Upgrading the MK3 with genuine HIWIN linear rails: Worth it?
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- Опубликовано: 11 ноя 2019
- The MK3 is a really easy platform to upgrade - but does it need a 200€ HIWIN linear rail kit?
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Hello Thomas,
I build industrial automation as my daily job.
This automations have a lot of rails, and the right way to calibrate them is a bit different as you did.
Ill try to make an accurate step by step guide.
1- First you put the rails in and the blocks (as you did)
2- Tighten the rail with 2 blocks making sure it is square to the X axis
3- Tighten the blocks on the fixed rail.
4- Place the carriage to one limit, and tighten the othe rail, but just on this limit side.
5- Slide the carriage to the othe side and tighten this side of the rail.
6- Tighten the remainig block.
7- Now you have to loosen the blocks one by one and tighten them again. Ma ke sure to have only one block loose at the time.
8- Check for unwanted friction, if there is any start all over again.
Protips: Never use power tools for this applications, they can shift parts around (even blocks that weigh 1kg)
You don't have to be super gentle with this stuff, being industrial they are pretty hardcore (but don't drop them)
and for last, if you follow all my steps and you can't go away some little noise remember that the rails can bent some times. The only way to make them straight is to fix every hole on a machined plane.
Hope this was helpfull :D
willyminime good post 😁
Great advise!
For newbies like myself, there are RUclips videos from bearing and motion-control companies that are demos of the described "proper" procedures for installing and aligning bearings. Thanks for the instructions!
Can confirm, this is similar to what we do at DMG MORI to our machines
@Thomas Sanladerer Pin this! This is very important!!!
"pulls out high precision rails"
"tightens with a power tool"
oh boy..
I seem to hear the clutch mechanism clicking, which is pretty decent on the Bosch drivers.
@@JeffDM I agree but my main concern is not over torquing. You lose a lot of feeling for how things are falling in place.
Tighten a bolt a little bit, check, align, tighten another one, adjust until everything falls in to place slowly and smoothly.
Thomas went for the AvE approach which might not be the best with precision machinery.
I've had the clutch on setting "3" almost the entire time - which I fund to be extremely consistent for mid/light tightening of M3.
@@MadeWithLayers But it is not, despite it being a torque limiter clutch, it still has enough mass to be equivalent to a mini impact wrench for a precision component that can throw off alignment. Would you like someone to build your 5axis CNC machine with an impact wrench?
Spent the whole video just wishing he grabed a plain old screwdriver! After I heard the price for these linear rails, it made me even more unease!
I was pretty sure that Josef Prusa said in an interview that they found that using other methods such as linear rails had no affect on print quality, so I guess it's good to know that he was correct
@Jazz Josef also said "we dont need 32 bit boards" :D
@@Arnipll Bill Gates said: "640K is more memory than anyone will ever need on a computer."
Oh boi, suck a spoiler there
@@RobNisters That has never actually been proven.
I think that the way the printer is designed to use the guides is very clever. As Tom noticed, the original design is just constrained, and well constrained. With rails, it becomes overconstrained. That is unlikely to improve precision, but is very likely to increase friction, which can lead to decreased precision.
the primary reason hiwin or other square profile linear guides are more rigid is because it can be mounted directly to a subframe and not just at each end (also things like preload but you probably want to avoid that in a printer). By mounting it only at each end it acts like a leaf spring when loaded in the middle of the guide.
Hi Tom, love your videos. When you're talking about difficult to see artifacts on the prints it would be immensely helpful to have some b-roll with something like a macro lense up close on the part so we can see too. In this video, I feel like I'm mostly just talking your word on all of the artifacting instead of seeing it myself. Still a good video though, looking forward to more.
Using those Linear rails, in an industrial manufacturing plant setting, we used to very tightly rubber shockmount those carriages [Just a thin rubber gasket really]. In our cases, over 1 metre length rails, without the rubber mount the rails would bind, and resonances would be setup through the rigid chassis and moving tool head. With them the rails would more or less self align, and run extremely smoothly.
I build machinery as part of my job. When we are using a pair of linear rails, we align and lock down one rail. The lock all bearings to the platen. This will align the rails to each other. Then we tighten down the other rail.
