|Keywords||Prototyping, rapman protocol,|
|Sustainable Development Goals|
|License||CC BY-SA 4.0|
|Affiliations||Queens Applied Sustainability Group
|Automatic translations||Français, Español, 中文, العربية, Русский, Kiswahili and others|
|Cite as K.laciak, Christine Blair (2010). "Rapman protocol QAS". Appropedia. Retrieved 2021-07-23.|
First Setup[edit | edit source]
- Complete the build of the machine, including extruder.
- Plug in extruder
- Load filament along filament feeders, into top of extruder, through pressure screws (they must be loose to do this) and into the hotend as far as it will easily go.
- Turn on RapMan
- Enter Manual Move mode, and move hotend over hole in print board
- Enter Tool Setup mode
- Set temperature to 235 for ABS to start (leave motor off) and wait for hotend to come up to temperature.
- Try to manually push the filament through the hotend and extrude it
- If you are unable to feed the material, the hotend is not hot enough. Heat it by 5 degree increments until you can push it with medium resistance - it should not be easy, neither should it be impossible. You should be able to push it manually to extrude around 1 to 2 cm/s out the hotend tip
- Turn on the motor at 4RPM (low speed)
- Tighten the pressure wheel screws until the filament is gripped by the extrusion screw and is extruding via the motor's pressure
- Extrude plastic for a few hours at around 10RPM. You will likely have to manually push the plastic down into the extruder by hand, as it will jam frequently with a new hotend.
- Try increasing the motor speed every half hour or so. You are looking for the machine to jam less often. Try changing the pressure of the pressure wheel to get it more reliable; we think that it just has to extrude plastic for a while though.
- Once your machine appears to have gotten over it's out-of-box-jamming, you can set the pressure wheel and extrusion speed to what it will be when printing. Start loose. Increase motor speed by 5RPM every 30 seconds to 40RPM, tighten pressure wheel screws if grip is lost as you speed up. Be prepared to loosen them back off if tightening them doesn't seem to be working, and to slow the machine back down again. If it jams for any length of time the filament will be stripped by the screw and wont grip - you must feed it through by hand to get past this stripped section, or you can remove it from the extruder and cut off the stripped section. If you're having lots of trouble with this step, the hotend might not be hot enough - turn up the temperature.
- Once everything is working, note the temperature you are extruding at - this will be your printing temperature to start.
- Continue to Leveling the bed, then Calibration, then Print a Part
Leveling the Bed[edit | edit source]
- Using "Manual Move" on the selection menu move the head over an area near one of the three bolts.
- Move the head till the nozzle is about 5 pieces of paper away from the head. This means that there is some friction when the head and the paper. If that is too difficult to move the head, turn the screw till the correct distance is found. Try not to ram the nozzle into the bed.
- Move the head to the next bolt and try to get the same distance between the nozzle and the board by turning the bolt.
- Move the head to the final bolt and try to get the same distance between the nozzle and the board by turning the final bolt.
- Repeat 2-4 till the bed is completely level.
- Esc "Manual Move" and go to "Home Tool Head" and press enter. This will home the head.
- After the head has been homed, assuming the nozzle is higher then the board, move the nozzle to the center of the board using "Manual Move". Check if the nozzle is 3 pieces of paper away with medium friction. If it is not change the height of the stopper bolt on the head. Shorten the length if the board is too far away, lengthen is it is too close. If the board is homed and it is too close to the bed and unable to move across it, lengthen the stopper bolt.
- Using "Manual Move" and move the board down (z-) so it can home its self properly. Never home the board without moving the board down, including right before running a file as the homed height is compromised if it is homed twice in a row.
- repeat 6-8 till the nozzle is 3 pieces of paper above the board.
How to Calibrate[edit | edit source]
- Ensure your board has been leveled (above) and you have followed the First Print instructions.
- Use this script to generate GCODE that will print a raft and a one walled object.
- Use the temperature you found in the First Print instructions above for Raft, Interface and Part Temperature to start
- Use the default settings for everything else (these work well; only change the settings if you intend to print differently)
- Copy the output into a text file and save as XXXXXX.bfb which a six letter/number name. Some new changes to the script allow more fine-tuning settings, comments have also been inserted in brackets which should be removed before the file is saved.
