My first build, all metal delta "The Imp"

I change the head, Finally decide to go with MK8 nozzle and keep the original block.

Im also tightening the belts right now, man im afraid something gonna break, im using a big screwdriver as lever and I almost can see my motor plate bend ( they are .250 X2.25 inch 6061 aluminum) there were pretty tight before but now! they register to a E note ( first chord) on a guitar tuner before they were -80 on E note , now they at -45 on E note and that pinching a 300mm on a 1 meter axis, the carrier is now harder to move up and down, I hope im not gonna bend a shaft somewhere, If the test fail and walls are still mess up, be sure I will lose them right away, I really dont like tightening those like that.

I test the new head, its not better or worse, same thing...

past 10mm/sec ex: ( G1 E50 F700) whatever I extruder at 190C or 225C, the motor skip step

if I speed up more than that , its start to grind the filament.

I start to think maybe the problem is the extruder , look like a airtripper+mk8 drive gear is no good for a 60cm bowden, If I look at the airtripper benchmark they say it good for 4.5 kg of force but start to lose grip at 4.7 kg and if tight enough on the gear , it will stall motor at 4.6 kg..

So do a long bowden really need that much force to push filament ?

Ill print slower and test the walls thing now, Ill report the finding.

Look like the belts tightening have a positive effect, walls are nice now, but they are some kind of artefact on 2 side only ( the one in front of the printer, and the one facing the Z axis)

Except my extruder problem that I have no idea how to fix, I think im making progress, im now ready to do the e step fine tuning. if I can figure the instruction for the test.. 95 % infill you want a small gap between line, and solid you want none, not very precise. Like how small you really want the gap...

The root cause might be your bowden tube itself. I had some ID 1.8mm tube from RobotDigg that was very hard to push filament through once it had teeth marks in it. Some other stuff from ebay was great, ID was 2.0mm and the filament flows through it easily.

4 kg is way too high a force to push down on your filament.

My tube came from robotdigg too but the ID is 2mm, not so hard to push through but there some friction of course since my bowden is 60cm and curve a little,you can see it on one of my prev picture, page 2.

I print a cylinder today and it look even and nice all around except where the head were starting/finishing before going to infill, it leave a vertical line all over the cylinder and I can see the head bumping when reaching that spot. I have to tune the retract I guess , I was using a pretty low retract (2mm)

Im not saying I push 4kg , just that the airtripper and mk8 combo were benchmark to 4.6kg ... I just dont get my extruder problem, I push it to 225C so even is my thermistor is off a little and the placement is NOT at the nozzle but in the corner of the heating block ( right on top of the cartridge heater) it should not be a temp problem... it cant be off 30C right?

At 225C the filament was really leaky exiting the hotend but was still skipping the stepper.

The mark on the cube are on 2 side were one in front of the Z and the one in front of the printer but both side at the same spot exactly, so Y axis on a delta

Have you tried pushing filament with extruder teeth marks through the bowden cable?

The only reason I knew that the robotdigg tube was bad was because I had some other ebay stuff on hand. Virgin filament went through the RobotDigg bowden tube just fine, whereas stuff that had been through the extruder was quite grabby and hard to push through the tube.

It's early days yet, but consider making a flying extruder. You can easily cut the length of your bowden tube down to 20% of its current length, which improves print quality immensely.

Ill check the bowden with extruder filament today, I dont want to go flying extruder yet, I need to know what speed I can reach before doing that so I know what the flying extruder cost me in speed and if its really better than a tuned bowden setup, there just too much tuning I have to do before messing with that. I wont know if I gain in quality if I go flying right now.

Quote
GroupB
I test the new head, its not better or worse, same thing...

past 10mm/sec ex: ( G1 E50 F700) whatever I extruder at 190C or 225C, the motor skip step

That is normal if you are using a standard 0.4mm nozzle. The feed rate rate doesn't generally exceed 5mm/sec during normal printing.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Last time I print 80 mm/sec infill I was skiping and grinding a little and 60mm/sec perimeter was on the skiping limit too. I was expecting a little more than 60 for internal perimeter I guess.

Any tip or trick to push that limit while using .4 nozzle?

Im using using a metal /ptfe now the ptfe go to the egde of the heating block then is 2.04 mm to the nozzle with a cone end then to 2.4mm nozzle style mk8 by the look of it the pressure look low( short small orifice). I also had polish that 2.04 mm part on this heatbreak

But I also have a couple all metal heatbreak no ptfe , I was planing to use them for higher temps plastic cause I know is not the best for pla. Are those all metal heatbreak can speed up the extruder?

What layer height are you using? With 0.2mm layer height and 0.6mm extrusion width, at 100mm/sec print speed the extrusion rate is 5mm/sec.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Using 0.2 height and I lets the witdh on default in slic3r (0)

I did not recheck with th new head , the prev head was skiping at 80

Edited 2 time(s). Last edit at 03/12/2016 11:37AM by GroupB.

