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Best Kossel XL or larger kit?

Posted by Qdeathstar 
Best Kossel XL or larger kit?
March 13, 2016 07:05PM
Hello guys,

After originally thinking about sourcing all the parts myself, i've come to the realization that its beyond my scope.. so i'm settling for the next best? thing. I am looking for a good quality Kossel XL or larger that i can buy. I was looking at the buildA3dprinter kit

[builda3dprinter.eu]

which would cost me around $650, but it has printed corners and i was worried that might be an issue. Basically, is there a better kit i can get for around the same ammount of money, i want it to be kossel this time around though. Thanks!
Re: Best Kossel XL or larger kit?
March 14, 2016 12:57AM
This one is quite high quality, I'm commissioning one for a friend right now:
[www.robotdigg.com]
Re: Best Kossel XL or larger kit?
March 14, 2016 06:27PM
Yes, i liked the aluminum corners, sadly they dont make an XL so i'd only be able to build 17cm... the XL goes to 26cm... quite a difference.
Re: Best Kossel XL or larger kit?
March 14, 2016 08:54PM
Quote
Qdeathstar
Yes, i liked the aluminum corners, sadly they dont make an XL so i'd only be able to build 17cm... the XL goes to 26cm... quite a difference.

You can request that they provide the parts to turn it into an XL when you order it, and they will provide longer extrusions, a larger heatbed and longer arms. This is what my friend did, and we ended up with a machine that can print at least 24cm diameter. I'm not sure about the actual max dimension, but I know that 24cm diameter is printable.
Re: Best Kossel XL or larger kit?
March 15, 2016 01:05AM
well, I asked them as you said but they said no. which is strange since they have the linear rails and extrusions for an xl....

Quote

Sorry that Kossel XL full kits are Not available.

Order can be followed on our website, thanks!
Best Regards,
Derek Meng
SKYPE: robotdigg WhatsApp: +86 17001516168
www.robotdigg.com More than 3D Printing
Re: Best Kossel XL or larger kit?
March 15, 2016 01:08AM
I was also thinking about this kit:

[www.hkbay.com]


1) is ramps enough for a delta xl?
2) could I get this and simply add these aluminum corners?
[www.robotdigg.com]

or p

[www.robotdigg.com]

Edited 2 time(s). Last edit at 03/15/2016 01:15AM by Qdeathstar.
Re: Best Kossel XL or larger kit?
March 15, 2016 03:39AM
You could also try Think3DPrint3D. They have a large Kossel kit in beta and have shipped an few already. There is a thread in this forum about a user's experience of building one.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Best Kossel XL or larger kit?
March 15, 2016 06:48AM
Well that's weird.

I've got an XL sitting on my workbench from robotdigg.
Re: Best Kossel XL or larger kit?
March 15, 2016 09:15PM
thank you, DC, I think I found the topic you mentioned, but it doesn't seem they ever finished it. It looks like they we having problems with calibration....


does anyone have a recommendation which company is most reputable. I bought a replikeo prussaI3 and while it was a great learning experience, all-thread and questionable electronics, I'm trying it avoid in the future. Also, since deciding originally on the prussa, I've learned that the kossells are just plain sexier.
Re: Best Kossel XL or larger kit?
March 15, 2016 11:59PM
Quote
Qdeathstar
Also, since deciding originally on the prussa, I've learned that the kossells are just plain sexier.

Sexy they may be, but that comes at the cost of accuracy. Deltas are pretty straightforward to get printing... but to get them printing dimensionally accurate parts, wherever they may be on the bed, is quite a difficult proposition.

Deltas suffer from pockets of error where something might print perfectly in one area of the bed, and be slightly off to varying degrees as you move it around the bed. Your best bet is to make your build as perfect as possible. By that I mean being within 0.03mm on all measurements. This includes things like the distance between towers, the length of your diagonal rods, the distance between diagonal rod mounting points, and the list goes on. Consider that many of those measurements are around 400mm, and now you realise that we're talking about better than 0.01% error. This is not an easy thing to achieve with normal tools or experience.

