@E302envy the backlash i'm experience (on all axis) is almost like a lag between direction changes. so when I take z to the hotend, and then start to move it down, the first layer (or even 2 depending on the layer height) won't actually move the bed... same thing happens if I reverse direction.. it takes a fraction of a millimeter of movement before it'll actually start to move.

Feel free to hit me up on email to chat more... I'd love to get into it a bit more w/ another sli3dr owner :D scoopthree(at)gmail(d0t)com

I might know the cause of your issue... as I've experienced it a little before :D

@vonGreezly - can u describe the issue you are having with the z backlash and what it looks like in your prints. I have been struggling with a what I think is a layer misalignment issue that i can not seem to figure out ( maybe it is actually z backlash ) . my printed layers are ever so slightly miss aligned which gives me un-smooth walls on a printed cube.

Anyone experiencing Z Backlash on this baby? I feel like there shouldn't be any... is my Z string not tight enough? i've got it workable in backlash compensation in the FW, but wondering if anyone else is experiencing this as well?

Finally got my Sli3dr up and printing pretty well! Need to dial in a few more things, but yeah!!

Was wondering though... Anyone else got one of these going, what're you using for print cooling?

I am expanding your design a bit ;)

X axis is assembled already, just the motor drive needs some more work.

https://github.com/sanchosk/My-PrintTable/blob/master/sli3dr%20variant%20-%20rope.skp

what do you guys do to stop the line from overlapping itself on the spools and causing a jam - this seams to get worse with the thicker you go with line?

FatFreddie, sounds good. I didn't know it existed. The kevlar weight is apparently minutely higher, but still doesn't matter. What I like is that the kevlar might be better for a heated build area. Dyneema is OK at 70C but apparently might creep at 80-90C if anyone ever went that high (well 90C is too high for an ABS build platform, but maybe some other plastics.)

FatFreddie, sounds good. I didn't know it existed. The kevlar weight is apparently minutely higher, but still doesn't matter. What I like is that the kevlar might be better for a heated build area. Dyneema is OK at 70C but apparently might creep at 80-90C if anyone ever went that high (well 90C is too high for ABS, but maybe some other plastics.)

I used 150lb kevlar fishing / kite line (plenty of suppliers on ebay) - it's a bit stiffer and doesn't take so long to bed in as spectra line.

@E302envy

You can buy spectra at up to 200lbs strength typically. I used to use 80lbs on my solidoodle but now use 200lbs. My main reason is actually for abrasion resistance, because for a while my pulleys weren't perfect and were wearing down the 80lbs over many hours. The 200lbs is proportionally thicker so it was slower.

Almost everyone is definitively using spectra . If you're having cutting problems then you need to investigate the interference. If you think you're over-tightening the spectra that is also possible but a little harder. In that case go up in size.

Hey guys - what line are u using for this guy. I have 80lb spectra but it keeps snapping and cutting under the mounting points for the x and y carriage. Any thoughts or recommendations.

Hi, i am making a printer based on this, but when X axis is moving, left side of Y axis get movement 1-2mm but the other side is stable, some one can help me?.

@E320envy does it only home in the wrong direction? Or is it just moving in the opposite direction all the time?

If you want, I can send you my working firmware, and you can compare.. Or even just use it.. Though you'd probably wanna dial in the max settings to that of yours so you dont crash haha

I'm not using any code at the beginning of the print. All was config'd via the GUI firmware editing tool linked in richrap's original firmware zip..

And are you incerting a command in your start code to tell the printer to move to the software z end stop before it starts the print . Not sure why I can't get my brain arround this and thanks so much for the help you have already given,!!!!!!

