Rack and Pinion Upgrade: Key to Faster Large Format 3D Printing (Part 6)
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- Опубликовано: 21 июл 2024
- 3X Speed and reliability with custom rack and pinion linear actuators for my large format 3D printer.
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Having printed with hundreds of kilograms of pellets, I've experienced both the incredible potential and the limitations of my DIY Large Format 3D Printer. Further, the acquisition of a new pellet extruder, with a volumetric flow rate five times greater than its predecessor, necessitated immediate upgrades to essential parts of my printing process, including the actuators for improved speed and reliability.
In this video, I detail the process of designing and machining custom carriages to integrate rack and pinion linear motion systems for the X and Y axes (speed!) and ball screw actuators for the Z axis (reliable). I also discuss the workings of the rack and pinion system, its components, and share insights on optimizing this type of linear motion setup for peak performance
Table of Contents:
00:00 - Introduction
00:56 - Relocating Printer
02:00 - Print Speed
06:56 - Z-Axis Ball Screws
13:49 - Ball Screw Actuator Assembly
15:08 - Upgrading the Gantry
16:32 - Rack and Pinion (R&P)
17:09 - R&P Components
21:14 - R&P Tensioning
23:48 - Mounting Gear Racks
24:50 - R&P Testing
28:54 - R&P Actuators Assembly
37:46 - Floating Printhead
40:53 - Machining Carriage Plate
#3DPrinting #LargeFormatPrinting #rackandpinion 
Наука
If you want to skip all the talking/theory the build montages start at 13:49 (Z-axis ball screws) and 28:54 (gantry rack and pinion). As you can imagine being able to not only move the print head around faster but also handle a larger extruder will make printing large objects (*cough* benchy *cough*) much easier! In part 7, we will take a close look at the extruder and wire it up for printing.
I just want to say i love the setup shown at 4:47 !
This is no longer a 3D printing channel. It is a mechanical engineering channel. And I like. Bravo!
This is a 3d printing channel? Weird.
Its insane we get this level of content for free on RUclips. Always a treat to watch
I feel guilty and near obligated to donate, I would if I wasn't beyond broke already. I do intend to pay my gratitude and will remember to come back and return as much as possible.
I actually love that the limited budget makes you have to think of more creative ways to solve certain issues. Makes the video that much better
That's what makes engineering fun, the art and science of compromise.
Cool video. Just to add what you said about belt driven machines: you can search for oscillating knife cutting machine. You will see a fast and heavy machine that a lot of times uses belt driven motion system. The ones I know from years working with cnc machines and are belt driven (some are rack driven) uses 40mm at5 or at10 belts. They are fast, heavy and cut a few layers of smooth material.
Also, my company builds 5m long Router machines that are belt driven. A good 30-40mm at5 can do the job, just make sure that you have something holding the end of the motor/reducer shaft, otherwise you will bent it haha.
I was upgrading the Z axis of my printer and watching you make several upgrades to yours. I'm an engineer and your design is very good, good choice with the rack and pinion. Very good job.
Humbling to see a gantry that weighs more than all my machines combined. Chapeau!
Happy to see you again in 2024! It's an unbelievable project which is one of the best on RUclips! Keep going and have fun!!!
Never leave comments, but this is amazing.
The alignment of the ballscrew is absolutely critical. The waterjet I used to run had a number of issues because the ballscrew was out by 0.03mm.
The amount of work that went into this even the great models of the gears, just wow!
thank you for the video, Dr. D. This is one of the (very) few channels that can retain 100% of my attention span
So happy to see you back with another video
Excellent video doc, and some fine engineering. Been waiting to see what you came up with and really can't wait for the next!
The level of engineering put into this is mind boggling! Extraordinary impressive.
That is mighty impressive. Great design work, and a ton of machining and assembly 👏
I must applaud your ability to repeatedly say the words, ball, double ball, nut, and screw while maintaining a completely straight face! 😂 Great video and well explained!
Incredible and efficient upgrades! These kinds of fixes are what leads one to designing the bigger, better end product and starting their own company. 😉
Rather than relying on motor rotation for determining the position of the XY axis, could you use linear scales, like a lathe/mill DRO, to track actual position of the print head? This should alleviate any loss of accuracy due to backlash. Just a thought.
