Re: Threaded Rod vs Pitch September 03, 2017 07:02AM |
Registered: 10 years ago Posts: 14,672 |
Quote
Dark Alchemist
One thing the Dentist mentioned above is dead straight they will lose sync but according to Prusa just slam Z all the way up until you hear the motor(s) doing the ratatatatat sound for a few seconds as it will not hurt the motors and both motors will be back in sync. This is his way he tells everyone to do it on his MK2 series of printers.
Re: Threaded Rod vs Pitch September 03, 2017 10:51AM |
Registered: 11 years ago Posts: 1,277 |
That is the whole point is that on a Prusa 2 motor design (I am sure all of them are like this) that they share the same driver. In a real world situation it would use separate drivers and have some precise way to drive both to precision but the costs would rise substantially. Having just an ordinary endstop on each Z side (in a dual controller setup) would not suffice as I found they bounce and a mechanical switch is only good to the hundredths digit (some to the tenths). Now I loved when I changed over from a mechanical endstop to my home made magnet as it is so precise and that might work in a two motor setup but with auto bed sensing (ABL) that wouldn't work.Quote
dc42
Quote
Dark Alchemist
One thing the Dentist mentioned above is dead straight they will lose sync but according to Prusa just slam Z all the way up until you hear the motor(s) doing the ratatatatat sound for a few seconds as it will not hurt the motors and both motors will be back in sync. This is his way he tells everyone to do it on his MK2 series of printers.
Alternatively, if the Z leadscrews are driven by independent stepper drivers and you have a Z probe, you can probe the bed and use firmware to adjust the leadscrews to level the bed. RepRapFirmware had this functionality, and I've heard that Repetier has it too.
Re: Threaded Rod vs Pitch September 07, 2017 07:19AM |
Registered: 6 years ago Posts: 1,007 |
Re: Threaded Rod vs Pitch September 07, 2017 09:18AM |
Registered: 11 years ago Posts: 1,277 |
Three motors for Z? OUCH. Which one does that?Quote
MKSA
There is a simpler, cheaper way, just ONE stepper, one belt, one pulley per leadscrew. No coupling that introduces wobbling. This two steppers config is a DESIGN FLAW. Yet, people keep using it, poorly justifying it, keep reinventing unsatisfactory if not blatanly wrong ways to circumvent it etc.... Worse, others than the Prusa are afflicted by this, some even worsening it by using THREE motors plus leadscrew !
Re: Threaded Rod vs Pitch September 07, 2017 10:59AM |
Registered: 10 years ago Posts: 14,672 |
Re: Threaded Rod vs Pitch September 07, 2017 12:27PM |
Registered: 6 years ago Posts: 1,007 |
Re: Threaded Rod vs Pitch September 07, 2017 12:30PM |
Registered: 6 years ago Posts: 1,007 |
Re: Threaded Rod vs Pitch September 07, 2017 02:01PM |
Registered: 11 years ago Posts: 1,277 |
The thing is we are talking about the setup all of these systems use which is two motors one cup, errr driver. In a perfect world 3 motors and 3 separate controllers would rock and precisely for the reason you mention.Quote
dc42
Three leadscrews driven independently plus a Z probe allows you to perform automatic bed levelling (and I really do mean bed levelling, not bed compensation). Three leadscrews driven neither by independently-driven motors nor by a single motor and belt drive gives twice as much to get out of sync as two leadscrews does.
If it was done with separate motor controls then it would be wonderful as it could do an actual bed level instead of compensation, as DC42 mentions, but that is not what we are talking about here as they all share the same controller which is beyond retarded.Quote
MKSA
Quote
Dark Alchemist
Three motors for Z? OUCH. Which one does that?
On Thingiverse, reinvented regularly for CoreXY, H bot ... machines. You can't tell it is wrong, they take it personally
Re: Threaded Rod vs Pitch September 07, 2017 02:12PM |
Registered: 11 years ago Posts: 5,780 |
Re: Threaded Rod vs Pitch September 07, 2017 02:55PM |
Registered: 11 years ago Posts: 1,277 |
We all know where you are coming from after all of these years. Hell, make the damn thing 1,000 kilogram that requires a special concrete slab that was engineered dead flat and none of this would be needed.Quote
the_digital_dentist
I have noticed that the 3D printing community as a whole exhibits a propensity for overly complicated solutions to 3D printing problems. Why use solid construction and a flat bed plate when you can throw a bunch of motors/drivers, screws, sensors, power supply, and software at the problem? There's no cost benefit analysis done to figure out whether it might actually be cheaper to build the thing solidly instead of using a bunch of active measures to fix the problems that cheesy construction creates. People would rather spend money on fixes for problems than on preventive measures. No one seems to care about the reliability of the proposed solutions, either. If it looks good in a youtube video, it must be good!
