scale model of a mendel90 anyone?

Hi all,

suddenly an idea entered my brain ... what if it would be possible to print a scale model of a mendel90? Not a full working model of course, but maybe with moveable axes? To show to friends, to sit at the desk ... the real thing isn't very move around friendly.

I would like to start with the frame. But I don't know how to configure the (which) .scad file(s) to give me only the frame to export it as .stl. The same goes with the other assemblies. Any help with this would be very much apprechiated.

The size of the scale model could be anything smaler than the 20cm in all dimensions. The greater the better I guess. Maybe the rods don't need to be printed - 3mm filament should be o.k. if the scale is chosed right.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Its kind of a cute project.... You may be able to print a full model as one solid thing (no movement) directly from the Mendel 90 model... You could put a conveniently large object on the bed to act as support material for the x access..... Although ideally that object should be a smaller M90 and......

Whatever you do you should film it!

Hi,

I tried to export a .stl out of the .scad file - with no luck. The full model isn't manifold and Openscad does not export a .stl. So I tried to reduce the parts. The baseplate, the gantry and the both side stays worked. But I ran out of black PLA ... it only sufficed to print the baseplate. So I print it one by one. Otherwise the prints need much support at the gantry gap and the fan hole.

In general, I re-scaled the Mendel90 to 40% - this gives me a maximum area to print the baseplate of 185mm by 167mm. All other parts will be smaller ...
I use the various .scad files in the views folder and reduce the output from the called files by commenting lines of objects I don't want. As soon as I got what I want I export it as .stl and hand it to netfabb for re-scaling it to 40%. There are .stl's where netfabb shows problems - but they're easy to be repaired.

Today - after work - I try to print the 5 stepper motors by changing the filament from silver to black and back to silver. After that I should print all the fixing blocks.

I'm not sure if I should glue all the parts together or if I should use small screws. Glueing PLA isn't easy I know ...

Pictures and more are following!

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Hi,

the stepper motors:

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Cute!

Hi,

I just assembled the frame and screwed the z axis Motors to it. The y axis motor is mounted too.

So far, I used M1.6 screws, nuts and washers to hold the parts together. They match very well the original M4/M3 (some holes need a bit drilling with a 1.5mm drill).

To mount the motors I drilled a 1.5mm hole into them. It worked very well.

M1.6 screws are ... tiny ...very tiny. Patience was the rule to success.

Photos tomorrow, too tired to do it now.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Hi,

now the pictures - have fun!

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

I am looking forward to seeing your Wade's Small Gear!

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Looking good and this may be a minor point but I noticed that you have the post-print bed cooling fan protector cover on the wrong side of the dibond sheet. (Although as you do not have the fan installed, this may be deliberate).

I saw the same 'mistake' on the photos which you took showing your LED lights and camera in another recent thread but as said, given that you don't have a bed cooling fan installed, it makes no difference to the operation of the printer.

Alan

p.s. I only mention this because I made the same error when I built my M90 and before I installed the bed cooling fan. (In my case it was the eagle eye of Mrs Nophead who picked this up!).

Edited 1 time(s). Last edit at 07/08/2014 05:45AM by Alzibiff.

Quote
Alzibiff
Looking good and this may be a minor point but I noticed that you have the post-print bed cooling fan protector cover on the wrong side of the dibond sheet. (Although as you do not have the fan installed, this may be deliberate).

I have my fan guard installed like this also. Reading the build manual:

The four screws pass through a plain washer, the fan guard, the left stay, the fan (if fitted) and
finally a nyloc nut. There isn't a washer behind the fan because fan frames tend not to have room for
one.

I took this to read that the fan guard is fitted inside the machine to protect fingers roaming around the bed while the fan is active. Why would you want the guard outside?

Regards,
Neil Darlow

Edited 1 time(s). Last edit at 07/08/2014 06:46AM by neildarlow.

---

I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Quote
neildarlow
I have my fan guard installed like this also. Reading the build manual:

The four screws pass through a plain washer, the fan guard, the left stay, the fan (if fitted) and
finally a nyloc nut. There isn't a washer behind the fan because fan frames tend not to have room for
one.

