Foldable, portable CoreXY (Fusebox derivative) if anyone's interested i'm doing a foldable, portable 3d printer that is based on the fusebox (a corexy design). i will be moving every month for a year, to a different country each time, developing an eco-conscious laptop and i cannot be without a 3d printer. if anyone's interested do contact me. outer dimensions of the box when stowed are 457 x 405 x 150mm. CAD design is being developed here: git clone http://hands.com/~lkcl/foldable3dsandwich200/ and you can take a look. review assistance greatly appreciated. [attachment 74586 sandwich200.assembled.png] [attachment 74587 sandwich200.stowed.png] https://reprap.org/forum/read.php?397,639675,639675#msg-639675 Tue, 21 Jul 2026 18:45:29 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?397,639675,673038#msg-673038 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,673038#msg-673038
IMG_0224.jpg



very slow internet connection here (affected by rain) video to upload of unpacking later, but here's the new plotter carriage with 6x3x2.5mm bearings and 7mm v-rollers printed from Polycarbonate. they're actually a mix of 7.0mm and 7.2mm rollers as i am still experimenting working out what size will result in there being both no play but no binding in the bearings. my feeling is that it's going to be something between 7.05 and 7.1mm which is a bit of a pain.

at the moment with mostly 7.0mm rollers and one 7.2mm roller on each the rods slide reasonably cleanly but i can definitely feel them stalling at different points as they move. this might still actually be okay but i will have to see.

still to print out is the idlers, and still to design is a fan holder. will be going to boston on the 15th and also need to print out a new arrangement for the top to fit cleanly without breaking. so much still to do.
]]> lkcl CoreXY Machines Fri, 10 Jun 2016 07:22:27 -0400 https://reprap.org/forum/read.php?397,639675,671272#msg-671272 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,671272#msg-671272
i need to redo the z-assembly bottom extrusion holders, they stick out far too much. also i think the belt must have been catching on something as it was extremely loose and needed retightening. so much to sort out.

oh, i think i worked out an offset corexy rod arrangement that could fit the removable flex3drive. bit tricky but doable. not horizontal x-rods, not vertical x-rods, but offset in *both* x *and* y.

for the plotter arrangement the 9x5x3mm bearings i was given don't look like they'll work, there is simply too little space. i am likely going to need to use 6x3x2.5mm or 6x3x2 bearings, these go into RC helicopters and RC motors so are actually very high spec and mass-produced so prices should not be completely mad.]]> lkcl CoreXY Machines Sun, 05 Jun 2016 10:55:06 -0400 https://reprap.org/forum/read.php?397,639675,668875#msg-668875 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668875#msg-668875
  • QTY1: rubber bath-mat
  • QTY4: 18in carpet tiles
  • QTY1: 50m duct tape
  • QTY200: packing styrofoam bubbles
  • QTY4: ultra-thick polythene bags
  • ...

it's a 3D printer for god's sake! what the hell are materials like these doing in a 3D printer? oh wait... it's portable, i'm out of time, and it has to be packed in a hurry... :)



just my luck... there wasn't enough time for me to work out where to fit the 2 front lead screws. yes those are carpet-tiles. the rubber bath-mat has been cut in half, and double-sided duct-tape used to stick it to the bottom of the hardboard. the carpet tiles we happened also to have lying around, i haven't time to attach them yet but will do so once i have worked out how to firmly attach them. the nice thing is, all these wooly rubbery materials act as dampening on the hardboard.

that's a 500mm ruler on the top so you can see scale, it's a suit bag we happen to have. i hadn't time to do internal photos as i was packing it up, but i basically dropped styrofoam pieces into the bags that various 3d printer filaments arrived in, flattened them out and used them as internal padding. the pieces move so i will have to work out some time how to make them stick or just find a more suitable material later.

