http://forums.reprap.org/read.php?177,767087,779977#msg-779977
ok so i screwed up. i didn't do a full force-analysis of the plotter design concept, and it was only when i tried turning each of the motors that i realised that with a double pulley system the force on one is double that of the other. with the two pulleys being separated by 320mm that means that just turning the motor *will* cause the X/Y-ends to "shear".
this is... bad :)
fortunately someone posted a few days ago that they have a concept which they've named "Edge-XY" - similar to CoreXY except the single X-Gantry (the horizontal bar of an "H") is replaced with *dual* X/Y (cross) rods. now, what's particularly fascinating about Edge-XY is that an important and previously under-appreciated design flaw of CoreXY is completely sorted!
also very fortunately, the EdgeXY concept is very very similar to what i was trying for the Riki200 plotter concept... so i can convert over to EdgeXY with very little extra work. about 16 hours of re-printing parts but about... a week's worth of CAD design effort. which isn't too bad for correcting a major design cock-up :)
i will try to work in the double-pulley system into the redesign: due to the fact that the belts are fixed onto the moving X/Y-ends of the EdgeXY it would be a 3x force multiplier not a 4x one, but also the forces (the pulleys) would be *on the same blocks* (separated by about 20mm) and would be force-balanced.
made that mistake once already.... not doing it again :)
l.
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On Tue, Jul 25, 2017 at 10:32 AM, Luke Kenneth Casson Leighton < lkcl@lkcl.net> wrote:
fortunately someone posted a few days ago that they have a concept which they've named "Edge-XY"
Actually, they called it EtchXY -- probably in reference to the etch-a-sketch toy.
similar to CoreXY except the single
X-Gantry (the horizontal bar of an "H") is replaced with *dual* X/Y (cross) rods. now, what's particularly fascinating about Edge-XY is that an important and previously under-appreciated design flaw of CoreXY is completely sorted!
I'm not convinced it's so much better -- think you've overlooked something in your analysis. (I'm going to register and post a reply in that reprap forum thread.)
But even if I'm wrong about the rigidity... why bother? The thing that made CoreXY special is the combination of non-moving motors with a simple (thus cheap and lightweight) gantry. Once you've committed to the more complex (thus expensive/heavy) dual-gantry setup, as seen in both your Riki200 design and Etch-XY, I don't see any benefit to be had from long timing belts wrapping around a half-dozen pulleys; there's a much simpler way to drive each axis independently with non-moving motors.
For the X-axis, you put two shafts parallel to the Y-axis, at the left and right sides. They each have two timing belt pulleys (at the top/bottom ends), supporting one loop of timing belt to drive each green block. One shaft is coupled to the motor, the other is an idler.
For the Y-axis, exactly the same thing, rotated 90 degrees.
Or perhaps you've considered this and aren't doing it because of construction details. Etch-XY has 8 short shafts (idlers on the fixed chassis -- not counting the motors or idlers on the moving gantries), all with parallel axes (Z-axis), while the simple solution has 4 long shafts in pairs (X-axis and Y-axis) -- it seems simpler and easier to me, but then I'm a machinist by trade, so I'm not used to thinking in the constraints of 3d-printed and/or laser-cut construction...
Benson Mitchell
On Tue, Jul 25, 2017 at 6:20 PM, Benson Mitchell benson.mitchell+arm-netbook@gmail.com wrote:
I'm not convinced it's so much better -- think you've overlooked something in your analysis. (I'm going to register and post a reply in that reprap forum thread.)
that would be superb
But even if I'm wrong about the rigidity... why bother?
pulley system - doubling.
mass is also equal for x and y.
corexy has the weight of the x-gantry. moving in Y has more inertia that X.
speed for this design i intend to try 500mm/sec and greater. that's TEN times what most people would ever conceive of running a 3D printer at. the ultimaker-2 is only rated for a maximum of 250-300mm/sec.
