Controller board must have add-ons

[Blowtorch]

Shopping for a controller as an OpenPnP newbie can be confusing, as all boards are typically advertised for 3D printing, often with a bunch of add on accessories.  These include various displays, with buttons and rotary encoder etc.  Also include boards such as RPI4, or ethernet or wifi, etc etc. 

However, the use case is completely different for OpenPnP, so I imagine all these add-ons are redundant, as you controlling the board directly from a PC.  

Are there any bits that are useful or do they just get in the way?  

[bert shivaan]

I don't think it is really useful IMHO.

I know some have used them for machine status things, but I think it is not really needed. Just fluff to make things fun for the builder

--
You received this message because you are subscribed to the Google Groups "OpenPnP" group.
To unsubscribe from this group and stop receiving emails from it, send an email to openpnp+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/5faa26b9-4afc-47e1-9373-d5d6f0b58f91n%40googlegroups.com.

[mark maker]

Hi Blowtorch

this is in deed an ongoing problem. The 3D printing extras costs money, makes boards heavy and large, uses up IO pins for nothing. They're spec'd for slow motion, or high torque, large motor and FET currents. On the other hand, features needed for PnP are missing, like high motor voltage (for speed), vacuum sensing, current regulated (breakout) LED rings, USB hub and USB isolator.

An optimal PnP controller would IMHO reside on the head, so it must be small and light.

There have been many announcements for PnP specific boards, some by users of this group, but so far I have yet to see a board that is available to buy, and has good support for OpenPnP features.

In the end I guess it is a "size of market" problem.

_Mark

[Shai]

Hi Blowtorch,

We offer a board specifically tailored to PNP users (without any extra features that are not related to PNP,) that you may want to have a look at: https://www.deltaprintr.com/product/rapid-star-board/

-Shai

[mark maker]

Hi Shai,

Cool!

I didn't know it is available to ship. Is this new?

Feed-back:

I tried to add it to the cart to see price and stock availability, but this doesn't work (Firefox):

_Mark

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/7b3770de-9a80-4084-b352-7384a256677fn%40googlegroups.com.

[Niclas Hedhman]

Same thing for me; Brave (Chromium-based) and for Chromium itself as
well.

On 2022-07-03 12:51, mark maker wrote:
> Hi Shai,
>
> Cool!
>
> I didn't know it is available to ship. Is this new?
>
> Feed-back:
>
> I tried to add it to the cart to see price and stock availability, but
> this doesn't work (Firefox):
>

> _Mark
> On 03.07.22 04:11, Shai wrote:
>
>> Hi Blowtorch,
>>
>> We offer a board specifically tailored to PNP users (without any
>> extra features that are not related to PNP,) that you may want to
>> have a look at:
>> https://www.deltaprintr.com/product/rapid-star-board/
>>
>> -Shai
>>
>> On Saturday, July 2, 2022 at 4:38:28 AM UTC-7 ma...@makr.zone wrote:
>>
>> Hi Blowtorch
>>
>> this is in deed an ongoing problem. The 3D printing extras costs
>> money, makes boards heavy and large, uses up IO pins for nothing.
>> They're spec'd for slow motion, or high torque, large motor and FET
>> currents. On the other hand, features needed for PnP are missing,
>> like high motor voltage (for speed), vacuum sensing, current
>> regulated (breakout) LED rings, USB hub and USB isolator.
>>
>> An optimal PnP controller would IMHO reside on the head, so it must
>> be small and light.
>>
>> There have been many announcements for PnP specific boards, some by
>> users of this group, but so far I have yet to see a board that is

>> available to buy, _and_ has good support for OpenPnP features.

>>
>> In the end I guess it is a "size of market" problem.
>>
>> _Mark
>>
>> On 02.07.22 11:38, Blowtorch wrote:
>>
>> Shopping for a controller as an OpenPnP newbie can be confusing, as
>> all boards are typically advertised for 3D printing, often with a
>> bunch of add on accessories. These include various displays, with
>> buttons and rotary encoder etc. Also include boards such as RPI4,
>> or ethernet or wifi, etc etc.
>>
>> However, the use case is completely different for OpenPnP, so I
>> imagine all these add-ons are redundant, as you controlling the
>> board directly from a PC.
>>
>> Are there any bits that are useful or do they just get in the way?
>>
>>
>> --
>> You received this message because you are subscribed to the Google
>> Groups "OpenPnP" group.
>> To unsubscribe from this group and stop receiving emails from it,
>> send an email to openpnp+u...@googlegroups.com.
>> To view this discussion on the web visit
>>
> https://groups.google.com/d/msgid/openpnp/5faa26b9-4afc-47e1-9373-d5d6f0b58f91n%40googlegroups.com

>> [1].