1:12 If it's hard to show on camera just take a picture.
Yep, macro cameras work well. I still have a Konica Minolta dImage Z5 that I use for macro work down to 2mm - it's perfect for examining individual pixels of LCD screens. The Ipevo V4K USB document camera is surprisingly good, too, though I haven't explored it completely yet.
Seriously. Replace the camera man on camera two with a still camera, and the video would become much more informative.
@@darrinbrunner6429 i think there is only some one on b cam
Hi Thomas,
I study High Tech engineering, which is a continuation on Mechanical Engineering. Within this study, my specialization is Mechatronic system design. I'm currently doing my Master's thesis and am working on a properly constrained gantry system, which uses state of the art technology. I can not say much about it, since I intend to start a company with it, selling 3D printers and laser cutting machines.
Basically every machine on the market nowadays uses a heavily overconstraint set-up. Having 2 cylindrical bearings perfectly aligned (functioning as a single bearing, theoretically) and having another one to cancel the rotation, already overconstraints your system by 3 (1 free translation means 5 constraints, each set has 4 constraints, totalling 8 constraints. 8-5=3). Now, doing the same for hiwin linear rails, we get a sum of 5 overconstraints (5+5=10 constraints, thus 5 overconstraints).
What's the result of overconstraining? Not only does it introduce higher order harmonics, your system is no longer statically determined. Binding becomes more of an issue, which might not be noticeable at first or by hand, however at the microscale it's noticeable. Often relaxing a certain bearing helps, since you reduce the amount of overconstraints and thus the harmonics.
One thing that confused me in this video is... Why do you wiggle the bed back and forth sideways, while the direction of actuation is through the centre of mass of the bed in the same direction as the bearings slide... The vibrations from the x-axis shouldn't cause much vibrations on the bed, since the frame is very stiff and its amplitude is very much degraded.
There's one side question I have. Once I finish my product, I intend to start-up and kickstart it. What conventions do you usually go to in Europe?
Keep up the good work!
As a physics major, I'm reminded of the damped harmonic oscillator (mass on a spring with friction) and the classic analysis about over-damped, critically-damped, and under-damped conditions. After increasing stiffness, maybe you can also, somehow, increase dampening and/or modify the mass of the system?
It would be interesting to analyze a Prusa i3 with something like a vibration sensor, and then do a "proper" analysis of the ringing and then optimization to reduce it.
Maybe a wider belt for the y-axis would increase dampening?
perhaps giving enough 'slack' in the tension of the Y belt might help some what? I like the widening idea.
Stefan has got you covered! ruclips.net/video/Ws1JfHl3Y0o/видео.html
Thanks Tom! Will definitely go watch Stefan's video.
@@evlsc400 Changing the tension of the belt will only change the frequency of the belt oscillation. If you want to dampen its resonance, you need to add some spring made of a different material. For example a belt tensioner with a metal spring. Maybe not one on the belt, but as a holder of the belt wheel. Still this only reduces any resonance frequency, but it will not remove belt vibration completely.
Gijs Noorlander so a spring loaded belt tensioner? If those exist I’ll test them this weekend.
Pro tip:
Use a guitar tuner (or app) on the belt before and after to make sure you get the same tension.
Also, use silk PLA or shiny PLA to make ringing artefacts more visible. Black PLA printed hot also shows artefacts more.
Why can't I see the horizontal print lines? Is it the camera?
Nice to see upgrade videos still coming for MK3 with the mini coming soon !
thank you for this review thomas
how is the noise level of the hiwin compared to stock on travel speeds > 100ms/s ?
tia
For this application linear rails from your favorite chinese store for around 15 Euros for a 500mm rail are just as fine. Most of the time they are perfectly usable out of the box. Should they not run perfectly smooth just tear down the block and wash it and the bearing balls in solvent to clean out the dirt from manufacturing. I have been happily running banggood rails on my corexy for a long time.
Is there a specific vendor you would recommend?
The ones I got have play in the block ;-;
I really like your channel you have a great way of explaining things and give honest evaluations on products.
