New Z probe

The last thing I wanted to do for my UP Plus 2 rebuild was to change the Z probe. The original Z probe is a micro-switch that is attached to the hot-end before calibrating. The UP Studio software has a calibrate function to allow bed leveling before printing. The probe would be manually attached, the calibration routine run via software and then the probe removed before starting the print. The same procedure can be done through the Marlin firmware I am running and G code commands via Octoprint but it is a pain. I want to be able to just press print and forget it.

My old Prusa Mendel printer was capable of auto bed leveling via an RC servo retracted Z probe. This worked well with the only problems being the twisted frame of the machine causing issues towards the end of its life. I considered mounting the servo Z probe to the Up but wanted to try something new. I had seen non contact sensors before and wanted to give them a try.

After looking around the internet I settled on an LJ18A3-8-Z/BX 8mm Inductive Approach Proximity Sensor. This sensor will trigger when a piece of metal is brought within 8mm of its end. Since the bed of the Up is made of aluminium this is perfect. The sensors 8mm activation is repeatable to within ± 25um which is suitable for printing at 0.1mm layer height when printing on a raft like I do. The sensor is bolted onto the side of the hot-end adapter and can be manually adjusted without much difficulty.

Inductive probe mounted to the side of the hot-end adapter.

The wiring was a little interesting as the sensor runs off 12V but the Arduino take 5V inputs. There is a lot of discussions around the internet about how to interface these sensors with the Arduino with much arguing about voltage dividers vs opto-couplers vs transistor logic. I had a look at the sensors data sheet and saw that the sensor has a NPN Current-Sink output which means that the sensors output is grounded when active and floating otherwise. I checked that the Arduino input is set with a pull-up resistor and the firmware input is active low then connected the sensor output via a diode with the anode to the Arduino to prevent any 12V from getting through and that is it. Enable auto bed leveling in firmware and add the G code to the slicer software and now the Up is print and forget.

The last thing was to add a print job cooling fan and duct to the hot-end. This fan and the hot-end fan are both controlled via the RAMPS. The hot-end fan is on the third power output of the RAMPS and is set to turn on when the hot-end temp is above 50 degrees. The second fan is switched on via a relay from a spare output pin on the Arduino and is controlled via G code. All the wiring is brought up to the extruder via the existing Up wiring harness.

New power supply for my rebuilt Up Plus 3D printer.

With the addition of the Raspberry Pi to my rebuilt Up Plus 3D printer I now have three power supplies connected to the machine. The heated bed is using the original 19V power supply that came with the Up, the RAMPS 1.4 and hot-end are using the 12V supply from my old Prusa and the Raspberry Pi is using an old 5V phone charger. This is a lot to connect to start the printer.

I want to simplify things by just using the 19V supply and fit the machine with two step down voltage regulators. I would need one regulator to step the 19V down to 12V and a second to step down again from 12V to 5V. The 5V is easy as the Raspberry Pi Zero W only draws 250mW max so any USB power supply will work. I settled with a dual USB 15W switch mode supply that can handle 6V – 40V input. The larger supply and dual ouput would be handy if I add a WiFi camera later.

The 19V to 12V supply needs to supply the RAMPS 1.4, Arduino, stepper motors and the hotend. I calculated the peak power draw to be 30W (2.5A). I chose a 50W Power Supply Module that included an LCD display that shows the current draw and voltage. The Ebay listing shows that the unit can supply 35W constant without cooling and 50W with the supplied heatsink. I also added a cooling fan.

The supposed 50W power supply the couldn’t handle 30W

The first test run had the 12V supply showing peak current draw of under 2.5A so less than 30W but the heatsink was getting too hot to touch even with a fan on it. 10 minutes into the print the printer stopped with the 19V supply shutting down due to short circuit protection. The second MOSFET on the 12V supply had failed short circuit. I contacted the Ebay seller wh didn’t respond to any e-mails. Swindled.

With a doubtful attitude to Ebay sellers I decided to replace the 50W supply with a 200W supply. This new supply doesn’t have a fancy LCD but it shouldn’t burn up during basic use. I kept the cooling fan just to make sure and the power supply is cool during use.

The new 200W 12V supply.

Now with only one power cable this printer is almost looking finished.