> --
> You received this message because you are subscribed to the Google
> Groups "OpenPnP" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to openpnp+u...@googlegroups.com.
> To view this discussion on the web visit

> https://groups.google.com/d/msgid/openpnp/7b3770de-9a80-4084-b352-7384a256677fn%40googlegroups.com
> [2].

>
> --
> You received this message because you are subscribed to the Google
> Groups "OpenPnP" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to openpnp+u...@googlegroups.com.
> To view this discussion on the web visit

> https://groups.google.com/d/msgid/openpnp/9e160aca-50b9-347a-34f1-804a4c972d19%40makr.zone
> [3].
>
>
> Links:
> ------
> [1]
> https://groups.google.com/d/msgid/openpnp/5faa26b9-4afc-47e1-9373-d5d6f0b58f91n%40googlegroups.com?utm_medium=email&utm_source=footer
> [2]
> https://groups.google.com/d/msgid/openpnp/7b3770de-9a80-4084-b352-7384a256677fn%40googlegroups.com?utm_medium=email&utm_source=footer
> [3]
> https://groups.google.com/d/msgid/openpnp/9e160aca-50b9-347a-34f1-804a4c972d19%40makr.zone?utm_medium=email&utm_source=footer

[Blowtorch]

> An optimal PnP controller would IMHO reside on the head, so it must be small and light.

Would it not make sense for a controller to reside in normal place due to wiring (heavy power supply wire, USB control, X & Y axis etc), but have a 2nd controller board on the head for Z, nozzle rotation, vacuum sensors for part detection, etc?

It could be fun to take an opensource board like the big Duet, and split it into 2, removing printer bits not needed like all the mosfets for the extruders and bed and adding new parts, but keeping pin configs the same as much as possible so we can use the same firmware...?  I am new to this game and have yet to place a single component so take my ideas with a pinch of salt.

[Jarosław Karwik]

It makes sense - I made such proof of concept with my controller design.

But after testing it proved to have several disadvantages:

- it is more expensive as second CPU costs, requires second firmware (which costs time)

- the synchronization between main and head CPU is complicated - I got mine working, but it was non-trivial as most of the cheap and simple connections have limited bandwidth ( like CAN,/FDCAN  RS485).  Ethernet might do, but then you pay extra $ fro components and PCB size grows

There are such solutions - Duet has CAN based extension boards, however targeted for single channel encoder based axes ( as I recall)

But there there is quite interesting alternative - you put only stepper motors on head  and connect step/dir signals  using differential lines - RJ45 cables are relatively cheap ( even these better quality designed for frequent bending)

You end up with simple board - just RS422 lines. I also added differential i2c for end stops and vacuum sensors.

[Mike Menci]

For Head  4x Nema8 2 x Nema 12(14) there is no need for much power and heavy voltage wires... 

Interesting is as well Teensy 4.1 version ; 

https://cdn.hackaday.io/files/1752097496141856/T41U5XBB%20v207.pdf
https://www.tindie.com/stores/philba/

Mike

[Mike Menci]

https://forum.pjrc.com/threads/61622-Teensy-4-1-Based-CNC-Controller/page3

[mark maker]

A ton of the signals are needed on the head. You need USB anyway (Top Camera) and all the cables that you can save by moving the controller to the head are much thicker in sum, especially if you use shielded and drag chain grade cables per motor, and per signal destination.

The PSU cable is not that bad, and given good bypassing (caps) on the controller, you can probably add them with no shielding.

One option is to use dedicated drivers on the Y, or the Y and X motors and drive those with STEP/DIR signals coming back from the head (very thin). These drivers can take PSU voltage bus style.

The Rapid Star board seems to support all that, does really look good!

I would prefer that option to having two controllers. Having one controller guarantees hard real-time coordinated motion.

Note that some Duet 3 boards can drive sub-controllers over CAN in a coordinated manner. So this would give you another option.

Note, I'm excluding electronic feeders here. Having a separate central feeder controller (or multiple) is certainly valid, and there is no down-side (these do not need to be hard real-time coordinated).