The thing that made CoreXY special is the combination of non-moving motors with a simple (thus cheap and lightweight) gantry. Once you've committed to the more complex (thus expensive/heavy) dual-gantry setup, as seen in both your Riki200 design and Etch-XY, I don't see any benefit to be had from long timing belts wrapping around a half-dozen pulleys; there's a much simpler way to drive each axis independently with non-moving motors.
not "and guarantee rigidity and add a pulley doubling system and also guarantee equal mass distribution" as well.
For the X-axis, you put two shafts parallel to the Y-axis, at the left and right sides. They each have two timing belt pulleys (at the top/bottom ends), supporting one loop of timing belt to drive each green block. One shaft is coupled to the motor, the other is an idler.
i know the sort of thing: i've seen it in use: it's used in the ultimaker-2 and also in an open design pick-and-place amachine. the amount of force on the belt is considerable. with the EtchXY design the force on the belt is halved due to the pulley system.
For the Y-axis, exactly the same thing, rotated 90 degrees.
by the time it's all assembled, the 2 belts, 4 pulleys, 4 shafts, then 4 sets of rails/rods, it really does add up very quick in terms of ccomplexity. then you have to CAD design it, make sure that everything fits, that's a month's work right there...
Or perhaps you've considered this and aren't doing it because of construction details. Etch-XY has 8 short shafts (idlers on the fixed chassis
M5 16mm bolts, 2 M5x18mm washers. $0.02 each. 625 bearings. saves a lot.
-- not counting the motors or idlers on the moving gantries), all with parallel axes (Z-axis), while the simple solution has 4 long shafts in pairs (X-axis and Y-axis)
plus 4 pulleys and 4 sets of rods/rails
-- it seems simpler and easier to me, but then I'm a machinist by trade, so I'm not used to thinking in the constraints of 3d-printed and/or laser-cut construction...
pick-and-place, cnc, etc it's all the same principle. except CNC needs huge force and precision, whereas 3D filament deposition needs speed and precision. CNC typically uses backlash-free screw-drives, low pitched, with planetary gearboxes to get the forcee and accuracy.
i'm looking for a trade-off which maximises mm/sec/$ so a weird combination of ways to increase speed without compromising rigidity, using components that are considered "budget" but are not "cheap and nasty", they're just "cheap" :)
so adding pulleys to reduce the force on a standard "cheap" 6mm GT2 timing belt, that's important, because now you can try going twice as fast but still use... cheap 6mm GT2 timing belt. otherwise you would need to use GT3 and 8 to 10mm, that's no longer "cheap".
make sense?
l.
On Tue, Jul 25, 2017 at 2:28 PM, Luke Kenneth Casson Leighton <lkcl@lkcl.net
wrote:
But even if I'm wrong about the rigidity... why bother?
pulley system - doubling.
Okay, but you aren't getting that with EtchXY (see below). And you can add it to my proposal just as easy.
mass is also equal for x and y.
Which is also true for my proposal.
corexy has the weight of the x-gantry. moving in Y has more inertia that X.
Yeah, I'm not suggesting CoreXY -- I do get why that's quite unsuitable for what you're doing.
The thing that made
CoreXY special is the combination of non-moving motors with a simple
(thus
cheap and lightweight) gantry. Once you've committed to the more complex (thus expensive/heavy) dual-gantry setup, as seen in both your Riki200 design and Etch-XY, I don't see any benefit to be had from long timing belts wrapping around a half-dozen pulleys; there's a much simpler way to drive each axis independently with non-moving motors.
not "and guarantee rigidity and add a pulley doubling system and also guarantee equal mass distribution" as well.
The mass distribution seems fine; motors, shafts, and pulleys are all non-moving. The moving parts are the gantries and extruder platform, all just the same as you have them. Likewise rigidity seems pretty solid, with one belt per block.
As for pulley doubling, it's simple to add. I just didn't go into details because I'd assumed you were willing to give it up, since you're talking about using EtchXY which lacks it.