Prowler at the 2019 Australian Feather-weight Nationals

Last weekend was the 2019 Australian Feather-Weight Nationals and Daniel decided the enter Prowler. Prowler has been fairly unchanged since last year except for swapping the friction saw blade with an all purpose demolition saw blade. The controls were also divided between Daniel driving the robot and Andrew controling the weapon. This is the first time with both of us controlling the same robot and was hoped to remove some stress from Daniel while trying to drive and operate the weapon at the same time. Oh, and a new paint job.

The competion was held over 2 days with 2 qualifying rounds held the first day. Prowlers first match was against a lifter called Pooper Scooper. Going into the fight we were concerned about Prowler being turned over but Pooper Scooper’s weapon failed early in the fight. The new saw blade worked well on the mild steel and UHMW Polyethelyne top on Pooper Scooper creating several cuts in the top. A nice win to start the weekend.

The second fight was against Bob who is a viscious looking horizontal spinner. The concern here was that the blade whould hit the spikes on the front of prowler and bounce up into the saw arm. Daniel decided to drive aggresivly to prevent Bobs weapon from getting up to speed. During one attempt at sawing into Bob, Prowler drove Bob into the arena wall and Bob bounce up into the saw causing the saws bearings to pop out. After this Bobs weapon also failed and it became a pushing match. Fortunatly Prowler was able to out-wedge Bob and the arm could also clamp Bob to help drive Bob into the walls. During all this driving and attempted clamping Daniel realised that one of Prowlers drives would cut out while the arm was being raised or lowered. Fortunatly Prowler still won the fight.

Upon returning to the pits I refitted the weapon axle and replaced the bearings and checked that the saw was running true. The drive problem while the arm was being moved was determind the be a low voltage cut-out of one of the drive ESCs. To test this the ESCs were swapped with Berserkers ESCs (because Beserker just happened to be in the car) and Prowler worked ok. Prowler would keep Berserkers ESCs for the second day.

The next day the 2 wins had allowed prowler to qualify for the top 16 finals. The first match up was against The Undertaker which is a under-cutter spinner with a 4kg weapon. Fortunately for us the weapon was not working as The Undertaker had burnt out all its weapon motors the day before. This left The Undertaker fighting as a wedge with extra AR450 plates added to its top for extra armour. While Prowler could not cut into the heavily armoured top of The Undertaker we still won by judge’s decision. Now in the top 8.

Unfortunately the 4th fight was against Abomination, an extremely powerful and well built vertical spinner. Daniels idea was not to box rush but to move to the centre of the arena and hope that Abomination would not want to attack Prowler head on but try to circle around us. Being such a powerfull vertical spinner Abomination would have trouble turning to maneuver around Prowler and Prowler could attack the side of Abomination while it was struggling to turn. Despite Daniels over thinking, Abominations builder Michael just drove head first into Prowler and out wedged us. Prowler was thrown onto its back but self righted quickly. Abomination continued to attack and hit the side of Prowler immediately and the shock caused the liner actuators cast aluminium gearbox to shatter and the saw dropped to the floor. Daniel continued to attack and Prowler was thrown into the air a couple of times before landing on its front with the 2 spikes and the saw touching the ground. With the linear actuator broken Prowler couldn’t right itself and was counted out.

So Prowler went 3 – 1 and ended in the top 8 which is pretty good. Abomination went on to win the competition with straight KOs so we lost to the best. No major problems to try and fix between fights and if we had a spare linear actuator Prowler could have been ready to go again in a few minutes. Quite a successful weekend.

Adding a Raspberry Pi to my 3D printer

Now that I have my 3D printer running reliably and the RAMPS 1.4 mounted I want to disconnect it from my laptop. At the moment every time I want to print something I need to connect my laptop and leave it connected for the duration of the print. There is an option to add an SD card reader to the RAMPS but that would also require adding a control panel to the printer. It is cheaper to add a Raspberry Pi.

I have been using OctoPrint software on my laptop which also has a pre-made Raspberry Pi ROM called OctoPi that can be loaded directly onto a Pi. OctoPi is designed for a Raspberry Pi 2B or 3B and offers camera support out of the box. Since I am on a budget I decided to just use a Raspberry Pi Zero W. There is several reports of OctoPi not running on a Zero W mostly because the single core processor can’t support running the server and the camera streamer simultaneously. Since I don’t even have a suitable camera I don’t think this is a problem.

After loading OctoPi and running through the setup the printer worked first time exactly as it did from my laptop. The next problem is that I wan’t to print directly from my phone. OctoPi has an option of adding a slicer plugin on the Pi and while looking through the options I came across AstroPrint. AstroPrint is a cloud-based 3D printing system that includes a selection of slicers. Files are uploaded to AstroPrint, sliced in the cloud and then sent to OctoPi via a plugin.