Hi Thomas ,
if I want to modify the original Prusa i3 mk3 printer and change my
heated bed for a bigger size bed or extend z axis , does the printer
recognise the extension in the axis and would auto bed levelling works
I have a DYI Prusa with several modifications. It has considerable amunts of play in the y and x axis, but always in directions perpendicular to the axis movement. So far, I am happy with the amount of ringing in the prints, nothing out of the ordinary.
Love these techy videos. And thanks for being so honest!
Excellent Review! Good to have such honest reviews.
Great review, thanks for your work, & your honest thoughts
Looking at how you are printing the model, aren't the nose ringing artifacts along the x axis ?? why are you judjing the improvment of installing linear rails on Y axis by artifact occured in the x Axis? Am i missing something?
Yep; there are a *lot* of issues with this video. It's kind of sad; I really like Thomas' content, and he really does put in an honest effort to teach people and clear up misinformation, but he produces so much misinformation himself and seems completely unaware of it. His recent Solar Battery video was a *really* bad case of this, and so is this video.
Hi Tom, one of the thing we saw in the early days of DIY 3D printing was similar artifacting. Ours was caused by really tight belts. The 2mm teeth were giving us that slight imperfection. We wanted tight belts for precision. We gave our belts 1/2 a twist so they had the smooth side rolling against the pulley/bearing. That simple fix made our prints super smooth.
Very interesting, I actually thought of that too. Don't they skip occasionally tho?
Hey Tom, thanks for this tryout! I'm now glad with my original bearings and the little space they have. So my Mk3s is fine as it is :).
Schönes Video und Grüße aus Süddeutschland!
I got the best improvements when I upgraded the Z axis bearings to PTFE bushes
I would love to hear more about that !
Where could we get those? I did a search but couldnt find that. Also would that work for mk3s?
@@Gefionius IGUS bushings, I printed my own to the tolerances of my printer in TPU.
8:00 i think the y-carriage plate is symmetrical so you can have 2 bearing right or left, you can just turn/flip the plate.
A bit upsetting that the rails are not sitting on the aluminium profiles but instead sitting on wobbly plastic pieces.
They specifically point out the orientation you should be using in the guide.
We see this on our clients that buy Raise3D units, particularly engineering clients, that have an instinct to tighten every bolt. This is a mistake on the Z axis where the threaded bearings are intentionally loose to deter Z axis artifacts. They get binding as soon as it's over tightened so agreed the first one looks better for similar reasons!
Liking your honest review - no manufacturer favoritism here - and I agree with your findings - makes total sense 👍
For a while I was having all sorts of similar Z banding issues. But if I ran my finger along it I couldn't feel any sort of banding. The issue ended up being that the eSUN grey I was using (that I buy in 3kg rolls) had a large amount of pigment variation. So it wasn't actually a layer or printer issue at all. Changing to a different vendor's filament made it disappear all together.
If you trace the history of the short-lived E3D BigBox project, you find the banding issue there as well. It seems that their primarily used stepper controllers caused some of it by introducing rounding errors in some zones. You always have to look at the whole system.
@Jim Bob I think it was just the bulk rolls - printing out some vase mode models made it visible and obvious when you looked at it. I'd not had that issue with any other eSun filaments, and I've been through probably 50kgs of it.
Great video, thanks Tom!
I noticed on my Prusa i3Mk3S was producing Z axis banding as yours also does. I also noticed the extruder was sometimes pulling hard enough on the filament to slightly deflect the print head. This was with the stock Prusa filament holder.
My fix was a completely new filament reel and axle running on sealed bearings that puts nearly zero stress on the print head while feeding filament. This change made a noticeable improvement in the layer artifacts. My latest prints are about 50mm tall and are very close to perfect exhibiting almost no layer issues. And yes high quality filament is a must... great video as always Thomas.
@thomas: What is the length of the linear rails? We have some lying around with 300mm and wondering if I could use them as the block won't reach to the end of th rails ...
Would it be a good idea to use the hiwin rails only on one side to not "overconstrain" the system ?
Do you have a link to the active cooling fan duct? Yours looks like it is not stock.
About a minute into the video and WOW that production quality! The close ups look fantastic! Good Job Tom!
what about if your having issues with y axis crashing? will this stop the bed from hitting the frame?