Thanks for sharing. You are a great engineer and teacher. South Africa approves.
Man, this was a LOT of work! I have a rack and pinion CNC that I have been trying to complete for more than 5 years. I feel your pain!
i cant help but giggle every time he says "ball nuts"
👏Bravo! Awesome video! so much good info and good practices. can't wait for the next video!
Cannot wait for the next episode! Keep up the good work!
Very Impressive! I like all of the explanation of you choices.
I can't wait to see this beast in action! 180mms is impressive i can barely go to 100 with my hold cr10 you make me want to upgrade! Good luck Dr!
Cant wait to build my own one day :) hope you still make all the files available one day once she's all done. Keep up the epic videos doc
Awesome video, I think you did great with the choices you had.
this is pretty cool. you can gain more travel by splaying the x axis rails top and bottom and supporting the extruder head in between them. resolves motor conflicts and symmetric split of travel in the y axis.
WOW, that's one heck of an upgrade!! That's a BIG printer, you printing complete cars? LOL!! Thanks for the video, very interesting and informative.
I absolutely love the fact that you can literally sit inside of your printer to work on it lol. You've created one serious beast of printer. Which seems to be really well done btw.
Thank you for the video. I can see you gave the design changes a lot of thought!
The one thing you didn't mention, is calibrating the real encoder travel along 1500mm. The one problem with rack and pinion is that a small error will add up and you end up with shorter or longer travel.
Just wondering if you gave it some thought or not but maybe it does not matter for this application.
I really enjoy the video though. Cant wait for that benchy.
I've worked on printers this large. If you're going to be running ball screws, you need to do weekly maintenance in greasing them. We did some calculations where I work at, and x and y travel for a week of printing on a machine that size is several hundred kilometers which is usually the measured grease interval for ball screws.
sick work dude, don't tell me you produced the timelapse tunes too haha keep it up man this thing is gonna rip!
Nice work!!! And good luck!!!
Now that's a big pp energy shown here xD
Outstanding work dude. I'm stunned.
Sub for sure.
All hail to the kaiser of 3d printing x)
goddamnit i love your videos so much! every day i see a drdflo video is a massively amazing day
I'm going to watch this channel repeatedly until im convinced to make one and hide it somewhere.
YESSSSSS A new DrDF vid dropped!
This thing is becoming more and more monstrous as time goes on, love it :)
I am however seeing an upgrade potential for one of your other machines... a toolchanger for the CNC, no more standing around awkwardly with a tool in your hand waiting for a cycle to finish :P
worth the wait. excellent!
Man this content is great. I need MORE. MOOOOORE
awesome and brilliant well done mate.
Outrageously good content! More more more!
You could use the idea that the extruder will trigger a switch if moved upwards to probe the bed. The Voron Tap mod does the same and reaches verry high precision
Amazing work!
Such a treat to watch
your other option (although perhaps difficult due to space etc) is to mount your motor to your motion assembly and use a smaller ball screw that is fixed and drive the nut with the motor.
Probably not needed at this scale, but once you go large format like a gantry cnc (and you want more accuracy than a rack can give) it is a clever solution as you can tension your fixed ball screw and don't need to worry about whip as it isn't turning.
Nice video! FYI, Roboze has chozen to rely upon rack & pinion drive for their industrial grade 3d printers. As far as I know, they're the only company doing so.
One thing some people do when designing with very long and heavy ballscrews is that they make the screw stationary and the ball housing the rotating part. Same can be done with the cheap trapezodial screws as well by making the nut rotate and the screw stationary.
Do you have an example? I’ve never never heard of that. How would it even work? The nut in the ball screw needs to be fastened to the load. How do rotate something thats fastened?
Then, you also have to move the motor so it travels along with the load.
Quite the mess if its even real!
you can use ball chain or cable winding actuators (fishing line or even steel cable)
Bravoo! Very good job!
I found your channel a while ago with smaller 3d printers. I visit today and i'm scratching my head, wondering when you managed to fit 874 years of mechanical evolution into a few months...
You could place the Y racks "flat" and in turn the motors verticaly, that would also allow for different theet sizes. Great project btw.
Using HTD8 belts would provide immense thrust and they are quite easy to tension. They can be ordered with mounting blocks and you just need to make sure you can tension the belt from one side. the blocks can be tighten in travel direction with simple screws and you can then clamp the block, once tensioned enough.