there is a clear need for doing a version 3 of this printer, but what i want now is an experimental design to see how far things can be pushed. can you *really* make a decent compact 3d printer which survives transit on airplanes as normal-sized stowed luggage in the hold? we'll find out - i'll do a video of when it gets unpacked at the other end, to see if i worked out where best to put the foam packaging...
]]> lkcl CoreXY Machines Sun, 29 May 2016 12:07:35 -0400 https://reprap.org/forum/read.php?397,639675,668772#msg-668772 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668772#msg-668772







aaand i'm going to have to stop work on it for a while. the reason is: 625 bearings for double-v rollers are just far too big to fit in the available space. luckily, after speaking to jason from mutley3d, because i have one of the flex3drives he designed, i now know that there exist something called MR95ZZ bearings (9mm OD, 5mm ID, 3mm width). i've tried these out in the CAD and they are *perfect*. in fact, i've been able to undo some of the horrible compromises i was going to put in:



you can see there i've put back the 3rd rail bearing on the y-axis that i had to remove due to lack of space (sort-of bright reddish round things). also, i can now put in much thicker v-rollers, the ones i made for the 625 bearings were.... well, they were pathetic to be honest. cracked at the first opportunity.

what i learned from this first carriage attempt is that the positioning of the roller bearings is critical: they *have* to be evenly spaced. distance between the 2 above and the 1 below *must* be equal. if you put them too close together you get a lever effect which can easily put enough force on the double-v rollers to split them in half. but, because of the oversized bearings i couldn't *put* them equally spaced.

with the 625 bearings they are not only too close to the outside (so can smack into the rod holders) but one on each axis is far too close to the belt bearing holders. by going to MR95ZZ bearings all those problems go away. they can be evenly spaced, i can have 3 per square rod, they can even go a bit further apart to give better stability, and many other things.

one thing you can see on those images, the belt bearing holders actually stick out by nearly 3mm from the carriage. there is a corresponding slot in each of the rod holders for this bearing to fit into! space is so stupidly tight here that i am having to do those kinds of tricks. clearances are literally 1mm in more places than i can count.

y'know... it's so silly, i only need about 1.2 metres of PC or Delrin to make the double-v rollers, they're so small
]]> lkcl CoreXY Machines Sun, 29 May 2016 04:57:45 -0400 https://reprap.org/forum/read.php?397,639675,668311#msg-668311 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668311#msg-668311
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realthor
Is the alu solid bar smaller in cross-section than 1515?

yes - it would be 0808 in the same terminology. 8mm x 8mm instead of 15mm x 15mm. of course i am putting it 45-degree-on so it's actually 8mm*1.414blahblah]]> lkcl CoreXY Machines Fri, 27 May 2016 06:51:00 -0400 https://reprap.org/forum/read.php?397,639675,668288#msg-668288 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668288#msg-668288 realthor CoreXY Machines Fri, 27 May 2016 05:29:01 -0400 https://reprap.org/forum/read.php?397,639675,668286#msg-668286 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668286#msg-668286
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realthor
Why not use 1515 T-slot it's lighter and stronger than solid bar... and better than square alu tube...

this is solid square bar not square tube i'm using.

15x15 as the name suggests would be 15mm wide and 15mm high. that would mean that when crossing one over the other there would need to be about 31 to 32mm between top and bottom extent... i would run outside of the box when stowed.

also, the further apart the centre of gravity is when pushing side-to-side and the bars are offset in height the more torquing there can be on the carriage. push on X and it torques more around the X-axis. push on Y and it torques around the Y-axis. i'm already unhappy with how far up the belts are compared to the centre of gravity, but have to go with what i have for now.]]> lkcl CoreXY Machines Fri, 27 May 2016 05:27:09 -0400 https://reprap.org/forum/read.php?397,639675,668283#msg-668283 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668283#msg-668283 realthor CoreXY Machines Fri, 27 May 2016 05:17:44 -0400 https://reprap.org/forum/read.php?397,639675,668279#msg-668279 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668279#msg-668279
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realthor
Will you be using ALU tubes for the active XY driving linear elements?