@vongreezly - am still having issues over here - rest all my firmware setting to match the config.h on Richards github page - except for LCD and printer size and end stop inverting as I am using optical end stops. Y homes great - z now homes to min end stop at bottom of printer but x homes in wrong direction. What am I missing here. Basically I am try to understand why any of these setting would be different then RichRaps ( besides end stops being optical and different LCD )

Does anyone have a working Slid3R working video of the X,Y,Z pulleys while the printer does a full print volume jog? I am really interested in seeing both the X and Y bobbins while the printer does a full bed rectangle and also the same for Z with a top-bottom jog for a few times. But I can't find anywhere on youtube/web any Slid3R in motion/printing maybe?

As I see it mentioned on reprap forums on many threads concerning belt-Z I am getting more and more curious.

Also another question: how much can the design be stretched on the Z until the bobbin string walking is too much? We can calculate that for a 16mm bobbin and 300mm Z there should be 6 spectra coils on the bobbin. Now if the spectra is say 1mm in diam, 6 rotations of the motor will have the 6 coils walk away from the original position with 6mm. How can we assess how much are these 6mm affecting the spectra tension? Will this weaken the string?

Spectra line takes a little while to settle down (big tighten after 1 day, smaller after two, smaller still after three), kevlar line settles down faster and isn't as stretchy generally.

http://imgur.com/Mz33lvK

Here's the checkbox I was talking about. To get the Z dialed in, I homed, and then adjusted position until it was at the optimum print-height (using a piece of paper as you said), and then re-entered that value for Z height, and then reflashed the firmware with the new settings. Took a few times to get EVERYTHING perfect, and there is also a little bit of adjustment to be had in your bed (depending on how you did it)

Regarding your spectra line tension, it could be slipping maybe? I've got mine setup so I can adjust from either side of a spool by tightening the bolts that the spectra ends on. This also took a little bit of playing around, and I ended up re-wrapping my X spool because I didn't have enough coils on it.. .but yeah, it seems to stay tight.

One of the really good things of building this guy is that I have never used sketch up before and had to teach myself how to use it and I am now really starting to like it. Once you get used to it I think it is a fantastic tool !!! Thx RichRap for that lol!!!!!

Ok that would be great - that's was what I was thinking also but when checking the config.h on RichRaps github sli3dr page it shows the z set as min and hence me question. - can u also describe how you calibrated the z to be at the correct night for printing - on my prusa i3 it is done with a pice of paper and adjusting the z end stop to get nozle to bed night right - am completely missing how to do it on this for some reason - thanks for the help guys and sorry for the dumb questions

@E302envy if you're using the repetier web interface to config your firmware, there's a check box that inverta the home direction. I believe I also set my home endstop as a max endstop instead of a min... I can try and get a screencap if / when I get these kids to sleep...

Hey guys - for the guys with running machines - I have a question. I finally got my machine up and working but am struggling with the z platform and how to get it set right - it homes great but when I try a test print it stays at home. I think I am missing something in the slicer that tells it to move the z platform up to the print head - any help would be great - thx guys - also my spectra line seam to keep losing tension for some reason - any thoughts ?

I'd be ok with jogging it top bottom for several times, maybe 10 or more to see how the spool of spectra behaves while moving towards the motpr and back. It would be also interesting to have the string split and a spring inserted so we can see the change in tension when the spool walks away from the straight-ish line.

@realthor I'll try and get a vid sometime soon heh. I had a bit of a meltdown @ the hotend, so things are kind of apart and haven't had time to put 'em all back together yet... Z still functions, so I can zip it up and down a couple times if that's all you're lookin' for?

Ok, i get it, maybe 100-200 steps/mm are something to be aimed for. Is there any video in the wild or something you guys can shoot so we can see the Z in action, maybe jog it from end to end while focusing on the motor/bobbin. I hope it's not too much to ask but I would really like to see it in action.

@realthor

The Smartrap Core use 20 teeth pulleys with a diameter of 12.7mm. If they are using 1.8° motors and 1/16 micro steps they get 3200 steps over 39.9 mm travel. That's 0.0124 mm travel / step or 80 steps / mm (since it's not a lead screw).