Some people will say that modern 32 bit boards have amazing auto calibration routines, which is true. However if your plate is slightly non-flat (as they all are) then this non-flatness throws off the calibration routine and introduces larger errors elsewhere.

To be honest, most people won't notice those errors. But I have, and it frustrates the living daylights out of me. Note, if you do notice that parts print larger in an area of the bed, there's pretty much no way to figure out what's wrong, without meticulously going over every measurement again.

Building a cartesian printer such as a CoreXY would easily allow much better accuracy, without spending weeks going around and around in circles trying to figure out why parts are printed at different sizes in different areas of the bed. However if dimensional accuracy isn't all that important, then Deltas are a great solution.
Re: Best Kossel XL or larger kit?
March 16, 2016 12:52AM
I think I'd rather have a higher quality delta than a low quality prussa. I think getting everything level is key,. I have a torpedo level.. and a four foot level for the towers.... but, if you have an idea of additional calibration tools that would be useful, I'd appreciate it.

Edited 1 time(s). Last edit at 03/16/2016 12:53AM by Qdeathstar.
Re: Best Kossel XL or larger kit?
March 18, 2016 08:18PM
DC42,

I tried contacting think3dbuild3d but I wasn't able to get a response. What is the best way to contact them?
Re: Best Kossel XL or larger kit?
March 19, 2016 05:13AM
I'll send them a reminder of your interest. I think the reason that they haven't released the large delta yet is that they are waiting for the sheet metal corners to become available. The Robotdigg aluminium corners are very nice but rather expensive.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Best Kossel XL or larger kit?
March 19, 2016 07:18AM
Quote
dc42
I'll send them a reminder of your interest. I think the reason that they haven't released the large delta yet is that they are waiting for the sheet metal corners to become available. The Robotdigg aluminium corners are very nice but rather expensive.

They're also a bit floppy for an XL, I'm having to brace mine with turnbuckles and wire, just to get it square and solid.

Edited 1 time(s). Last edit at 03/19/2016 07:18AM by nebbian.
Re: Best Kossel XL or larger kit?
March 19, 2016 04:38PM
Thank you dc42. I am excited to start this project and put my el-cheapo prussa i3 in the garage.
Re: Best Kossel XL or larger kit?
March 19, 2016 05:08PM
I suggest you to have a look at this one from Ultibots:
Kossel 250 V-Slot

Edited 2 time(s). Last edit at 03/20/2016 06:27AM by valba.
Re: Best Kossel XL or larger kit?
March 19, 2016 11:05PM
Quote
nebbian

Some people will say that modern 32 bit boards have amazing auto calibration routines, which is true. However if your plate is slightly non-flat (as they all are) then this non-flatness throws off the calibration routine and introduces larger errors elsewhere.

Non flatness of the plate can be calibrated out on a Duet controller, the biggest problem I've found is plates having variable stiffness across the plate when using contact probes, again this can be calibrated out with a Duet.... if you have multiple plates then beware, if they have different stiffness or flatness then they can throw out your calibrations, if you want to use multiple plates then verify they calibrate the same, or have a calibration plate and production plates.

Quote
nebbian
To be honest, most people won't notice those errors. But I have, and it frustrates the living daylights out of me. Note, if you do notice that parts print larger in an area of the bed, there's pretty much no way to figure out what's wrong, without meticulously going over every measurement again.

Only partially true, every dimension on a delta has an effect on each of the three Cartesian axes, so if you have an error it could be due to any of the key dimensions, so you need to check them all, but the rules are simple, easy to measure and easy to adjust.


Quote
nebbian
Building a cartesian printer such as a CoreXY would easily allow much better accuracy, without spending weeks going around and around in circles trying to figure out why parts are printed at different sizes in different areas of the bed.

