a better way to loosen things up, before I jump in and start making modifications?

Hello I put the bearings on the rod first and coerced them to fit until they were sliding smooth on the rod.. on the bottom.. I pried it open also but after printing a while and sometimes accidentally manually hitting the left side too hard the lips on the bottom cracked and finally both fell off.(too much stress by prying them open). but I printed it out again.. and used a drill bit to make the hole for the bearings a little larger, its been fine ever since..

Edited 2 time(s). Last edit at 08/23/2015 09:07AM by mike3.

Making progress! I managed to screw up the heat block with my poor attempt at tapping a hole for the thermistor so I'm waiting, yet again, on a shipment from China.

All of the motors are running well (after adjusting the reference voltage on the DVR8825 drivers, they were way high). I think I have the x and y motors connected backwards (I wasn't sure of where (0,0) was initially but I see now that it is defined by the location of the min endstop switches) but that is an easy fix. One thing I found though is that the endstop switch that rides on the xy head is too low relative to the carriage it is supposed to make contact with. It just barely makes contact with the bottom edge of the carriage and I could easily see the switch skimming underneath it. Is this something others have encountered? I'm using the 1.2.4 pieces in case that is something that has changed. I think for safety's sake I'm going to glue a piece of wood or plastic under the carriage to assure positive contact.

I should probably post pictures. I feel bad that I have been sucking knowledge from these boards without giving anything back, at least in the form of pictures of entertaining mistakes .

It was my plan to finally get to print this weekend, but I suffered another puzzling set back. I'm using DRV8825 stepper drivers with these nema17 motors: motor. When I raise the bed via Repetier's manual controls, the z-axis motor runs smoothly. However, after about 15 seconds the bed suddenly drops to the bottom. I can immediately raise it back up manually in Repetier. Thinking that the driver was overheating I lowered my reference voltage from .7 to .6 on the drivers, added the heat sinks (although the DRV8825 theoretically can handle more current without them), and put a fan blowing on the ramps board. No difference. I switched out the driver for a new one, and the same thing still happens. Is this an issue with the Ramps or arduino board? Problem with the motor?

I'm just going through an experiment with DRV8825s. Been getting some unpredictable results - strange movement the first time I give a manual command on each axis. Using z screws so wouldn't notice a fall to the bottom. Tried repetier firmware too instead of marlin but not really got to grips with it yet. Can't get quieter than the A4988s yet.

I am obviously not familar with any of the drivers but went with the DRV8825s as part of an aliexpress "package deal". The features set, as described by Pololu is pretty good. Of course I'm certain its possible that the Chinese copies aren't up to par. I switched driver boards with the one from the x axis. Same issue.

Hi Michael Brock.

I am using a different Controller board than you (Duet) BUT it sounds like you are having a similar problem to what I had. My problem was that the Z axis goes into idle mode if nothing happens after a certain amount of time. With Idle mode, the power to the motors decreases while the machine sits idle for a certain amount of time. So, especially because I have a belt drive Z axis like you, the weight of the print bed can no longer be supported by the motor and it falls.

I know this pertains to the DC42 fork of firmware for the Duet, but maybe you have something similar in your config file.

The solution for me was to change the optional I parameter in the M906 command in config.g. The I parameter defines the percentage of normal current that the motors get after a few seconds idle timeout. Default is I30 (30 percent). So try changing to I50 or higher.

M906: Set motor currents
Example: M906 X300 Y500 Z200 E350 I30
Sets the currents to send to the stepper motors for each axis. The values are in milliamps.
The dc42 fork of RepRapFirmware supports an additional I parameter. This is the percentage of normal that the motor currents should be reduced to when the printer becomes idle but the motors have not been switched off.

Thanks for the reply! That give me something to look for; I'll check it out.

I found related forum posts pretty quickly once I knew what to look for. In configuration_adv.h:

#define DEFAULT_STEPPER_DEACTIVE_TIME 60

When the stepper motor is inactive for 60 seconds it is shut down. I guess this isn't typically an issue during a print, and I suppose someone who knew what they were doing and not watching a youtube video while attempting to set the z-axis/sensor offset might get it done before then!

Thanks for the tip! Finding this has improved my mood considerably. I am really enjoying putting this together, but looking back, the degree of my ignorance was astounding!

baby steps. raising the DEFAULT_STEPPER_DEACTIVE_TIME did the trick. Now I am experiencing a new issue. When homing the z axis, the bed rises but it does not raise until triggering the proximity sensor. It stops a few centimeters low. It thinks this position is home and won't let me raise it higher.

