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HugoW's CoreXY machine

Posted by HugoW 
HugoW's CoreXY machine
September 14, 2017 05:11AM
Hi all,

herewith I start my thread on my first 3D printer. I have little knowledge on the subject, what I know I learned on this forum and by googling. I started this project in my head end of last year (2016) and did the first purchases mid-February I think. I don’t really have a budget (not as in undefined, but as in non-existent), and I am very happy with the two second hand NEMA 23 motors and the huge 24V power source I received from a friend and fellow hobbyist for free.

The idea was a 400 x 400 x 250mm printer, but I got a stack of 500mm long 2020 and 2040 extrusions for almost nothing of Marktplaats (Dutch Graig’s list sort-of) which shrunk the area to about 350 x 290 x 220. I might scale it up later. The bed plate is 440 x 440 x 8 mm tooling plate, resulting from a bit of dumpster diving. A local machine factory left-over for a few bucks and they cut it to size for me, too. I was very happy with it, although I might change to (mirror) glass later. This bed with its mountings now weight 6,2 kg. which is a lot, and the alloy tooling plate easily scratches and is expensive to replace.

The thing has pooped its first plastic last weekend, all axis are moving, the X and Y homing is done. I am currently waiting for the servo to arrive on which I will fit the Z-axis switch. I could fit an inductive sensor while I still have the tooling plate bed, but I bought one which arrived faulty (or I messed up, I don’t really know) and with my glass bed desires in the future I thought I’d go the micro switch / servo route.

The controls are now a RAMPS 1.4 set-up with external drivers for the X, Y and Z axis. The Z motor is an overkill NEMA 34, I still had that in the shed from another project. There is currently a 12V buck converter powering the Arduino Mega but that will soon be dumped as I fitted a bigger / better 5V regulator to the Mega. I just need to put the diode back onto the RAMPS to make that work, 10 of those are still on the slow boat from China.

I still miss some support shafts on the Z-table. I need a 24V hotend heater cartridge (it currently runs a 12V version on 24V at ¼ power by cutting the PWM to 64, but should the MOSFET ever give up it will get four times the power it likes…). When the servo arrived and works, I need to fit it and clean up the wiring. I think I need a better extruder gear, this one slips a lot. I have something like this:

But I think I need something like this:

I have about a gazillion more wishes on my list, but the first and biggest wish it to actually print something. The purpose of this machine is to produce home-designed parts for my RC cars.

Now for some pics which I never seem to be able to rotate correctly:

Although I start this thread as a log for me personally and for others to inspire, all constructive input is welcome!



Edited 2 time(s). Last edit at 09/14/2017 05:21AM by HugoW.
Re: HugoW's CoreXY machine
September 14, 2017 07:44AM
What electronics package is that? Nice job, BTW!
Re: HugoW's CoreXY machine
September 14, 2017 07:53AM
It's a basic RAMPS 1.4 with three TB6560 drivers via extension boards for the axles. The extruder runs on a normal 4988 driver on the RAMPS.

Re: HugoW's CoreXY machine
September 14, 2017 11:43AM
It might be the weird perspective, but in the top view picture the belts look like they are not aligned?

Rule #1 for CoreXY: belt sections which change their length during moves have to be parallel and perpendicular all around.

Edited 1 time(s). Last edit at 09/14/2017 11:45AM by o_lampe.
Re: HugoW's CoreXY machine
September 14, 2017 12:50PM
What is this servo?
Most printers use stepper motors.
Your NEMA 23s are stepper motors

Looks like extruder is using NEMA 17 stepper motor

? Z axis switch on servo? What is this for? Z axis limit switch? Why?

RAMPS drives stepper motors usually 4 drivers X, Y, Z and extruder
What firmware? Marlin?

What type of extruder --- home made MK 8 type

If it works fine? But the mess is going to lead to problems?

confused smiley
Re: HugoW's CoreXY machine
September 14, 2017 01:18PM
@0_lampe; yes, the belts are almost perfectly alligned. I still need to fit some shims under some pulleys but everything is set within 0,5mm.

@cozmicray; they are all stepper motors, NEMA 23 for X and Y and 34 for the Z. 17 for the extruder. The extruder is an MK8 from which I cut off the base and put my own base / bearing block in place. The servo is for mounting a retractable Z-axis homing switch. That is required for Autoleveling the bed. It runs on Marlin. Not sure what mess you mean, I mentioned I'll clean up the wiring when the servo is wired up. The wire guide hook is aleady in place as you can see.


Edited 1 time(s). Last edit at 09/14/2017 01:18PM by HugoW.
Re: HugoW's CoreXY machine
September 17, 2017 12:00PM
It works and yes, I am pretty exited about that! And yes, I am aware the result sucks, but anyway...

First attempt, too much opening between bed and nozzle:

Second attempt, I call it a success!
Part 1:

Part 2:

The print is not entirely done. Half way the second top layer it pulled loose from the bed and I retrieved it manually. I was going to shoot the third and final clip just when it happened, so I didn't.

Pics of the result (bad result is a result, too, right?)

I have two improvements on my mind. It seems to underextrude a bit, but the main problem is the extruder gear slipping. I need to buy a better one. Why it pulled the print loose in the final stages I don't know, yet. But it might be a side effect of the underextruding and the gear slipping, it might pull on the print when the head moves and the material does not flow. So new gear, first, maybe a few steps less per mm, and then we'll see what it does. Right?

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