K8203 Extruder feed erratic

Hi Fafnir,

Sorry to hear that you’re having extruder problems again. I also occasionally have this happen on my printer too.

I am still running 1/16th stepping on the extruder, with the 8825 and a 0.9-degree stepper. I am also running 8825’s at 1/32 stepping for both X and Y axes without any problems.

Flashing the firmware does not affect the stepper drivers. (The drivers do not get reprogrammed.) The only firmware changes needed when you change drivers is to set the steps-per-unit to match the new setup. This just ensures that the Arduino controller knows how far each motor pulse will take it. So you may need to re-flash the controller, but only if the steps change.

Switching to RAMPS is not terribly complicated, but some effort is required. I was able to buy a RAMPS 1.4 board and an Arduino Mega 256 controller for about 1/3 the price it would have cost for a replacement Velleman controller. But I don’t think there is any inherent advantage in using the RAMPS solution instead of the stock Velleman controller if it is already working properly. (I only switched to get a second extruder output.)

I think the better change you can make is to upgrade the power supply if you haven’t already. I am using an external bed heater supply, but also recommend using at least a 150W supply to power the rest of the printer. The stock 100W supply is a bit overworked sometimes.

I had some improvement when I added a heat sink to the extruder motor. I think heat sinks on the stepper drivers and also a fan on the controller board would help even more. As the motor coils and driver circuits get hotter, they will draw more and more power until the PS can’t keep up any more.

Some types of filament are more prone to clicking and extruder problems than others. I also have found it necessary to clean the extruder gear and PTFE tubing on occasion, as small bits of material in there can cause the clicking problem. When I am using filament that will not cooperate, I slow the print speed to 50% during solid fill layers, and this seems to help.

TL;DR: RAMPS is a good, inexpensive replacement for the Velleman controller, but probably in itself is not going to solve any problems for you.

Best of luck!

Hello Dr V

Stripped the extruder and fitted new nozzle and replaced the driver. Now working well. No evidence of blocked nozzle - extruded diameter was normal 0.36mm.

Normally I have set VRef by checking from the test point and ground. This new one only showed line voltage at the test point. Had to test between the trimmer and ground. Is this normal?

Still on 1/32 step and running very smoothly with the new driver. May try 1/16 at some stage - but leave well alone for the present!!

Thanks once again for your help it is much appreciated.

After 2,100 print hours with the K8203 I’ve noticed the most failure prone part is the PTFE tube. This is a weak point on my Rostocks as well (I have 3 x Rostock Max V2 as well).

Repeated heating and cooling of the interior PTFE tubing causes a reduction in the diameter, and higher friction on the filament. I’ve used canola oil to extend the life of the PTFE tube beyond the finish of the current print with some success, but on the long term Canola oil seems to foul the PTFE tubing.

I’ve found the best way to test for PTFE fouling is to let the machine cool to ambient, remove the PEEK and nozzle in 1 piece (mine is set on a 4-pin MOLEX for ease of removal) and then remove the nozzle. Push on the filament side (leave 2-3 inches of filament hanging from the PEEK isolator); if the PTFE tube comes out it’s probably time to replace it.

I’ve been getting 300-500 print hours out of the PTFE tubing, and about 1,000 hours out of the .35mm nozzle before replacement. I’ve been keeping the fouled nozzles in the hope of one day cleaning them out, but I have yet to find a method to strip them back down to the bare brass as if it were new.

What have you been getting?