For quick prints of simple models AstroPrint works well enough but if the model needs some fancy slicing then it is better to use a desktop slicer. AstroPrint also does not include many options to control the printer so I still need to use the OctoPi web interface or an android app.

The next problem created by adding the Raspberry Pi is that it needs a seperate 5V power supply as the RAMPS cannot supply enough current for the Raspberry Pi and the Arduino. Now I have 3 power supplies plugged into the printer, a 19V, 12V and now 5V.

KOB2 Diary – Part 4

Day 15

  • Go into the competition at 10:30 while Connie and Alice stay in the hotel. Plan is just to chat with people and watch some fights.
  • I noticed all the eliminated chinese robots are moved to different benches, but the builders and their equipment are gone. Leslie tells me that the robots are paid for by KOB and must be left behind. The builders took all the spare parts and leave the empty chassis. The international teams are oblivious to this since they don’t really chat to the chinese teams.
  • Brian Nave is getting bored and is challenging people to a fight. We don’t know when the intruder robots will final be introduced into the competition and the teams are tired of sitting around and doing nothing. I accept his challenge to test his new robot and are told we can have the arena during lunch. But it will take 5 -6 hours to repair Huntsman as I haven’t touched it since it was eliminated and I left my batteries and radio in the hotel. Directors say it is ok and we can fight tomorrow.
  • Pull everything back out of the crate and start fixing. Requires 3 people to bend the side of the chassis into shape. I had Robert Nani from team Monster and a random chinese fella who was walking past stand on one side of the robot while I used Cat King’s giant wrench to pry the damaged side. Wish I took photos of that. Actually Robert was with me for the entire repair, trying to learn how I designed and built the robot. Severely underestimated that pink beater.
  • Robot almost ready for testing at 6pm, just requires some soldering for motor plugs. I was correct in the 6 hour estimation for the repair time.
  • Competition fights finally start, but apparently are only “practice matches” so that the celebrities can learn about the robots on their leagues. The builders don’t want to damage their robots in fights that won’t count and decide to not use their weapons. This results in some boring fights. Some Chinese men from the audience come to see my robot and are rather impressed. Would rather talk to me rather than watch the fights. The directors start complaining that the builders will win money for each win they get, so they should be trying to win, but the builders ignore them. I doubt the fights would get aired.
  • Catch a taxi for the hotel at 8pm rather than watch the fights and wait for the bus. Turns out the bus left at 1am.

Day 16

  • Head in at 11:30 to finish getting the robot ready. Just need to solder some plugs onto a new weapon motor and put in the batteries.
  • Told we can have the arena in the afternoon, but that didn’t happen. They were filming team meetings and didn’t want too much noise.
  • Put Huntsman in the test arena. Everything works fine. Drew a nice crowd.
  • KOB people still asking if I want to fight Shredderator. They seem to think it is a bad idea and I’ll just get destroyed. I just laugh.
  • Competition fights happen at night, 3 fights scheduled between two leagues. One league wins the first 2 fights, so final fight cancelled.
  • Told we can borrow the arena at 9:30pm
  • Huntsman been prepared all day, feel confident.
  • Put it in the arena. Word gets around and a large crowd forms, including Emma Dumont. I feel extra nervous as I can finally fight in front of a celebrity and show what they missed out on. The arena lights have been turned off and “need to rest”, so we have to find portable lights. Go to turn on the robot and sparks arc up from the screw driver on the drive side. Decide to dismiss it. When doing the prefight checks the robot fails to move. Go back in to check the robot and find the drive power is off. Try to turn it on, more sparks, power light comes on and then dies. I get asked if I can fix it in the arena, but I worry it is a battery short and decide that it will be safer to take it back to the bench for a complete check rather than risk a battery fire.
  • While getting the robot out I hear Emma making rude jokes about my robot. So annoyed and hate her. Other builders tell her to be quiet.
  • Bench check shows that batteries are fine and the power lines running from the left to the right side of the robot had been pinched between the frame and the weapon motor. Riding on the trolley over the bumps to the arena must have rubbed through the wire. Every time the screw driver touched the switch and the lid the robot would turn on. The sparks are the capacitors charging. Once the screw driver was removed the robot would switch off. The power light would stay on while the capacitors discharged. If I turned the power screw 2 more turns the robot would have turned on fine, but risked a short as the chassis was grounded.
  • Shredderator continues to drive in the big arena for practice. Fight postponed as their batteries were flat and the work crew wanted to prepare the arena for tomorrow’s filming.
  • Go back to the hotel. Not happy.