i found a company in holland, aluminium-shop.nl i think it was, which is local and they do solid 8mm aluminium bar. i will replace it with solid 8mm square carbon fibre later, but the bars are i think are 114 grams and the same in carbon fibre is like *twelve* (12).

basically i initially avoided the solid 8mm square rods because i thought they would be not as strong as solid 8mm *round* rods.... when in fact the cross-section is larger and when put at 45 degrees there is more height... doh.


yeah saw that i love the carriage holder it's very elegant, nothing like the dog's dinner i've rush-jobbed...]]> lkcl CoreXY Machines Fri, 27 May 2016 05:01:03 -0400 https://reprap.org/forum/read.php?397,639675,668274#msg-668274 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668274#msg-668274
Check this out: https://www.youtube.com/watch?v=AD1-YF7_s8g]]> realthor CoreXY Machines Fri, 27 May 2016 04:31:47 -0400 https://reprap.org/forum/read.php?397,639675,668270#msg-668270 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668270#msg-668270
IMG_0214.jpg


first three parts, left x-end and 2 motor holders, they're really quite high-stacked but just about fit into the box when stowed. had to put in an LM8UU not an LM8LUU into carriage ends so that the square rods have a bit more to go through and be more stable.
]]> lkcl CoreXY Machines Fri, 27 May 2016 04:22:49 -0400 https://reprap.org/forum/read.php?397,639675,668166#msg-668166 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,668166#msg-668166
movers are coming tomorrow to take 14+ boxes away.

photos when i have time.]]> lkcl CoreXY Machines Thu, 26 May 2016 19:13:32 -0400 https://reprap.org/forum/read.php?397,639675,667739#msg-667739 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667739#msg-667739 realthor CoreXY Machines Wed, 25 May 2016 17:14:27 -0400 https://reprap.org/forum/read.php?397,639675,667708#msg-667708 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667708#msg-667708
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realthor
I have never considered to dimension the belt routing to achieve standard lengths... that's a nice tip. Am calculating it as we speak :D
With rods and most other stuff we can get the lengths we require but with belts I don't think to have seen vendors that cut it to length and keep the same price. I may be mistaken of course.

i hadn't really consciously thought about it, i know that alfa-tech3d.com supply pre-cut lengths and kits with GT2 gears already in them, but mostly i understand they cut to 1m lengths.]]> lkcl CoreXY Machines Wed, 25 May 2016 15:54:30 -0400 https://reprap.org/forum/read.php?397,639675,667703#msg-667703 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667703#msg-667703 With rods and most other stuff we can get the lengths we require but with belts I don't think to have seen vendors that cut it to length and keep the same price. I may be mistaken of course.

Edit: well, I wasn't as lucky as you :P ... attached...]]> realthor CoreXY Machines Wed, 25 May 2016 15:30:03 -0400 https://reprap.org/forum/read.php?397,639675,667695#msg-667695 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667695#msg-667695
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realthor
That's some departure from your initial design.

it's not even corexy, and apart from a plotter and a few experimental 3d printers it's entirely new (or, what's old is new.... again) but belts for this layout? that's not been done before.

Quote

It's interesting to see your development going at such an alert peace ... (as opposed to my mostly digital endeavor - I am so slow with actually building anything :P )
Now let's see the real thing...

yeah tell me about it :) no i learned the fast pace from software development with scripted programming languages. you have to iterate... *fast* and in as small increments as possible (just very very quickly). also i'm not particularly tied to one specific architecture - i am however tied to some specific *requirements* - i am quite happy to rip out anything that doesn't work, assess something new and try it.]]> lkcl CoreXY Machines Wed, 25 May 2016 15:02:16 -0400 https://reprap.org/forum/read.php?397,639675,667682#msg-667682 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667682#msg-667682 Now let's see the real thing...]]> realthor CoreXY Machines Wed, 25 May 2016 14:44:01 -0400 https://reprap.org/forum/read.php?397,639675,667540#msg-667540 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667540#msg-667540 www.youtube.com] i am pleased and greatly relieved to be able to say with confidence that the belt lengths (sub-1500mm) are okay. one has only 25mm to spare but that is enough. if this was a larger 3d printer, even by 10mm on one side, a 3m belt simply would not be enough, it would be necessary to buy an off-the-shelf 5m length and throw away 1.7 to 1.8 metres. so it is a lucky fluke.






