Smartrapcore ALU

by smartfriendz Sep 10, 2015
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Is there an up to date BOM anywhere? I see the plates were just updated a week ago, it'd be really helpful to have an updated BOM as well.

I have been wanting to make a 12x18 printer for awhile, and I noticed the SmartRapCore wood version first. It makes everything so easy with JSCAD, just telling it what bed size I want and it telling me the size to cut everything too. Then I saw this ALU model, then there seems to be an even newer one out there with a much different Z. Is there any kind of calculator to determine what size extrusions to order based on bed size? How do you find the original Onshape document? When I search SmartRapCore ALU I get a bunch of results where other people have taken the original, editted, and left the documents public but I can't find one with the owner being 'Smartfriendz'.

Can anyone confirm the lengths of the aluminum extrusions and rods needed for this build?

Digging through the OnShape file I was able to determine the following:
• 8 x 400mm 2020 extrusions (X&Y)
• 4 x 300mm 2020 extrusions (Z)
• 4 x 285mm 8mm rods (X&Y axis)
• 2 x 315mm rods (Z axis)

The reason I ask is because in the onshape file the connecting corner end caps are NOT present, but, if these end caps ARE used, wouldn't this require the rods to be slightly longer?

Also, these lengths all differ from the BOM, which appears to be outdated (as it's still calling for 6mm rods).

What sizes heat bed are these measurements for

Your correct with all the 2020 extrusion lengths.

As for the rods, my Smartrapcore Alu Kit has the following rods (roughly measured from it's already built)
(2) X rods - 290mm 8mm
(4) YZ rods - 320mm 8mm

Thanks for the information on this. How are the 2020 extrusions capped on your kit? Are they the flat plastic caps like the picture on thingiverse (the blue flat pieces)?

Yes, although my kit contained black parts. The 2020 extrusions used M5 Button Head Socket Cap screws to make the frame with those plastic caps on the exposed ends. The button-head just slides in the extrusion profile with a few access holes drilled for an allen-key and the center of the 2020 extrusions are tapped.

Thanks for this info!

Hi, What print settings are recommended for the printed parts of the design?

Hi. I'm really confused right now. I'm looking for the dimensions of the profiles, but there are different length measurements on the Onshape file and the BOM. What are the exact length of the profiles for 20x20x20 build area? Any help would be appreciated.

Anyone have a good nozzle cooler for this one?

Yep I have a tweaked fan duct hot end cooler, part cooler combo here: https://cad.onshape.com/documents/d5d46f319cbc497d89007f95/w/97f3a44485e240be9b96b7fb/e/b62884c912e34fcaa37abd4c

All parts in red are modified / tweaked to suit my needs. This was redesigned as I had a larger fan available and wanted to experiment with onshape too.

This works great and give just enough part cooling to ensure great bridging in PLA.

I will upload a 'thing' later to update.

Badaboom badabing: https://www.thingiverse.com/thing:1382066

50mm Fan Duct - e3d V5 compatible

Hello there,

thank you for sharing this 3D Printer concept.
One question: What are the exact dimensions of the aluminum profiles? In the BOM I can only see the length.
aluminium profile l=400, I guess it's 20 x 20 mm? And what groove? 5 mm or 6 mm?
Also in the BOM, I have a question to "pack Z".
8 M3x16
3 ???
1 1 nema17

Thank you very much for helping.

Same question, what is the unspecified 3 pieces in the BOM? Thanks!


i have ask the french forum it's 6mm profile.

is it possible to extented it to support 200x300 heated bed ? thx

Yes you can.
You must extend Y axis

Hello! Is it possible add hot bed to printer ?

Hello !
Yes ! :)

Will you update the BOM to reflect the recent changes you made to the model you sell on your website?

Especially using only 8mm rods

Comments deleted.

Onshape is giving me a hernia lol

Thanks for this wonderfull deisgn. I'm in the process of building and acquiring parts and found that the "XY Bearings Right" in onshape has a small error. The hole is not at 1cm from the edge but a bit more to the inside. It was an easy to fix in onshape.. I'm going to change the belt driven z-axis to a threaded rod type.. just dont like build platforms falling down:-)

Thank you :)
Yes I have fix it in onshape and i fix it now in thingiverse thank you

Comments deleted.

May I ask for suggestions on what software to use for g-code generator and printing on Windows?