Deltas have zones where they have greater sensitivity to calibration errors if you draw a triangle between the towers this is your sweet spot, and you should easily be able to get good accuracy in this area, as you venture outside this triangle your accuracy is more sensitive to calibration errors until you get to the periphery between two towers where you will expect the greatest sensitivity... the point is, none of this is a mystery or inexplicable, and if your spending weeks going round in circles then you probably have a poor understand the kinematics, which itself is understandable if your not a math major.

One of the biggest problems people have with Delta calibration is when they get confused between good calibration and reducing the mean error to zero, yes a good calibration will have an error close to zero, but its possible to obtain a zero error without doing good calibration.... every-time I hear someone tell me they have great mean calibration error yet crappy parts I discover they have invented a cool way of cheating the calibration!



RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD
Re: Best Kossel XL or larger kit?
March 20, 2016 01:12AM
Quote
bgkdavis

Deltas have zones where they have greater sensitivity to calibration errors if you draw a triangle between the towers this is your sweet spot, and you should easily be able to get good accuracy in this area, as you venture outside this triangle your accuracy is more sensitive to calibration errors until you get to the periphery between two towers where you will expect the greatest sensitivity... the point is, none of this is a mystery or inexplicable, and if your spending weeks going round in circles then you probably have a poor understand the kinematics, which itself is understandable if your not a math major.

One of the biggest problems people have with Delta calibration is when they get confused between good calibration and reducing the mean error to zero, yes a good calibration will have an error close to zero, but its possible to obtain a zero error without doing good calibration.... every-time I hear someone tell me they have great mean calibration error yet crappy parts I discover they have invented a cool way of cheating the calibration!

I should mention, the parts I notice the errors with, are parts similar to lego, that utilise an interference fit between them and other printed parts. I need a tolerance of better than 0.02mm on a ~7mm measurement. I've noticed that I can print two parts in the same plater, separated by ~15mm, and discover that the two parts have a different feel when pushing them into a single receiver. I can't measure the actual difference in size with any level of confidence. But I can feel it, I know it's there.

As I mentioned before, most people don't need or would know how to measure this level of accuracy. But it's important to me.

I know that it's not inexplicable, and I have a reasonable grasp of the kinematics. But my point still stands: if you spend the same amount of time calibrating and tweaking a cartesian, vs a delta, you'll end up with a much more precise cartesian printer.
Re: Best Kossel XL or larger kit?
March 20, 2016 01:58AM
A tolerance of 0.02mm is a minor challenge for machinists, and its even a challenge to achieve with plastic injection molding, and would certainly be considered beyond the machine capability of a reprap, not even the filament your using is manufactured to this tolerance, and the variance in filament diameter alone will probably contribute 0.02mm variance to your final part size.

To put this into context, if I wanted a CNC to reliably operate with this kind of accuracy it would be built with linear scales and probably calibrated and compensated with laser metrology, it certainly would not feature stepper motors and open loop control, and definitely would not have belt driven axes.



RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD
Re: Best Kossel XL or larger kit?
March 20, 2016 06:48AM
Regardless, I have achieved that (or close to it) with my machine. It wasn't easy by any stretch. I feel that it would be easier to achieve that level of accuracy with a cartesian than a delta, that's really my point.
Re: Best Kossel XL or larger kit?
March 20, 2016 09:32AM
what kinds of tools do you think I should have to calibrate a delta? I've got a caliper, level, square, as well as, ofc, an assortment of hand tools.. but anything else you'd recommend?
Re: Best Kossel XL or larger kit?
March 20, 2016 09:39AM
well.. think3dprint3d is no longer offering the XL beta kits. They are working on a smaller kit in between the XL and a mini. I am dissapoint!

so, I guess it's between HKbay, builda3dprinter, or the utilibots one.
Re: Best Kossel XL or larger kit?
March 20, 2016 10:19AM
Or build your own like I did. See the link to my blog in my signature for details.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Best Kossel XL or larger kit?
March 20, 2016 10:39AM
Quote
Qdeathstar
what kinds of tools do you think I should have to calibrate a delta? I've got a caliper, level, square, as well as, ofc, an assortment of hand tools.. but anything else you'd recommend?

