Dr D-Flo's big build
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@Rushmere3D said in Dr D-Flo's big build:
Can't wait until he attempts the life size benchy.
Where's he going to put it?
Duet WiFi hardware designer and firmware engineer
Please do not ask me for Duet support via PM or email, use the forum
http://www.escher3d.com, https://miscsolutions.wordpress.com -
I think he is on this forum somewhere, but I forgot his username ...
@dc42 if he is smart he will raffle it off to one of his viewer so its not his problem anymore (-:
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Paging Doctor Flo
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I just got an envy-attack
His garage is bigger than my house and he got plenty of donations from sponsors. sighI hate him
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@Herve_Smith personally I have had nothing but positive communication with him via Instagram but than I'm not so arrogant to question someone's project.
I've only made a few project type YouTube videos and the amount of people who think they can tell you how to do things is annoying.
The amount of planning and costs that must go into a project like this I'm sure he just wanted to follow his own plans.
Follow my adventures in 3D Printing, laser cutting and electronics. https://linktr.ee/Rushmere3D
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The craziness of life and some now fixed printer problems have delayed this project... But, I am hoping to set sail during this upcoming 4th of July weekend!
Also, in my home state of Tennessee any watercraft under power (even one with an electric trolling motor) needs to be registered with the coast guard or else I am going to be stuck sailing on private ponds outside of strip malls lol! So, I will have to address those state regulations during the design/printing of the boat.
As a side note, I was rewiring an old Flashforge at work, and man, my latest upgrade to CAN expansion boards on the large format 3D printer has completely spoiled me... I am excited to see what other expansion boards will be released. I still have my fingers crossed for a digital or analog galvanometer expansion board as I am still tinkering with my SLS printer build, but this would also be useful for any laser marking application.
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@DrDFlo said in Dr D-Flo's big build:
some now fixed printer problems
If you refer to the closed loop steppers; IMHO they are just band aids to cover up some design issues. Maybe related to the donations from sponsors? Sometimes you have to use, what you got, right?
I'm not sure if you want to use this channel to discuss the build?BTW: we recently discussed galvos here, maybe you find some inspiration for yours?
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@o_lampe said in Dr D-Flo's big build:
If you refer to the closed loop steppers; IMHO they are just band aids to cover up some design issues. Maybe related to the donations from sponsors? Sometimes you have to use, what you got, right?
I was referring to pellet feeding issues, but I am open to discuss any of the printer's design elements. Of course, the overarching design constraint was capital. So let's assume that you had the same budget as I had, which was about $7,000 for the frame, 7 linear actuators, and custom brackets to attach everything together. BOM here. Would you source completely different components or tweak the ones I had?
A bridge-style mill or Kuka robotic arm would both be better platforms for pellet extrusion, but the cost and power requirements are prohibitory for my garage operation.
I am upgrading to a 12 mm high-helix lead screw for faster travels at lower RPMs, but I am limited here by the c-beam aluminum extrusion profile
@o_lampe said in Dr D-Flo's big build:
BTW: we recently discussed galvos here, maybe you find some inspiration for yours?
Excellent, very timely!
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@DrDFlo said in Dr D-Flo's big build:
Would you source completely different components
Not completely other components, but
- leadscrews on XY gantries are not my liking. They're OK for Z-axis, since gravity takes care of backlash there and Z is slow anyways.
- Since the extruder is a bit underdimensioned for the 5mm nozzle (20mm/s, really?) it is OK to use slow leadscrews too. But two bads doesn't equal good
- 1000$ for the boro-glass plate... was that the only option to print all the filaments you're planning to use? Not sure about the exotic stuff like PA or PEEK, but I'd try FR2 or FR4 sheets first.
- Steel panels for the enclosure will not help to keep the chamber at steady temps. These forced air enclosure heaters will make a lot of draft, which isn't good for ABS.
- You're mixing steel panels and aluminum extrusions like there is no thermal expansion issue.
- Same for the C-beam leadscrews: how do they compensate thermal expansion, when fixed at both ends with radial bearings? You've mentioned 2mm expansion, that's alot.
- The crossbeam of the X-axis is fixed on both ends. You had to do that, because of the donut-bearings you're using. (forgot the english term for these, sorry)
I could rant on and on, sorry if I sound harsh. My english skills are lacking.
Just my 2 cent anywaysPS: the forced air chamber heaters are not in the BOM, right?
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All great points! Couple responses:
@o_lampe said in Dr D-Flo's big build:
leadscrews on XY gantries are not my liking. They're OK for Z-axis, since gravity takes care of backlash there and Z is slow anyways.
You can't use belts at this size, so that leaves rack and pinion or ball screws. Both of which I would gladly upgrade to, but $$
@o_lampe said in Dr D-Flo's big build:
Since the extruder is a bit underdimensioned for the 5mm nozzle (20mm/s, really?) it is OK to use slow leadscrews too. But two bads doesn't equal good
Not sure what is meant by this. For non-vase mode prints, like the generative design desk or even the roof panels, higher travel speeds between print moves would greatly speed up the print times and there would be less oozing to clean up. So faster print speeds with less lead screw whip is definitely my most pressing issue.
@o_lampe said in Dr D-Flo's big build:
Steel panels for the enclosure will not help to keep the chamber at steady temps. These forced air enclosure heaters will make a lot of draft, which isn't good for ABS.