these show the top and bottom belt paths, which are separated (offset) by something like 30mm. this was unfortunately literally the only way to stay within the size and height pre-existing constraints, and it is less than ideal, but that's just how it is.

round the GT2-6-16t motor gears i've marked the path with curves. i was able today to add to the python source code a class which "collects" belt segments. i didn't add in the arcs because that's complicated maths and i haven't time to do it, so i am just using the fact that there are two full revolutions worth of "arcs" round a 16mm diameter bearing, per belt, which comes to 100mm extra per belt. the python class adds up the length of the belt segments, end-result is that those lengths come out to 1332 and 1374mm respectively: manually add 100mm to each and one belt length has literally 25mm to spare and the other has 107.

the discrepancy can be attributed to the fact that the carriage is wider than it is long, where you end up with a *four-fold* multiplication of any extensions to width or height being added/subtracted from the belt. why four-fold? because the belt is doubled-up and has to go round to attach to opposite sides. total: four times back and forth.

in other words if the carriage bearings had to be even 6.5 mm closer together on the X direction, or if the X-ends had to be as little as 6.5mm further apart, this project could have failed!

in short, i am one jammy b*s****d :)
]]> lkcl CoreXY Machines Wed, 25 May 2016 07:25:58 -0400 https://reprap.org/forum/read.php?397,639675,667360#msg-667360 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,667360#msg-667360 youtu.be]]]> lkcl CoreXY Machines Tue, 24 May 2016 16:24:21 -0400 https://reprap.org/forum/read.php?397,639675,666547#msg-666547 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666547#msg-666547
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cozmicray

I believe these requirements will be used for just ONE printer

:S

yeahh i definitely need to do a v3 to clean things up. ehh the whole idea is, i go through this stuff, experimenting and trying new things, working out how to do it, so that other people don't have to. they can just buy a kit. or copy the end-resultant successful ideas.]]> lkcl CoreXY Machines Sun, 22 May 2016 13:07:38 -0400 https://reprap.org/forum/read.php?397,639675,666271#msg-666271 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666271#msg-666271
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cozmicray
My sketch was not to scale at all, and the size of all components
is arbitrary.

understood. i rescaled it in my head, placed actual parts where they'd need to be.... sadly it didn't work. but for other people (with that one small correction) the idea would work very well.

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Your requirements / constraints way beyond insanity or practicality.

well, it is what it is. no use getting stressed about it, although that's exactly what's happening

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Are you building 10 -15 coreXY mechanisms to swap out on top?

can't. i don't have enough spare extrusion to make a replacement. and only the one printer available. so i have to do it as a single "design, verify-by-hand, print, disassemble, rebuild, pray" cycle. i still have the v1 frame (minus the printbed) - i suppose as a last resort i could part-disassemble the v2, reassemble the v1, and use that - so the extrusion that's in it i do *not* want to cut it up.

so, that's why i have to use what i've got, stick with what i've got, and absolute minimise and restrict the changes to the top assembly.

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7 days to finish? I think it has been 7 months

under three, and that's two revisions. it's why i'm not going to revise the frame (again) as i simply don't have time.

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Beyond insanity

gaaah tell me about it. actually, insanity is defined as "trying the same thing over and over, expecting each time a different outcome". as it's never been attempted even *once* it has to be described instead as "totally bonkers and completely out on the edge of being risky beyond belief".

yeah. i'd settle for that as a good description :) i am reaaallly looking forward to a nice calm time when i don't have to focus on this quite so hard...]]> lkcl CoreXY Machines Sat, 21 May 2016 12:18:24 -0400 https://reprap.org/forum/read.php?397,639675,666267#msg-666267 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666267#msg-666267 is arbitrary.