7:12 They likely had the thought, but ultimately decided against it to keep the price a bit lower. Those rails are pricey.
Some recent releases from Chinese market participants might match a better price/quality balance. You simply don't need the HiWin precision when other parts of your gear don't meet the same precision level. Still have to see a 3D printer with a cast mineral concrete bed... :)
🔴"ahh, it's not perfect. . . ." 🤔 I feel you there 😂.
"There is no room for inaccuracy" looks like you have loose hiwinas so there is still room for inaccuracy.
Hiwin carriages are divided into several types in this respect, one has a clearance (smaller balls), the other type does not have this clearance but requires more powerful motors.
Look on the box ZO, ZA, ZB is this parameter.
13:57 "while this last print is going..." ehm... Tom we can see the finished third print in front of you :D
That's because it's a timelaspe recording put in a picture in picture placed in after just to show you it printing. Does not mean it was not the actual print :D
@@brianwild4640 But the print wasn't going when he said it was. That was the dry humour Pouya was going for. Do you always come in when someone makes a joke and tell everyone "well technically...."?
Krytern yes I do
Now the question is: Are you leaving them on, or switching back to the original rod setup?
Why would he switch back?
@@emmettmartin2639 Because he said he preferred them before it was changed? So wouldn't it make sense he might consider switching them back? Come on this isn't rocket science.
The best way to fix the inconsistent extrusion problem (which i assume is the cause of your issues based on your description) I’d suggest getting the bondtech upgrade for the mk3, which uses the original bmg geared style extruder. A lot of users had this issue, and fixed it with this upgrade.
Those Z axis artifacts you're talking about may be related to the bed's temperature control. The bed expands and contracts while is trying to keep the temperature constant, thus changing the top surface height. You should check your BED PID values although it may not improve your results.
I've been trying to understand the inconsistency issue(s) of the Mk3 for months now, read countless forum posts and asked the 602 community in discord (which I can recommend btw).
First of all I installed a reverse bowden as suggested in the video too, and it really helped a lot. Mind, that you don't need to minimize slop here, so a 3mm inner diameter/4mm outer diameter PTFE tube works wonderfully!
Everything else probably comes down to the extruder itself. Many people reported significant improvement after installing a geared extruder like the Bondtech upgrade. Although a bit pricey it also reduces weight and extruder motor temperature, which on top of that can't be transferred to the actual gears and with that the filament anymore, so it won't soften. Prusa actually uses this method in their Pursa Mini printers now, which I find somewhat ridiculous...
Another thing of course is heat creap which causes the filament to stick slightly on its way to the nozzle and therefore causes layer inconsistencies. Swapping the silent but weak noctua fan for one with higher static pressure like models by Sunon seemed to help a lot by keeping the cold end, well... colder. So these are the most important upgrades I'm planning to install next.
Hope that helps some people =)
I always thought these HIWIN rails need to be supported over their whole length...🤔
Yes!
And they should be mounted to honed or finished surfaces, meaning cnc milled, precisions fitting edge!
Even a aluminum extrusion frame has a large deviation compared to the tolerances required for these rails to funtion to full specs!
I guess it prevents them from bending if you do that, but I'm not sure it's strictly needed. Also if you fix it to a different material technically it could bend depending on temperature.
Totally. They flex in the middle. The kit should include a shim for the middle sections.
@@StrathpefferJunction Then you can add supports and shims for each hole. I would have expected to see Tom using a dial gauge to show any before / after effect. They cost about 15 Euros in an electronic version, the purely mechanical fashion less than 9 Euros, when I looked last week. And you can use them the rest of your life.
Ulrich Kliegis Tom has multiple gauges as you’ve described which he has used in other videos.
Are there any backlash settings in the original that should be removed when applying this upgrade?
My heart is breaking with all that power drill tightening
M3 screws, through a 3D printed plastic adapter and the rails are supported only on the ends, so...it doesn't matter anyway :D
Back in July when I did upgrade my Prusa MK3 to linear rails, it cost me under $40 bucks not 200 Euros. Print quality stayed great but the lower noise level of the heat bed was well worth doing it. Also you can gain up to 15mm or Y travel if you want it and more Z if you want it but that will stop the Self tests from working so I kept my travel the same.