And regarding the width of the belt: the weight you are using is still minimal, compared to what such a belt can handle. a 30mm width belt is defenitely enough here.
What you could also use (though a bit more expensive) is a mustang style belt. this has angled teeth, aligns the belt drive perfectly and mitigates vibration from engaging/disengaging teeth
38:50 did you get your finger i saw that look at the fingers for blood and the good. I know that feeling. DR. you are so smart some of the stuff you are going with this monster is just unbelievable. cant wait to see what's next.
An idea, on long runs you could add nutless supports that are pulled out from the bearing end when the head is close to the drive end. And they could act as a cable guide from the side
The movement shot at about 33:58 is one for your highlight reels
Great work, keep rocking! Looking forward to see the future of it! Just a thought from a fella engineer: would it be a more elegant solution and better overall to use a single plate on the back rail mount of extruder? Instead of 2 separate plates, held together by wires.
You may want to flip the gas strut upside down; those struts tend to have a little oil mixed into the gas to lubricate the sliding gasket, which of course settles at the wrong end if you have the strut oriented the way you do at the moment. This Old Tony points this out in his Maho CNC conversion series, where he is using struts to offset the mass of his table for the vertical axis.
Wow... Fantastic video... Just curious... Was that the tormach Shear hog you were using for the perimeter machining of that part?
Man, that's a beautiful machine! But I wonder: is it REALLY necessary to be so stiff and heavy? (...) Looks it will be SO SLOW compared to anything we are using right now. I am super curious to see the parts you print with it - comparing to a much simpler design like the Elegoo OrangeStorm Giga printer.
I enjoyed the music as much as the video it self... ni e project
I am wondering with all that weight now how will those v wheels will tough, keep us updated!
amazing build, thanks for sharing. 38:49 careful, we need your hands functional
Did you check if the garage door can still open ? lol Nice updates to the printer, very cool !
Biggest Voron TAP ever, LOL!
by the way - our machine throws 14kg extruder at 1.7m/s with no sweating at 2000mm/s accell :) So servos and belts are the solution for sure. You are right ;)
6:35 you could compensate for the weight of the assembly with a counterweight system similar to the one used in elevators
With the two rails, what if you also put them on opposite sides of the center rail so that the heavy print head acts torques into both of them? It should simplify the design by using the weight of the print head as the weight that presses the gears together.
I would be interested in an analysis on different types of print beds on a printer this size.
I just found your chanel through this vid @DrDFlo but I can already tell it's time to subscribe, this was great and I'm looking forward to parusing your other content.
I wanted to ask though, instead of the gas strut that you'd need to remove for more travel, could you not use a simple, shorter and very stiff spring mounted within the height consterants of that top plate to get the same result? You could go with one in compression or tension depending on the type of spring you find that gives you the needed lift, and it shouldn't be too bad to incorporate an adjustable plate where you can increase or decrease the tension as needed using a bolt and jam nut.
Absolutely Insane
Is there a reason not to put the emergenzy z switch on the carriage on the bottom? This way it can be nc, and be more likely to catch failures.
on your point that belt driven machines are only laser cutters and light toolheads, gerber made sign cutting machines that cut aluminium in 6x12 foot sizes that were belted X and Y axis machines to give you an idea of how much weight they threw around, a factory option was a 10kw spindle
look up gerber advantage router
definitely agree that racks are better though
Would a cycloidal reduction on the stepper motor be doable for less backlash? Or would it be difficult to get or make a compact enough gear box
how accurate is the floating print head and switch? could it be used like a jumbo sized Voron Tap?
Amazing!
Do you compensate the termal expension of the printer itself? If the temperature rise by 20°, the gantry get half of an Millimeter longer.
you could also turn the nut and fix the ball screw in place
How about a counterweight on the other side of the gantry to cancel out the cantilever generated by the extruder?
What ball screws do you have on your mill? Didnt see them listed anywhere and it looks like the guy you got the kit from passed away.
i have been using ballscrew drive nuts - hence i dont have to spin the screw just the nut
i wonder if doing something like putting 2 helical racks in opposite directions to make a 2 piece herringbone style deal would help in any way, while being far cheaper (if more bulky and complicated) than an actual herringbone rack
Just a matter of software to get that crash-detector to be used as an bed leveling tool??