- Copy the file to your SD card,
turn off machineturning off the machine before changing the files on the SD card may have been causing some dives and insert SD card
- Follow the instructions to print a part #1-6 to print the calibration object.
- Use a pair of calipers/micrometer to measure the thickness of the wall at the top and bottom. The wall thickness should be 0.72±.01 mm for 0.4 layer thickness setting and 1.8 perimeter width over thickness
- If you don't measure 0.72±.01mm, increase or decrease your extrusion speed (RPM, line M108) and repeat until you do. The relationship at 16 mm/s head speed is approximately 0.02 mm wall thickness change each 0.5 change in RPM
Determining Required Calibration Accuracy[edit | edit source]
The following calculations were done as a theoretical estimate of the required calibration accuracy.
- assume that z/σ_z = x/σ_x where σ is the error on the measurement
With this assumption, any errors in calibration cause a uniform percent change in all dimensions
- assume 2 layer height is the maximum error
This assumption may be wrong, as if too much material is being deposited, the layer will be squished flatter; however there has been little testing of this to date. It would be reasonable to assume that this assumption can give as much as 3 x error in the resulting calibration accuracy.
With these assumptions and the known number of layers in a part, we can calculate the required accuracy in x (wall thickness):
x = 0.72 (or if not using default settings, perimeter width over layer thickness * layer thickness)
σ_z / z = 1 / (number of layers in part)
σ_x = (σ_z / z) * x
σ_x = perimeter width / number of layers in part
For a part with 50 layers (typical of the taller mendel parts) this gives a σ_x of 0.036 mm. For very tall parts with 100 layers, this gives 0.016 mm.
How to print a part[edit | edit source]
- Turn on RapMan, go to manual move and move head above the corner with the hole.
- Escape manual move and go to tool setup.
- Increase temperature to your printing temperature, from First Setup (250 degrees Celcius for us presently), and allow to warm up. The head should start oozing at about 220 degrees celcius, if not there is a problem, either your extruder is blocked up or your thermistor is reading incorrectly.
- When warm, extrude at varying increasing temperatures, this makes sure your nozzle does not get blocked during the printing of a object. Make sure to do at least 2 meters of extruded material to make sure the extruder is extruding well. Make sure to check if the extruder is taking in filament and that your extruded material is smooth.
- Now one can print, load file quickly so that temperature is not lost. Make sure to reset the device measuring the kiloWatt hours and timer.
When the print is 3 degrees away from goal temp, prep the filament puller by turning the gears pulling the material down counter clockwise.
- Carefully watch the start of the print, looking for 'diving' and acting to prevent machine damage when it occurs. Steps to take if a dive occurs
- Start the timer and print at the same time.
- C Blair 20:08, 19 July 2010 (UTC) insert: ensure filament feed reel is not tensioning the filament at all.
- Depending on how reliable your Rapman is, check on the Rapman every few minutes to make sure the extruder is still extruding, that the fill for the object is not too wavy and that there is little ooze on overhangs. If there is a lot of ooze on overhangs, this generally means that it is printing at too hot a temperature.
- When the print is finished, remove it from the board carefully. If it is severely stuck to the board, remove the board before removing the item so as not to shake the machine too much.
- Mark down time and kiloWatt-hours used by the machine.
- Weigh the object to find out how much plastic was used. Be sure to include the mass of the pre-fabricated extrusion and the boat - record separately..
Creating a part[edit | edit source]
Follow instructions 3D Model to G-Code File for Rapman
Maintenance[edit | edit source]
- oiling bearings
- replacing motors (extruder motor runs especially hot)
- printing replacement cracked parts
- cleaning extruder screw hourly
- cleaning out extruder (not hot end) weekly/monthly
- belt replacement
- PCB upgrade/replacement
Print Troubleshooting[edit | edit source]
The troubleshooting page of the Bits From Bytes wiki also has a few tips.
Layers are Delaminating[edit | edit source]
- This is usually due to a jam in the extruder, and missing some of the layers. Ensure the filament wheel is very loose, and watch the print to catch errors.
- This could also be possibly solved by using acetone to melt the layers together after printing.
- This is exacerbated by warping in the parts, which rips them apart along a failure line.
