DuetWIFI migration

dc42 · 12 Jul 2016, 06:49

The bulls eye spirit level was sensitive enough to reveal a tilt when the effector was close to one of the towers. The rods are accurately made to equal lengths, so I corrected it by rotating the carriage on the carriage truck.

mhackney · 12 Jul 2016, 12:04

Here's the IR Probe mount I made for the TrickLaser MetalMax effector along with my custom water cooled E3D V6 hotend and volcano. The clearances look closer in the photos, I'll put Kapton tape on the backside of the board t be safe but I think I'm ok. The mounting system can slide up and down (slots in the printed red mount) and forward back (a slot in the mounting ear on the red mount) so I can fine adjust the probe position.

Next step is to wire it up to the Duet WiFi and get it running.

dc42 · 12 Jul 2016, 13:47

It looks like you could trim the component wire stubs on the back of the board a little more.

One concern I have with that cantilevered sensor mount is that the plastic part only needs to soften and warp very slightly to change the relative heights of the sensor and the nozzle.

mhackney · 12 Jul 2016, 16:48

Thanks David, yes I did that and then Kapton tape. I'l keep an eye on the plastic part. It is mounted to aluminum - a big heat sink and it is very far away from the heater. Worse case I'll machine one in aluminum but I wanted to try this out quickly.

mhackney · 7 Dec 2016, 19:03

David, I seem to be missing something trying to setup the IR probe. I followed the instructions on your blog. That all went well. https://miscsolutions.wordpress.com/mini-height-sensor-board/

When I get to the part to test and configure the probe I do as you say:

heat the nozzle (and bed)
home
lower the head until the nozzle touches the bed (paper test)
issue G92 Z0 (and I see Z set to 0 in DWC)
raise head 5mm
issue G30 S1
the Z value I read off in DWC is 1.0mm

I use this value to update my config.g:

M558 P1 X0 Y0 Z0 H5 F500 T12000
G31 P400 Z1.0

And reload config.g when asked.

Now, I home and run auto calibrate. When done, it seems like my Z=0 is set about 1mm above the bed. What am I missing?

FYI: bed is PrintBite

dc42 · 12 Jul 2016, 20:15

Micheal, it's G30 S-1 you need to run to measuring the trigger height, not G30 S1.

mhackney · 12 Jul 2016, 20:26

Thanks David! Literally, in my browser looking at https://miscsolutions.wordpress.com/mini-height-sensor-board/ I see:

define that position as Z=0. Raise the head 5mm and remove the paper. Then send G30 S-
1 to probe the bed at that point without adjusting the Z height setting. Read off the Z
height and use that value for the Z parameter in your G31 command in config.g. Please

I guess my mind saw the "-" and figured it was a continuation to the next line.

dc42 · 12 Jul 2016, 20:31

Thanks for pointing this out. I just checked, and I see exactly the same. I'll re-word the paragraph to prevent the text wrapping at that point. [Edit: I just did that.]

mhackney · 12 Jul 2016, 20:49

Minor thing but those of us with bifocals appreciate it!

Things are working well now. Starting to do some more complicated printing. So far so good. The steppers are much much quieter.

bot · 12 Jul 2016, 21:11

Please tell us how you like the printbite compared to pei!

mhackney · 12 Jul 2016, 21:19

They are different beasts @bot. I still prefer (and only use) PEI for my production fly fishing reels as it leaves a perfect matte finish. PrintBite leaves a textured finish. But, PrintBite works with a wide variety of materials that PEI doesn't (PEI is really restricted to ABS, PLA and HIPS) like Nylon, NinjaFlex, PET, PVA. If you don't have a preference for the surface finish, it is good stuff.

mhackney · 12 Jul 2016, 21:46

By the way, no network disconnects for over 24 hrs.

dc42 · 12 Jul 2016, 22:30

@mhackney:

By the way, no network disconnects for over 24 hrs.

Thanks for the update! For those who were getting just occasional network disconnects, the single retry I added for status poll requests should fix that. Using the default Ajax timeout of 8 seconds, I find that the retry can generally handle the board being reset too..

mhackney · 13 Jul 2016, 20:58

David, I have finished making a suitable PEI bed to use with the IR probe following the instructions on your blog (painted back side, bake in oven). I then recalibrate the probe and that seemed to go well. But…

My calibration is bad (typical deviation of 0.086) but very good when I switch over to my FSRs (I have them both installed so it is very easy to change from FSR to IR Probing) it is pretty good (deviation 0.45) although not as good as I'd like.

Some questions...
I scuff the surface of my PEI with very fine sandpaper (600 grit) to leave a matte finish on my parts. I installed this PEI with the original glossy side up (painted the matte side as per your instructions) and then scuffed the top. Do you think this would have any effect on the sensor? I wouldn't think so if PEI is IR transparent.

dc42 · 13 Jul 2016, 22:13

I don't think it would make much difference which way up you put the PEI. I think the next thing for you to do is to measure the trigger height at a few widely-separated probe points. If you find significant differences, then use feeler gauges to see whether they are due to the edge of the sensor board being at different heights when the nozzle is touching the bed - which would indicate that effector tilt is a problem..

mhackney · 13 Jul 2016, 22:23

Thanks David, I posted a rather long post on the delta google group. I installed a bulls eye level and my effector is dead level everywhere it moves. I also see very different calibration results between 6 pt and 3 point probing - 3 point is VERY low deviation (0.007). I need to digest this and think about next steps. But I think measuring trigger height makes sense.

dc42 · 14 Jul 2016, 01:26

I suggest you measure trigger height differences using the FSRS too. You may find that the FSR setup is more sensitive when you probe close to one of the FSRs, and less sensitive when you probe at the centre.

mhackney · 14 Jul 2016, 02:08

Good suggestion thanks. Then I can compare results across both probes.

