Can you switch to relative coordinates before moving? I guess it kind of depends on if you are using endstops. A move like G1 X9999 Y9999 wouldn’t hurt anything in my printer, because if soft stops. I think my gcode is something simple though like a relative X20 Y20 or something, then a jump up of Z5.
That seems like a good idea, I’ll give it a try 
Covered the tubes with carbon vinyl to make them lighter. Very useful if you plan to use your CNC on a race track.Ha. I really enjoyed reading about the progress of this project. I want to buy or build one for my son next year and love the versatility of Printing, Engraving, Milling, Laser & Plasma. I need a large format printer like this! Keep up the good work.
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Gentlemeeeeeeeeeeeeeeeeeeeeeeeeeens, welcome back to she shop.
I’ve printed a few stuff this week, so I thought I’d share:
I’ve almost completed the laptop arm version 2. Here is how it went so far:
One of the two main arms bones, it took about 3 hours to print and came out close to perfect:
[attachment file=66899]
The main joint where the laptop support panel and pivots are attached. I was worried that it would detach from the build surface but it didn’t move at all (took one hour and a half I think):
[attachment file=66900]
The arm is now almost completed. I’ll just have to redesign the big laptop bracket part (the giant red part where the laptop is attached) and to re print the orange part in red, since I didn’t have enough orange filament. I was really quick to print all of these. I think it could have been done in one day if I didn’t have to work.
[attachment file=66901]
[attachment file=66902]
The arm works very well, it feels way sturdier than my previous version. But it works pretty much the same, I had no complaint about my previous iteration since it was already fine, despite its flimsy look.
Some details of the joints:
[attachment file=66903]
[attachment file=66904]
Another thing I’ve made: an enclosure for my e-motorbike charger.
The charger was originally a big 48V server power supply. It has been converted to 76V to match my battery, but it looked like a big metal brick, without any kind of protection. My garage is always covered in dirt, and the charger is often on the floor so I was afraid it would ingest particles of metal and die prematurely.
So I just printed a few parts at each end, which includes some filters and some shock pads, as usual covered the stuff in carbon fiber vinyl to make it lighter, added a handle and voila. It took less than 3 hours to print everything.
[attachment file=66905]
[attachment file=66906]
I’m very happy with this stuff, it works great, it’s convenient and the filters make it a lot more silent (servers power supplies are usually extremely loud).
I’ve also installed my second extruder motor for spool unwinding, but I forgot to take pictures so I’ll be back and talk about this system tomorrow 
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You are getting entirely too fancy with everything. They both look amazing, you are getting good with the CAD!
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Love the weight reductions bro. I add stickers to my car to add extra horsepower.
Your laptop arm thingy has inspired me to make my own. As soon as I can 3d print again I will that on the list.
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Great!
I’ll publish the files whenever I’ll finish the last 4 parts if you want.
I need to create a thingiverse account since there are many stuffs I printed that I can share. You’ll need at least a 300mm build surface to print that, I think that’s the maximum dimension of the biggest part.
You’ll also probably need a big nozzle, otherwise printing that stuff will litterally take weeks, plus it won’t be very strong.
Hi guys,
So, as promized yesterday, a little feedback about how the double extruder system performs.
First, I printed the brackets. It is just 3 parts, a clamp to attach around the stepper and a long arm to attach it to the spool tube. Nothing really special.
[attachment file=67009]
I then connected the stepper in parrallel to the other extruder stepper, and used a flexible tube between bowden tube between the two.
It looks like this:
[attachment file=67010]
[attachment file=67011]
It was pretty easy and straightforward.
So, does it works?
Well yes, it does. It seems that the layers are slightly better aligned, but this is not a very huge improvement at regular speeds. I now realize that most of the imperfections might come from the slicer and/or the cooling.
The positive things that this system does: the load on the Z axis is constant no matter where it is and no matter the speed. I did see some nice improvements on layers consistency when running at really, really insane speeds and accelerations (I turned the knob to 350% of print speed (my original speed is not slow at all to begin with) and 6000 (yes, 6000, this is not a typo) acceleration settings in the firmware. Well there is no problem with that, at least no mechanical accuracy issues, despite my extremely long Z axis. The only issues are due to the filament not cooling fast enough on some corners, so it’s being dragged a little by the nozzle, hence some imprecision. But it is way better than it used to be in this regard.