- ABS glue suggestions forum post
Raft is not sticking[edit | edit source]
- generally means that the raft temperature is too low
- ensure your z-height above the board when you Home is approximately 3 paper widths
- Can be due to part warping as it cools, rips the raft up.
- Can be fixed with a wider raft margin, or a more dense raft; or changing the nozzle lift for the raft
Raft/print is wiggly[edit | edit source]
- if it is both the bottom layer and the top layer, it means your extruder is too far from the base
- if it is wiggly on the bottom in certain areas, generally means the board is not level or that it has started to warp
- if it is the top part of the raft, it could be mean extrusion speed is too high or too low or that the base is moving down too far
- if the print is wiggly but the raft is not, that generally means your printed layers are thinner they are suppose to be or that your bed is moving down at rate that does not match your layer thickness (calibrate your machine)
- It is possible that the extruder is not extruding enough filament (partial jam)
Extruded filament is bumpy[edit | edit source]
- either it is too hot or too cold
Filament is not coming out[edit | edit source]
- Extruder head is blocked - drill out the hole again, or buy a new extruder
- filament is stripped so there is nothing for the screw threads to grip
- screw is so covered in plastic dust that it can't pull the filament down, it's threads are filled
Filament is not coming out fast enough[edit | edit source]
This means there is too much resistance in the extruder. Possible causes:
- Hotend nozzle is blocked
- Filament is stripped where it contacts the feeding screw
- Feeding screw is so covered in plastic dust that it can't pull the filament down
- Hotend is filled with gunk
- Extruder feedpath is filled with gunk
- Hotend is not hot enough
- Too much resistance from filament stock wheel (ceiling mounts have addressed this; ensure your filament wheel can rotate freely)
- Pressure wheel isn't tight enough
- New nozzles tend to not feed as well when they first start - not sure why; extruding plastic for a few hours may fix this. After 10 hours or so of printing with our first hotend we noticed improved performance, after 4 hours of extruding with our pre-built BFB hotend
- If it's the base layer, the head can be too close to the print bed, blocking the end and causeing too much pressure to extrude filament
- The extruder feeding screw has trouble gripping if the extruder bolts are loose
Nozzle plows into board[edit | edit source]
- fault in file reading from the SD card - the firmware only catches this after the first instruction; follow guide to SD card maintenance
- the head has not been leveled properly
To Fix[edit | edit source]
- ALWAYS constantly watch the machine as it comes up to temperature during file prints (after it homes), keeping a close watch on the thread's rotation speed, the distance of the head off the board, and listening for any strange sounds when it starts to move
- If any of the above occurs, Immediately turn off the machine
- Immediately hold the board down away from the nozzle with your hand; do not release until you have manually moved the board away from the head
- Turn the machine back on, enter 'manual move' mode, and move the z axis down at least 1cm away from the board, further if you intend to leave it there (the heat from the hotend damages the print board if it is in the same spot for more than a few seconds)
- Further instructions here
Nozzle plows into printed part over time[edit | edit source]
- the layer thickness is greater/close to the amount the base moves down, so over time the object gets closer to the nozzle till it finally plows into it.
- The motor could also be skipping in the Z axis, hence not moving the platform down enough. This could be due to either the belt skipping or the motor loosing steps.
- If the raft is lifted, some areas of parts may be closer to the nozzle where they are not held down.
To Fix[edit | edit source]
- Follow How to Calibrate instructions above
Print Stops[edit | edit source]
The motherboard has hung. Note the GCODE line displayed. Turn off the machine. Move the bed and part away from the hot end.
Read this article about how to recover from a printing crash.
If you are not planning on recovering, remove the object and restart your print as usual.
Violent shaking when homing[edit | edit source]
This is due to the limit switches not being pressed properly. On the Queen's machine, there is an extra nut added to the Z-positioner bolt; this can interfere with the y limit switch if it has been shook loose and is not snug against the plastic.
Bed is Warping away from the nozzle in the middle[edit | edit source]
- This is from the heat of the nozzle on the bed, this causes the plastic to warp away from the nozzle.
To Fix[edit | edit source]
- Put a coin under the middle of the print board
How to fix a warped print bed[edit | edit source]
- Put pennies underneath the area which has warped (generally it is the middle). This is what I have done and it works well.
- Put more bolts in along the side of the board.
What to do when Nozzle Plows into Bed/Print[edit | edit source]
- Stay calm.
