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Building a large Delta, doubts about sizing.

Posted by andrer 
Building a large Delta, doubts about sizing.
July 02, 2019 11:13PM
I've seen different information about delta sizing. There's the "ROD_LENGTH * COS(20)" rule that would get a 163.23 printable radius with The 400mm rods I have.

I've based a lot of my project on DC42's build. he's using a 360mm rod, which according to this rule would result in a 149.9 printable radius. He's using a 330mm diameter plate with a 300mm diameter heater. Which would be close to that.

Another spreadsheet with delta sizing calculator i've found (https://docs.google.com/spreadsheets/d/18Ksk-PurRoSelYDKVunN9ACZezn1TM7utqjWYc-56s0/edit#gid=0) gives me that for a 400mm rod length the printable area would be 360mm.

This calculator

[danalspub.com]

inputing 500mm horizontal / 1000mm vertical and 400mm rods is outputing a printable radius of 221.48.

What would be a good size for a 400mm rod?(this I already have. i'm trying to figure out the extrusions for the printer)

I'll be using a Haydn Huntley mag rods on a smart effector and a Duet.

Edited 1 time(s). Last edit at 07/02/2019 11:15PM by andrer.
Re: Building a large Delta, doubts about sizing.
July 03, 2019 02:09AM
It depends on if you want the horizontals inside or outside of the print area. Outside of the print area makes it easier to build an enclosure and you can lay the printer on its side for transport without worrying about the weight of printer resting on the print bed. Inside the print area will give you larger print area as the towers will be closer to the bed.
Re: Building a large Delta, doubts about sizing.
July 03, 2019 02:15AM
I can work with the horizontals inside the print area. I'll remove the bed if I need to transport it anyway (As i do with a small kossel I currently have). I'll also use an enclosure that's separate from the printer. IF I can get it to 360-380mm would be perfect.
Re: Building a large Delta, doubts about sizing.
July 03, 2019 02:53AM
Quote
andrer
I've seen different information about delta sizing. There's the "ROD_LENGTH * COS(20)" rule that would get a 163.23 printable radius with The 400mm rods I have.

I've based a lot of my project on DC42's build. he's using a 360mm rod, which according to this rule would result in a 149.9 printable radius. He's using a 330mm diameter plate with a 300mm diameter heater. Which would be close to that.

The printable diameter of my delta is 300mm. The 15mm margin is for bed clips and fixings. So 149.9mm is spot on.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Building a large Delta, doubts about sizing.
July 03, 2019 10:55PM
dc42 So the 20 degree rule should be followed.

I've been playing with the Danal's simulator, according to it:
Frame Horizontal: 445mm
Frame vertical: 1100mm
Rod Length: 400mm
Rail length: 820mm
With the build plate constrained by effector tip, the printable area would be 370mm.
I understand, as etfrench stated, that the print bed will be larger than the horizontal extrusion.

But would it be mecanically sound?

The simulator is giving me 21.1 degrees on the edge, using 2040 robotdigg extrusions (which I plan to use).

Edited 1 time(s). Last edit at 07/03/2019 11:04PM by andrer.
Re: Building a large Delta, doubts about sizing.
July 04, 2019 02:52AM
The length of the horizontals depends on the vertices you use. When I upgraded my delta from 2020 to 2040 verticals, switching from the 2020 to 2040 Robotdigg aluminium vertices, I found that the horizontals needed to be longer (by 36mm AFAIR) to get the same amount of space inside the towers. This is because the Robotdigg vertices allow the horizontals to overlap some of the width of the verticals.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Building a large Delta, doubts about sizing.
July 04, 2019 11:29AM
I will be using robotdigg's vertices on bottom and top joints.

I'l make the horizontals 36mm longer then. Thank you!
Other than this, is it mechanically sound? If so i'll be ordering the parts I need.
Re: Building a large Delta, doubts about sizing.
July 04, 2019 01:05PM
36mm longer than what?



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Building a large Delta, doubts about sizing.
July 04, 2019 04:37PM
445MM + 36mm as they overlap with verticals. Or should I keep at 445?
Re: Building a large Delta, doubts about sizing.
July 08, 2019 10:53AM
I had all these questions when I was first considering a custom delta. I would theorize, use calculators and do maths all day, in the end I found it best to spend my time with a CAD program and model it up. Then I could actually see how it would work. I could see how parts would interact and if I needed to redesign any of the (very few) plastic parts I had, I could.

Here's a link to a bottom plate and the Robotdigg motor vertices to get you started if you wish.
They're modeled to dc42's current build, and are being used by alex773

https://cad.onshape.com/documents/85b6557a3c0ab84fc4194e4f/w/c48e4e24416adafc999e37d3/e/9b4dd5ab5ca785a23e5a1023

It used to be the whole printer as dc42 built but I've since changed that. But, if you searched the public documents in Onshape, you'll find it because I know many people made copies.


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Re: Building a large Delta, doubts about sizing.
July 19, 2019 10:46PM
I will use that. I'll assemble the base and top of the delta as soon as the vertices arrive (robotdigg is taking a while to ship it, i don't know why). and i'll measure the bottom plate to adjust your model and have it machined.
Re: Building a large Delta, doubts about sizing.
September 13, 2019 08:14PM
I built a custom Delta, combining both David Crockers delta design and a design I found at Norwegian Creations (https://www.norwegiancreations.com/). Anyways, my horizontals are 455mm, verticals 1000mm, rods are 400mm. The bed is 330mm with a printable area of ~310mm and maybe 430ish height. The entire bed fits within the confines of the Alu extrusions - except for the bulldog clips. I'm using a flex3drive with the smart effector and getting very reasonable prints. I also went with the RobotDigg corners and Alu extrusions from Misumi. Overall, the printer is pretty solid.
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