Printing ABS was more exploratory, and I admit there are quite a few improvements that could be made. Most large format 3D printers do not use any sort of chamber heat. I visited Oak Ridge National labs the other day and they print ABS nonstop on their BAAM, but their secret is that they use chopped carbon fiber composite and also formulate their own ABS with additional additives to prevent it from warping. I am sure they also have their print speeds carefully tuned.
@o_lampe said in Dr D-Flo's big build:
You're mixing steel panels and aluminum extrusions like there is no thermal expansion issue.
This is not an issue. Panels have through holes that are larger than the bolts. Also, there is a rubber washer between them. Perhaps more of a concern is the steel lead screw in each of the actuators. I am looking at a high-helix aluminum lead screw from Igus, which would solve this but this a costly component and the thread is proprietary.
@o_lampe said in Dr D-Flo's big build:
The crossbeam of the X-axis is fixed on both ends. You had to do that, because of the donut-bearings you're using. (forgot the english term for these, sorry)
These are angular contact bearings, which take on the axial load when tightening the lead screw.
@o_lampe said in Dr D-Flo's big build:
I could rant on and on, sorry if I sound harsh. My english skills are lacking.
Just my 2 cent anyways
I have immensely enjoyed building this project and interacting with the community. The printer works well with PLA and PETG (not yet shown on video), but now I am in the phase of determining what upgrades are worth the performance increase while not having to rebuild the entire machine. -
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@DrDFlo said in Dr D-Flo's big build:
can't use belts at this size, so that leaves rack and pinion or ball screws.
Compliments, you have a great printer and you have a new subsrciber on YT.
There is a solution which may interest you, called ServoBelt:
https://www.cnczone.com/forums/linear-and-rotary-motion/59570-forum.html
For other use cases, there is also a version of it for rotary axes called ServoBelt Rotary. Both are patented *), but the inventor created the thread to help noncommercial users.
The solution uses belts with the advantage that stretching of the belts is limited by the construction.*) reviewing the thread on CNCzone, I see the patent may be abandoned or expired, but I am no patent expert...
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Thanks for your reply.
@DrDFlo said in Dr D-Flo's big build:
So faster print speeds with less lead screw whip is definitely my most pressing issue.
I agree with that. A belt drive might have it's own demons, but who cares about ringing while doing fast travel moves? I think Duet toolboards come with acceleration-sensor to dial out ringing anyway.
HTD3M belts is what I'm using on my CNC and they were strong enough to rip my gantry apart when one of the Y-motor failed.One more thing about ABS printing: the pellet conveyor blows lots of cold air into the chamber while filling up the funnel. That air should be guided outside of the chamber or it will cause turbulences and a sharp temp-drop right above the extruder.
@DrDFlo said in Dr D-Flo's big build:
These are angular contact bearings, which take on the axial load when tightening the lead screw.
No, I meant the GE12 spherical bearings. They allow some DOF should the Z-axis sag, but not in the right direction. A Maxwell or Kelvin mount system would be better also for thermal expansion. Here's my approach for a 3-point Maxwell mount. Does also work for 4-point Z-axis.
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@JoergS5 said
There is a solution which may interest you, called ServoBelt
When I eventually get back to my CNC build, this is what I was going to do (though not buy the commercial solution), using 3mm HTD belt, which meshes with itself nicely. My hope is that it reduces the ‘springiness’ of the belts enough to cut aluminium.
Ian
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@DrDFlo said in Dr D-Flo's big build:
You can't use belts at this size
Ivan's print head is significantly lighter than yours but belts appear to be working for him on a similar size printer:
https://youtu.be/TKE7-Q5jBjE?t=479
Be interesting to do an examination of where the cross over point is for belts vs screws in terms of as weight / acceleration / top speed trade offsIf anyone has a link for some research on that I would be interested!
P.s. nice find with the servo-belt @JoergS5
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@T3P3Tony said in Dr D-Flo's big build:
Ivan's print head is significantly lighter than yours but belts appear to be working for him on a similar size printer:
@Phaedrux said in Dr D-Flo's big build:
Modix does.
Perhaps, I wrote a standard FFF belt configuration off to quickly, but with pellets, my print head weighs > 30 lbs (13.6 kg), which is likely 10x heavier than Modix or Ivan's. For a belt to work, I will have to use a thicker belt and tensioning will be a concern because those c-beams are likely to buckle.
@JoergS5 said in Dr D-Flo's big build:
There is a solution which may interest you, called ServoBelt:
https://www.cnczone.com/forums/linear-and-rotary-motion/59570-forum.htmlA pinon belt system, such as the one you linked is definitely interesting. I need to think about it more, but it may be possible to implement with with only a small modification to my carriages, if I can run the belt on the back of each actuator. I see that Bell-Everman NEMA 23 actuator supports 50 lbs. Cool!
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@DrDFlo said in Dr D-Flo's big build:
my print head weighs > 30 lbs (13.6 kg), which is likely 10x heavier than Modix
This may be the case. The Modix head is quite heavy as it is but probably not 30lbs.
At the meter scale everything becomes harder!
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@DrDFlo said in Dr D-Flo's big build:
I will have to use a thicker belt and tensioning will be a concern because those c-beams are likely to buckle.
The cross section of the C-beam isn't very stiff. I'm surprised you use V-rollers for such weight? The rollers can pry open the V-shaped extrusion. Especially, when the unused V-slots aren't closed. (I hope, I made myself clear)
How much airflow does the vibrator on the extruder generate? Another source of turbulence and temp-drop, messing up ABS prints?
Extending the exhaust of the turbine is an easy fix, I guess.