Day 17

  • Alice and Connie not feeling well, so I decide to stay in the hotel during the day. Send a message to Brian to say I still want to fight and he can call me if we get the arena.
  • New stroller arrives, so test it out by walking up to the big shopping centre for dinner. $35, bargain.
  • While eating dinner I watch a mother hold a small child while it went to the toilet in a rubbish bin. And then a few minutes later I watch a man search through the bin for a water bottle. I’ll never forget that sight.
  • While at the shops we get a message from Brian Nave that we have the arena for a fight. Quickly find a taxi and Leslie to head in. Connie and Alice stay behind at the hotel.
  • Fix the broken wire with an empty coke bottle to protect it from abrasion. Do 3 bench tests.
  • Head into the arena. Only a quarter of the crowd of the previous night. But that gives it a more underground feel, just like when I first started. Feel more relaxed.
  • Fight went to plan. Finally drove calmly. Drive slowly to keep the spinner in front of me. Use the armour to box Shredderator into a corner. One of the impacts breaks Shredderators shell and causes it to lose balance and affects its control. I tried to hit it with the axe, but it was in the far corner and the poor lighting made it hard to judge distance, so I missed. So bugger it, I’ll just keep ramming and not worry about being out manovoured. Get Shredderator into a corner and go in with the axe even though I can’t see. The robot bounces into the centre of the arena, but has lost drive. I hear the Shredderator team yelling about a fire and that it was dead too. Double KO.
  • Lost drive because the battery unplugged and weapon from a bent motor (again).
  • The KOB arena crew and Blanka Botz (only guys watching) give me the win. Claim victory. Head back to hotel. Only at competition for less than 1 hour.
  • Go back to the hotel and hear that Shredderator lost its shell and drive base.
  • Slept very well.

Day 18

  • Go down to breakfast. Hear teams at other tables talking about me and the fight. Several teams come to congratulate me.
  • Walk over to the convenience store before going into the event. Bump into John Reid who congratulates me on the fight. Almost cried. Last time I tried to chat to him was in 2005 when I asked on a forum about kinetic energy calculations for electric hammers. All my robots use the calculations from the ideas he gave me. No longer care about the previous 2 weeks.
  • Catch the 11:30am bus.
  • Spend the day slowly fixing the robot.
  • Several robots ask for a fight. Feels like builders have finally realised that I’m not a noob. Organise fights with Orby, Medusa and Ground Dragon.
  • Watch a few fights. No idea what stage of the competition we are up to. If I go back I’m going to take a white board to keep track of things.
  • Go back to hotel on the first bus.
  • Hear on WeChat that the next day will be interesting with a strange fight format, but unsure if we’ll go in. Maybe have a relaxing day.

Adding a heated bed to my rebuilt Up Plus 2

So now I have my rebuilt Up Plus 2 3D printer working I need to tidy up the electronics. To do this I downloaded a RAMPS 1.4 case off of Thingiverse and set to printing.

The first problem I had was bed adhesion. The buld plates that came with the printer are similar to a prototyping PCB perf-board with hundreds of tiny holes in it. The PETG filament I am using sticks to the board well enough but all the holes make for a really rough bottom layer. After a little Googling I found that the Up software slicer uses a raft for bed adhesion so I will try that. It took some adjusting to get the first layer height offset correct but it is working.

The second print on the rebuilt Up Plus 2 was a case for the electronics

The next problem was that the prints are warping badly. I had not wired up the bed heater yet as I still needed to change the thermistor. The Ups original 100 ohm thermistor doesn’t work with the RAMPS controller so I replaced it with a 100k ohm thermistor. With the RAMPS power supply set to 13.5V the bed could only reach 65 degrees celsius and even then took 45 minutes to get there. The recommended bed temperature for PETG is 70 degrees so the best I could manage was still 5 degrees too low.