Cura is really great !

Any chance that in the future the wood chassis version and the aluminum chassis onshape files can be split out into there own independent versions? Right now working on building a wooden version and I have to sift thru all the parts that include the aluminum version. Also a note on the wooden version left motor bracket doesn't line up with the new back bracket. Any chance also in the future there will be a general list of the screw types to use for either version? Thanks for the great work!

Yes, i think we will separate them . It's becoming a little "messy" and we get too much parts for a simple tab interface ( we NEED folders there :) .
Sorry for the bug in wood version ? thanks for the feedback i will have a look to that tonight.
The full detailled bom is coming very soon now , it will be a pdf in the files here and maybe in onshape doc too .
thank you .

That is great to hear! That is the issue I'm running into as well with using onshape at the moment, the moment you start to have too many shapes it becomes a cluttered mess. I requested folders for there outliner in assembly, it would be nice if they gave tab groups as well to keep projects cleaner. Thanks again and looking forward to the bom.

Another question, I've got most of the XY axis system rebuilt in onshape for my setup and I'm noticing that Y slide bearings and the back bearings for the GT2 belt don't line up perfectly. I was wondering if in the coreXY system if these bearings need to line up in order for the belts to work at there best. Thanks! P.S. Which I could post a picture up cause I could show easier than explaining it :D

do got more info over the aluminium profiles like to add raspberrypi and cam to those bars dont now how deep the grooves are what shape those grooves have to make piece that can fit around those bars

Hi this maybe a strange question but could this design be scaled down to 50%? I have several 3D printers and want to build a small CoreXY printer just for fun. Buildarea of 10x10x10 is enough. Can I use the same parts and just cut all the beams in half resulting in a footprint of 20 x 16 x 15 cm (original 40 x 32 x 30 cm)?


It should work . We are going to publish some calculations to find out the sizes of aluminium profiles and smooth rods ( maybe also the length of gt2 belts ).
We would use the onshape source for that . There is in fact some fixed sizes for each axis ( motors, Yslides, Z motor) , then we add the build size to that and find our lengths.
Tell us if it works ? I'm curious about a small one :)
thank you

I couldn't find a follow up post on a 100x100x100 build area. Do we just reduce all extrusion and smooth rod lengths by 100mm? Thanks!


Is there a new method for routing the GT2 belt for the Z axis?
Or are the teeth just facing the wrong way on the Zslide_belt part?

I think I have got the path figured out:

  • mount the end of the GT2 belt in the holder with the teeth
  • go immediately down the side of that same holder to the pulley on the stepper
  • around the pulley and up to the bearing in the Ztop_belt part
  • around the bearing and straight down on the right side of the block on the right side of the belt holder
  • loop around that block and up again through the same space between that block and belt holder where the first part of the belt runs (so it locks teeth on teeth)

I do not see any other way...

hi 3DFreezeMe,

I'm really sorry we didn't explain this new Z attach , it's quiet hard to find out and you found it, almost :) There is a vertical hole there and you should put a m3x30 in it. It will be used to tension the belt. The way to put the belt is exactly how you found out ( congrats !!! ) but when you come back from the top, you will make a loop to pass under the m3x30 before to go back to the teeth.
use the m3 to tension the belt.
Assembly videos are coming really soon now ( today or tomorrow) and it will be really more simple to see it ! sorry again for the delay .

Hi smartfriendz, no need to make an excuse for any delay.

Most of your design choices are so clear and thoughtfull, that a manual is hardly needed.

I saved the mystery of the two holes for today to solve. No need for that anymore, I guess.

Please help. I have finished printing all of the parts and purchased the extrusion for the aluminum version. I can find all of the parts except for the right hand side rod retainer that attaches to the right hand stepper motor. I am just probably overlooking it somehow. Any help is appreciated.


Thank you very much. Now I can continue the assembly.


Hi MOndo,
Thx for the feedback. It was indeed missing here . Now it's repaired.

Some files look difrent on photo
Then then download version parts

hi tenij :)

yes, we update constantly because it's still young design. We don't re-update the pictures each time so you can see differences .
usually, the updates are made to make the assembly more easy, but the main features don't change.

Hi, nice work :-) How long are the profiles? Or what is outher dimension of the printer? Thanks

hi otomar,

thx :) we will update the full detailed bon here very soon now , we lost some time about that because we changed some little things.