I tried yesterday to do the fine E step tuning but the part took too much time at 30mm/sec 195C so I set it to 40mm/sec 0.2 height and 0.5 width at 210C and it skipping, grinding again like crazy as soon as I finish the first layer at 20mm/sec and start perimeter or infill at 40mm/sec.

I was extruding in the air at 5mm/sec at 195C but I cannot print at 40mm/sec, you said 5mm/sec extruder should give me 100 ish mm/sec, how come I cannot pass 40mm/sec?

Its really starting to piss me off at a very high level ! what the hell is the problem here ?

There not much friction in the bowden tube, the ID is 2mm, the head was clean and polish, the temps of the nozzle if fine, its a little hard to push with hand but I guess its normal.

One thing is the extruder motor is acting weird , If I ask it to manually extrude say 5mm, it will retract 20mm, then I try repeat the command and nothing work, I have to input a new number say extract 10, then it extrude 50... The direction is mess up sometime and it will not extrude/retract the good amount. Im using the reprapfirmware 1.09r dvr8825 hack DNewman made for me but its missing delay on direction , maybe that came from there.

I will change back the firmware to a 1/16 driver version only and switch again all my drivers and give it a last try, if it still mess up after that , I guess Ill try another firmware or just lets it sit there for a couple weeks to calm myself , so far its only a source of frustration.

I think you may have generated a gcode file that uses absolute extruder coordinates, but you have the firmware set to expect relative extruder coordinates. My suggestion:

- If you are using any slicer except Cura, configure it to use relative extruder coordinates, and include a M83 command in the custom start gcode.

- If you are using Cura, then it doesn't support relative extruder coordinates. In this case, include a M82 command in the custom start gcode.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I was already set in relative for slic3r and I figure the absolute for cura last week. The problem dont come from there

its probably head pressure, bad extruder/ drive gear or maybe firmware since im using a experimental firmware

Maybe my thermistor are not config alright... I dont think its that because even if I jump the temps to 220C its still grind/skip and by hand its the same kind of pressure

im using those thermistor : 3950 1% and I set this code in my config:

M305 P1 T100000 B3950 R4700 H0 L0

its configure alright ?

I have one 2 ir thermister but cant read the head with them but its reading 23.6C when off and my room temps is close to that, 22C

I remove the bowden and try to push the filament directly and its the same force needed bowden on or off ( pretty hard to push) and even with the bowden doing loop the filament is easy to push without much friction( not connected to the head).

So Bowden is rule out.

I remove the nozzle ( at 160C), it came clean and the plastic did not stick to it.

the ptfe in the heatbreak are clean and intact no deform or burn.

With the nozzle removed , trying to push filament at 200C require the same force as with nozzle in ( its hard to push) . so maybe the heatbreak 2mm portion is doing something wrong... I polish it but its not free flow at all. How easy it should be to push a 1.75mm filament in a 2mm heated hole...? should not be hard ...

will it work better if I reverse the heatbreak so the ptfe is going directly to the nozzle? metal 2mm hole>ptfe 2mm> nozzle, in that case the ptfe will enter half way the heating block

The fact that you can extrude into air at over 5mm/sec suggests to me that your extruder is working OK. Are you certain you are not over-extruding? Have you calibrated the extruder steps/mm? Can you extrude a large amount of filament continuously at 5mm/sec?

Can you confirm that you have NOT enabled pressure advance (M572 command)?

I guess it's just possible that when the other motors are moving quickly, the PSU voltage is dropping, or something else is happening to affect the extruder current. Perhaps you should test extruding into air with the head moving in the XY plane at the same time.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I did many 50mm at 6.66 mm/sec at 200c in the air but sometime the extruder get confuse and retract a random number while I ask it to extrude. This only happen while doing manual control and only since I flash the drv8825 special timing firmware.

I do not have pressure advance.

Im using a 350 (12v ,18A) watt computer psu with load on the 5v line right now (im not using any heatbed so load is 4 stepper and 40w heater), but I have a 300 24v I plant to set up soon.

I think the problem is with the heatbreak, I dont know how hard is supose to be to push filament with hand but its pretty hard right now. I still have a clone j head to try but they got bad review so im not in a hurry to try it and having to rewire everything again.

Is my thermistor is configure right (B3950)?

Your thermistor config looks correct, assuming the "3950" in the Robotdigg description refers to the B-value, and 3950 is very plausible. If you have a multimeter with a thermocouple probe, you can check the calibration by feeding the thermocouple probe into the hot end in place of the filament.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I thought my multimeter dont have temp but it do, I just have to find the probe now

Quote
GroupB
I remove the bowden and try to push the filament directly and its the same force needed bowden on or off ( pretty hard to push) and even with the bowden doing loop the filament is easy to push without much friction( not connected to the head).

So Bowden is rule out.