Instead of anchoring the ends of the loop directly to the moving blocks, just put pulleys there, and bring the end back to the fixed chassis to anchor it. Going back to your original diagram for the Riki200, it's just like the bottom 20% of that diagram, but the belt wraps 180 instead of 90 degrees around those chassis-mounted idlers. (And of course, it's rotated 90 degrees out of the page.)
If that was unclear, say so -- I'll come up with a sketch.
For the X-axis, you put two shafts parallel to the Y-axis, at the left and
right sides. They each have two timing belt pulleys (at the top/bottom ends), supporting one loop of timing belt to drive each green block. One shaft is coupled to the motor, the other is an idler.
i know the sort of thing: i've seen it in use: it's used in the ultimaker-2 and also in an open design pick-and-place amachine.
Ah, good.
the amount of force on the belt is considerable. with the EtchXY design the force on the belt is halved due to the pulley system.
But the force is only halved for the Y-axis in EtchXY. Look closely -- the X-axis is anchored directly to the green blocks, so the accelerating force is just the sum of red and blue belt tension. (The distribution of force between the red/blue belts (50/50 at center, progressively worse towards limits of travel) does help vs some other designs, but that benefit applies to the parallel-shafts system, too.) And given you seem to be building a square printer, you should be accelerating pretty much the same amount of mass around in X and Y -- so you have to design (choose belts and/or limit acceleration) based on the axis without mechanical advantage.
(It would be different if your build volume is way out of square, such that the yellow-block gantry masses twice the green-block gantry -- then you have mechanical advantage right where you need it, so the same acceleration in X or in Y give similar cable tension -- but AFAIK you're not doing that sort of build.)
by the time it's all assembled, the 2 belts, 4 pulleys, 4 shafts,
then 4 sets of rails/rods, it really does add up very quick in terms of ccomplexity. then you have to CAD design it, make sure that everything fits, that's a month's work right there...
Yeah, but you've got all the rails and rods, exactly the same -- it's really just 4 short belts vs. 2 long belts, 4 long shafts vs. many short shafts, and especially the pulleys. I think as a result of whatever misunderstanding has you thinking I'm adding extra rails, you're also overestimating the design work involved to redo it -- it should only be a little more radical than redesigning for EtchXY.
Etch-XY has 8 short shafts (idlers on the fixed chassis
M5 16mm bolts, 2 M5x18mm washers. $0.02 each. 625 bearings. saves a lot.
Wait, 6 of those 8 are tooth-side-in -- and you're still wrapping them around bearings instead of timing belt pulleys? I wouldn't have thought you could get away with that! But if so, that does make a bunch of the savings/simplification I thought I was getting illusory.
-- not counting the motors or idlers on the moving gantries), all with parallel axes (Z-axis), while the simple solution has 4 long shafts
in
pairs (X-axis and Y-axis)
plus 4 pulleys
Actually 8, really (2 per shaft, 2 shafts per axis, 2 axes), whereas I thought you had 10 pulleys all told (two on the yellow blocks, 6 fixed, and 2 on the motors), based on where the belt wraps tooth-side in, whereas really you have... just the two on the motors?
Although, now that I think... hey, if you can wrap timing belts around bearings, so can I!
Keep the drive side (per axis) one long shaft + 2 pulleys on the drive side, but for the idler side use M5 screws/625 bearings just like you're talking about -- so it is just 4 pulleys after all. (Oh, and a couple flexible couplings, or yet more timing belt pulleys, to couple the motors to the drive shafts.)
and 4 sets of rods/rails
Again, you've already got all the rods and rails -- that stuff would really be _exactly_ like you have it. You're "only" redesigning the 4 green/yellow blocks to put the idler axes horizontal rather than vertical (pretty simple, I think), and completely redoing the motor/pulley mount brackets at the 4 corners of the frame (not really simple) -- point is, all the linear rails and rods stay in exactly the same places they are.
I don't think the shafts should be a big deal (Sure, not as cheap as M5 screws, but still can be pretty cheap... nothing fancy, just cold-drawn rods), but I see where the pulleys add up. The one thing that might make it worthwhile is that it dodges the skew problem completely -- each block is completely controlled by one belt.