Test your end stops. M119 will tell you your endstop status. If Z is triggered you need to change its logic. Test by running M119 without metal near probe and led off. It should be untriggered. Then again sticking metal near the probe. When the led lights up run M119 again. It should be triggered. Once your sure your endstop logic is functioning correctly try again. Btw if your axis thinks it's at zero, you can bypass it by telling it that it's not at zero. G92 Z20 tells it that Z is at 20, which will allow you to move it 20mm. Be careful and don't crash your axis.

Edited 2 time(s). Last edit at 09/21/2015 12:24AM by madmike8.

Also, check the value of Z_MAX_POS in configuration.h and raise it if it's lower than your real Z travel.
I haven't seen this with marlin before (I 've seen it though with grbl), but I always had this defined to be larger than my real Z travel.
The reasoning is that, while trying to reach home (during homing), it travels more than (Z_MAX_POS - Z_MIN_POS) and it stops because it thinks it's gone out of bounds...
Heh, it's a shot in the dark but you don't lose anything to try it

This was it! I had set the Z_MAX_POS to a little less than my planned build volume and the distance from the bottom of the z-axis to the homing position was exceeding the Z_MAX_POS - Z_MIN_POS difference.

Thank you!

Michael

Quote
mandrav
Also, check the value of Z_MAX_POS in configuration.h and raise it if it's lower than your real Z travel.
I haven't seen this with marlin before (I 've seen it though with grbl), but I always had this defined to be larger than my real Z travel.
The reasoning is that, while trying to reach home (during homing), it travels more than (Z_MAX_POS - Z_MIN_POS) and it stops because it thinks it's gone out of bounds...
Heh, it's a shot in the dark but you don't lose anything to try it

I love this forum! People just helping each other out - it's a great example of the best of human nature.

I have prints! Unfortunately, they are only barely 3D but it is a step closer. While printing, the first layer or so went down pretty well (I have some tuning to do there still but one thing at a time). However, extrusion then stopped. The extruder drive was simply gouging a hole in the filament in an attempt to push it forward. Turned out that the filament was stuck in the heat break. Thinking it might be "left over" from previous attempts, I cleaned it out and tried again. Same exact thing happened. My theory on the cause: my hot end is quite a bit longer than the one used by Smartfriendz (I'm using a "fine tuned" cheap j-head clones from Aliexpress) and the fan mounted to the carriage is only blowing on the top half of the heat sink. I have one of the clip-on fans and I'm going to try switching to that fan today to see if it helps.

Hi, I use a cheap "aliexpress" e3d clone too.
Look like u are using a too low PLA temp. I usually use 200° or 205° without heated bed, and 195° with heated bed.
Also, check that the temp. sensor is in good contect with metal. If not use alu foil (cooking one!) to made good contact.

Hope it help.

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Zlob
Hi, I use a cheap "aliexpress" e3d clone too.
Look like u are using a too low PLA temp. I usually use 200° or 205° without heated bed, and 195° with heated bed.
Also, check that the temp. sensor is in good contect with metal. If not use alu foil (cooking one!) to made good contact.

Hope it help.

Those two "prints" were done at 210. I started at 195 but got no extrusion so I increased it. But, now I am starting to doubt my thermistor table. I have the EPCS 100k B57560G1104F that Rcjoseb recommended in his "hotend rework" document. I didn't see a table for that thermistor in marlin so I added a custom table that I got from [reprap.org]. I'll have to revisit that and make sure the table is correct.

Argh! I changed to a more accurate thermistor table, cleaned out the hot end and nozzle and tried again. Same result. I pre-heated the nozzle to 210 via the manual controls in Repetier Host (with both the hot-end fan & print fan running). I then fed filament 1mm at at a time until I got flow out of the end. Then I go to the slicer tab and start the print. The printer homes and probes and starts the print. Goes well for the first few layers then the filament simply stops feeding. The extruder is still pushing it but just eats a hole into the filament. I can extract 10 mm or so but then that too sticks.

This is the j-head rework following rcjoseb's document. The heatbreak is all-metal, no ptfe liner.

My understanding of the process isn't sufficient for me to figure out where the issues lies.