While I had changed the thermistor I didn’t change the heater cartridge in the Ups bed which was designed to work with a 19V power supply. The RAMPS 1.4 has a seperate power input for the heated bed but a look at the schematic shows that the MFR1100 11A PTC resettable fuse is only rated for 16V. A look at how these PTC fuses work and at the datasheet for this particular fuse I see that the critical part is not the voltage but rather the power consumption as the fuses rely on heating of the internal elements for them to work. If more than 16V is applied to the fuse while it is failing then the extra power consumed by the fuse while the internal resistance rises can cause the fuse to fail in a non-resettable way. But since this is what fuses usually do I am willing to risk using the standard PTC fuse at 19V.

I wired up the original Up 19V supply to the 11A input and left the 13.5V supply on the 5A input of the RAMPS and gave it a go. Now it reaches the target 70 degrees in under 15 minutes and has no trouble maintaining that temp.

I had started printing the case for the RAMPS before fixing the bed heater and the case had warped and the print failed when it seperated from the raft 3/4 of the way through. Since it took 14 hours to print as much as I did I didn’t want to start again. I cut the part that printed successfully of the bottom of the model in Cura to finish the print with the bed heater active and then glued the top to my failed print. The pieces don’t quite match due to warping but I now have a momento of how the printer worked before the improvements.

Ramps 1.4 case for the Up Plus 2

KOB2 Diary – Part 3

Day 10

  • Awake at 9am, missed breakfast again.
  • Arrive at venue and told that I am allowed on tv beside Connie. The next stage may involve running and they are afraid to let Connie run. Pregnant ladies are not allowed to do a lot of things in China. Lucky I had the red shirt.
  • Next stage involved all the contestants in the losers lining up and waiting. Each team captain was given a remote button to press. There was a count down and being first to push a button allowed you to chose another robot to fight. The remaining teams then ask to challenge the robot that managed to push the button first by running onto one of 6 platforms on the stage. The first team would chose from these 6 teams who they wanted to fight. The production crew thought we would all think slowly and then walk to the platforms. But we all knew who we wanted to fight and everyone wanted to run to be the first to the stage. The back row of competitors had no chance to making it to the podiums and it was an unfair situation. After the first two selections they decided that it looked too bad for tv with all the pushing and shoving.
  • So they re-ran the setup, but this time just made us stick up our hands to ask to fight. Technically I didn’t need to help Connie as putting up your hand was safe for a pregnant lady, but they already filmed me for the introductions, so I was in. Or they forgot I was there.
  • We already found 6 easy robots and 6 difficult robots. We decided to not press the button and wait to see who the selected robot was. If it was easy, we would challenge, if it was hard, we would wait for the rumble. In hindsight this was a bad idea, but we had no idea how this format was going to work. Unfortunately all the easy robots got selected first. The walker, Barbie, Frog all got selected in the first 4 groups. BBQ, Hippo and several other strong robots were still in the selection group. Didn’t look good for the rumbles.
  • While the first 4 fights were happening we decided to press the button and found the robots we would select. Better to not wait for the rumble.
  • In the second round we tried to press the button but weren’t fast enough. However Snake and BBQ got selected and so were the robots I wanted to fight, Doctor, Silver Scorpion and ICEwave. We stuck our hands up, but no one wanted to fight us. We were going into the rumbles with the middle range robots.
  • They gave us the rumble list while we were watching the fights. We drew the girly vertical spinner, pink beater and a wedge lifter from the college team who were next to us in the pits. The two spinners did not seem reliable.
  • Connie spoke with the college team and the vertical spinner and found that they wanted to all attack the beater first. First the spinner would hit the beater and then the wedge would hold them while I came in with the axe. Sounded perfect as I could wait for the first 15 – 30 seconds and let the spinners kill themselves. But best not to make plans.
  • We were told that our fight would be the next morning and to go and get some sleep.
  • Couldn’t sleep.