I love this, I learned a lot. I wish you would still show us the more technical side of 3D printing and not so much of the here's where I can go and here's what I can do side of it all. I am not trying to bring your channel down, I have learned a lot but I love the old stuff and wish you would do more in that aspect.
Hello Thomas,
Do you think using a "thread locking product/glue " may help in these circumstances. As they are often used in high vibration machinesry to prevent loosening. Apologies if this has been asked before.
A great video, I like the end result that spending a lot of money may not make much or any difference, but , many of us enjoy the hunt
Thanks for the info... I have been waiting for a linear rail version of the Prusa printer for a long time. I think it may have been beneficial to print a simple test cube. That way you can see how much effect you are having on the Y axis.
Cheers,
Greg
I floors me that time and effort was taken to reduce 'wobble' in the wrong place.
No matter how rigid the frame, rails, table, floor, building, Earth, there is a weak link right under to the model!
Springs.
They are a safety device to prevent damage, until you have learned enough to prevent nozzle-strikes!
Put the leveling knobs where the springs lived.
Install lock-nuts where the leveling knobs came from.
Mechanical Leveling becomes a truly 'one-time' event.
Level opposite corners with the knobs, then lock them down with the lock-nuts.
Never adjust one knob by itself!
Once you have 'A' and 'C' locked down, 'B' and 'D' are next.
Never ever ever ever ever ever 'level' just one corner, you are warping the plate!
Three points define a plane, and there are four points attached.
What happens to the shape of that plane if only ONE point is moved?
Warping.
And we don't like warping.
Doesn't matter if it makes that corner 'right', it is inducing mechanical stress for the other three corners.
Adjust opposite corners as a pair!
One goes up, one goes down, until they are both 'perfect'.
Only then can the other two be adjusted in the same way.
Anycubic MEGA X, Mingda Rock 3 Pro.
No springs, no adjustment to bed in 100's of hours of printing.
Take the printer apart, put it back together...don't even have to check leveling!
It just works.
Robert is you parents sibling.
From my experience, the belt tension is the biggest contributor to Y axis problems on MK3. Cranking it up helps constrain the bed more than fiddling with the rails.
What I'm thinking about doing, at some point in the future, is to swap the X axis rods for a rail. The print head is rather heavy and the entire assembly is plastic and thin rods, so there might be some play in there.
Yes. From years of experience with home-brew plotters , engravers, cnc and a 3D printer , keeping the belt resonance under control is vital (I built a wire drive plotter once , it rang like a guitar string , wild resonance!) adding a couple of idler wheels (or even long slides) on the long return run can help . Too much tension is as bad as too little - it really a case of observing and making adjustment s to kill any bad resonance.
Getting rid of the z axis artifacts fully is near impossible tbh
Moving belt mounting point 3mm higher also makes Y movement just slightly less uniform
Ah yes, the tool to fasten RC Car wheels at 3:23 . I also use mine as default hex nut fastener for small ones. :D
Hey Tom,
First thanks for your videos. They are much help! Could it be that the issue of ringing is more pronounced because the lack of slop in the bed?
Could you point me to a video about the calibration of a Anet A8 axis?
what is the larger printer to the left??
I expect the difference to be highlighted by larger prints where the mass creates more kinetic issues. Perhaps loading the linear rail with a 1lb weight while printing smaller test parts like you did would be more illustrative of the linear rail performance.
I printed PETG bearing blocks for my bed and it's near rock solid, maybe 0.2mm wobble up and down under force. And prints look better than before.
Great, high-quality video tutorial + review. Love it! Also, the ad-sponsor + print time lapse was really slick. Well done all around!
It is a pity that the kit does not have 2 milled aluminium plates to fully support those beautiful rails.
Any chance that the wobble is applying a naturally reduced jerk, and that by reducing jerk on y-axis you'll get better results?
Hi Thomas, a bit off topic but have you tried the ultra 316 stainless filament from BASF? You mentioned filament development in the meltzone podcast, just wondered if you had tried this ...I’d be interested to see how it got on and whether it is possible to debind and sinter at home?