Perhaps the best answer is to modify EtchXY to give you pulley reduction on both axes? That change is pretty straightforward. But I don't see what to do about the skew problem...
so adding pulleys to reduce the force on a standard "cheap" 6mm GT2
timing belt, that's important, because now you can try going twice as fast but still use... cheap 6mm GT2 timing belt. otherwise you would need to use GT3 and 8 to 10mm, that's no longer "cheap".
make sense?
Yeah, absolutely. I'm sure there are reasons not to gang two or three 6mm GT2 belts on an extended pulley to get more strength?
Benson Mitchell
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Tue, Jul 25, 2017 at 9:27 PM, Benson Mitchell benson.mitchell+arm-netbook@gmail.com wrote:
On Tue, Jul 25, 2017 at 2:28 PM, Luke Kenneth Casson Leighton <lkcl@lkcl.net
wrote:
But even if I'm wrong about the rigidity... why bother?
pulley system - doubling.
Okay, but you aren't getting that with EtchXY (see below). And you can add it to my proposal just as easy.
i keep getting *really* confused by the pulleys in the EtchXY :) example: right motor turns one revolution, left-side-belt from motor gear leading to yellow block is doubled-back... therefore it's a pulley arrangement. green block moves 1/2 speed.
mass is also equal for x and y.
Which is also true for my proposal.
indeed.
The thing that made
CoreXY special is the combination of non-moving motors with a simple
(thus
cheap and lightweight) gantry. Once you've committed to the more complex (thus expensive/heavy) dual-gantry setup, as seen in both your Riki200 design and Etch-XY, I don't see any benefit to be had from long timing belts wrapping around a half-dozen pulleys; there's a much simpler way to drive each axis independently with non-moving motors.
not "and guarantee rigidity and add a pulley doubling system and also guarantee equal mass distribution" as well.
The mass distribution seems fine; motors, shafts, and pulleys are all non-moving. The moving parts are the gantries and extruder platform, all just the same as you have them. Likewise rigidity seems pretty solid, with one belt per block.
As for pulley doubling, it's simple to add. I just didn't go into details because I'd assumed you were willing to give it up, since you're talking about using EtchXY which lacks it.
see above....
Instead of anchoring the ends of the loop directly to the moving blocks, just put pulleys there, and bring the end back to the fixed chassis to anchor it. Going back to your original diagram for the Riki200, it's just like the bottom 20% of that diagram, but the belt wraps 180 instead of 90 degrees around those chassis-mounted idlers. (And of course, it's rotated 90 degrees out of the page.)
If that was unclear, say so -- I'll come up with a sketch.
yes please - can we discuss it on the reprap forum? it's easier as they have the means to upload (and inline) images. upload the file then hit "create link in message" button, hit "preview" to check it...
For the X-axis, you put two shafts parallel to the Y-axis, at the left and
right sides. They each have two timing belt pulleys (at the top/bottom ends), supporting one loop of timing belt to drive each green block. One shaft is coupled to the motor, the other is an idler.
i know the sort of thing: i've seen it in use: it's used in the ultimaker-2 and also in an open design pick-and-place amachine.
Ah, good.
the amount of force on the belt is considerable. with the EtchXY design the force on the belt is halved due to the pulley system.
But the force is only halved for the Y-axis in EtchXY. Look closely -- the X-axis is anchored directly to the green blocks, so the accelerating force is just the sum of red and blue belt tension.
nom, nom, nom, nom.... ah ha! yes! ok so now i know why i was so totally confused: if i looked at one axis i would see a double-pulley system, then looking at the other it wouldn't have one.
ah ha! yes - i know how to fix that: you'd need to put idlers on the green blocks, and have the belt-mount points fixed in each corner (not to the green blocks)
by the time it's all assembled, the 2 belts, 4 pulleys, 4 shafts,
then 4 sets of rails/rods, it really does add up very quick in terms of ccomplexity. then you have to CAD design it, make sure that everything fits, that's a month's work right there...
