Posts made by tenaja

@Generic-Default, this looks like an interesting project. As somebody who has owned a CNC machine shop, I'm curious... Are your encoders on the motors, or are they linear encoders? If the former, how do you handle backlash adjustment?

Can you do g-code modifications on the machine?
Did you fix the pause (m0 &m1) so they function like real cnc machines?

I've used the duet boards on a few little jigs, but for more complicated machines, I stuck with Linux CNC... Primarily, to avoid bringing the duet up to industry standard. Kudos to you for making it happen!

@dc42 said in Duet3 as hardware for LinuxCNC?:

@tenaja said in Duet3 as hardware for LinuxCNC?:

@joergs5
In a normal cnc machine, with a normal cnc controller, if you need to make an adjustment in the middle of the program, without restarting, these are the steps:

• Hit pause
• Navigate to the offset page
• Make the adjustment
• Navigate to the program page
• Hit start (to continue the gcode where you left off)

The program continues from where it was, using the new offset.

How would that workflow be on duet?

Hit pause, send the command to change the offset, hit resume.

But then when you turn it on the next day to make another, is that number retained, for every tool?

@joergs5
In a normal cnc machine, with a normal cnc controller, if you need to make an adjustment in the middle of the program, without restarting, these are the steps:

• Hit pause
• Navigate to the offset page
• Make the adjustment
• Navigate to the program page
• Hit start (to continue the gcode where you left off)

The program continues from where it was, using the new offset.

How would that workflow be on duet?

I, too, vote to get rid of the specialty kinematics for duet 2. I have around 6, and none need more than simple xyz or corexy.

@joergs5
I've purchased numerous used industrial items on ebay. Often you can get the expensive item at a cheap price... But sure, sometimes they operate at cheap performance.

But at that savings, you can get two or three and have a backup... And still be under half price. As long as the eBay item isn't removed due to wear, and it's the same part number.

@hebigt
The printers vary so greatly that any generic comparisons can't be better than fifty percent accurate.

Check out all3dp.com for some decent msla printed parts photos. They have comparisons that are generally driven by affiliate links, but they seem to at least actually test most of the printers they "review".

@arnold_r_clark said in Duet3 as hardware for LinuxCNC?:

... the base/core offsets would be contained within the config.g

And this is the reason "offsets do not exist" from a CNC users perspective. You cannot very well rerun your config file in the middle of making a part, to make an adjustment, and then resume the part.

Now, if you could run an immediate command to adjust the offset, that would be an inconvenient workaround, but if it wouldn't mess with your gcode file position, it could work.

And my experience with cnc and 3d printers is that the former is far more accurate and repeatable. However, the precision required is also often far more demanding... But tools regularly need replacing, and the tools vary. Every time a tool is replaced, the offsets typically require adjustment... But you can't know the adjustment amount until you've cut chips. And you don't want to discard that cutting progress just because an offset needed adjustment. It's often not like filament, where it's so cheap it doesn't matter.

@rjenkinsgb
Steppers can do just fine in a milling machine. If you size them properly and know their capabilities, and stick to those capabilities you will have no issues.

You have to plan ahead not to overload them, especially if you are pushing the limits of weak steppers. Sure, you also have to do that in servo cnc gcode, too, and at least those machines will stop in an error. OTOH, with LinuxCNC, you could add encoders, and have the same feedback and error faults. (This is a "why LinuxCNC" thread, afterall.

I have found the gwizard feeds & speeds tool invaluable in ensuring you don't take more of a cut than a machine is capable of.

@arnold_r_clark said in Duet3 as hardware for LinuxCNC?:

@tenaja said in Duet3 as hardware for LinuxCNC?:

@dc42 LinuxCNC lets you set up a chart of offsets. This lets you set up a list of workspace offsets (i.e. for your vise corner--or several vises, if you have multiple setups at once) and also a list of tool offsets (to set tool diameter and length, in a mill) for numerous tools. It also lets you edit any offset in the middle of a cut so you can adjust for tool wear, etc, and have immediate corrections.

How do we do those things with RRF?

