In early 2021 I decided that I was going to try to produce formwork (for poured structures such as concrete) out of recycled plastic bricks. This was in part because I'd heard that there's timber shortages, a crisis in plastic recycling, and I always wanted to figure out what to do with my waste 3D prints. In discussions with concreters and other builders who use formwork, I was told that the resulting surface finish of the structure was a very important consideration when selecting a material for formwork. This is why formply, with it's smooth exterior laminate is the industry standard, even if it rapidly becomes a waste product.

This lead me to come up with higher specifications for tolerances & surface quality than the original, open source brick tooling designed by Precious Plastic. However I was determined that the geometry of their brick was still suitable for formwork, with the addition of a compression step, and more precise (machined rather than welded) parts.

As a result I started work late last year in building a PrintNC specced to my project, with hardware that I am familiar with (Duet). This week, using steel I milled and cut on the PrintNC I was able to produce my first "early production brick"*.

The mould's design is simple to replicate, costs less than $300aud, $200usd, 170gbp, etc. and can produce bricks without additional tooling, with nothing more than your body weight and some** heat.

*that didn't break into pieces as I demoulded it.

**understatement.

A motor mount I redesigned for my PrintNC, printed in solid ABS, with an acetone coat.

Potato quality photo of a drilling operation.

Concept render of the intended use of the bricks.

Explanatory render of the tooling.

Photo of the early tooling used to produce the first brick. The internal plate is heated using regular 3D printer heater cartridges, and the side walls could be heated with heater pads.

The first brick, made out of ~2.1kg of waste PLA. Note the smooth sides and sharp corners of the external surfaces.

3D printed 1:4 scale model of the brick with poured concrete inside.

I'm a tab hoarder. A lot of people are these days. My browser is currently using in excess of 4gb of ram, and that's much lower than normal. Finding my Duet tab in all that mess is difficult, so I tried to figure out a solution, that didn't just involve using another browser. Fortunately, there is just such a solution for Chrome. It results in a permanent, separate icon on the taskbar for Duet Web Control, and even a custom icon so I know instantly where to click to bring it up. There's even the potential of colour coding the icons, so you can run multiple printers at once.

As you can see above, I'm using a Duet like logo on the taskbar, and I have a variety of other Chrome icons on the taskbar. The way to do this is is:

• Hit the ... button
• Hit settings
• Manage other people
• Add person
• Choose a name and an icon
• Hit add

Now you have a new browser window. Load up Duet Web Control in that.

I prefer to set the following:

• ...
• settings
• Continue where you left off

And in order to have a custom icon replace the chrome icon as I have:

• Right click the new user shortcut on your desktop (chrome creates these automatically)
• Select properties
• Change icon
• Pick an icon

http://www.iconj.com/ico/l/u/luw61wizfw.ico - link to the icon I made.

It's trivial to change it's colour.

@dc42 said in Help regarding my CoreXY:

1. To change to a right hand coordinate system, add parameter Y-1 to your M667 command, or swap the X and Y motor wires.

2. The jerky Z movement probably means that your Z acceleration in M201 and/or maximum Z speed in M203 is set too high.

HTH David

In the "Configuring RepRap Firmware for Core XY" doc it says:

"Important: make sure that you have chosen a right-hand axis system. That is, looking down on the printer the +Y direction should be 90 degrees anticlockwise from the +X direction. If instead it is 90 degrees clockwise, you have a left-hand axis system, which will give you mirror-image prints."

But there's no note on this setting. My CoreXY is right handed, and this forum reply was the answer I needed. Maybe the doc could be updated?

@norder @norder the tool I'm making drives a pin that locks a mould shut. Basically, there will be a slot in the bottom of the mould, and the stepper (with a threaded shaft) would drive a block (purple on thingiverse) in to the slot. This is crucial because I'm using compression moulding, and will use the ram that compresses the mould to eject the plastic part, once it has cooled down.

There are no doubt more elegant solutions to this, but I have these pancake steppers on hand.

https://www.thingiverse.com/thing:5467974 - initial design, with a copy-pasted preamble from this forum post. Bill of materials, basic instructions and STL of basic tool dimensions is included.

Not too sure if it's relevant, but I'm getting reset buffer blocks via the COM port now. Not sure if that was happening previously.

Firmware version 2.02beta1(RT0S) - date 2018-08-12b5
Duet Wifi 1.02 or later

Using M588 S"*" to forgot the existing network, allowed me to use M587 S"network" P"password" to connect (M552 S1) to a new network. I'll check now if I can still connect to the old one.

Final edit; problem solved by deleting the network and reconnecting. No idea why.

Video here; https://www.youtube.com/watch?v=OEH4pMnpgps

Probably not a lot of content that those who keep up to date are unaware of. But I am pretty sure that's a picture of a familiar interface for many of us.

@Phaedrux Thank you for the detailed instructions!

@dc42 That's interesting that you're able to do a software fix for hardware interference. I'm curious how that works. But I think I'm happy enough with confirmation that this could be the panel.

I'll update the firmware and see how I go.

Twice now, my Duet Wifi 1.02 printer has E-stopped, without any interaction. The console reports:

Cancelled printing file ****.gcode, print time was Xh XXm
Emergency Stop! Reset the controller to continue.

The second time this occurred a dialog popped up in DWC stating that the firmware still reports that it's halted, asking whether I want to restart again. Restarting again resulted in a printer reporting idle.

Firmware version is 2.02(RTOS) (2018-12-24b1)

I have a PanelDue attached, and no separate E-stop wired up.

Is this likely due to a fault in the panel?

Ok, so I just recalled that my plan was not to do a 'sensorless home', but to travel backwards for the full length of the axis, and assume the axis is at zero because of stalling. Just a small FYI.

@dc42 thanks! So you basically reduce the current just for homing? Makes sense to me.

Will the stall homing work across multiple motors?

@norder @norder the tool I'm making drives a pin that locks a mould shut. Basically, there will be a slot in the bottom of the mould, and the stepper (with a threaded shaft) would drive a block (purple on thingiverse) in to the slot. This is crucial because I'm using compression moulding, and will use the ram that compresses the mould to eject the plastic part, once it has cooled down.

There are no doubt more elegant solutions to this, but I have these pancake steppers on hand.

@bot aha, yes, that's what I thought you meant. I think that won't be a problem in my case.

@bot when you say mechanical damage, you mean to the stepper, or the parts attached to it? I am using very low amp pancake steppers in the hope this has the same effect.

I will be using some spare stepper motors to drive pins to close a mould that I've designed via a Duet 3 board. The steppers are small and low current Nema17s, but will conduct the same range of motion with each operation. As a result, I want to be economical, and control them all via the same stepper driver on the board.

However, I want to be sure this won't cause any damage to the board. The reason I'm concerned that it might, is largely that I know very little about electronics, but also that I plan to home the pins by deliberately stalling them out. That is ... I intend to drive the stepper in reverse until the 'pin' element is hitting the plate the motor is fixed to. I'm concerned that stalling one or multiple motors might present a problem for the stepper driver?

Below is a basic render of the pin (in purple), driven by a threaded shaft. STL here.

https://www.thingiverse.com/thing:5467974 - initial design, with a copy-pasted preamble from this forum post. Bill of materials, basic instructions and STL of basic tool dimensions is included.