This printer has always been a bit persnickety. It is 3+ years old and was one of the first laser cut Rostock Max kits. I've replaced everything except the frame and towers. My other 4 deltas have FSRs and Duets and calibrate to <.0.03 deviation repeatedly.

mhackney · 14 Jul 2016, 18:48

David, I have now run a set of trigger height and calibration tests. I've attached a screen capture of the spreadsheet I used to collect the data. Some comments before the data:

This data was collected on PEI with a black back.
Hot end = 190°C
Bed = 55°C

Data Collection Process

Home
G0 to the Probe position (with Z5.0)
Do the paper test and run G92 Z0 to set Z=0
Remove paper and run G0 Z5 then G30 S-1
Record trigger offset run 1
Raise 5mm and run G30 S-1 again
record trigger offset run 2

Repeat 1-6 for each point on spreadsheet.
Once data collection was complete, I ran the auto calibration twice (6 factor) and recorded the deviation.

I ran the IR Probe first then reconfigured and then ran the FSRs.

Note that my FSRs are not aligned with the columns or midway between columns, they are actually 30° offset from the column. The FSR positions are shown in the spreadsheet. This was done for installation simplification (the Rostock Max has a snowflake insulator that mounts in such a way that this is the natural alignment)

I calculated average, standard deviation, minimum, maximum and delta (max-min) for each run.

And here is the data:

Some comments:
Firstly, I was surprised at the poor FSR calibration deviations. I am not sure why this is. I have checked everything about the machine and it was calibrating much better the other day. But this is the data I collected. (Update as I write this: I realize that I have been probing on a 100mm radius in the past, so the results described below are more in line with this printer's past performance.)

I do have a level installed on the effector and I looked at the level at each of the probe positions and there was absolutely no deviation of the bubble.

Interestingly, the FSR results at the 240° probe position (alpha/X tower) is the worse and this is the location where I saw (and see) the nozzle "skate" slightly on contact with the bed. I thought this might be a belt issue and tightening the belts did improve things a bit. I plan to eliminate this probe location and rerun auto calibration and see what happens.

Note that if I decrease the probing radius:

(FSR results):
120: 0.137 (as I collected in the table)
110 decreases to: 0.071
105 decreases to: 0.062
100 decreases to: 0.053

(IR Probe results)
120: 0.135 (as collected in the table)
110 decreases to: 0.115
105 decreases to: 0.080
100 decreases to: 0.094

I verified these results with multiple runs. FSR probing IMPROVES with decreasing the probing radius and IR probing GETS WORSE with decreasing the probing radius.
I have a hypothesis about this but I'll wait to hear comments and feedback! David, I would greatly appreciate your feedback on this - including if this was a valid test and experimental design!

Toddimus · 14 Jul 2016, 19:47

Another data point…

I also have a Rostock Max (V2) with FSRs and the JohnSL board. I installed some Hall Effect sensors in lieu of the mechanical ends stops at the top, which may give slightly more repeatable results for end stops (as opposed to the mechanical stops). I have the JohnSL board sensitivity set to whatever was default. I didn't have any extra jumpers lying around.

One thing I did differently than your notes above show is that I only did an initial home/delta auto-calibration at the beginning of the whole test run. It sounds like you homed after each point. I'm assuming this probably doesn't matter. I also took 5-6 probe values at each point. Interestingly, the values measured at the same probe point varied by around 0.04 to 0.06mm across the multiple probes done one right after another.

Your offset numbers look similar to mine, except that mine were slightly lower (average around -0.24mm, min -0.19mm, max -0.33mm). With a 140mm probe radius (6 points at periphery, 6 halfway and one center), I'm getting right about 0.100mm standard deviation after an auto calibrate. I also saw this number much lower (around 0.06-0.08mm) when I used a 120mm probe radius. I found that I needed to adjust the Z offset for the probe (i.e. center point) from the original values I found during calibration, in order to get a correct first layer height.

As an aside, I notice that one of my FSRs takes more force to trigger. I can tell this when I'm probing between the towers and only one of the LEDs lights up, when two theoretically should light up. I designed some little FSR mounts that use the snowflake mounting holes and keep the sensor aligned with the axes, as opposed to being offset as you said yours were. In other words, the mounts/sensors are concentric with the snowflake mounting holes and frame base mounting holes adjacent to the towers. The backside of the sensor itself is centered over the top of a carefully prepared countersunk hole that places the top of a flat head screw co-planar with the floor of the FSR mount. I'm still not sure I like my FSR mounting setup because I'm concerned it might be a bit over-constrained in the X-Y directions. This may be the cause of the one sensor taking more force to trigger.

Which brings me to my next question... does everyone like the little orange silicone pads that come with the FSR kit? I'm wondering if they have too much "springiness" or softness. I put one on the base of each plunger that comes into contact with the sensor itself.