Having a cursory glance at the duet g-code dictionary it that shows that

G10: Set workplace coordinate offset or tool offset

Is what you want, and I would surmise that with macro's you could create a "chart" of differing offsets contained within those different macro's and call that macro to set the differing offset as required.

Yes, I saw that, too...so how would you set up a chart of those so they were not littered around your code, unfindable and uneditable on a whim?
Having the feature in a 3d printer config file where you are controlling the extruded quantity and having it on a mill where you swap out tools many times in a setup and have the need to compensate for tool wear regularly (and instantly) are two different things.
From a CNC operators viewpoint, a one-time code buried in the gcode file does not encompass tool offset that a real cnc machine control does.

@dc42 LinuxCNC lets you set up a chart of offsets. This lets you set up a list of workspace offsets (i.e. for your vise corner--or several vises, if you have multiple setups at once) and also a list of tool offsets (to set tool diameter and length, in a mill) for numerous tools. It also lets you edit any offset in the middle of a cut so you can adjust for tool wear, etc, and have immediate corrections.

How do we do those things with RRF?

@dc42 said in Duet3 as hardware for LinuxCNC?:

@tenaja said in Duet3 as hardware for LinuxCNC?:

Another example is the need to configure e.g. extruders or heaters when you do not want those. LinuxCNC, for instance, only requires configuring systems or i/o you intend to use.

You can configure no extruders and no heaters in RepRapFirmware 3.

I will look at what the NIST standard says about M0 and M1.

Backlash compensation is scheduled for implementation in RRF 3.5.

That is great news we are getting blacklash compensation--it could be a big step forward for a lot of projects.

I forgot one last important point--offsets; both workspace and tool. They are super helpful with CNC, and I would never dream of using a CNC machine without them. I tried it on my first hobbyist machine, and it was a big relief when I upgraded its controller. That was the last time I will ever work with CNC without offsets.

@markz said in Duet3 as hardware for LinuxCNC?:

@smoe Is there a reason you want to use LinuxCNC?

I am not the OP, but I can give a few reasons, coming from the perspective of someone who learned Fanuc first. (Fanuc is the most common control used on industrial ["real"] CNC machines.) Please do NOT read this as a Duet flame, but a few "reasons" why someone would want it to interface with LinuxCNC.

I have put duets in a handful of benchtop machines, and really like it...for 3d printers or small, limited machines. However, if you learned on a Fanuc or other real cnc controller, compared to LinuxCNC, duet software is like an annoying little toy that does not quite get things right, and always makes you wish for something better. Sure, it's perfect for 3d printers, and for hobbyists who haven't learned otherwise, but there's just those things where Duet fall short.

Here are a few examples.

The Duet "ignores" M0 and M1 for conditional stop. This is unsafe if you do not know it is nonstandard. Every industrial machine on the planet works like LinuxCNC and not like Duet. Every Yasnac, Fanuc, Haas, Fadal, General Dynamics, Flashcut and LinuxCNC machine I have ever used has been predictible with their behavior of M0 and M1, and none of them match Duet, and this is just one rudamentary command that should be simple to implement.

Another example is the need to configure e.g. extruders or heaters when you do not want those. LinuxCNC, for instance, only requires configuring systems or i/o you intend to use.

Duet cannot handle backlash, and that's critical for any application where precision is critical.

LinuxCNC has its flaws, but at least it follows industrial standards. Also, once you get comfortable with its interface, it is more comfortable than yet another new "non-standard" interface that is yet another hobbyists interpretation. And, it has interface choices.

LinuxCNC cannot toggle parallel ports fast enough, so they have used Mesa fpga cards to allow high speeds. I know there's a Raspberry Pi port, but it also has limitations. I could easily see a blend, like RPi & Klipper where the RPi runs the interface, and the Duet handles the I/O, instead of a Mesa card. With the Duet being a dumb pulse generator & I/O hardware, the RPi could make it into a very pleasant cnc experience.

Thanks for sharing--that's very cool!

I have a slide for the z axis of a similar size. My plan is to use it to lift a corexy stage. Perhaps I should consider polar.