- Push down board and press Esc. If the line is really long (it only esc after a line is finished) turn off the rapman right away, turn it back on and go to "Manual Move" and move the board down.
- After is has esc and moved to waiting position, turn off machine.
- Turn on machine.
- Check if the board is level.
- Move the board over the hole in the one corner and warm up the machine to 245 Celsius.
- Extruded at increasing rates. If it doesn't start oozing at 220celcius or extruding at all your nozzle is blocked or broken.
Printing RepRap Parts on Rapman[edit | edit source]
If you are trying to build a Reprap using your Rapman here are some useful tips:
- A RepRap supplies site has just started for people to buy and sell important components for RepRap www.reprapstores.com
- A European equivalent exists http://www.mendel-parts.com
- Here is a is a list of the parts I ordered in Canada and their prices: Media:Parts_for_reprap.odt
- Putting a bit of acetone on the parts allows the layers to meld together better (make sure to wash after)
Settings Used for Print[edit | edit source]
These are the values that were changed in skeinforge to print our parts
How to Dip ABS part in Acetone[edit | edit source]
It was suggested on the Rapman forum to dip abs in pure acetone to create a stronger part are it melts the abs on the outside of the part.
What not to do[edit | edit source]
- Larger parts will often have voids in them unless you have 100% fill. When the part is dipped in acetone, the acetone with get into those voids and have a difficult time evaporating out and so will make your part become squishy.
- The longer you keep the part in the acetone, the more acetone that will get inside and the squishier the part will become. As well, when the part is drying if it has a lot of acetone in it, the acetone will try and evaporate and cause the object to swell.
- When the parts come out of the acetone, they will be sticky all over and so should be handled with tongs and placed on a piece of parchment paper as so not to stick (as it will with paper towel).
- If the print has places where the abs didn't extrude properly, the object may sink in those areas (the more skipping of the abs, the more sunken it will be).
What to do if your parts seem ruined from acetone.[edit | edit source]
- Don't lose hope.
- Poke small holes into the squishier parts to let air in to allow the acetone to come out.
- Don't squeeze or deform, as it will stay in the deformed shape.
- Allow to air dry for a couple of days, the less squishy ones should dry in a day, the really squishy ones should take a couple of days.
- Once hard sand or fill the bubbles and voids.
How to fill voids[edit | edit source]
- Wearing gloves and using a container that will not be melted by acetone, mix scraps of abs with a little acetone.
- Mix the abs around till it reacts with the acetone and becomes a sticky putty.
- Put putty into voids and allow to dry.
Drying should take a couple of hours.
What to do[edit | edit source]
- For larger parts:
- While wearing gloves, dip a paper towel into acetone.
- Rub paper towel on part till it seems shiny.
- Put part on parchment paper to dry.
Drying should take about 15-20 min unless the piece got really soaked in acetone
- For smaller parts (that are 100% fill, as they are too small to have voids):
- While wearing gloves, using tongs, quickly dip part into acetone.
- Quickly dab off part with paper towel.
- Put on parchment paper to dry.
Drying should take a couple of hours.
Acetone Glue[edit | edit source]
- this is best done in a fume hood as the acetone is very smelly.
- Choose a dish/bowl/beaker that is expendable that will not be melted by acetone.
- Place scrap pieces of abs into the bowl, a few pieces are needed, the best being the rafts from printed objects.
- Put on gloves and pour acetone into the bowl, a little less then the amount of plastic in the bowl.
- Mix around and let the acetone become a milky colour.
- Let the mixer sit for a couple of moments till the plastic in the acetone starts loosing its shape and the acetone becomes milky.
- Initially the acetone/abs milk will work as a good glaze for parts to bond their layers together more. This can be applied with an expendable brush, gloved finger, or paper towel dipped in the substance. As the Acetone starts to evaporate the milk will congeal a bit and become a very good glue to glue pieces of abs back together. After 5-10 minutes the mixture will congeal a lot and become a sticky clump which is good for filling in holes in parts.
- Either peel the plastic out after it has congealed a lot or run water into the beaker when the glue is still wet and pull plastic out. Try not to let it dry completely in the bowl as it will harden to cement.
- All this was done with 100% acetone which can be bought at Home Depot (it is used as paintbrush cleaner).