Let's compare with two known machines using lead screws:

My old PrintrBot Simple 2013 Makers Edition use the imperial 1/4"-16 Acme screw (1.5875 mm/ revolution) which give me 1,0000009765625 mm z-axis movement at 2015.75 steps / mm . That's 25 times higher resolution than the SmartRap Core.

The Ultimaker's Z axis screw is 3mm/turn, they use 1.8° motors and 1/8 micro steps which gives

0,001875mm z-axis movement per pulse or 533,33 pulses for moving 1mm. That's 6.66 times higher resolution than the SmartRap Core.

I'm aiming at 200 steps / mm which is 2.5 times better than the SmartCore and I hope I will be satisfied with that. it's almost one third of the Ultimaker and one tenth of the Printrbot Simple though.

I guestimate it will be sufficient, but if I need more resolution I have a number of ways to increase it.

There are 1/32 step drivers available, I can design a smaller bobbin and I have an idea of how to increase resolution with a factor of 2 if necessary.

Ok, just finished reading a nice article on fine machinery errors (http://m.machinedesign.com/archive/resolution-resolved) and understand better the Phenomena. However i fail to see why finer grained possible resolution helps. The controller tells the motor to turn 100 times to achieve 0.1mm on Z ok? Many mechanical hanical errors later the bed usually moves less than commanded rather than more but it will still rotate 100 times before it stops. On the other hand, a less fine grained resolution system will tell the motor to rotate 10 times to achieve the same advancement of 0.1mm. The needed torque is higher and the errors are added up the same way as with the finer grained system. Are we talking about the jerk resulted from trying to move with less steps the desired distance? Can you give a better example on why rotating 100 steps for 0.1mm is better than 10 steps?

Thanks.

@bringho

"There is a difference between mechanical z-axis resolution and print resolution (layer thickness)."

I am not that experienced in 3D printing, just wetting my hands so forgive my ignorance.

I understand your point, there should be some give so you can adjust in smaller increments the imprefections of the printbed. Is there any other reason why you would want a capability of much better mechanical resolution than the printing resolution? I ask you this as I want somehow to assess how much fine grained do I need this mechanical resolution because I want to avoid the gearbox.

Can you shed some light on the solution chosen for smartfriednz's smartrap core, which uses a belt for Z also without gearbox and on direct drive. Are they achieving much fine grained Z mechanical resolution than my example below?

@realthor

There is a difference between mechanical z-axis resolution and print resolution (layer thickness).

Since you will never be able to adjust your bed to be perfectly planar to the extruder.

You need to be able to handle that difference in height over the surface of your print bed.

Don't you think it would be wise to use a smaller z-axis movement / step than the 0.1mm layer size to solve this problem?

Uhh, got lost in your calculations. Let me try this way... I have a 200steps/rev motor and want a z resolution of 0.1mm. This is the norm, right?

Ok we need that the circumference of the bobbin divided by 200 must equal to 0.1, right? This is 2*pi*r/200=0.1 => r=0.1*200/2*pi ~=3.183mm. This means the needed bobbin for the gearless 200steps/rev motor will have a diameter of 6.366mm.

Because the motor shaft is 5mm itself, it is quite difficult to get a bobbin of 6.3mm diameter. To reach to your 18mm bobbin and still have the 0.1mm resolution i have to activate microstepping by a factor of 3 (18/6=3). So with x3 microstepping I would reach 0.1mm resolution on Z without gearbox.

So why do you want lower than that as a resolution? I see 0.005mm z-axis movement in your comment. That is pointless for the current 3d printers. Even for a SLA printer is not achievable.

Now we must take into account that the smaller the bobbin the more revolutions will spectra have to make to achieve sufficient grip. But this increases the "string walking" which translates to all kind of issues, from uneven tensioning (when the spectra on the bobbin gets further away from the straight line it would make between the bearings should it have been a timing belt instead, it continuously tensions the wire before it comes back to the starting point when you turn the motor in the other direction).