Day 11

  • Depart for venue at 9:30. Not enough sleep.
  • Contemplate testing the robot. Not sure when the fight starts so decide I might not have time after the test to charge the batteries.
  • Called to line up for the fight at 10:15. I was the first to be ready, as usual. I was told that I could control the weapon while Connie drove the robot.
  • Our fight was up second. The first fight is delayed due to workers fixing the lighting inside the arena, and then delayed due to robots not powering up. I wish the other teams would do more testing.
  • Checking out other robots in the line up behind the stage. The vertical spinner was having weapon trouble and the wedge was still unknown. Decided the beater was dangerous and needed to be attacked. Couldn’t trust the other drivers.
  • Finally in the arena at 11:30. There is no audience, commentators, walk in introductions or interviews for our rumble. Feeling like it won’t even go to air.
  • Fight delayed as some directors still weren’t told that I could be near the arena or help control the robot. The communication skills of these people are terrible. The TV production directors wanted me to stand with Connie and help control the robot, and the KOB production directors wanted me away from the arena. I didn’t know what to do to make them happy. Eventually a TV director pushed me in the back toward the arena and yelled to start the fight.
  • Fight finally starts 10 days after the robot was first charged and ready. And after watching 58 out of 60 robots get their turn in the arena. A couple of the robots even had 3 fights before we had our chance.
  • Robot dead after 15 second. Only swung the axe twice. I moved cautously as I wasn’t sure how the other robots would behave. I could see the beater was really moving fast and seemed more dangerous than I remembered. I tried to have a swing at it. Clipped the beater on the first swing and got flipped. Self-righted fine. Went in for a second attack but the axe swung slowly. The base mounts on weapon motors had bent during all the testing. The extra stress during the fight caused the motor to bend forward and jammed the sprockets together and derail the chain. The axe stopped in mid-swing. The slow swing allowed the beater into the side of the robot, which hit the chassis just in front of the wheel. This is the only spot on the robot without 10mm plate. The chassis supports bent, which caused the first stage gear alignment to get ruined. I then lost a tyre when the robot came down from the hit and then got pushed into the arena drum spinner. Luckily after all these hits the robot landed the correct way up. With the axe jammed forward and the loss of the right wheel there was no weight on the left wheel and the robot was immobile. The beater robot got stuck in the arena saws a few second later and the vertical got flipped by the arena. The wedge won.
  • Went back to pits to pull apart robot and prepare for another fight, only to be told that there were no rumbles or exhibitions for the robots eliminated at this stage. 30 robots go home this day followed by a 3 day break.
  • Sad, angry and disappointed all at the same time.
  • Watched the celebrities chose their teams. Didn’t see the celebrities view our fights. I feel they never saw my robot.
  • Watched the American gold fish driver get really angry and destroy his radio with a hammer. But he got 2 fights, 1 win and a loss, which was more than we had.
  • Contemplate packing the robot, but too drained.
  • Started organising earlier plane tickets home.
  • Gave a set of the used drive batteries to the nice Chinese guy who owned Silver Scorpion. He seemed rather shocked that I would be that nice.
  • Lots of Chinese guys came for photos with me or Alice. We seemed popular and everyone says they wished they saw me fight.
  • Asked to reassemble the robot for a group photo. Impossible to replace the tyre in the 30 seconds I was given.
  • But still had to wait 30 minutes for the photo to be taken, so could have got the tyre on.
  • Couldn’t smile for the photo, held Alice in front of me instead.
  • Told we were needed for a meeting. As usual the directors hang around us, but seem to refuse to look at us and then walk away. No meeting.
  • Went back to the hotel and then out to dinner.
  • Couldn’t sleep. Worse than the previous night.

The damage

Day 12

  • Woke at 3am to check the contract. We miss out on all the promised prize money.
  • Woke again at 8am, bus leaves at 12:30pm to take people for interviews. Connie won’t be interviewed. Decided to go pack the robot and tools and finish with the whole competition.
  • Arrive at venue. Most people are just the builders who are eliminated and packing equipment.
  • Only takes 30 minutes to put everything in the crate. Catch taxi back to the hotel.
  • Start drawing a new robot and go to dinner. Started drawing a double spinner since the celebrities only liked robots with spinners.
  • Find out it will cost $450 each to go home early. Cheaper to stay in China.

Day 13

  • Rest day. Feeling better.
  • Go the aquarium with Connie, Alice and Leslie. Alice goes insane over seeing fish.
  • Head to shopping centre next to Aquarium. Alice has a 2 year-old melt down. Turns out Leslie is allergic to mango. Decide to go back to the hotel. Taxi driver got lost.
  • Find out Catherine got fired because we weren’t in the competition anymore. I feel really guilty.
  • Connie tries to find a way to visit her family in Hong Kong for a week. Discover Alice would need her birth certificate for a travel pass. Idea abandoned.

Day 14

  • Be lazy in the morning.
  • Go into the city during the afternoon with Leslie and Catherine.
  • Visit the M&M and Lego shop. Alice goes insane again.
  • Nice dinner in a fancy hotel, but still cheap. As a thank you and apology to Catherine.
  • Visit the Bund at 8pm. Way too many people. Feels like the population of the Gold Coast in one place.
  • Go back to the hotel. Decide to go back to the competition tomorrow.