-Derek

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Here is my maintenance log for record:
Date Octoprint Action $ Time Notes Last
26-Feb 618:55:39 Clean rails, lubrication N/A 10 Squeaking heard during print was from cable chain. Machine needs to be vacuumed (debris)
27-Feb 635:55:43 Unclog nozzle with drill bit/LCRT N/A 10 Very thin extrusion on Black Battery case. Almost spongy. Issue seems to have been cleared. 17:00:04
28-Feb 662:46:05 Adjusted bed height for PS4 hook logo N/A 2 Logo was closed off with Green color. 26:50:22
2-Mar 709:49:52 Unclog nozzle with drill bit/LCRT $1.00 10 Broke drill bit in the process. 9.2 grams lost, 4 hours print time lost. 47:03:47
3-Mar 723:19:22 Unclog nozzle with drill bit/LCRT N/A 5 Thin extrusion on priming pass for color change. 13:29:30
4-Mar 740:27:18 Nozzle replacement, rebuild extruder, lube rails $4.26 60 Old nozzle was gummed up with extrudates. 17:07:56
10-Mar 846:54:10 Unclog nozzle with drill bit/LCRT $1.00 5 Color change purging showed signs of clogged nozzle. 106:26:52
13-Mar 907:55:55 Clean rails, lubrication N/A 10 Black rings seen on x axis 61:01:45
17-Mar 950:00:00 Unclog nozzle with drill bit/LCRT $- 10 Failed print, clogged at the end 42:04:05
17-Mar 950:00:00 Flashed Rpi. Server crash. N/A 40 Unable to connect!. Lost all history. Need bigger SD Card for long timelapses 0:00:00
18-Mar 0:00:00 New Baseline for math
18-Mar 7:30:08 Unclog nozzle with drill bit/LCRT $1.00 10 Bad call, nozzle not clogged. Broke drill bit in process. 7:30:08
19-Mar 46:39:40 Adjusted bed level, too high $- 1 39:09:32
20-Mar 69:29:33 Clean rails, lubrication $- 5 Black rings seen on x axis 22:49:53
30-Mar 197:57:42 Unclog nozzle with drill bit/LCRT $- 5 Extruder clunk during 1st and 2nd layer of arachnid print. 128:28:09
30-Mar 203:32:06 Unclog nozzle with drill bit/LCRT $1.00 5 Extruder clunk, weak infill. Broke bit, but fixed problem. 5:34:24
30-Mar 222:08:04 Unclog nozzle with drill bit/LCRT $- 5 Extruder clunk, weak infill. 18:35:58
3-Apr 274:59:26 Clean rails, lubrication $- 5 Black rings seen on x axis 52:51:22
5-Apr 300:15:06 Unclog nozzle with drill bit/LCRT $- 0 Extruder clunk on first layer. Too many glue layers on bed. 25:15:40
5-Apr 303:08:03 Extruder Overhaul $1.00 1 Extruder hard jammed during Facehugger. Spare nozzles ordered. Disassembled and cleaned hotend. 2:52:57
25-Apr 652:52:53 Extruder Overhaul $2.00 0.5 Knocking during USAF stand. Broke 2 drill bits in the process. Replace Nozzle next time. 349:44:50
26-Apr 657:00:00 Nozzle replacement, rebuild extruder, lube rails $4.25 1 Old nozzle was gummed up with extrudates. 4:07:07
26-Apr 657:00:00 PEEK Isolator destroyed $123.65 1 Replace extruder. DOWN FOR MAINTENANCE 042616 @ 1741 PST. 0:00:00
15-May 864:44:56 Unclog nozzle with drill bit/LCRT $- 0.5 207:44:56
19-May 932:12:59 All is well, time hack No issues, printing well. 67:28:03
20-May 962:15:07 Spliced 24VDC feed to heated bed $- 0.5 Solder joint used. Possible fire hazard, watch item. 30:02:08
21-May 984:02:59 Replaced Z axis pulleys $0.50 480 Z drive inop. Pulleys not gripping respective shafts. 21:47:52
26-May 1085:18:40 Replace Nozzle and PTFE tubing $4.25 30 Increased jam and feed issue frequency. PTFE tube has bulge and obvious blockage. 101:15:41
2-Jun 1211:44:23 Lubed rails. All is well $- 0.1 126:25:43
4-Jun 1261:39:15 All is well, time hack 49:54:52
10-Jun 1293:23:32 Blew out fans, drilled out nozzle $- 30 Blew out machine with compressed air. Extruder knocking during multipass 31:44:17
12-Jun 1317:49:02 Replaced PTFE Tubing, lubed rails $0.25 30 Extruder knocking on codsworth print. Buldge found in PTFE tube. 24:25:30

Hi djkirkendall

What is PEEK? Is it the whole extruder including motor?

You mention Rostock printer. Can you reliably change colour mid-print? For me the major advantage of the K8200 is that the extruder is fixed and there is no risk of shifting the register of the print while changing colour.

On your second post. Can you reliably drill out a blocked nozzle? I would have thought the cost of the drill and the risk of breakage is hardly cost effective over just buying and using new nozzles.

You mention using glue I print directly on to glass (2mm picture frame) See my post on ‘need some guidance’ in this forum

PEEK is that beige isolator between the extruder and nozzle.

I haven’t found a way to reliably change colors mid-print with the Rostock without disturbing the coordinate system. While the RSMV2 smokes the Velleman for surface quality, the Velleman does a better job on batch prints (20 small pieces, etc) and the filament change mid print is child’s play.

I use a .30mm drill bit to clear .35mm nozzles. They run about a buck apiece on Amazon. I use a “Low Cost Rotary Tool” from Harbor freight I bought for $8. When I break bits, it’s usually my fault.

I’ve been using a mirrored glass / glue stick combo since the start, and I almost never have bed adhesion issues. It works, so I see no need to change it. I also use a large sponge as a skimmer to take the glue off in seconds with a couple of passes.