The negative thing is that it seemed to lower the individual power of each extruder motor quite a bit. I guess that this is because they are wired in parrallel, I’ll build a little series adapter to check if this solves the problem. With less power the motors sometimes skipped steps (only at high speeds for very long paths), which never happened before. On the positive side both motors stays cold, while the extruder motor used to be crazy hot before (to the point that it was melting its support, I had to add a fan and a heatsink to cool it).
I’ll do some more tests in the coming weeks:
Try to remove the bowden tube between the two motors, since it shouldn’t be necessary at all. This should reduce the overall drag a little, both on the Z axis and on the motors themselves
Try to disable the second motor and just run the plastic through the bowden tube. But the load on a single extruder motor might be too high
Try different retract/prime configurations and settings.
So far it seems to be useful, the improvement is marginal at low speeds (but still there is actually less Z wobbling) but seems to be quite significant at high speed. But now the real limit to super high speed seems to be in the plastic flexibility and in the slicer. From what I’ve seen so far, no slicer have been optimized for big nozzles diameters and for very high speeds, there are some parameters that I would like to change but unfortunately they don’t exist in any slicer I’ve tried. One of the most important ones would be to have some kind of configurable delay for bowden tubes (move the extruder motor slighlty before it should theoretically move, so that the pressure builds up at the exact right time), and different speeds depending on which way the path goes. If the extruder comes to a corner, depending of whether this is an inside turn or an outside turn the speed must be different, otherwise, for instance in an inside turn, it will ruin your print because the filament might not have enough time to cool of, thus being dragged by the print head.
I hope the slicers will finally start to keep up with the hardware at some point, this gets a bit frustrating.
W.r.t. slipping at high speeds, in straight paths:
Are you running out of heat? Certainly splitting the current will half the torque, but that’s the situation where the heat block will have the most trouble.
W.r.t. your slicer improvements:
Marlin has a pressure based improvement. Klipper also supposedly considers extruder pressure and not just distance. That might be a better place to fix it than the slicer.
Hey Dui, I would make it easier on you dual paralleled extruder steppers by making inserts for the inside of your filament spools so that they will roll on bearings around your inch diameter pipe. three bearing on a plastic printed C piece on each side would mean the unspooling would be a lot smoother. I recently made a four bearing holder where the spool ran on its rims inside of my dry box and its made a ton of different to the quality.
I also converted to borosilicate bed and 8mm inductive sensor and the quality has shot up again. just waiting on the hosepipe of the correct ID for the water cooling mod to do your e3d mod. I have a set of new nozzles to experiment with which is very exciting to see how fast I can put an anet a8.
And I got a fan thermometer controller (thermostat) to install on my enclosure then I can have the entire chamber temperature controlled so my prints should never lift, despite my unheated garage through the night.
Heat capacity of the block might be the primary root cause, but I can’t go really much higher since I’m already extruding at 225 degree C. I might need to machine a bigger heating block at some point to increase the heat capacity. But I didn’t have this issue with a single motor, running at similar speeds. So I guess that it because of the way motors are wired together, they get less current, so less torque.
How do they sense the pressure?
Do you have the name of this function in Marlin so I can google it? Thanks!
(P.S: what is the meaning of “W.r.t” ?)
They aren’t measuring it, just adding a “fudge factor” to accommodate it. They specifically menion higher speeds.
“With respect to”
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Actually the issue is the inertia of the spool, because it is quite heavy and the accelerations are quite high. So whenever the print head moves, at some point it will suddenly drag the spool, but since the spool weights a lot it has quite a bit of inertia at the beginning, no matter how smooth the spool runs against the tube. The actual drag doesn’t make a big difference.
Great! Post us some pictures once you’ll make it!
Yeah, that’s something I wish I could do. My wooden frame has many qualities, but being able to fit some kind of enclosure on it isn’t at all one of them… It would take some really huge modifications and I don’t have enough space in my garage to do that 
But actually a simple heated bed works absolutely fine at avoiding warping. I never really had any warping issue on my prints after installing the heating tile and the auto bed leveling, and I don’t even use brims or rafts. So you probably shouldn’t worry too much about that, unless you are printing some exotic materials (I mostly stick to PLA).
Enclosures are mostly good for layers consistency (it reduces Z wobble and other things like that).
Ahhh ok, it’s the linear advance stuff. I wanted to try this function for a while and then totally forgot about it
I guess I’ll have to experiment with this, but I really hate editing the firmware when it works fine… I’ll try to motivate myself and do it this evening.
Well, I tried the linear advance yesterday.
Unfortunately for me, what sounded like a walk in the park (just had to uncomment a line in the firwmare) ended up being a mess.