Converting Up Plus 2 to run off of a RAMPS 1.4

With the mechanical repairs done to the old Up Plus 2 I was given I can start on replacing the controller board. The old board had a faulty Y stepper motor driver and wasn’t compatible with the thermistor in my new hot end so I am fitting the printer with the controller from my old printer.

There are several guides on the internet about how to setup and commision a RAMPS 1.4 board in a new 3D printer and I don’t feel like writing my own so I will go over the basic steps here. If you need a more comprehensive guide I would suggest starting here.

  1. Load the latest Marlin firmware onto the Arduino and load OctoPrint onto my laptop and verify that the two can connect to each other so I can use OctoPrint to control the printer.
  2. Connect the endstops to the RAMPS and use the M119 Endstop Status command in the OctoPrint terminal to verify that the endstops work. The Z endstop was connected to the Upper Z Endstop port and the Z probe connected to the Lower Z Endstop.
  3. Connect the motors (while powered off) and check motor direction is correct. I manually moved to carriages to their centers by hand and then jogged the motors 10mm using the OctoPrint controls to check the direction. Since the Z axis is belt driven and falls under its own weight if the motor is off I had to hold it in my hand before driving it. The directions were corrected in the Marlin firmware configuration.h file before reflashing the firmware and trying again.
  4. Check the motors home correctly. This was done with the Ups original magnetically attached Z probe stuck onto the X carriage bracket. I had my hand on the power switch before triggering the home button so I could power off the machine if the motors started homing in the wrong direction. Only the Z axis was wrong and this was corrected in the configuration.h file.
  5. Check each axis Steps/mm setting is correct by measuring starting distance of each axis’s carriage in relation to the printers fame and then using OctoPrint to move the axis 50mm and measuring the real world movement. I found that the Marlins default 80 steps/mm matched the X and Y perfectly and didn’t need adjusting so I set the Z axis to the same 80 steps/mm.
  6. Added the dimensions of the bed into the firmware.
  7. Set Z-probe pin to be the same as the Z endstop and measured and entered the Z probe offset from the nozzle. I also enabled Safe_Z_Homing at the center of the bed as the Z probe was not homing over the bed. Verified with G28 command.
  8. Set Auto_Bed_leveling_Linear in the firmware using 3 points per axis.Verified with G29.
  9. After running G28-G29 I used OctoPrint controls to move to the center of the bed and lowered the nozzle close enough to the bed surface so that a piece of paper could barely fit between the nozzle and the bed. Then I used M114 to read the current position and calculate the correct Z-Probe Z offset and updated the firmware. I like to keep the firmware up to date rather than using EEPROM commands as this means I have a backup of the configuration and if the controller blows up I can reflash a new controller and skip most of these steps.
  10. Connect the extruder drive and verify the drives direction and feed rate with the hotend removed. The rate is checked by feeding a few cm of filament through the extruder and wrapping some tape around the filament where it exits the extruder. I then use OctoPrint to extrude 50mm and measure how much was really extruded using the tape as a reference. I then calculate the error as a percentage and adjust the steps/mm in the firmware by this error. I then repeat the test until the error is as low as possible.
  11. I refitted the hotend and switched it on to check that it heats up. I no longer have an IR thermometer to verify if the thermistor table is correct as the kids wrecked it thinking it was a hammer so I have to presume that the reported temp is accurate. Next I ran M303 C5 E0 S200 to auto tune the PID values and updated them in the firmware.
  12. Test print time!
The first print on the Up Plus 2 was a new E3D fan shroud

KOB Diary – Part 2

Day 8

  • Caught the bus at 10am
  • I waited and watched the selections and fights all day with not much to do.
  • Connie locked up inside the filming pits, but allowed out during the later part of the day. She over heard the celebrities say they are only wanting spinners.
  • All rounds of the selections were done. Connie was not talked to by any of the celebrities until after they had filled their 3 spots. The American and Old Soccer Guy came to talk to ask her about Huntsman and were surprised that she spoke perfect English, answered every question confidently and mentioned that we’ve been competing for 16 years. Once they found out how experienced we were they were disappointed that they didn’t talk to us earlier. Annoying.
  • 12 of the 48 robots didn’t get selected to fight in the first round. Earth Mover was selected to join a team without having to fight, so the remaining 11 become losers without fighting. Doesn’t seem fair. We could have at least had a practice or demonstration fight.
  • Connie kept practicing driving. Got a lot better and drove all around the pits. Started getting in other peoples way, but was doing perfect flick-turns.
  • TV Production crew feeling sorry for us. Might find a way for me to be more involved, including possibly controlling the weapon.

