Continuing the 3D printer thingy - Page 6

gninnam · #51 18th January 2019, 09:10 AM

MJ - printer nozzle scratch/gouge.

I levelled the bed and printed something off with no issues, then once cooled removed from the bed then started on the next items but it kept on buggering up. The filament not sticking.

So redid the file to only have the one item, started to print again and every now and again could hear a click. after 40 seconds or so realised the print head was diging into the plate - gave it a clean (as can be seen by the residue of the acetone) but now damaged......

Ray - good work with the build of the modules

MikkiJayne · #52 18th January 2019, 11:50 AM

That's the right hand Z motor dropped - the CR-10's killer flaw. I check it every print for that exact reason. I'm planning to design an end-stop for it so it can't get below the left hand motor - basically a block at the same height as the Z endstop switch. I'll post it up when its done.

gninnam · #53 18th January 2019, 12:17 PM

Cheers - doing my fruit in!!

tc4332 · #54 18th January 2019, 12:34 PM

We have not suffered that problem.
My Son suggests swapping the suspect motor with the extruder motor and retry. He's thinking it could be a quality control thing with stepper motor production.

MikkiJayne · #55 18th January 2019, 01:27 PM

Its not the stepper motors - its the basic design of having two motors doing the same job with no mechanical synchronisation. Most dual-z printers can suffer from it, but the CR-10 seems to be particularly bad because the wheels allow the X axis to twist in the frame. Printers with linear bearings tend to stay straight once they're properly set up. With the CR-10S, as soon as it finishes a print and turns off the steppers the weight of the X axis can cause it to drop slightly on one side by rotating the lead screw. You'll see it happen in macro if you put any weight on the X axis bar while it's powered off - it'll spin the steppers and move down the Z axis.

Now it may be worse on some printers than others as it could change depending on how square the frame is or indeed how tight the wheels are. Mine likes to drop about 2 steps so I know to correct it. Sounds like Andy's has done the same.

gninnam · #56 18th January 2019, 02:01 PM

Based on what MJ has said I think after every print the bed will have to be checked for levelness - perhaps Ray's son's suggestion might be worth a try though if they haven't suffered the same symptoms ??

MikkiJayne · #57 18th January 2019, 02:16 PM

Check the X axis for level, not the bed. If the X axis is not level and you adjust the bed to suit it then you're effectively printing a parallelogram! Both things could be parallel, but not perpendicular to the Z axis.

I set mine up by powering up the Z steppers (lift Z by 1mm) and then measure the distance from the X axis to the frame with digital calipers. I'll adjust the right hand Z axis by hand until the measurement is the same, and only then will I do bed levelling. That way I know its parallel and perpendicular.

Z drop is a well known characteristic of the CR-10S, and indeed the CR-10 when modified to dual Z. There are dozens of designs on Thingiverse to mitigate it, mostly toothed belts to keep the two motors in sync. I think a simple block to level the Z carriages before printing is probably simpler though

gninnam · #58 18th January 2019, 07:14 PM

Will have a go over the weekend and report back boss

tc4332 · #59 19th January 2019, 02:34 PM

Just to let you know what we are thinking.
Seems OK apart from me having to fund it.

First is the Duet mother board

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

Second is the piezo contact sensor

https://www.precisionpiezo.co.uk/shop

There are a few more things that Craig would like and me being a sucker for gadgetry, looks like some more deep research.
One of the major plans is to use linear bearings.

MikkiJayne · #60 19th January 2019, 02:58 PM

At that point why not build yourself a new printer?

I keep looking at my CR-10 thinking some nice Misumi rails would bolt up nicely to the 2020, but then I have a sanity check and realise the CR-10 will never overcome it's limitation of moving a big heavy bed around so there is (IMO) marginal scope to improve it.

A CoreXY design like the Hypercube or HyperCube Evolution is superior in pretty much every way to the CR-10 and can be built for about the same price (notwithstanding a Duet board). Until of course you start looking for best-of-breed everything

Hypercube by Tech2C: https://www.youtube.com/watch?v=n2jM...fe9rtiwvvRGCzw

Hypercube Evo by Scott3D: https://www.youtube.com/watch?v=1rctCsUGnX8

Do that Duet some justice and put it on a printer than can keep up with it

My Hypercube frame arrives on the 30th of Jan so the CR-10 is printing parts in preparation. I'm going to run it on a cheap MKS Gen 1.4 to get it running and then either upgrade it to a Duet / Lerdge, or build an Evo and put a Duet on that.

Voron is another open source CoreXY which is worth looking in to btw.