Yeah, but you've got all the rails and rods, exactly the same -- it's really just 4 short belts vs. 2 long belts, 4 long shafts vs. many short shafts, and especially the pulleys. I think as a result of whatever misunderstanding has you thinking I'm adding extra rails, you're also overestimating the design work involved to redo it -- it should only be a little more radical than redesigning for EtchXY.
i've come up overnight with an alternative, which i'll post on the forum.
Etch-XY has 8 short shafts (idlers on the fixed chassis
M5 16mm bolts, 2 M5x18mm washers. $0.02 each. 625 bearings. saves a lot.
Wait, 6 of those 8 are tooth-side-in -- and you're still wrapping them around bearings instead of timing belt pulleys?
yyyup :)
I wouldn't have thought you could get away with that!
you can ... just about :) surprisingly. it starts to get pretty noisy at high speed though.
... can we move this entirely to the forum? [snipped rest]
Yeah, absolutely. I'm sure there are reasons not to gang two or three 6mm GT2 belts on an extended pulley to get more strength?
cost and space. seen it done - but on an all-aluminium design (CNC machined) where the parts were strong enough to withstand the extra height (double stack of pulleys).
l.
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Wed, Jul 26, 2017 at 11:14 AM, Benson Mitchell benson.mitchell+arm-netbook@gmail.com wrote:
On Wed, Jul 26, 2017 at 2:39 AM, Luke Kenneth Casson Leighton <lkcl@lkcl.net
wrote:
... can we move this entirely to the forum?
You bet. It may be a couple hours before I have a chance to sketch things up, but I'll see ya there.
ok :) i do lots of free-hand drawings with the gimp. honestly if it was easier to sketch it and photograph it i would do that... but i can't be arsed to keep swapping out the memory card.... and put my daughter's colouring pens back in their box :)
l.
On Tue, Jul 25, 2017 at 2:28 PM, Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
pick-and-place, cnc, etc it's all the same principle.
OK, forgive me for going slightly off-topic here, but this whole time, I've been sitting here wondering if you're batshit crazy, or if your 3D printer design will work as well as you say it will work. That's mainly because I do think it's crazy to be designing a machine in 2017 when there are so many existing designs out there that work. I remember your arguments from before as to why, so my purpose of writing this isn't to bring the motivation back up. Originally I didn't really have a leg in the fight, but as I've been looking at the CAD screenshots and build pictures from your recent work, it is actually starting to take the shape of something that I had started to design about a year or so back, for the purposes of SMT pick and place. Looking at the pics at http://forums.reprap.org/file.php?177,file=96492 and http://forums.reprap.org/file.php?177,file=96491 it looks alarmingly similar to what I had originally intended to design. The only differences are what gets mounted on the head, and I probably would have went with Hiwin rails instead of pulleys. There's enough room on that head for cameras, a Juki nozzle or two, and a height touch-off probe.
Differences in 3D printing philosophy aside, I think that this design could possibly be useful for an SMT pick and place frame.
At this point I'm just going to sit here and patiently wait with popcorn in hand and wait until the whole thing plays out. I'm not in any real rush so it wouldn't even be in 2017 before I would start building one.
Anyway, good luck with the whole thing. I still think you're batshit crazy, but in some evil genius way, if you can pull it off.
On Sat, Jul 29, 2017 at 3:22 PM, Neil Jansen njansen1@gmail.com wrote:
OK, forgive me for going slightly off-topic here, but this whole time, I've been sitting here wondering if you're batshit crazy, or if your 3D printer design will work as well as you say it will work. That's mainly because I do think it's crazy to be designing a machine in 2017 when there are so many existing designs out there that work.