I took this to read that the fan guard is fitted inside the machine to protect fingers roaming around the bed while the fan is active. Why would you want the guard outside?

The manual, as quoted is consistent with the fan guard on the outside. From the head of the screw (on the outside of the machine), the parts listed are in order: plain washer, fan guard, left stay, fan and then nut. If you start with the head of the screw on the inside, then surely the order gets muddled and would be, plain washer, fan guard, fan, left stay and then nut

Having the fan guard on the outside protects fingers and anything else getting caught in the fan - there should be no fingers probing around on the inside of the machine anyway when it is working.

Take a look at the first rendered image on this page: [hydraraptor.blogspot.co.uk]

Alan

Quote
Alzibiff
The manual, as quoted is consistent with the fan guard on the outside. From the head of the screw (on the outside of the machine), the parts listed are in order: plain washer, fan guard, left stay, fan and then nut. If you start with the head of the screw on the inside, then surely the order gets muddled and would be, plain washer, fan guard, fan, left stay and then nut

If you put the guard on the outside of the machine then following the guide as screw, washer, fan guard, left stay, fan (if fitted) then nyloc nut would put the fan on the inside of the machine. I have followed the order described in the manual and have fan guard inside and fan outside.

There is definitely ambiguity here and the fact that people fit the guard in either orientation suggests that something needs correcting.

Regards,
Neil Darlow

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I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

Quote
neildarlow
.... would put the fan on the inside of the machine.

Which is exactly where my fan resides, nearer to the print bed than if it was on the outside. Sorted!
Hope this diversion hasn't taken too much attention away from Stefan's model

Alan

The guard goes on the outside of the machine and the fan, if fitted, goes on the inside blowing towards the bed. I don't see any ambiguity if the instructions are read while consulting the assembly diagram.

If the fan was on the outside and the guard inside you could easily stick your fingers in the rotor of the fan. The guard would be over the stator blades so pointless.

When the fan isn't fitted it doesn't really matter but I think it looks better on the outside.

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[www.hydraraptor.blogspot.com]

Quote
nophead
The guard goes on the outside of the machine and the fan, if fitted, goes on the inside blowing towards the bed. I don't see any ambiguity if the instructions are read while consulting the assembly diagram.

If, by the assembly diagram, you refer to page 13 of the Build Manual there is no context because the fan, fan guard and fixings are shown in isolation without reference to the left stay.

The assembly diagram on page 27 shows the fan guard on the outside of the printer but, as no fan is present, it gives no clue as to which side of the left stay the fan is fitted.

As the designer of the machine there will be no ambiguity for you but even Alan mentioned that he originally mounted the fan guard on the inside of the machine - so it is a mistake that can be easily made.

To me, it made sense to mount the fan externally so the wires could be routed along with the left Z motor wires. I can easily move the guard but not so easily the fan. In fact I like the ease of access having it outside gives e.g. for cleaning dust out of it.

Regards,
Neil Darlow

---

I try to write with consideration for all nationalities. Please let me know if something is unclear.
Printing with Mendel90 from fedora 25 using Cura, FreeCAD, MeshLab, OpenSCAD, Skeinforge and Slic3r tools.

I like having the bed fan on the inside as that way the end of the fan is closer to the bed with the part being cooled so the air has not spread out as much when it hits the part. I drilled an extra hole for the wire just under the fan so it could come up the outside like the z wires.

Yes I think it will cool faster on the inside and the only purpose of the fan is to speed things up.

I run the wire up the inside of the stay and then through the same cable tie as the Z motor wires at the top.

For the guard to be effective with the fan on the outside it would need to be fitted on the intake side of the fan, which would need much longer screws.

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[www.hydraraptor.blogspot.com]

Quote
nophead
Yes I think it will cool faster on the inside and the only purpose of the fan is to speed things up.

I created a cowl to direct the air across the bed, which I find cools the object to its 'popping off' point even quicker.