_Mark

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/eeea55c7-3a07-4214-91a0-c5c5d27db022n%40googlegroups.com.

[Shai]

Hi Mark & Niclas,

You need to select which board version you want before adding it to the cart. There's a full 6 axis board and an encoder version board. Can you try selecting which one you want from the dropdown and let me know if it works then?

This board isn't new. We've been selling it for at least a year now.

-Shai

[Shai]

Mark & Nicolas,

Please try again, it should be fixed now. Sorry about that.

-Shai

[mark maker]

Works.

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/753d3c40-cd6f-4f9b-912a-c8304d1f556bn%40googlegroups.com.

[Litterio Andrea Guainella]

Hi Shai,
I am planning to replace my stock liteplacer motors X, Y with this model and this driver and reading this post I am interesting about rapid board in encoder version but I am little bit confused with motor current.
As you write "DO NOT GO OVER 5A INCLUDING MOTOR CURRENT" you mean that max power supply to motor is max 5A at 36VDC?

What do you think by reading the specifications of the motors that I would like to use (4.2A for each motor: X, Y)?

 .

LAG

[Shai]

Hi,

If you're going to get the encoder version, and plan to power a 4.2A motor, there's no reason to get power from the board. You should be connecting power separately to the motor driver you plan to buy and let it power the motor. And then you just use our board for DIR/STEP/EN. Makes sense? Our board has a 10A fuse on it, but you really should only be going 50% of the way, which is 5A. Machines typically don't need to power all peripherals at the same time, so you're unlikely to reach 5A I would think. But in any case, with an external driver/motor that size, you need to connect the power separately.

-Shai

[mark maker]

Just as a side note: large current (pulsed) power taken separately can shift and bounce the ground. You should aim for external drivers with opto-couplers (or similar) for the DIR/STEP/EN.

In PnP you cannot usually consume that much current, because at high speeds the back-EMF is too high. You'd need low-inductance steppers or higher voltages. Be sure to use the full 36V!

See the "Higher Voltage, please!" section here:
https://makr.zone/choosing-a-motion-controller-the-panucatt-azteeg-x5-gt-32bit/455/

_Mark

--
You received this message because you are subscribed to the Google Groups "OpenPnP" group.
To unsubscribe from this group and stop receiving emails from it, send an email to openpnp+u...@googlegroups.com.

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/5e2fa240-de5f-4a12-82a8-571d38506346n%40googlegroups.com.

[Litterio Andrea Guainella]

Thank you Shai for clarity  actually it is logical as you say :-)

Thank you Mark for good mention article.
For more context clarity I will be open a new post because I don't want go OT.

LAG

[dc42]

Motor speed is an issue for 3D printing too, because the speed of printing is partly determined by travel speed over the length of the print. Does PnP really require higher speeds than fast 3D printers? What X and Y speeds and accelerations are desirable for typical machines running OpenPnP?

You can get an estimate of the maximum motor speed possible before torque drops off for a given motor and supply voltage using the calculator at https://www.reprapfirmware.org/emf.html. To get high speeds, choose low inductance motors, but make sure that the current you need to operate them is within the limits of the stepper drivers on the board.

When using high speeds and accelerations, ringing is a problem on 3D printers. I would expect ringing to be a potential issue for PnP machines too when placing small components. Some firmwares (RepRapFirmware and Klipper) support input shaping to reduce ringing.

Assembling a board designed for 3D printers with some of the mosfets and associated connectors left out may make sense if you are building several PnP machines, but the saving per board would only be a few dollars per board. You will need some of the mosfets anyway to drive the vacuum and lighting systems.

[mark maker]

Hi David,

> Does PnP really require higher speeds than fast 3D printers?

Yes. Much longer travel on average, more time to get really fast (I'm comparing to consumer size 3D printers, and correspondingly sized printing models here).

> What X and Y speeds and accelerations are desirable for typical machines running OpenPnP?

There's no limit 😎

>  I would expect ringing to be a potential issue for PnP machines too

Yes it is. Input shaping would be nice, and our discussion somehow stalled, I'll continue in the other thread:

https://groups.google.com/g/openpnp/c/5SJMYX110p0/m/9vUKh9ZcAgAJ

_Mark

To view this discussion on the web visit https://groups.google.com/d/msgid/openpnp/ce43ba4f-ab03-4239-9a5d-2adc9c24846dn%40googlegroups.com.