*sigh* i know it seems that way but i am not kidding when i say that literally every single 3D printer i've seen has some form of design flaw or is made from materials and parts that are just... too far-out expensive, given that the requirements are to maximise mm / sec / $.
maximising mm / sec / $ has some very _very_ specific implications, that you can either minimise $ or you can maximise mm/sec (or both). unfortunately many of the "minimal $ 3D printers" are so shit that to try to increase mm / sec results in f*****g worse-than-useless quality. aaand unfortunately, many of the high-end 3D printers where $ is high, the amount of $ that went into their construction is completely insufficient to compensate for their $, such that the "mm / sec / $" metric is *WORSE* than that of a cheaper crappy 3D printer!
thus i am therefore looking for something *in between* those two extremes... and i absolutely kid you not, there is *literally* not a single one.
the ultimaker-2: absolute stellar mechanical design, i give it a 100% score for mechanical design rigidity... except it's $2,000 and uses a bowden tube. if you know about bowden tubes (latency/play requiring 4-5mm of retract to compensate!) or have ever had nightmare problems with bowden tubes, you'll know what i'm referring to.
prusa i3 and prusa i3 clones: vertical carriages (almost 100% of them), which are just too shit to even remotely consider. vertical carriages result in the entire head mechanism twisting and bending the rods and the X-ends so badly that the head can actually bounce around, causing both Z and Y variation.
the list just goes on and on, eliminating every single pre-existing design out there.
I remember your arguments from before as to why, so my purpose of writing this isn't to bring the motivation back up.
oh, ok :)
Originally I didn't really have a leg in the fight, but as I've been looking at the CAD screenshots and build pictures from your recent work, it is actually starting to take the shape of something that I had started to design about a year or so back, for the purposes of SMT pick and place. Looking at the pics at http://forums.reprap.org/file.php?177,file=96492 and http://forums.reprap.org/file.php?177,file=96491 it looks alarmingly similar to what I had originally intended to design.
very funny :) well, it's GPLv3+ licensed parametric (python) source code, so you're more than welcome.
The only differences are what gets mounted on the head, and I probably would have went with Hiwin rails instead of pulleys.
there's MGN9C Hiwin rails underneath the X and Y ends. two MGN9C blocks. actually MGN9 was a mistake: i should have made it MGN12 - the MGN9s are actually only about 6.5 to 7mm wide where the 2020 slot is 5.5mm with a 0.5mm curve on each edge.... damn things keep *dropping into the slot* and end up at an angle, pretty much no matter what i do.
this is a pain in the ass, to say the least. but... *sigh*.... it's what i got now.
There's enough room on that head for cameras, a Juki nozzle or two, and a height touch-off probe.
... just. if you don't need fans. which you shouldn't. there's about... 50x50mm of clear space without hitting any bearings or rods, and there's also space in between the bearings @ 25mm x 25mm to give a maltese-cross style amount of space to put "stuff".
Differences in 3D printing philosophy aside, I think that this design could possibly be useful for an SMT pick and place frame.
yehyeh it could.
At this point I'm just going to sit here and patiently wait with popcorn in hand and wait until the whole thing plays out. I'm not in any real rush so it wouldn't even be in 2017 before I would start building one.
well give me a shout as i do want to make one at some point
Anyway, good luck with the whole thing. I still think you're batshit crazy, but in some evil genius way, if you can pull it off.
:)
On Sat, Jul 29, 2017 at 04:04:56PM +0100, Luke Kenneth Casson Leighton wrote:
thus i am therefore looking for something *in between* those two extremes...
Just because it looks sufficiently different that I am surprised to not have seen it mentioned here yet:
(However still at pre-order stage, ``Estimated Delivery: November 2017''.)
Wolfram
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Sat, Jul 29, 2017 at 5:51 PM, Wolfram Kahl kahl@cas.mcmaster.ca wrote:
On Sat, Jul 29, 2017 at 04:04:56PM +0100, Luke Kenneth Casson Leighton wrote:
thus i am therefore looking for something *in between* those two extremes...
Just because it looks sufficiently different that I am surprised to not have seen it mentioned here yet:
PRINT HEAD TRAVEL SPEED Up to 100 mm/s
i'm doing 150mm/sec print speed and 200mm/sec travel speed even on the cheap taobao clone.
l.