Your requirements / constraints way beyond insanity or practicality.
You left out assembly only requires kitchen utensils and a Ninja blender

Are you building 10 -15 coreXY mechanisms to swap out on top?

7 days to finish? I think it has been 7 months

Beyond insanity

I believe these requirements will be used for just ONE printer

:S]]> cozmicray CoreXY Machines Sat, 21 May 2016 12:06:13 -0400 https://reprap.org/forum/read.php?397,639675,666206#msg-666206 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666206#msg-666206
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cozmicray
Use of a spring tension idler near motor,

occurs to me, you could as easily use a strong spring on the belt-end holders, but i feel that the same d-shape arrangement that nophead uses on the mendel90 x-carriage belt adjustment would do as well, it's a 2-to-1 gear ratio on the M3 screw, as it turns out that the D-shape is a pulley-system.


]]> lkcl CoreXY Machines Sat, 21 May 2016 07:04:49 -0400 https://reprap.org/forum/read.php?397,639675,666173#msg-666173 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666173#msg-666173
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cozmicray
I have lost track of pre-existing constraints

Maybe like this --- motors at corners
motors up, shafts pointing down

Use of a spring tension idler near motor,
gives you good contact arc on drive pulley

[attachment 78428 Plotter_Belt_2_j.jpg]


:S ::o I am crazy for continuing this insanity!!!!!

i am definitely running my health into the ground with the stress and long hours, that's for sure.

i really appreciate the effort and the clear drawing, cozmicray, and apart from one technical error it would actually work very well in any other design. couple of specific reasons why i can't use the approach you describe as a retrofit in this specific design:

the size of the motors relative to the available space (which is 312 x 358mm and cannot be changed without a total redesign) is much larger than you're normally used to, so the scale of the motors you've put in there is off by something like.... a factor of 1.5 maybe even 1.8. so, the frame comes literally in a hard line down about 2mm from that bottom left yellow bearing, and chops off the left-hand side of the motor, likewise on the right side. i have *six* millimetre clearance either side of the 300mm rods to play with, on either side.

so this is why i've put in the same 2 extra idlers per belt that the other guy who did that amazing all-aluminium printer did, the one where he even made his own extruder, and was getting an insane 9,000mm/sec travel speeds.

also, because of the space constraints, the left-side spring-loaded idler would, unfortunately, need to occupy the same space as various things such as the static linear rods/rails (in particular, the horizontal one at the top between the motors), and the belt would be likely to hit various things as well.

the motors cannot point upwards because, all told, they would be approximately 60-80mm above the level of the frame: thus, when the printer is folded they would stick out about 30-50mm through the side of the box.

the shape of 312x358 is a longer rectangle than you've drawn, so the top two moving (direction-change) idlers would be on a rail that actually goes *through* (into) the motor. the rail needs to be about.... 30mm lower than it's been drawn, because the distance from top to bottom, as drawn, is something like 330mm, which is outside of the constraint of being exactly 300mm so as to be able to use a 300mm 8mm rod.

also, the distance between the two motors would be such that those two direction-change idler bearings and their associated carriage would crash into the motors, the spring-loaded idler, the fixed belt-end holder.

also, with the belt going along the top, there, it's in the way of the place where the extruder motor sits.

so although in principle it's a great idea, ray, which would work extremely well for any other circumstances, it would work well for a 3d printer that has around a 400 x 400mm top for example... but not here. if you're going to do 400x400mm, then you might as well do what the original plotter design does, which is put the motors 1/2 way down each side.

those are the main things. there is one design flaw however in the diagram, which is independent of the extremely tight space constraints: the top right spring-loaded idler should be on the *top* static-length red belt, not the variable-length right-side belt. i've made the correction, here:

