Concrete 3D Printer Build

Thread Starter

dexrod12

Joined Jan 25, 2022
1
Hey all, I'm new to the land of forums, so please be gentle :)
I'm building a concrete 3D printer for school/personal passion and don't know a lot about electronics (I do see the irony here). I have 6 Nema34 stepper motors (bipolar) with 6A each. (model number is 34HS31-6004S1, https://www.omc-stepperonline.com/download/34HS31-6004S1.pdf). I've found a variety of drivers that would work for each of the motors, but I need a control board set up that can handle all those drivers. I've looked around and asked some of my friends but no luck (to be honest I'm not really sure what I am looking for beyond it needing to have 6 driver connections) Any control board suggestions or directions would be appreciated!
Thanks!
 

Alec_t

Joined Sep 17, 2013
12,744
Welcome to AAC!
Will the two extra motors be involved in mixing the sand, cement and aggregate for the concrete? If so, 6A motors may not exert enough torque.
 

MisterBill2

Joined Jan 23, 2018
11,621
I routinely see a four-axis motor controller board advertised in Electronic Design magazine, and elsewhere. I have not investigated them at all.
You will need to take a lot of precautions with the mechanical portion because concrete mix is a nasty abrasive material that will destroy bearings very effectively.
 

MrSalts

Joined Apr 2, 2020
1,585
Hey all, I'm new to the land of forums, so please be gentle :)
I'm building a concrete 3D printer for school/personal passion and don't know a lot about electronics (I do see the irony here). I have 6 Nema34 stepper motors (bipolar) with 6A each. (model number is 34HS31-6004S1, https://www.omc-stepperonline.com/download/34HS31-6004S1.pdf). I've found a variety of drivers that would work for each of the motors, but I need a control board set up that can handle all those drivers. I've looked around and asked some of my friends but no luck (to be honest I'm not really sure what I am looking for beyond it needing to have 6 driver connections) Any control board suggestions or directions would be appreciated!
Thanks!
Try this site. They have been managing 3D printing open source projects for years... I have built one and it works well.
https://reprap.org/wiki/RepRap
They have all the parts, recommendation and other info you'll need for "standard" 3D printer. Modifying for concrete is yo to you. You may be better off with a wand type instead of a rigid x, y, z axis box. Look up French 3D concrete printer. In other words, buy a used robotic arm.
 

drjohsmith

Joined Dec 13, 2021
383
I'd assume you will be using pre mixed concrete,
the type that's pumped

https://www.totalconcrete.co.uk/news/concrete-pumping-work/

The immediate problem with printing,
is the cure time,
you can only lay say 100 mm of concrete before it slumps to one side,
and pumped concrete tends to be more fluid than this,

then you can not add on top of it for at least an hour,
but if you leave it more than that , then the layers do not bind,
water can get through the gap, and rot the rebar thats needed.

https://www.sika.com/en/knowledge-h...P,possible with traditional concrete formwork.

https://www.3dnatives.com/en/how-does-a-concrete-3d-printer-work-080120215/

As a basic
I'd suggest that you keep the concrete away from, in a separate machine than the robotics,
 

MisterBill2

Joined Jan 23, 2018
11,621
Two motors on the X and Y axis make sense, and it might even work to drive two motors in parallel, if they never slipped a step. That could be an easy way to get by with fewer drivers, as a twp motor axis certainly needs them stepping in unison.
As for the concrete doing the slumping and squeezing, I have read articles about some concrete printing done by NASA, and so it seems that there may be a solution to that issue. Probably a different mix, or adding a stiffener like fiberglass threads. I recall many years ago that we stiffened soft molded polystyrene by adding about 2% long strand glass fibers. I don't recall the details, other than it worked very well. That was open-molding, not injection molding.
 

drjohsmith

Joined Dec 13, 2021
383
Glass is a potential problem
Something bizarly called concrete cancer ..
Nothing to do with cancer ,but.
Has to be the "right kind of glass"
It's available commercially .
Or use steel fibres ,
They are great, but you have to address the problem of them sticking out of side , and rusting and spiking people .
And adding any fibres makes pumping more of a problem
If think NASA's work is for low gravity , alternate / zero atmosphere and cost is not a problem .
Making a shelter of moon or martian dust is much cheaper than sending big lumps of metal into space.
 
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