Support on proposed High Speed 3D Printer

selva_tvi

Hello all,

We are planning to build a Core XY 3D printer. Mainly for high speed. Print volume - 300x300x300mm

Duet 3 Mini 5+ with Panel Due 4.3"
Orbiter 2 Extruder with Rapido UFH hotend with Hardened steel nozzle. (Direct Drive)
Hiwin MGN9 or 12 Guide Rails for X & Y with Gates GT2 12mm belt and pulleys
Hiwin C7 Ball screws with Dual Z with Motech 1705HS200A motors
7075 Aluminium bed 6.35mm for Print bed
AC heat bed with SSR

We have built decent CoreXY 3D Printers previously. All were built with a maximum acceleration of 1500mm/s2 and max speed up to 120mm/s

Now we want to increase the acceleration up to 6000mm/s2 and speed up to 300mm/s. After reading multiple articles we found Hevort is doing better. He has achieved up to 800mm/s with Teknic ClearPath.

But when we read multiple discussions here, we are really not sure that anyone has achieved better results with Servo motors or Step Servos to connect with DUET.

Teknic ClearPath is a costlier option. We are planning for two alternates:

Going with Makerbase Servo42C closed-loop controller. We have used it in our other CoreXY 3D Printers and found decent results. But when we increase the speed up to 300mm/s, will it work as expected?
https://www.aliexpress.com/item/1005003380483496.html?spm=a2g0o.productlist.0.0.29396a24zRjyLq&algo_pvid=8d8825ce-b4f2-4536-a98f-155bebe611c8&algo_exp_id=8d8825ce-b4f2-4536-a98f-155bebe611c8-3&pdp_ext_f={"sku_id"%3A"12000025511516070"}&pdp_pi=-1%3B19.6%3B-1%3B-1%40salePrice%3BEUR%3Bsearch-mainSearch

If this is acceptable, then this will be an easy option to connect directly to the DUET board.

Stepper online is giving somewhat cheaper Closed Loop Stepper kits.
https://www.omc-stepperonline.com/closed-loop-stepper-kit

They have Nema 17 and 23 based controllers. If these work best with DUET boards, which one will be best (Nema 17 or Nema 23)?

But, here we have to add 'Duet 3 Expansion Board 1XD' to control the motors I hope.

As we saw multiple posts for connecting the Servos with DUET and nobody has given any proven result, we are in doubt to proceed with the above kit.

Kindly give your valuable thoughts on the above.

Thanks in advance

dc42

@selva_tvi the Duet 3 Mini can provide at most two sets of step and direction outputs for servo or other external drivers, and for most drivers they would need to be level shifted from 3.3V to 5V. So it probably not what you are looking for.

As well as the solution you already identified (Duet 3 or 3 Mini + EXP1XD boards), the solutions we have for closed loop steppers or servos are:

Duet 3 ~~MB6HC~~ MB6XD provides 6 sets of step/dir/enable outputs with 5V signal levels. It has no internal drivers, but you can connect EXP3HC or TOOL1LC expansion boards of you need some regular drivers too.
Duet 3 expansion board EXP1HCL is a CAN-connected expansion board for driving a single stepper motor with encoder. It can be driven by any Duet 3 main board including the Duet 3 Mini.
Duet 2 WiFi or Ethernet + Expansion Breakout Board had five internal drivers and connectors for external drivers, with either 3V differential or 5V single-ended outputs.

The MB6XD and EXP1HCL boards are both in pre-production stage, so not widely available yet.

mrehorstdmd

@selva_tvi At least one person here has built their corexy using servos and achieved high print quality. As I understand it, they used iHSV servos with a 3:1 reduction to get the necessary resolution (the iHSV servos have Hall effect encoders that limit resolution). I tried it myself without the 3:1 reduction and got poor print quality- lots of "salmon skin" or maybe "tree-ring" artifacts. I intend to try it with some reduction to improve resolution.

I built a couple corexy sand tables driven by the same iHSV servos and was able to run the mechanism up to about 2000 mm/sec with acceleration of 20,000 mm/sec^2 (yes, 2 gs!). They could have gone faster but I used 20 tooth drive pulleys and ran into the 3000 rpm limit of the motors. I used Duet 2 Wifi with an expansion board to get the step/dir/enable signals for the motors.

https://vimeo.com/424381250

https://vimeo.com/422175403

selva_tvi

@mrehorstdmd @mrehorstdmd Thanks. I have already read your blogs and discussion about the use of iHSV servos.

https://drmrehorst.blogspot.com/2020/11/heres-what-happened-when-i-swapped.html

Also, I saw your post that you also didn't get the results with Servos with DUET. Any solid data or discussion where someone have proven good results with Stepper Servos?

And what about the Makerbased Servos? Any inputs from your side pls..

selva_tvi

@dc42 Thanks. Even your documentation is very clear for the connections of External Stepper drivers.

But I hope mostly no user has got any fruitful results with Servos or Step servos connected to DUET boards.

Can you please support us in finding the right user who has proven it already?

mrehorstdmd

@selva_tvi I have designed a circuit board for a protection circuit that may save you having to replace some electronics if you end up using servomotors and running them very fast. The schematic is from a GeckoDrives app note.

alt text

I have not assembled and tested the board yet (waiting on back-ordered connectors), but the project file is here: https://drive.google.com/drive/folders/1gcWIDbrikqigsv8qqhZrozVmTr-VLcnQ?usp=sharing
and BOM is here: https://docs.google.com/spreadsheets/d/11N4fHIwaWW3gTsieLKXYEkDYC8u6roJjRu1BrG9OEN0/edit?usp=sharing

selva_tvi

@mrehorstdmd Thanks for the support. Let me try this.

samlogan87

I am currently upgrading my printer to run and print at much higher speeds. When I am needing to whip up a prototype, I don’t see why it needs to take 30 hours to do so have been spending a bit of time working on it. I am running the EXP1HCL boards on my x and y. I am running them at 48v and I have had the printer running at 1m/s and 30k acceleration. I have not yet printed at that speed as I have had to remake some parts, in particular the x axis gantry as the aluminium I used was too light and cause no end of grief with bed levelling. I am just waiting on LDO to bring out their high speed steppers with encoders so I can make use of the closed loop functions of the HCL board. I am pretty pleased with it. I also have the orbiter 2 and a magnum+ hotend.

Sam

oliof

@dc42 said in Support on proposed High Speed 3D Printer:

Duet 3 MB6HC provides 6 sets of step/dir/enable outputs with 5V signal levels. It has no internal drivers, but you can connect EXP3HC or TOOL1LC expansion boards of you need some regular drivers too.

did you mean the MB6XD?

dc42

@oliof said in Support on proposed High Speed 3D Printer:

did you mean the MB6XD?

Yes, I did. Thanks for pointing out the error. I have corrected that post.