Re: Threaded Rod vs Pitch September 07, 2017 03:55PM |
Registered: 10 years ago Posts: 14,672 |
Re: Threaded Rod vs Pitch September 07, 2017 04:25PM |
Registered: 11 years ago Posts: 1,277 |
See, what he says is right but not practical as well due to costs, weight, etc... Sure, grab a Bridgeport that can weigh 500-1000 kilogram and it would make one hell of a 3d printer but would be slow as hell too but it would be dead flat. Having a tooling plate is all nice but I have seen tooling plate buckle, and warp, over time when applying 450-700 watts from heating elements too and that was with Mic 6 so far from cheap and even a Bridgeport has to be made true every six months to a year and, as I mentioned earlier, weight close to 500-1000 kilogram.Quote
dc42
Digital dentist, you appear to me to be confusing using mesh bed compensation (often incorrectly called mesh bed leveling) to compensate for beds that are not flat and gantries that sag, with using multiple independently-driven leadscrews to get a flat bed level - as an alternative to using manual levelling screws and a belt drive to keep the leadscrews synchronised.
If I were building a printer with a bed moving in the Z axis, I would probably view independently-driven leadscrews as a simpler solution than a belt drive, because I am more comfortable with electronic engineering than mechanical engineering. I guess the reverse is true for you. What I think we are both agreed on is that having multiple motors without independent control and a Z probe is the worst solution.
Re: Threaded Rod vs Pitch September 08, 2017 01:10AM |
Registered: 11 years ago Posts: 5,780 |
Re: Threaded Rod vs Pitch September 08, 2017 01:39AM |
Registered: 11 years ago Posts: 1,277 |
Re: Threaded Rod vs Pitch September 08, 2017 03:57AM |
Registered: 6 years ago Posts: 1,007 |
Quote
Dark Alchemist
The thing is we are talking about the setup all of these systems use which is two motors one cup, errr driver. In a perfect world 3 motors and 3 separate controllers would rock and precisely for the reason you mention.Quote
dc42
Three leadscrews driven independently plus a Z probe allows you to perform automatic bed levelling (and I really do mean bed levelling, not bed compensation). Three leadscrews driven neither by independently-driven motors nor by a single motor and belt drive gives twice as much to get out of sync as two leadscrews does.
If it was done with separate motor controls then it would be wonderful as it could do an actual bed level instead of compensation, as DC42 mentions, but that is not what we are talking about here as they all share the same controller which is beyond retarded.Quote
MKSA
Quote
Dark Alchemist
Three motors for Z? OUCH. Which one does that?
On Thingiverse, reinvented regularly for CoreXY, H bot ... machines. You can't tell it is wrong, they take it personally
Re: Threaded Rod vs Pitch September 08, 2017 04:07AM |
Registered: 6 years ago Posts: 1,007 |
Quote
Dark Alchemist
We all know where you are coming from after all of these years. Hell, make the damn thing 1,000 kilogram that requires a special concrete slab that was engineered dead flat and none of this would be needed.Quote
the_digital_dentist
I have noticed that the 3D printing community as a whole exhibits a propensity for overly complicated solutions to 3D printing problems. Why use solid construction and a flat bed plate when you can throw a bunch of motors/drivers, screws, sensors, power supply, and software at the problem? There's no cost benefit analysis done to figure out whether it might actually be cheaper to build the thing solidly instead of using a bunch of active measures to fix the problems that cheesy construction creates. People would rather spend money on fixes for problems than on preventive measures. No one seems to care about the reliability of the proposed solutions, either. If it looks good in a youtube video, it must be good!