On Sat, Jul 29, 2017 at 11:04 AM, Luke Kenneth Casson Leighton < lkcl@lkcl.net> wrote:
*sigh* i know it seems that way but i am not kidding when i say that literally every single 3D printer i've seen has some form of design flaw or is made from materials and parts that are just... too far-out expensive, given that the requirements are to maximise mm / sec / $.
Ehh... How many months have you been at this design so far? You could have bought some crappy printers, taken a few months to print the parts, and could have moved on with the other (arguably more important) EOMA68 development and manufacturing stuff. As it sits right now, you've not printed a single production frame, because you're too busy designing a 3d printer. Even after you've made your first one, there are still some sizable risks before you go out and build a fleet of them.
Your "existential 3D printing moments" blog post was on May 16, where you said that with 10 printers, it would take four months of 8 hours a day printing to make these parts. Assume 16 hours per day, that's two (2) months with the same amount of machines. Or, for 24 hours a day (3 shifts), it's now down to 1.3 months.
If I were you, I'd literally be done by now. That's because I would have used "status quo" 3D printers that would have been running and happily turning out parts back in the month of May (possibly even before that). If that 'four month' estimate was for the "fast" machines, then yea, maybe I'd be only halfway done? But then again that's still further than where you are right now. Labor is cheap where you're at. I'd have no issue running a small operation 24/7 if that's what it took. Hell, we did that in China when I was out there.
Maybe you're over-thinking it.
Just sayin' ;)
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Sat, Jul 29, 2017 at 6:38 PM, Neil Jansen njansen1@gmail.com wrote:
Ehh... How many months have you been at this design so far?
although i've pretty massively lost track of time, i think it's been 5 weeks (including parts ordering) which is pretty damn fast for an entirely new 3D printer. for comparison, i was forced to spend an emergency 3 weeks recovering the shit-for-brains taobao clone.
the level of ignorance that's propagated throughout the 3D printing world is stupendously high, neil. and, worse, the fucking idiots who supply 3D printers over here don't fucking well respect the GPL, and, even worse than that, are quite likely to ship you a TOTALLY DIFFERENT SET OF PARTS from the ones you paid money for!
i can't risk even buying some arbitrary off-the-shelf pile-of-crap from a china supplier - done it twice already here and it was utterly pointless.
this really is the only safe way to do it: take advantage of the low cost of parts, and do the design right. it's the only way i'll know i'll get something that will work, not least because if there *is* something wrong i don't have to fucking well reverse-engineer 80% of the fucking parts like i was forced to with this fucking shit-for-brains taobao clone even before *getting started* with fixing the damn problem.
nnnnggggh :)
printer. Even after you've made your first one, there are still some sizable risks before you go out and build a fleet of them.
... which is why i'm happy to take my time doing it.
Your "existential 3D printing moments" blog post was on May 16, where you said that with 10 printers, it would take four months of 8 hours a day printing to make these parts. Assume 16 hours per day, that's two (2) months with the same amount of machines. Or, for 24 hours a day (3 shifts), it's now down to 1.3 months.
If I were you, I'd literally be done by now.
you wouldn't... because the laptop's design is still at the prototype phase. there's several months including redesigning and prototyping the laptop PCBs before that casework redesign work can even begin.
Maybe you're over-thinking it.
i'm not: there's also the fact that the unanticipated costs have eaten into the available budget, making it impossible to entirely fufil the promises made (if this is news to anyone, it's not news: i've mentioned this many times, many many months ago). also mentioned months ago, i am also therefore working on a staggered delivery strategy, and also mentioned months ago i am looking at other projects in order to raise extra funds.
one of those strategies mentioned is to have a second set of designs on a second crowdsupply campaign *using the exact same PCBs and using the exact same LCD as will go into the laptop* (an all-in-one PC). that thus increases the ordering quantities for those parts and thus *reduces* costs [for both campaigns], as well as reduces risk and development costs for both projects.
the 3D printer is an extra arm in that same strategy. it's *not* just being done "because i feel like it".
l.
arm-netbook@lists.phcomp.co.uk
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Wolfram Kahl