Bulding a Mendel90 and Nozzle sizes - advantages and disadvantages?

Hi All, I'm planning on building a Mendel90 from scratch, using my Mendelmax 1.5 for printing the printed parts.

I've been researching what I need to do and I have read on the wiki page that the printed parts need to be printed with both a 0.35mm and 0.4mm nozzle. I only have a 0.4mm nozzle though, am I out of luck? Could I print the whole lot with a 0.35mm nozzle instead?

Also, has anyone sourced and built their own Mendel90 rather than getting a kit from Nophead? Any tips?

HI cosmicr

You can print the vast majority of the parts with a 0.4nozzle, its only the wades gears that are better printed with a 0.35 or smaller. One "cheat" is to tell Slicer you have a 0.35 nozzle fitted when you slice those gears. The whole project is parameterised in OpenSCAD so you can define a different nozzle size and regenerate the stls if you wanted to.

I built quite a few Mendel90s from Nophead's original design with hand cut MDF frames, but for ease of assembly and accuracy I highly recommend getting a CNC routed (or lasercut) frame. I think Nophead may provide just the CNC'd dibond frame - worth asking. The other parts can be sourced from a number of different suppliers and the build manual is very good.

Regards

Tony

[blog.think3dprint3d.com]

I currently print all the parts with 0.45mm nozzles. To do the gears I use 0.2mm layers with W/T set to 2.25 and that seems to give the same definition as when I did them with a 0.35mm nozzle with 0.3mm layers and W/T = 1.5. The downside is it takes longer and they stick so hard I usually have to knock them off with a hammer using a sacrificial gear to avoid damaging the teeth.

Yes we sell the Dibond on its own, see [forums.reprap.org].

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[www.hydraraptor.blogspot.com]

Thanks for the replies - I will give it a shot. W/T == width/thickness? Are you referring to filament or nozzle? Just looking in config.scad there's layer_height, filament_width (which is layer height * 1.5? doesnt seem right), nozzle_length(I think this refers to the mendel90). In dibond_config.scad there's default_wall and thick_wall, I don't think its either of those. In slic3r I can change both the nozzle and filament width. I currently have it set to 0.4 and 3 (I'm using 3mm PLA).

Sorry if these questions are a bit mundane, am I out of my depth?

Yes W/T = width of filament path / layer height.

The Mendel90 parts are designed to be printed with 0.4 layer height and 0.6 filament width, i.e. W/T = 1.5. I used to do that with a 0.4 nozzle but the ABS I could do that with is no longer available so I now use 0.45mm nozzles.

If you change the values in config.scad then all the parts will change slightly and maybe the hole positions in the sheets. With a fully parametric design it is hard to anticipate all the things that will change.

You can generally slice the parts with smaller layers and or smaller widths but there might be a few problems. Support membranes may be more than one layer. You might get some gaps that can't be filled.

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[www.hydraraptor.blogspot.com]

I built mine from scratch. I have never seen so well put together OpenSCAD automation to pump out perfect parts customized to my parameters.

I decided to build mine from MDF since I had a bunch laying around. It is perfectly flat and square. I primed and painted all surfaces and edges to avoid any moisture issues throwing off dimensions.

It is rock solid and printing like a champ. The whole thing is PLA except for the Wades and Wades Gears. I could not print ABS with my nearly dead Prusa i2. It took all the poor thing had to print the Wades in ABS .. then died.

My Prusa i2 was acting funny the whole time printing the parts. So even though I had a .35 nozzle .. I can't tell you things were extruding perfectly accurate. Everything still fits together well.

I sourced my power supply from ebay. Belt, pulley, electronics, linear bearings, etc from Makerfarm.com. Hardware from Home Depot and McMaster.

Thanks again for all the replies everyone. I had a go last night at the wade's small gear, it seemed to come out okay in PLA, so I then tried the calibration piece (cal.scad). I realised I've got bigger problems. The piece was coming out 39mm in one direction and 38mm in the other (instead of 40mm). I've got to get the calibration a bit closer before I undertake this big task.

Thanks again for all the help, and thanks jamesmoe for your info on the self sourced build.

I'll post an update once I get going.