Thank you for the input!

This will in turn drive a screw, so as far as the belt drive go I should only need the 16:40 gear ratio. Into a 2mm pitch screw should give me 4000 steps/mm and optimal layer heights for any multiple of 0.025 which is seemed quite convenient as I'll likely use from 0.1mm and up in 0.05mm steps. (1.8deg steppers x16 microstepping) Well thats wrong, Prusa cal thingy ignores microstepping for optimal z height for screws?! Oh well, different gear ratio it is then..

Found a page with simpler math for working out the center distance from the two pitch diameters and belt length without having to resort to nasty trig functions so will incorporate that

K=4 * L - 6.28 * (D + d) a=K^2 b=(D - d)^2 c=(a - 32 * b)^0.5 C=(K + c) / 16

0_1558490767271_4e5a9da4-df15-4ffe-9b30-a0ed522c224a-image.png

I print various brackets that have no real fine detail but need to be tough and so use PETG using 240 deg nozzle temp, 60 deg bed temp (blue tape) and zero fan. 3 walls and 20% gyroid infill and they come out just fine. I reinforce some regions in the part with 90% infill as you can see here

0_1558420577615_Screenshot_2019-05-21_07-36-02.png

0_1558420588123_Screenshot_2019-05-21_07-35-48.png

I figured out that it's nearly identical to the Bondtech Mini gears, since I completely overhauled an old extruder design (with the Bondtech Minis), used the Hobb Goblin in the new redesign, but never changed the settings, and it printed a calibration cube perfectly.

For those who find this topic later, the final answer is the effective diameter is 7.28mm

The teeth of the Hobb Goblin digs way deeper than the Bondtech, which is great for my 2.85mm filament, but it might be even a bit too deep for 1.75mm (only guessing, I can't test this since I don't have 1.75mm filament).

As @OBELIKS said, re-check M92 values. And as your printer is a delta, re-check the calibration.

@phaedrux Fascinating stuff - thanks for sharing.👍

I attempted a poly tower, but it ended up poorly because the slicer can only handle even numbers, so I had to print two shells and that kept the heat too close.

Normally I print that model with one shell.

@phaedrux

Thanks, I will try again.

I used hair-spray and it helped, but I am so glad I haven't seen any cracking or warping issues, and the best part is parts seem to be 100% accurate, a 20x20 cube comes out at exactly 20x20.
That FilamentOne place was fast as hell to get it out to me, ordered Saturday, got it Monday!

I have suspicions it's made by Filimentium, same reel design, and the company used to sell that brand.

Going to re-print my cooling duct since the one I have now is a rough mess- $9 glow in the dark ABS on ebay gets you $9 quality.

Thanks for the information. Extrapolating (yea I know) the line it appears to fall inside but right at the edge of the area. I don't know if it will make any real world difference but I think I'm going to try the SS-01E which is a low force model.

anycubic released different stages of development under the same name. so you do need to verify your values.

Re Linear Rails
Yes, I have modified my Prusa to linear rails mounted on 3030 extrusion. It has made the printer bed far more stable. Improvement to print quality is minimal but there is a big improvement to repeat-ability. The only calibration I really need to do now on a regular basis, is to level the Z axis.
The original 8mm diameter rails and bearing arrangement is easy to build and probably just about adequate and cost effective for the loads involved but not good engineering practice IMO.
The linear rails do need precise alignment and setting up, but once done, the bed runs smoothly and stays in alignment.

For two aluminum 1/4 inch plates, I am getting a $450 price quote.
The tolerances quoted are not great.
As you can see I have staggered holes to accommodate different geometries.

The real kicker is that if you go up to 25 parts the price goes down from $200 each to $80-$100 each.
It would be great if this could be cost-shared in some way.

alt text

...now for something different.

NXD evo (RepRap forum in german language with some pictures and links)
NXD evo at work (Google video)

NXD evo CAD (Onshape)

@dc42 said in Measuring heated bed resistance:

Did you measure that with the bed heater disconnected from the Duet? If yes then get a new multimeter.

I'm gonna get a new multimeter. 😂

@vwegert I kind or forgot but I actually made a video of my purge bucket in action. If it's any use, check it out here https://www.youtube.com/watch?v=zNNmZCXErYY&lc=z234cfh4dkylhh4ra04t1aokgl1ownrihxxz0fiwil5xrk0h00410

65 is pretty hot (at least to me it is).
PEI is awesome. Try dropping to 60 or 58.

I got an MK3 recently. Love it. I try PETG recently on the MK3, Love it.

I used it to re-print some parts on my dimond hotend mini kossel Duet Wifi.. Lovin it.
I swear the more extruders, the more problems. lol

0_1546458555589_Heat_tower_190-240_Bridge.stl
From http://www.thingiverse.com/thing:2223651

And yes I use the same model for both fan and temp. It's a decent model because it has bridges, overhangs, sharp corners and curves.

This may be of interest to you. https://manual.slic3r.org/advanced/flow-math

Take a look at this for a breakdown of what you'll need to know.

https://duet3d.dozuki.com/Wiki/Going_from_Marlin_on_Arduino_to_RepRapFirmware_on_Duet

I would like this feature too, measuring extrusion at different speeds for non-linear extrusion takes most of my tuning time.