So from this point of view the bigger the bobbin the better. Which is why RR introduced the gearbox I would guess.

If you find a way to prevent string walking then you can get away with a very long and thin bobbin (coupler from 5mm shaft to 8mm threaded rod comes to mind). Do an image search for "Spectra Drive" or "Fishing Line Drive" if you are interested.

Edited:

@vonGreezly, I've been doing some calculations this evening and my conclusion is that we need at least 1/16 microstepping with this motor / gearbox configuration.

@realthor, sorry about the confusion, I was thinking about the hold torque being multiplying by the gearbox ratio.

Here are my results:

200 steps / revolution multiplied with the gearbox ratio gives 1036 steps per revolution with this Nema 17.

Adding 1/16 microstep we get 16576 microsteps / revolution of the bobbin.

The difference with this configuration compared to a lead screw is that the z-axis lift with lead screw can be as low as 1.5mm compared to 56.55 mm with the current bobbin of 18 mm diameter. That's a factor of 37+ times...

Selecting 0.005mm z-axis movement / microstepstep gives me a circumference of 82,88 mm or a bobbin core diameter of 26,38mm (0.005 * 16576 = 82,88, 82.88 / p = 26,3815... This would give me 200 microsteps (or 12.5 full steps) / mm lift in the z-axis which is roughly one tenth of the steps / mm on my old PrintrBot Simple (using 2015.75 microsteps / mm). While needing less than 2,5 revolutions to cover 200 mm Z-axis height!

Selecting 0.00333 mm z-axis movement / microstepstep gives me a circumference of 55,254mm or a diameter of 17,588 mm which is close to the original bobbin diameter of 18 mm and use 300 microsteps / mm, an 50% more than the larger bobbin.

Of cause you could aim for a bobbin of 10mm diameter but it would only give you 31.416 mm z-axis lift / revolution. You would need to wind up 6.4 revolutions to get a z-axis lift of 200 mm. The fact that the gearbox output axis is 8mm will probably induce other problems...

I'll probably settle for 200 microsteps / mm for the (first) bobbin in my own machine ,)

@RichRap, what's your thoughts on this?

One final thought: It should be possible to use a variation of the y-axis configuration for the z-axis to get a mechanical reduction of travel by a factor of 2 (to double the amount of microsteps / mm) but it would probably be overly complicated and the benefit is questionable.

@bringho : Hmm, we must have posted around the same time as I didn't see your comment before posting. Ok, I don't know where I have mistaken in my calculations, I anyway used the info on the website I have mentioned.

Ok, 0.28 without microstepping. If you only increase the microstepping by a factor of two or four then you get in the usual resolution range. I don't think that reduces a lot the torque.

Anyways I can see your point now but I was wondering why for example the smartrap corexy design by smartfriendz doesn't use any reduction for their direct drive belt Z axis.

Thanks for your answer.

Ok, I assumed 1:1 for the direct drive which is wrong. I assume from the picture that the diameter of the Spool is around 35, maybe 45mm so the rapport is not 1:1 but about 9:1, which makes my calculations below update to 0.00625*9=0.05625mm/microstep, still within the normal resolutions, where 0.1 is the norm. And I have calculated with full stepping. The norm is x16microstepping.

Please let me know where am I mistaking :-/. I don't mind buying the gearbox, but if it doesn't help why waste that money.

@bringho so I should be running the z w/ no microstepping? That all kinda makes a lot of sense... Gotta reconfigure some stuff hehe

No, the gearbox ratio is 5 point 18 to 1.

I don't remember the original diameter of the z-asis bobbin but my version has a diameter of 18mm which gives me a circumference of 56,54mm. That is the z axis travel for one revolution of the motor axis.

Divide with 200 for a 1.8° motor and you get 0.28 mm travel / step.