Just confirming, did the filament have extruder teeth marks in it? I found that robotdigg tube to allow virgin filament through, but once it had teeth marks it was hard to push through. This is just the bowden tube, not connected to anything at the other end.


It sounds to me like your motors are fine, I'd just swap the extruder driver board to a 16 microstep board (4895 or whatever those red ones are that you've got spare), halve your extruder steps per mm, and try again. No need to swap the motor drive boards.

Yes , I tried with teeth mark and they sliding fine no more resistance than no teeth filament.

Its hard to switch the stepper driver to 16 with a radds, its all under the board to I need to remove the shield and to switch back to a A4988 I have to flash back the firmware to a normal one, im using one with longer time between pulse right now made for dvr8825.

I will take a temps reading tomorrow to rule bad temp out, then hook my clone j head see if its still doing the same , then if there still problem I will replace the drive gear and I will flash back to a official firmware and put a A4988.

I try to rule out one thing at the time

Took a temp reading with my multimeter (+/- 2% +1C ) directly in the melt zone , because of the placement of the thermistor in the heating block at the edge far from the nozzle but really close to the heating element, the offset is high , for example 190C on thermistor give 173.5C on thermocoupler, 220 give 196.5 , 240 give 210.2 I went like this till I hit 240c on thermocoupler (285C on thermisitor). As you can see the offset increase with the temps so I dont know exactly how im gonna configure this in RRF for a wide range of temperature.since there only 1 high offset ( H). Shoud I play witht the B3950 ? Anyway I made me a table of the melt zone temps in 5C increase just in case.

Anyway this could be the source of my problem ( or one of them) since I was printing at 200C to 210C (182C to 189C in reality)

One issue that affects accuracy is that the thermistor B value is typically quoted at relatively low temperatures such as between 25C and 75C, and drops off at higher temperatures. I posted about this last year in the Ormerod forum. Where the manufacturer publishes a table of resistance vs. temperature, you can work out the B value at 220C and use that instead. As you don't have the full data for that thermistor, I suggest you try reducing the B value in the M305 command until you get accurate readings.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
One issue that affects accuracy is that the thermistor B value is typically quoted at relatively low temperatures such as between 25C and 75C, and drops off at higher temperatures. I posted about this last year in the Ormerod forum. Where the manufacturer publishes a table of resistance vs. temperature, you can work out the B value at 220C and use that instead. As you don't have the full data for that thermistor, I suggest you try reducing the B value in the M305 command until you get accurate readings.

I have the full data, its the one I post in a previous post, I just have to figure out how to work out that B number from that list of resistance.

I enter the right B calculated with a office sheet, but the offset is still increasing with temperature, Maybe I should lower the B more but what im looking for is to make it more linear so I can set an offset that will work for 200C to 240C.

If I lower the B enough will that make it more linear ?

I am sorry, I have not found a post in which you give the resistance vs. temperature data for that thermistor. Three posts before this one you give some data points for the temperature read by the thermistor vs. temperature read by thermocouple.

From my previous experience, the B value at extrusion temperatures tends to be around 140 lower than the quoted B value.

I attach a spreadsheet that I use to do thermistor calculations.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
GroupB
Maybe my thermistor are not config alright... I dont think its that because even if I jump the temps to 220C its still grind/skip and by hand its the same kind of pressure

im using those thermistor : 3950 1% and I set this code in my config:

M305 P1 T100000 B3950 R4700 H0 L0

its configure alright ?

I have one 2 ir thermister but cant read the head with them but its reading 23.6C when off and my room temps is close to that, 22C

this post

I already found a sheet and its giving me B3911, but the offset did not change at all... still the same curve not linear between 200-240 , so an offset will make 200C right but 240C still wrong

So I drill another thermistor hole in line with the melt zone, and redid my test , its still all over the place... meaning I get a difference of -20C at 210C ( real 190) , -30C at 245C ( real 215) and -40C at 280C ( real 240) so I cant use an offset unless we able to do some kind of exponential curve offset with multiple entry to match the real reading.

I already fill up a spread sheet with the thermistor table R/T to find out a more precise B (3911 in that case), I dont want to change the thermistor right now to try another one cause I dont feel like rewiring again ( maybe later when I change to 24V)), so Ill probably keep that and check my temperature table each time I chose a print temps.

I am probably not the only one with that kind of exponential offset, I wonder whats the other guys are doing to calibrate they thermistor in RRF.

You can try calibrating the L parameter in the M305 command to account for low end ADC offset. With your chosen B value, pick a resistance that should produce a reading of somewhere between 250C and 300C. 220 ohms is often about right. Work out what temperature reading that should give you. Then connect a fixed resistor of that value in place of the thermistor, and adjust the L parameter to get that temperature reading.

Which version of the Duet do you have, and which firmware version?

Edited 1 time(s). Last edit at 03/16/2016 03:54AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].