A large roofing square is very handy (at least 300mm per side). This helps you get your towers aligned properly. That and a set of digital calipers can get you very close. Some feeler guages are also useful to shim out the extrusions by a set amount while you tighten the screws. I use this method when getting the towers parallel.
Re: Best Kossel XL or larger kit?
March 20, 2016 10:51AM
I am thinking about, but for example

Quote

Motedis sell two types of 20mm extrusion, the I-type and the B-type. I used the I-type, however it wouldn’t fit into the vertical holes in the Robotdigg metal corners without enlarging the slots with a Dremel, and I needed to tap the end hole M5 myself. So B-type verticals would probably be better, as long as the slots are not too wide for the wheels. Motedis only sells 2060 extrusion in I-type, therefore either the horizontal extrusions must be I-type, or you could use 6 x 2020 B-type extrusions for the lower horizontals instead of 2 x 2020 and 2 x 2060. Also note that the B- and I-type extrusions take different sorts of T-nuts. The B-type takes M4 T-nuts that rotate into place. The I-type take M3 or M4 T-nuts that can be pushed into the slot and have a spring-loaded ball to hold them in place.

You could use V-slot extrusion if you prefer – just check that your wheels are compatible.

this kind of makes my head spin. How much did you have to modify the metal corners? if I use B-type, like you suggest how do I know I they are not to wide? if I use v-slot, it seems like your BOM and mine will be significantly different.
Re: Best Kossel XL or larger kit?
March 20, 2016 04:38PM
I didn't modify the metal corners, instead I used a Dremel to widen the slots on the extrusion where they fit into the corners.

V-slot would certainly change the BOM. You would need different wheels and you would need to adjust the width of the carriage trucks - which is easy if you can use OpenScad. Even changing to B profile extrusion would need the carriage truck width to be adjusted - it may be that the carriage trucks that T3P3 use in their Mini Kossel R3 would fit.

Perhaps someone who has already built a V slot 2020 Kossel can advise you.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Best Kossel XL or larger kit?
March 21, 2016 11:12AM
After talking to Roland, it's seems like the main differences he making Is to go with a 24v heater, which will be smaller (250mm) but have the same frame. Swapping out the heatbed later sounds like an ok plan, and I think I prefer think3dprint3d's duet electronics to utililibots smoothieboard clone.
Re: Best Kossel XL or larger kit?
April 05, 2016 05:53PM
Hello,

Currently I am leaning toward the utilitibots model. It has metal corners and magballs... But I don't like the fsr or control board. How difficult would it be to swap it out for dc's ir sensor and duet electronics? What would I need to print to get it up and running?

Edited 1 time(s). Last edit at 04/05/2016 05:53PM by Qdeathstar.
Re: Best Kossel XL or larger kit?
April 07, 2016 10:30AM
You'll never find a kit that perfectly suits your needs.
As suggested by DC42, building your own model could be a better option for you.

You can take some ideas from different vendors and design your own.

For instance, if you have a closer look at this model Atom 2.0, you'll realize that 2040 frames and rails are a very good option for XL and XXL sizes.
HKBay Deluxe XL + metal corners is a very cheap starting option...

You could update this model in the future with faster electronics + IR sensors, etc...

Edited 2 time(s). Last edit at 04/07/2016 10:34AM by valba.
Re: Best Kossel XL or larger kit?
April 07, 2016 03:53PM
Or if you have the skill, build your own from bare metal, there nothing like looking at your delta knowing you build it yourself, I build mine from aluminum angle and Vslot 20X40 that I cut with a table saw and fine metal cutting blade and a drill press but if you have a 60 degree miter saw ( I have one now) its easier and more precise. I still have my design in PDF somewhere if you are interest. I also build my own bearing block and shaft and such but you can use commercial available one ( Actobotics have some)
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