Where did you purchase the extra heavy c-channel upgrade? I dont see anyting like what you indicated on the openbuilds web store. Do you have another source? Id love to go with heaver extrusions on my openbuilds cnc router.
Surprised you didnt test the OpenBuilds rack and pinion system. Its much lighter and not as durable obviously. Its also a lot cheaper and the ends match. I can see why it would struggle with that massive print head. Also c-beam filled with threaded rod and epox is a really easy way to make those beams as strong as steel, while also giving extra strong mounting points at each end.
Correct, this is why we use it on large format CNC already. :). It's more accurate than belts but a LOT faster than the ball screws will ever be. Also... God this makes me love my voron. 250mm/s is my baseline abs print speed and it makes me so happy....lol also kinda makes me want to throw a stealthburner on my big CNC tool plate and see if I can print a car... 😂 1:1 scale
Also...dude you have a mill, what are you doing? Machine the ends of the racks yourself and just cut off the excess rack at the end 😂 Lol you could do it with an angle grinder, with a proper mill there's no excuse. You really didn't need the dual stepper setup for the x... I've got a single nema 32 running on mine that runs a heavy rotary head usually and it's more than what's needed to mill metal...
One man craziness and brilliance and very expensive 3d printer
Do you make the plans available to we diy bulding it also?
Perfection.
money can get you things. bravo
Where did you source the racks?
Why not extrude into Bowden tube and print with a light head?
In the semiconductor industry there are wafer transfer robots of let's say 50kg that are moved across an envelope of lets say 10m by toothed belts. These robots position batches of wafers ~20kg. They achieve good positional accuracy and high speeds and accelerations. Yes, large steel reinforced belts will have high handbook tension values...but in practice they are tolerant of very low tensions.
I really like your implementation of the racks. Low cost and clean, nice work!
Wow, bravo! Do you know how many hours of work went into this? and now we get this as a video (extra hours) and the design is opensource (right?)! Thanks for all this information, very helpful for me personally. I am working on a project to recycle plastic household waste (as shredded flakes) with a DIY extruder system on a 3D printer. Very nice to see that you could find and show your solutions of the moving system.
I have a question about possible future developments. Peopoly's 3D printer (Magneto X) uses a linear motor system. If there were parts that were affordable and in a suitable form factor, could this be a possible design choice?
Thanks for your work! This is just so impressive and helpful!
On my system i drive the nut, and not the screw. that solves all whip problems at any speeds
Hey DrDFlo. Wanted to throw out a couple things that I'm not sure you mentioned. I know your ballscrew upgrade has many benefits other than solving the whipping and maybe the original plan was to do all 7 actuators with ballscrews. Since the ballscrews only ended up on the Z axis this negates the entire whipping concern. Whipping is primarily caused by the sagging of the screw when mounted in a horizontal orientation.
Another thing that I don't see mentioned often is a brief piece of info that some people may find useful or interesting, in response to 8:07 "So we should get accurate motion with the ballscrew". These ballscrews are (I'm assuming based on some of your comments) the typical low cost rolled ballscrews that can be found on ebay/amazon/aliexpress. These are *likely* what should have been C10 ballscrews but were rejected (and therefore sold cheap outside of typical industrial automation sales channels) and therefore *likely* worse than C10. The main point here is that the lead accuracy will be different for each of the 4 screws and it will actually vary along the length of the screw randomly as well. So even with a theoretical exact same rotational input to each screw - they will all move different amounts vertically and it will not be consistent. Now this probably doesn't matter for an application like this too much except in a rare case, but I thought it might be interesting to someone.
C10 travel distance accuracy is +/-210um per 300mm travel. There is no rating on the fluctuation in lead accuracy per revolution for C10 since typically nothing worse than C5 is used for accurate positioning. But for C5 which has 18um/300mm travel error - the travel distance fluctuation per revolution is +/-8um. Unclear what sort of fluctuations would be present in C10 since the process of rolling is very different from C5 grinding and some of the error comes from the individual ball variation. This gives insight into the different accuracy errors that can be expected from using a ballscrew in an application like this, and should help someone who wants to get to the next level in accuracy.
Will you motors not get hot going that fast that long?
You might be able to rotate the extruder 90 deg.