[attachment 78430 addon.php.jpeg]

just as on a corexy design it's absolutely critically important that those variable-length belt portions be lined up and remain in an absolute dead-straight line. the top-right spring-loaded idler is now sitting directly over the static belt-end holder, which is fine, it's at a different height. however..... it would be necessary to arrange clearance for the entire rail assembly that's going to come along, so that top-right motor might need to move a bit further up.

and that, almost certainly, would take the belt length beyond the 1.5 metres that i've already cut the 3.0m belt into. which, again, is yet another constraint that i cannot change within the (now) 8 days remaining until i have to get out of this country.

so, those constraints are - as hard-limits:

  • 7 days to finish a 100% working design with the available materials and parts to hand (28 625 bearings, LM8LUUs, LM8UUs, 4 geared idlers, GT2-16s, 300mm x 8mm chrome rods, 300 x 8 x 8 *square* rods)
  • 1.5 metre belt length per axis
  • nothing above the extrusion must be higher than 40mm above the top of the 15x15 extrusion
  • the extruder motor must be directly inline between (same y coordinate as) the two x and y motors i.e. nothing must occupy the space between the x and y motors. you can however go above or below that space - just that space exactly 44mm wide to fit an extruder motor has to be clear.
  • the width must remain exactly at 312mm
  • the depth must remain exactly at 358mm

ridiculously-tall-order but i think i can do it... with some compromises such as putting belt-teeth against smooth idlers. yuck.]]> lkcl CoreXY Machines Sat, 21 May 2016 04:14:46 -0400 https://reprap.org/forum/read.php?397,639675,666129#msg-666129 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,666129#msg-666129
Maybe like this --- motors at corners
motors up, shafts pointing down

Use of a spring tension idler near motor,
gives you good contact arc on drive pulley

[attachment 78428 Plotter_Belt_2_j.jpg]


:S ::o I am crazy for continuing this insanity!!!!!]]> cozmicray CoreXY Machines Fri, 20 May 2016 23:02:29 -0400 https://reprap.org/forum/read.php?397,639675,665907#msg-665907 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,665907#msg-665907
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dc42
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lkcl
here's a photo of the proof-of-concept (1-in-2 scale) which took only a couple of hours to mock up, and, importantly, allowed things to be "moved" so that they could be verified as having the right amount of travel and clearance:

A concern I have with that photo is that the belts are only going round the motor pulleys for about 90 degrees. Is that really enough, especially if you will be using 16-tooth pulleys? I would have aimed for 180 degrees by moving the idler pulleys.

ok so put in 8mm circles to represent 1-in-2 scale 16mm 625 bearings, redid the "belt" - it's rriiiight on the limit of what's possible within the pre-existing constraints. 180 degrees isn't possible, the pair of idlers being closer together means the path is longer by 20-30mm. 150 degrees or so should be okay. plus that means the idler's bolt wouldn't be right on top of one of the motor bolt-holes...



the mess for the other belt... gaah. it would actually be better to turn the belt round so that the teeth are facing outwards... wait... frick! which bleedin way are the teeth??? ok ok, on this purple one, they're already outwards, which is why the carriage-idlers are teethed... yeah ok whew that's the right way.

so, for the other belt with the dog's dinner mess of bearings (you can see what's planned in the photo, in that top left corner, belt isn't in yet, and one bearing is missing) it would be better to turn it round so the teeth are *inwards*... that would mean putting 2 smooth idlers on the carriage and toothed-idlers everywhere else.... argh i only bought 4 toothed idlers, i haven't time or funds to get more (only 8 days remaining in the country), i'd have to go with teeth-to-idlers when i'm planning to run this at 500mm/sec and above... argh... i could drop them in later i suppose if i plan for it now *sigh*.

normally on that plotter, the other motor would be on the top edge (as seen in the photos), it's that i have to get them into such a tight pre-defined space that's the issue. they can't go "inboard" because there's a 2nd piece of extrusion along the edges - the frame - which the top assembly sits on.