Re: Threaded Rod vs Pitch September 08, 2017 05:11AM |
Registered: 10 years ago Posts: 14,672 |
Quote
the_digital_dentist
I can definitely see the value in mesh compensation in large machines in which keeping everything flat and level enough to print is impractical. In hobby-size machines I just don't feel like it makes sense when it isn't particularly difficult or expensive to build the machine so that the bed and X axis stay flat and level enough to print on without frequent adjustment. The sort of things you do in the construction to make the machine stable also contribute to print quality, and consistency. Solid construction is generally more reliable than active solutions to the bed leveling/flattening problem, and when the inevitable failure occurs, much faster and easier to understand and repair.
...
System reliability is a function of the reliability of each part of that system. Two parts that make up a system, each with 90% individual reliability,result in 81% system reliability. Now imagine a cascade of 3 motors and their cables and connectors, 3 drivers, a power supply, a sensor and its cable, and software running on the controller, each with less than 100% reliability assembled as a system (actually, that just about doubles the complexity of the whole printer, which requires 3 motors, drivers, cables, etc. to move the mechanism). How reliable can/will it be? How does that compare to the reliability of a rigid structure held together with bolts and driven by a single motor? 3D printing is an inherently unreliable process due to the complexity of the mechanism and the the vagaries of molten plastic of unregulated composition. I prefer to keep the mechanism simple because I believe doing so makes it more reliable. My experience with my own and commercially produced printers at the makerspace tells me that my approach has value. Maybe you have experienced something else.
Re: Threaded Rod vs Pitch September 08, 2017 02:42PM |
Registered: 11 years ago Posts: 5,780 |
Quote
Dark Alchemist
Tooling plate that is 6mm thick and has 500 watts shoved at it (300 sq mm) will distort over time and all I ever hear is to just use the largest layer height you can for the first layer which, to my ears, is just a bandage to an issue.
Re: Threaded Rod vs Pitch September 11, 2017 08:38PM |
Registered: 11 years ago Posts: 1,277 |
I see you use reddit as turn_n_cough. Fact is I disagree because a bed costs me around 40 dollars on my 300x300 and it isn't even the real Mic6 it is from Alpha metals so costs about 1/3 to 1/2. 40 dollars every 2-3 years is not acceptable to me and is to you so we differ in what our pain threshold is at.Quote
the_digital_dentist
Quote
Dark Alchemist
Tooling plate that is 6mm thick and has 500 watts shoved at it (300 sq mm) will distort over time and all I ever hear is to just use the largest layer height you can for the first layer which, to my ears, is just a bandage to an issue.
What units of time are you thinking in terms of? I've had a 450W heater on SoM's 12.5" x 12" x 1/4" tooling plate bed for the last 3 years of daily printing, and as far as I can tell, it hasn't warped or distorted. Prints still stick reliably over the entire surface. I think if it did warp or distort, I'd just replace it another piece of tooling plate. If I get >3 years use out of a bed plate that costs <$15 (random rack at Howard Precision Metals), I can live with that. How many dropped, cracked, or chipped glass plates, and at what cost, will the average printer be replacing in that time?
The only place I've seen anything about thicker first layers is a tool-tip in slic3r. I believe that is aimed at people with the typical, sheet metal and PCB beds that bow when heated and are "leveled" with 4 screws. I always print with the same first layer thickness as the rest, typically 200 um, which works reliably from edge to edge. But you're right, I'd probably have some trouble printing a 100 um first layer over the entire bed surface. Thank goodness I've never needed to do that!
Re: Threaded Rod vs Pitch September 12, 2017 10:28AM |
Registered: 11 years ago Posts: 5,780 |
Re: Threaded Rod vs Pitch September 12, 2017 02:37PM |
Registered: 11 years ago Posts: 1,277 |
40 dollars (includes shipping) and IS cast tooling plate just made by another metals company. Here it is [www.midweststeelsupply.com] ATP5.Quote
the_digital_dentist
Let's see if I understand. You paid $40 for something that isn't cast tooling plate which is 1/3 to 1/2 of something (?) else, and it's warping because of the heat, therefore, my MIC6 tooling plate must be warping even though I've been using it for 3 years and prints are sticking like the first day it was on the machine. I'm having trouble following your logic.
Ebay has plenty of vendors selling MIC6 and other cast tooling plates. Here's the very first one that comes up on a search for MIC6 aluminum: [www.ebay.com] $25 for the plate + $15.32 shipping gets you a 12"x12" x 1/4" MIC6 plate for $40.32 all in. Yes, it's a bit steep, but not everyone lives close to Howard Precision Metals, and you only have to buy it once.