Day 9

  • Finally got the robot back from the holding area after 3 days. Batteries fine. Tightened a weapon chain as it had be worrying me.
  • Finally allowed back to the hotel at 1am.

Day 9 Continued

  • Woke up at 10:30. Told we weren’t needed for the day as the winners and international teams would be fighting.
  • WeChat blew up about a bad judge call between ******* and *******. Seems that the judge is using his own rules and not the standard international set of rules. None of the teams seem to understand how he is coming to come conclusions. I wish I was there to watch.
  • Caught a taxi to a big shopping centre. Brought a red shirt that matched Connie’s just in case I was allowed to help her.
  • While organising dinner got a call that the international fights were finishing and that we were needed for rehearsal. Seems that they can do 12 international fights in the same time it takes to run 5 Chinese fights.
  • Caught taxi at 8:30pm for the venue. Catherine stayed at the hotel with Alice.
  • Found that 4 international teams lost. 8 won. But it seems that everyone wants decision on the ****** fight to be reversed.
  • While Connie had rehearsal Chinese teams started asking a lot of questions. They are getting less afraid of me. Silver Scorpion wants to build a copy of Shunt and is asking how to copy my axe mechanism, but it seems a bit is getting lost in translation.
  • Medusa is made by a team of students and teachers. They  have also entered Thunder. We checked the calculations for the battery capacity of Medusa and found that the batteries are undersize for the weapon, which is why it dies toward the end of its fights. But the rest of the robot looks nice.
  • Connie came back with instructions of the next phase of the competition. Very confusing and involves running to be selected to fight, so they are letting me substitute for Connie as they are afraid of letting a pregnant woman run. They seem to be afraid of letting Connie do anything, which is why she was given fancy dust masks and an extra fancy chair in the pits. So I guess I can be her stunt man during filming.

Rebuilding an Up Plus 2 3D printer

I have had to pause work on my robots as I have not been able to get any reliable prints out of my old Prusa Mendel 3D printer. The frame of the printer had twisted again making auto bed leveling impossible while the extruder drive was failing. After moaning to my brother about the troubles he gave me a “new” printer. The “new” printer being an old Up Plus 2 that had previously been written off and stripped for parts.

The 2nd hand Up Plus 2 with covers removed to assess needed repairs

The first thing I did when it arrived was pull all the covers off to see how bad it was. The mechanical faults seemed to be limited to a broken Y belt clamp and a destroyed hotend. The Y belt clamp had been broken when the printer was pushed against a wall while opperating and there may be an accompanying electrical fault that I can’t assess without first fixing the mechanical issues. So first I designed and printed a new belt clamp using the old printer. Fortunately it worked the first try.

Next I needed to replace the hotend. The only hotend I had available was the E3D V6 on my current printer. So I downloaded some drawings of the E3D V6 and measured the Ups hotend and extruder and made a new mount for the hotend. The trick was to try and get the nozzle of the new hotend to be in the same position as the original nozzle. Since the E3D hotend is much higher than the Up hotend the new mount needed to raise the extruder a fair way. This new mount was the last print ever done on the old Prusa Mendel as I pulled the hotend out after it was finished.

With the mechanicals sorted I could test the electronics. I downloaded the Up software and connected the printer to my laptop. The first problem came when homing the motors. The X and Z axis worked fine but the Y axis whould crash into the front after homing to the rear. It seemed that the Y stepper driver IC was damaged and was stepping a different distance when moving one way than the other. That was very strange but not worth looking into after finding out about the thermistor problem.

The E3D V6 comes with a very common 100k ohm thermistor. A 100k thermistor is used on just about all 3D printers everywhere, except for the Up. The Up uses a much more uncommon 100 ohm thermistor. The different thermistors require different pull up resistors on the control electronics for them to work. Because of this the Up software would report a hotend temperature of over 300 degrees and refuse to run. To fix this I would need to replace the pull up resistor and then work on the Y stepper driver fault. Or replace the control board with my own. So I pulled the RAMPS 1.4 board out of my old printer to replace the Ups damaged controller.

The next step was to completly re-wire the printer and setup the firmware from scratch.