I stupidly named “good version” a non working version of my firmware. After adding the linear advance, I made a first attempt and smashed the print head into my bed. Luckily nothing broke. But I spent two hours trying to find that freaking correct version of the firmware with all my stuff working.
After finally finding it, I burned a motor driver from a loose connection. Yay.
Then I went for a linear advance test to find the correct K values. They developped a test script that generates a gcode file, which works fine to determine what K factor your machine needs (check here) Found out that on my machine a K of 70 seemed to work well for me.
On the first attempts, I noticed that my two extruders missed steps. They weren’t powerful enough to run smoothly. So I went back to single extruder to make sure it worked fine. Well, this linear advance feature kicks hard on our stepper motors… The extruder went blazing hot in 15 minutes, it actually went so hot that it crashed the Arduino, probably from the high currents it was draining. It did that 3 times.
Adding a little fan on it fixed the issue (at least for now), and I was ready for the first actual parts making. But since it was already late at this point I only did some small stuff.
So, aside from stepper heating, is this feature any useful? Well, hell yeah! This thing works very well. The corners of the parts I’ve printed looked amazing, the infill is better, the top layers are nice. Actually it is just much better everywhere, this is really a great feature, I can’t believe it is not enabled by default in Marlin.
I haven’t see any downside yet aside from this being hard on steppers. I still need to print many more stuff to see the limits of this option, but so far I was really, really impressed.
I’ll print a few stuff and post pictures later in the week
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Cool. It does seem like it should be more widely used but it does take some tuning per filament, and brand/color/chemistry even. I think if it were to get implemented into a slicer it would be a little more useful. Firmware tweaks scare people. From an “engineering” standpoint it makes a ton of sense but also seems like more work than most are willing to put in.
I feel like we are really close to the next printing level up. Not sure what it is but I have a gut feeling FDM is going to get a little boost.
I think that if any kind of breakthrough happens in the next few years, it might be with the addition of cameras and image recognition. If I had the luck to be any good at programming I thing I would look into this kind of things. Just imagine a few cameras around the nozzle, constantly correcting the flow, speeds, temps, etc, to get a perfect extrusion everywhere, that would probably lead to amazing results and much faster speeds.
Hi guys,
I’ve made a few more tests of the linear advance function yesterday.
So first, I wanted to see how some simple shapes would come out, so I printed a few basic stuff. The black one was printed before I enabled the linear advance. It looks way better in real life than on the pictures, but there were some issues, in particular with the corners.
I then made the same part but with linear advance enabled (the one in red right next to it). Just perfect, aside from the few first layers where I printed with too much material and no cooling. The corners are great and the sides are perfectly flat.
The other weirdly shaped part on the left was made to test dimensional accuracy, slight overhangs and more importantly the through holes. Everything came perfect. The holes were usually where I was having the most visible defects, most of the time I had to correct them with a file. I guess those days are gone now!
[attachment file=67230]
So, since everything came out right, I decided it was time for a real challenge for my machine. I’ve printed a lot of relatively easy parts in the past, so I wanted now to see if my giant printer was an actual decent printer, not only capable of fast printing big crappy parts, but also able to print relatively difficult and intricate stuff. I settled for the iconic little boat. I printed it twice the original size otherwise it would have been very ugly with the 1.2 nozzle.
First attempt was a semi failure: I printed it in vase mode by mistake and I had not enough filament left anyways. But the result was very encouraging and in the end I could probably use this thing to build a RC mini speed boat:
[attachment file=67235]
I went back to the slicer, put a 33% infill and printed again… And it came out without any problem. There are still some tiny little things to improve, but the result is just awesome for a first attempt.
It took around 1h50 min to print that stuff, at fairly low speed
[attachment file=67231]
[attachment file=67232]
[attachment file=67233]
[attachment file=67234]
[attachment file=67236]
Great success!
I still have a few improvements to make, I think most of the remaining issues will be solved with better part cooling and better nozzle thermal insulation, probably a bigger heating block to keep a more constant extrusion heat too. But I’d say that 99% of the hard work is now done.
I’ll also need to work on making the printer more reliable, make a cleaner wiring, stuff like that.
I’ll upload a short video of the print later today.
But wait… This freaking thing doesn’t work at all! Gimme back my money!
[attachment file=67237]
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That is great. I need to try that out. IIRC, you can completely disable it by setting the K to 0 if you wanted a comparison.
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Here is a short video:
Yeah, I might do that later. But I think there would be little point in wasting more material, the linear advance option clearly makes a huge difference, I wouldn’t have been able to print the boat remotely as good without it.
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