If you introduce micro stepping by 16 you get down to 0.017 mm / micro step movement and that may be sufficient.

Add the gearbox ratio of 5.18 and you are down to 0.0034... / micro step or 0.0545... mm / step without micro stepping while increasing the hold torque at the same time. I'm confident in following the original RichRap design in this case.

@bringho: but is it necessary? Are my calculations wrong? This reduction gearbox is 18:1 that is huge and I don't think it is needed. I wonder why did RR use it in the first place, which gets me to the conclusion that there is a flaw in my math :) .

I bought my Z-axis stepper motor with gearbox from robodigg.com.

Probably this one: http://www.robotdigg.com/product/103/Nema17+40mm+Stepper+Gearmotor

@E302envy richrap included a link in his firmware folder that takes you to the repetier firmware config wizard (suuuuper handy!!) Load in your config, and select the .92 version and then skip through to the download tab and redownload. Should compile fine~

@E302Envy did you try compiling as .92 instead of .91?

@EddyMI3D the sli3dr's mighty z axis cannot be bothered by such simple concepts as gravity. It might do that with a lot of weight on it, but not with the weight of anything it printed.

I see a greater problem in case the power goes off. So there is no more force from the stepper motor to keep the z-axis/heatbed in place and it will crash down. I would/will insert a worm gear to prevent this.

What reduction is the gear reducer at the Z motor and why is it needed? I've seen belt-driven Z (a la smartrap core) and they don't use gearing for Z. Wouldn't this work without the reducer? Assuming I am correct that this is considered a direct drive, so 1:1 gearing, then, according to http://www.shapeoko.com/wiki/index.php/Calculating_Z-axis you would get 160 microsteps/mm for a 200-step-per-rev motor, full stepping. That would be 1/160mm per microstep, which is 0.00625, a resolution which is more than the actual nozzles can handle (if I am not mistaking in my logic).

Thank you for that hint!

Will some time to finish my project, but I'm already collecting parts...

for some reason the firmware keeps failing when i try compile/ upload - any thoughts - am using the newest release of arduino ? fails in at lease 5 spots - i will grab the firmware off the github and try that - maybe mine is corrupted

Perfect guys - thanks for the answers - I actually found the files for the extruder that is used - well at least i think so. I believe it is Richraps goto rostock bowden setup modified for the Sil3dr - well at least that's what I will be trying. Going to also try the E3d Cyclops on this one. or cymera with to v6 Vulcanos for some really fast LARGE scale prints.

@E302envy The extruded stl's have never been released as far as I know.

@EddyMI3d Its usually Spectra Fishing Line. I personally use 80 lb line.

@E302envy The Z routing is the same as the Y routing just in a different orientation. Also, Looking at the door, the X motor is on the left, Y on the right. I also want to say the comments used to mention that the extruder was experimental and as of yet unreleased, though I think any bowden will do.

I'm think to apply this to my new project.

I like to know what kind of wire/cord do you use?

I am also wondering which gears wades extruded is in the photos as I really like that one ?

Thanks Von greezly - that is a little more help but it don't see any routing of the fish line like that in the pics from rich rap - still trying to grasp the z-axes line routing and where it is mounted on the actual z platform in the pics . Also when look at the machine from the front - which is the x motor and which is the y motor? Sorry if these are dumb questions - I am just getting to the stage of being able to string the motors up. I also am using a different style LCD screen (2004 LCD smart controller) and am not familiar with the repetier firmware - looked it over last night but did not find a section to choose LCD type like in marlin. Thanks for the help and responses guys - really hoping that Richrap could chime in with some closer up photos of the z stage and maybe a better explaining of how to attach spectra to the z stage !!

Absolutely!!! I owe thanks to everyone on the reprap community to get where I am today, in this case especially to RichRap for leading the way with this interesting machine!