In this configuration my fan is on the outside and the guard on the outside of that (the cowl stops me getting my fingers anywhere near the blades).
The cowl is designed (it's just a hull from cylinder to cube!) such that the exit is the same CSA as the fan duct - so the airflow is only redirected, not restricted.
I also chose to aim part of the airflow to the underside of the bed - if I'm in a hurry then I can slide out the wadding from under the bed and the combined airflow above and below cools the glass very quickly.

(Apologies for continuing to drag this off-topic!)

@QuackingPlums Would you be up for sharing the design files? (Maby in a new thread)

@bastard can we see the model M90 next to the real thing for scale? Its looking really good already... On tenter hooks to find out how you will tackle the rest.

Hi,

what a fan can do ... amazing!

Yesterday I printed the both fans, the psu and the three microswitches. The fan blades needed to be a bit longer to have a one solid object.



The microswitches ... 7.9mm x 6mm x 2.5mm ... need a rework.

I mounted the bed fan the way "nut, washer, fan, left stay, guard, washer, screw head".




@ElectroWomble - here you are:





Yesterday I bought aluminium rods for the three axes and to use it as threaded rod as well. I want to move the axes by hand, but screwing the z axis up and down will be too boring, so I think I can have it tight enough to have it stay at any height.

I'm thinking about a substitute for the belts. The material should be flexible enough to move around the fixed motor / pulley / idler. Maybe rubber or some kind of fabric could do. Do you have any ideas?

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Very impressive!

Perhaps you can print toothed belts using a flexible plastic, e.g Nylon, polyurethane or Ninjaflex. In fact, ABS is pretty flexible when only one layer thick. Or just use rubber elastic bands.

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[www.hydraraptor.blogspot.com]

Amazing!

You sometimes get very long elastic bands round some packaging... that could work.

Failing that a bit of elastic ribbon (Like whats in clothes) would work.

This is looking really good! I hope you're saving all the modified design files for us so that we can print our own once you've done all the hard work!

@ElectroWomble: sure, I'll stick the STL files for the cowl in another thread somewhere.

Hi,

Quote
QuackingPlums
I hope you're saving all the modified design files for us so that we can print our own once you've done all the hard work!

yes, sure I'll do that. I only think about where to put the files. I don't like Thingiverse. Github seems a bit too complicated for such a project where there aren't much changes expected. Repables looks good for me. Do you have other ideas?

I want to give not only the .stl files. I try to describe the entire way how I did the prototype, what and how many screws are needed and so on.

Yesterday I tried to open the Melzi files in Kicad to do a 3d rendering ... Nophead only provides a bare plate as a Melzi board in the drawings. But I had no luck. Neither the older version nor the newer version opens in Kicad. Maybe someone can help me out a little - I need a .stl file of a Melzi board. It does not need to be super accurate. A few chips and other components, connectors and screw terminals will do.

I sawed the aluminum rods to length and had to drill the y axis linear bearings a little to let the rods go through. They are aluminum welding wire with 3.2mm diameter. First I drilled with 3.2mm and got a very tight fit. With 3.5mm it's a bit loose. I'll see how the y axis will move when it's screwed together.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

If there aren't any freely available then I can make one up quickly. I've got a busy weekend ahead of me though so it'll be next week before I can start.

Hi,

more pictures from the last steps:

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Are you still looking for a model of the Melzi board? I just knocked this one up quickly from the dimensions specified in the RepRap wiki and positioned all the components by eye (I'm not by my printer so I can't measure it directly) - is it good enough for a model?:

Hi,

Quote
QuackingPlums
Are you still looking for a model of the Melzi board? I just knocked this one up quickly from the dimensions specified in the RepRap wiki and positioned all the components by eye (I'm not by my printer so I can't measure it directly) - is it good enough for a model?

yes! YES! Thank you very much! Impressive! As soon as I'm at home I'll try it out.

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016

Absolutely amazing!!!

Hi,

the Melzi board printed very well:



Here you can see how it's made.

I finished the hotend as well:



And the z-axis can now move along a M3 threaded rod:

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MfG / Regards

Stefan

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Blog / Gallery / Wiki / Mendel90 kit since Sep 2013 from Nophead / Original Prusa I3 MK3 since Feb 2018 /
OpenScad Workshop: Kursdateien
Octoprint Patron since April 2016