If the hypothesis is that belt springiness is causing the ringing artifacts, then would reducing acceleration/deceleration be an easy fix at the expense of some print time?
Does anyone know the lenght and width of these linear rails?
in my opinion, mounting the rails like this(not supported/screwed in along the entire length of the rail) takes away one of the major advantages of linear rails in comparison to smooth rods and linear bearings. now the rail itself can flex/rotate
Hi Thomas! What about noise? Do these reduce the noise profile?
I'd love to see you test/review custom extruders for the MK3S, for example the 'skelestruder' and the like.
Add some cork feet or a thick rubber mat under the printer to reduce resonance 'ringing' on the prints. you can also add them between the stepper motors and the stepper mounts to reduce it as well.
Since the bed is over-constrained and causes ringing in the system do you think adding rubber spacers underneath the u-bolt nuts would help to alleviate 1. some of the excess ringing, and 2. the wear of the textured surface over time? Of course you would have to use the same torque value over each nut to ensure consistent tightening.
I would be curious so see the results. These would be similar to rubber motor mounts to reduce vibration in the entire system. Thoughts?
Thanks for the video! I was considering this upgrade until I watched your review. Even though the Y-axis does not provide any benefit with linear rails, would it be advisable to consider the Z/X-axis? Maybe to ease the z-wobble, obviously, more work would be required to re-design the printed parts.
If u install clean and adjust properly and grease the blocks the improvement would be way better he didn't align the rail properly for one and two they need to be greased with a synthetic grease such as super lube they will out perform and other motion system i installed hwin mg linear rails on my x axis and y axis on my cr10s and I have gotten way better prints than with the stock setup
How many takes did it take for you to get through that first 5 second mouthful?
How do you know unless you print the exact same file all three times? And how can you be sure that the 3d printed parts in the Prusa aren't introducing some flex?
Why did you leave a gap between the rail and aluminium frame?
Some of us printing visor headbands for health services are seeing splits down the middle of prints due to backlash. They occur on curved narrow strips sliced with lots of walls so they are 100% filled without using infill. Where the walls meet in the middle we get splits as each side is printed in opposite directions. Would be nice to know if linear rails have less backlash than other designs.
With regards to the loss of height that 3mm is actually within the design tolerances of th MK3. You could combine this upgrade with an upgrade to the MK3S which would get you the height back. Another way to gain height back is to use the full volume volcano modification with which when fitted with the standard ED3 heaterblock with out the standard height adjusters would gain you 8.6mm.
You should start by acknowledging that the stock Prusa extruder and Noctua fan provide insufficient cooling for the v6 heatsink, and swap out that fan for a more powerful one, ie one that has a better static pressure rating. Prusa has also published newer revisions of the extruder which you should definitely upgrade too, or even look into other extruder designs provided by the community, if you dare try them. This has been recognized by many people as one of the main cause for the layer misalignment artifacts that you mention at the beginning (but were not inclined to acknowledge when the MK3 first came out)
I also think it would have given one less argument against this experiment if the exact same model had been used in the test prints. I understand the feature difference is minimal, but people will always get you on the fine detail, and in the spirit of scientific process I think this has value.
Which filament did you use???
Interesting video. I wonder if the results would have been different or more clear if the test model were more challenging - those planters are cute but look pretty easy to print.
it satisfied me so hard that you are using the bosch professional line ....
I’m really glad I watched this - I just put my order in this morning and was trying to find any upgrades I could install while building up the printer. As someone who works with industrial CNC machinery, it’s hard to look at 3D printed parts supporting the main axis, but clearly that’s not a bottleneck in performance!
Have you played around with any of the complicated analysis tools that use a print head accelerometer to tune motion on the fly to negate ringing and ghosting?
nice sweater. gives video good feel.
At maker faire I saw a screw-drived printer (used instead of belts). I guess a screw drived XYaxis is quite slower, but could it be an improvement in terms of quality?
great video boss. learned a lot as always. i think i might add this in: resonance/vibration is a frequency based phenomena. i find you need to dampen low frequency wobles, and also dampen high frequency wobbles. i think the looser holdey guys reduced the high frequency wobbles, but compromise accuracy. my 2 cents would be to find a way to dampen the high frequency vibrations in the stiffer holdey-guys. cos ultimately you want more precision and you get that from a no-move bed. i think the losey-holdey guys inaccurately solved the high-frequency wobbles problem. it would be cool to accurately reduce those high frequency wobbles.