yaargh stress! :) i'll work something out.
]]> lkcl CoreXY Machines Fri, 20 May 2016 07:23:37 -0400 https://reprap.org/forum/read.php?397,639675,665750#msg-665750 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,665750#msg-665750
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dc42
Quote
lkcl
here's a photo of the proof-of-concept (1-in-2 scale) which took only a couple of hours to mock up, and, importantly, allowed things to be "moved" so that they could be verified as having the right amount of travel and clearance:

A concern I have with that photo is that the belts are only going round the motor pulleys for about 90 degrees. Is that really enough, especially if you will be using 16-tooth pulleys? I would have aimed for 180 degrees by moving the idler pulleys.

yyyeah... it might be doable. i'll reprint some 8mm representations of the bearings and give it a shot. i have to miss the screw-hole points for the motors, but also, the extruder is level with the X and Y motors (sitting sideways!) let me do the equivalent photo to the above, of the current sandwich200v2....



that's a flex3drive coming off the extruder motor, arcing up to dominate the photo then going back down to the extruder. so the green belt has to miss the left of the extruder motor and the red the right (!) i can't move the motors further left, they wouldn't fit in the box when stowed....

.... oh god i just thought of something horrible - rotate the extruder motor (cock it up on one side) by 20 to 30 degrees around its axis of rotation, so that the green belt clears the *underside*, and the red belt, which would be slightly higher up, would go *over* it.... blerrrrgh. well i will do that only as a last resort.

i can't move the extruder motor further down (to where the z-motor is, for example) because there's not enough space. thank you to everyone for letting me think out loud here, btw.
]]> lkcl CoreXY Machines Thu, 19 May 2016 15:18:04 -0400 https://reprap.org/forum/read.php?397,639675,665748#msg-665748 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,665748#msg-665748
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deckingman

Or add a few more idlers - there's only 19 plus 2 motor pulleys. :)

nono, there's actually 6 more than that - another 3 are in v-rollers per axis :) amazingly it's actually not as many as are in the current sandwich200 v1, because i had 6 in the printbed cantilevered arms, and the corexy motors are inboard so required 4 more idlers than most people would have in a CoreXY. a trade-off between compactness and number-of-idlers that i was happy to make a decision on. oh, and four LM8UUs.

hey it's nowhere as many as the_digital_dentist uses - he doubles-up the 625 bearings and puts 8mm belts on!

i'll try and reorganise it tomorrow, but with only 1.5 metres of belt on both X and Y i'm pushing the limits to within millimetres of those pre-set limits. mmmm.... fuuun...]]> lkcl CoreXY Machines Thu, 19 May 2016 15:12:17 -0400 https://reprap.org/forum/read.php?397,639675,665742#msg-665742 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,665742#msg-665742
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dc42
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lkcl
here's a photo of the proof-of-concept (1-in-2 scale) which took only a couple of hours to mock up, and, importantly, allowed things to be "moved" so that they could be verified as having the right amount of travel and clearance:

A concern I have with that photo is that the belts are only going round the motor pulleys for about 90 degrees. Is that really enough, especially if you will be using 16-tooth pulleys? I would have aimed for 180 degrees by moving the idler pulleys.

Or add a few more idlers - there's only 19 plus 2 motor pulleys. :)]]> deckingman CoreXY Machines Thu, 19 May 2016 14:47:18 -0400 https://reprap.org/forum/read.php?397,639675,665708#msg-665708 Re: Foldable, portable CoreXY (Fusebox derivative) https://reprap.org/forum/read.php?397,639675,665708#msg-665708
Quote
lkcl
here's a photo of the proof-of-concept (1-in-2 scale) which took only a couple of hours to mock up, and, importantly, allowed things to be "moved" so that they could be verified as having the right amount of travel and clearance:

A concern I have with that photo is that the belts are only going round the motor pulleys for about 90 degrees. Is that really enough, especially if you will be using 16-tooth pulleys? I would have aimed for 180 degrees by moving the idler pulleys.]]> dc42 CoreXY Machines Thu, 19 May 2016 12:58:41 -0400