Any chance you can please share your onshape file for your modified 8mm version? Are your remix parts all modified to use LM8UU's?

The copy I made with all my alterations is public in Onshape, do a search on either 3DFreezeMe or Smartrapcore - Smartfriendz.
Then you open the design and you will have the option to make a private copy, which you can make public as well.

And yes, they have been adapted to LM8UU.

OK thanks. Ive found your version on Onshape but when i open it up it reverts to the Standard version. Strange.

Scroll the bottom row for.parts, mine are ending with _8mm or _8mm_HK13.
I did not update any assembled parts view, when you open a doc in Onshape, it defaults to the first tab.

You can delete all other tabs or copy them to another doc.

Thanks, thought it must have been something simple.

Elegant solution to the belt-crossing!

For all who want 8mm rod sized parts for the Smartrapcore standard version, feel free to get the seperate stl files of the remix I just uploaded:

Smartrapcore standard - 8mm rods - 13mm walls:

The parts without '_HK13mm' in the name are also usable for the ALU design!

Smartrapcore standard - HK13 (8mm rods - 13mm walls)

It looks like the head is for LM6UU bearings? Is there a version of this head for LM8UU bearings?

In the 15 minutes after posting this, i was able to modify the head in OnShape for LM8UU bearings. Printing now, will post my results! I love OnShape, thank you for making the Alu with it!

Great work Smartfriendz! I've was in the process of building the Smartcore 2.1 from the Jscad file, but now it looks ill be moving over to Onshape version. Thanks for the break down 3DFreezeMe.

You are welcome DigiTeck3D! Just playing and learning while doing...

Nice move to start using Onshape for sharing this great 3D printer design!
And a good motivation to start learning yet another tool...


thanks :) we believe it was our best shot to let anyone ( not engineer or developer ) copy the document and start to adjust options , or make new accessories.
We are working on a pdf in the first tab to explain a little more how the all document is built, and maybe a small intro about how to adjust important things.

A little tips section or intro for easy changing dimensions for at least the wall thickness (standard version) and rod diameter will be very helpful.

I succeeded in changing rod size to 8mm for the XY_motor_left and right parts. But when I try to change the dimensions for the wall thickness for these parts from the default 10.2mm to 13.2mm, the gap changes to the wrong side (inwards to the motor).

Dragging some lines in the sketch outwards results in most of the sketch to move, because of the constraints.
Onshape and the concept of constraints are both new to me, so I have a little learning curve to overcome.

Also the 'L' sign on the XY_motor_left part is mirrored after the mirror function.

I found out how to change the dimension for the wall thickness:

Let's change the XY_motor_right as example:

  • open the part studio for the part (the tabs in the bottom)
  • select front view (it zooms to correct side we want to edit
  • right click on the face of the side and select: edit sketch1
  • you will see the 3 horizontal lines with dimensions (left to right): 5 / 10.2 / nothing
  • select the '10.2' dimension text (turns into box and changes color)
  • press delete to delete the dimension for the wall thickness
  • select the Dimension (D) tool in the toolbar on top of the Onshape workspace
  • click on the right horizontal line with no dimension set (right side of the wall thickness that was labeled 10.2) and move your mouse downwards. A dimension will show (value 8.41).
  • no that part has been fixed

To create a new wall thickness value, just select the Dimension (D) tool again and select the middle line (currently without dimension) and start dragging down.

  • type the value you wish the wall thickness to be for your SmartrapCore printer design.
    The wall cutout will now be created correctly, without changing any dimensions on the side for the motor.

Now click the green V in the Sketch1 dialog box to close editing the sketch and it will be saved automagically.

Of course you need to change this for all parts containing wall thickness parts.

But then we have the issue that the extruded holes (for the Nema17 and screwhole to fix the smooth rod) are not translated and in the wrong place.

@ smartfriendz:
Is there an easy way to fix the holes to their related position in the part? Or better, how to change the wall thickness so the new size will be directed outwards of the wall i.s.o. inwards in direction of the motor?


Solution to the mentioned issue:

  • the function 'Fix' can be used to fix selected parts of the geometry within sketch1 (fix the lines in the right part on their current postiton)
  • when you now change 10.2 to 13.2 (the dimension for the wall thickness I need), the change will be directed to the left (outside) which we need).
  • the nema17 holes now also hold the correct position for the extrusion