Hey Tom, can you tell me whats the name of the soundtrack starting at 13:52? Cheers
Would I put shaping improve ringing?
Cool Vid, Thanks!
Ringing has nothing to do with the linear rails, but the linear rails expose the weakness and compromise with most 3D printer designs. There are a couple things that will affect the resonant frequency of a machine - its rigidity, and the inertia ratio (the ratio of the inertia of the load and inertia of the motor.) As to rigidity, probably the polar opposite of a Prusa frame would be an epoxy-granite frame with linear rails and ballscrews, or ACME or trapezoidal leadscrews and anti-backlash nuts. I also believe the belts can act as shock absorbers of sorts, but they only mask some of the underlying problems with designs like these. As to inertia ratio, having a too high inertia ratio can also lower the resonant frequency of the machine. One way of lowering the inertia ratio is by gearing down, which lowers the inertia of the load by the square of the reduction ratio. The only problem with that potentially is that the motor speed has to be increased by the gear ratio to reach the same speed. The big problem with direct-drive belt designs is that the pinion acts as a gear increaser, since one turn of the stepper will move the load the diameter of the pinion times pi. As just as the inertia of the load decreases with gear reduction, it increases with a gear multiplier. The other way of lowering the inertia ratio is to use a stepper with a higher inertia - a larger stepper. Changing to a less aggressive acceleration/deceleration setting can help as well.
This is why I am subscribed to this channel.
Despite there being no apparent quality benefits I’ll be doing this upgrade soon in the hope that it will get it back to somewhat quiet operation. The Y bearings on my MK3 have become increasingly loud in the last couple of months (after only ~150 h of printing) to the point where I’m afraid of keeping the neighbors up.
I'm curious about linear rails for this same reason, and also have insanely loud Y bearings after only a couple of months
I would test a better spool holder. The resistance of the spool has negative impact and x gantry wobble. I have found that on a direct drive it is noticeable and you touched on it.
Willyminime covered every mechanical issue that should have been addressed. One thing you highlighted was using the standard settings for all three tests. This in itself, is a testing flaw if the goal is to improve the precision of the model. In order to take advantage of a fully constrained and rigid environment, the settings need to be adjusted to account for the increased accuracy and coordinate consistency. The print settings of the model should now be able to leverage maximum performance - if the coordinates of both the X and Y axis are perfectly aligned during the entire process.
The linear rail upgrade to the platform, using the exact same settings for all three models, *proves* how badly the printer is when using *default* settings after the linear upgrade. Perhaps you should run another test and see if your results improve. I'm betting they will.
The mk2.5 upgrade kit come with a drill bit and a holder so you can drill out the holes for the zip ties so you can use u bolts.
What was the bed hitting into?
Tom - the benchmark of honest reviews. Thanks for doing what you're doing.
@Bubz of Steel That's a valid point. However, from my own experience I can say that sometimes it's difficult to take a camera picture of a print irregularity. Especially with light-colored filaments.
I'd say you don't need to take his word - you can test it yourself and see if you are going to get the same results.
So far, from my experience, when I've tested Tom's recommendations I had success.
So for me, he is a benchmark. Feel free to put your trust into any other person.
I was wondering if you and anyone else reading this could get rid of the z artifacts or at least figure out what causes them? All the printers I've tried out show those artifacts. They're not easily visible as you described but can definitely be seen when you look at the surface at an angle.
Some of that ringing could be related to the mount arrangements for the Y axis belt drive system. Both ends are at the center of a flexible beam. There is no solid support below the belt from the back to the front of the printer. I had the vibration on my Anet A8 which has similar but plastic construction. I mounted a threaded rod below the belt tied in at the front middle and back. No more vibration on in the print.
The benefit of profile linear rails is they can be mounted on a strong support beam! They ARE NOT designed to be used floating like this.
Those circular bearing rails actually have very tight tolerance, fully enclosing the rail, the downside is just they are unsupported.