I still have ways to go though... On the list right now is first and foremost the bobbins, then new top corners using the new larger rollers ( V625ZZ 625VV) and finally new Y-axis mounts and Z-axis mounts that includes spring loaded fishing line stretching. All will be done in Inventor (as I use it at work) but STL's and BOM will be provided as soon as I have something usable to share.

The rollers I decided on trying are these : V625ZZ 625VV V Groove Guide Pulley Rail Ball Bearings Metal (5mm*16mm*5mm), they replace the original 624VV V Groove Sealed Ball Bearings Vgroove 4 X 13 X 6mm 3mm bearings found on ebay.

Also I decided on these bearings for the Z-axis : 630VV 6*30*8 V Groove Sealed Ball Bearings 0.236'' Vgroove.

@bringho lookin' good man! you plan on sharing those files? ^^;

I've been working on two derivatives (one 200x200x200mm and one 300x300x300mm) since I saw this interesting machine a year ago. Unfortunately I'm not satisfied with doing one project at a time so this has been put on hold while updating my current printer to be able to print the thread bobbins more accurately than I am able to do now. My 200x200 machine looks like this at the moment:

[URL=http://s1067.photobucket.com/user/bringho/media/DSCF2434s_zpsr5hbpzu1.jpg.html][IMG]http://i1067.photobucket.com/albums/u434/bringho/DSCF2434s_zpsr5hbpzu1.jpg[/IMG][/URL]

It's not finished, I've found out that the small bearings for the fishing line wobbled so I have new, larger ones waiting to be designed into the machine, I have figured out how to include constant feather stretching of the fishing line but have yet to design/print the parts so there are some planned changed to do. the 300mm machine use most of these parts, only the motor mounts are expanded by 100mm. Hope to find time to continue with these machines asap!

@E302envy Here are some pics of my Z run. I need to rewrap the spool so that it in-line w/ the pulleys, but it functions for now :D Also, yes, you need to zero Z, and then move it up until you're at your print level and then add that to the firmware so that it knows where it's supposed to stop.

https://goo.gl/photos/xFoh74QnHbyMrLxm8

https://goo.gl/photos/NN8fZbzBki7sGa2u9

https://goo.gl/photos/fCAX4SLshpKXxGnw7

Hey rich rap - am trying to build a 300mm x300mm version of this and am struggling to figure out how the spectra line is connected on the z axes - none of the pics really show it - could you describe how you attached it to the z axes. - and was also wondering how the z axes does its homing as the home switch is on the bottom - do you have to calculate how far it should go up to be ready to print and put that in the firmware .

Thanks Kirk. I have had a few issues myself with the new Sketchup, it can get into some nasty states where files are not saved - read-only. If in doubt I would recommend also installing Sketchup Ver 8 for looking at older file types.

I have no idea where all the Sli3dr comments have gone? - I'll try to find out from Youmagine.

The file is still present, but if you are using the SketchUp add-in, you have to update that to the 2015 version to access the files. The update is damaged, so will generate and error every time on Windows 10 systems, because the file references a folder that does not exit: http://forums.sketchup.com/t/group-policy-blocking-install/5175

If you make the folder and upzip the Sketchup file, you can install all three files from the damage archive to the new folder you will have to create, and then execute the update to access the files. I have not tested the Pro version, only the 2015 Make to install on a 64 bit computer running Windows 10 and all updates.

Good fortune!

vonGreezly, it's not just you. I'm looking to adapt the sli3dr, but unfortunately dont see the comments I previously saw. I checked and the "waybackmachine" does not have a copy, unfortunately.

is it just me, or did all of the comments disappear? there was some really useful info in there... =\

Almost finished hoarding my pile of parts to get this baby running. was wondering if anyone could tell me what the cylinder which is attached to the lift stepper motor is... as seen is this pic: https://d36c0vbvwjb9cx.cloudfront.net/uploads/image/file/52250/large_Z_lift_line_S.jpg

Thanks,

-Casey