Lessons Learned from Resolution at 0.20mm
Dave Durant - DIY 3D Printer Vertical Resolution World Record Holder
With Dave Durant’s magic printer calibration program I was able to just specify what layer height (vertical resolution) I wanted – and it just worked. This is a totally new experience for me. Before playing with this program I spent time dialing in each version of ReplicatorG to my specific 3D printer’s settings – with different settings for my Cupcake than for my Thing-O-Matic. Now I can just choose my desired vertical resolution and FIRE THE MAKERBOT! If you’re planning on playing limbo with your computer too, there are a few practical concerns:1
- Careful measurement of the filament is important. Printing by laying down 0.2mm thick layers of plastic means your printer has to have a very good idea of how much plastic is coming in and going out. Dave’s magic program will figure how much is going out, so all you have to do is carefully measure your filament. I suggested my method the other day. You don’t have to use my method, but I would suggest that you can’t take too many samples in getting this right. Printing at 0.2mm layers means that over or under measuring will have a pretty big impact on the amount of plastic deposited at each layer.
- Attention to the build height is important. Printing at 0.2mm thick layers of plastic means that if your starting build height is off by as much as 0.1mm, you’re basically compromising half a layer of plastic. Being off by 0.1mm in starting build height just isn’t that much of a problem when you are printing at 0.4mm per layer – there’s plenty of room for the plastic to squish around and find a place to go. Make sure your Z maximum endstop doesn’t have a lot of wiggle, your platform is hitting the Z maximum endstop in the same area reliably, and that there’s not much wobble or wiggle2 in your Z stage that could cause a big variance in your starting build height. Also, be sure to check your printer’s auto-homing features several times before printing at this level. 3 If you’re not sure about how to calibrate the proper print height, follow these calibration directions.
- Having a perfectly flat build surface is important. Since you’re printing at such thin layers, inconsistencies in your build surface will be magnified through the layers as you print. You’ll want to make sure your build surface is totally flat – or flat to within about 0.1mm. If you’re very close to having a level surface a good way to test it is to print a large flat object. When that first layer goes down you’ll see the filament fuse together where the platform is at the proper height and either become individual strands where the platform is too low or it will start pushing plastic around where the build platform is too high. I would suggest calibrating your starting build height for the highest point on your build surface and, if you’re using an automated build platform, you can just slightly adjust the lower points by adding a piece of Kapton tape. Putting it under the belt in the lowest spots will raise your build surface very very slightly.
Next time – more about Dave Durant’s magic printer calibration program!
| Tagged with | calibration, fixing with makerbot, high resolution, printing, randd, research and development, resolution | 5 comments |
5 Comments so far
Caleb Cotter
This…this…is so…. amazing…. I….I….I…I am totally speechless as I bow down to this awesomeness.
Josh Cote
i have a suggestion for an improvement/add-on, why don’t we add a sensor to where most people put a cloth/sponge to clean off filament. that sensor can automatically sense depth/with of the filament and update the average on the fly.
could the program be implemented into the motherboard itself and attach this sensor to the extra pins? how hard would this be to implement?
Dave Durant
@Caleb: glad you like it!
@Josh: Rob Giseburt has talked about doing exactly that – putting encoders on the extruder to measure both the length going in and the diameter of the filament entering the extruder then using those readings to feed back into the system.
It’s definitely an interesting idea but I’m not sure how much it would help. Measuring length is a good thing but once we all move to stepper extruders, it shouldn’t really be needed – steppers are very consistant. Measuring diameter is even more interesting but if you do this above the pinch wheel, it’s telling you what the incoming volume *will be* in the future – until that measured bit hits the hot zone puddle, it’s not very useful. Measuring below the pinch wheel is better but it’s still a future reading and you risk measuring an oval instead of a circle. Then there’s the software/firmware to actually do something with the data, which is something I don’t think has been really thought out yet..
So.. Definitely an interesting idea but I don’t think we’re going to see it in practice any time soon – there are still some tricky bits to work out for it to be worth the effort. (or so I think, anyway. if Rob comments that I’m full of it, believe him instead)
tre3
Dave – if it’s going to be useful, you need to have the sensor tell you what will happen in the future. Knowing what happened in the past isn’t particularly useful. Since everything is fixed in place, how far in the future is known (or can be).
It would be cheaper to control the manufacturing process and hold it to stricter tolerances. No reason to add cost/complexity to every machine when you can add process control to one machine.
That said – I’ve been curious if feedback can be used from the motor current. Stratasys machines measure motor torque (unclear how they use it though). Knowing the torque and the rest of the mechanical system, one can calculate how much pressure is in the print head. Commercial extruder use head pressure to get consistent results – that’s basically what we have here…
Many stepper controllers already have a feedback pin – I wonder if that could be used…
Dave Durant
@tre3: I like the idea of getting feedback from the extruder motor more than trying to track filament diameters in route to the hot end puddle!