Have you seen any benefits or disadvantages to the polar system? Obviously, the center bearing has to be pretty stout, complicating the bottom, but it would simplify the other axis. Any other comments on what drove your decision, and thoughts now that it's completed?

Are speed or quality effected? (What speeds can you achieve?) What's your resolution at the outer edge like?

Thanks!

The industry standard for VFD's is 0-10v for the full range of speeds. However, you may need to poke around in the menu of that one to see what it is set for, because some can permit setting other signal requirements.

I really like the Duet, and have purchased a handful for tabletop units that are not printers. However, a machine that large is going to have backlash, and Duet requires a g-code modifying script...and that script is going to modify destination values rather than desired locations, so it is a little more consfusing if you need to stop mid-part and make an adjustment.

My preference is to use LinuxCNC for larger machines. It is very proven, and setup is highly documented for these types of applications...and backlash compensation is built-in. In addition, the variety of screen layouts available are specifically designed for CNC control, rather than tiny printer adaptations.

Without doing something to compensate for that backlash, you will not be getting the best the machine is capable of.

True, you can get anti backlash screws, and they'll make a better machines. But that doesn't fix the backlash in the bearings. It's also a lot more expensive.

NC switches are "Normally Closed" (conducting). You use that setup so when a wire breaks, you don't lose safety. Always consider safety when making setup choices. Maybe a router that operated at a snails pace with undersize motors doesn't have the same safety issues, but it starts good habits and avoid copy-paste into a machine that is more substantial.

You need NC end-stop switches so the machine stops if there's a broken wire, for safety.

That looks like a nice machine design... I've bookmarked it for my wish list.
Keep in mind that the duet fw doesn't have backlash compensation, and a nice machine like that will be held back by that limitation. A while back, somebody posted a python script (I think) to add it to the gcode. This is far from optimal, but a reasonable compromise.

I've used several duets on some small cnc's where backlash isn't a factor, but when (if) I build a cnc router, it'll definitely have a control with backlash in it. I found LinuxCNC to be excellent, and would certainly use it again.

Then again, if you are just making big wooden signs or other artistic objects, backlash is nothing... But some of those videos show the design cutting steel and aluminum, and it typically matters more with mechanical objects than artistic objects. Sure, you can fudge it like we do with our 3d printers (add 1 percent here & there, etc) but it's easier when it's accurate.

@tinchus, steppers have natural resonant speeds that vibrate and might even stall from the vibration. This is especially evident at full and half steps.

what microstepping have you set? Increasing the number of microsteps/step will reduce this.

look at the Dice. Might not be big enough for you, but should be precise enough.

Regarding soluble support...I have used it with my first 3d printer (almost 10 years ago), but never use it. It's such a hassle to set up correctly that unless you absolutely need a perfect surface finish with no break-off or razor marks, it's not worth the effort. Another thing that nobody ever discusses is how many hours it takes to disolve the support...it takes forever.

one more thing...you cannot trust the online reviews, even from reputable youtube stars. Those people are often given units that are better tested/debugged than what is available to us in the general population. My choice had raving reviews from dozens of "reputable experts" online, but I regret not getting a common brand.

What you can trust is the millions of reddit threads of people discussing their issues.

When buying cheap, buy popular. At least, in the 3d printer space. Pretty much every 3d printer made in china is going to have crap parts. Fixing the crap is easier with a popular machine. I read lots about 3d printers, and have not heard of 1 & 3 on your list, so I would avoid them at all cost.

I made a mistake and bought an "improved ender 3 clone" last year, and have regretted it, for several reasons. Sure, it was "better" than the ender 3, but some of the areas that made it "better" also made it worse. For instance, the print bed is 20mm larger in x & y for a larger print area... it would be nice to be able to make bigger parts, right? Unfortunately, it's still cheap chinese garbage, so the outer edges are warped so bad that the outer area is not useable...the usable space is about the same. Unfortunately, those larger 250mm square print beds are not common in the aftermarket, so to buy a quality aftermarket replacement meant buying an Ender 3 bed, losing any benefit of the larger print volume. So, any aftermarket printer-specific parts are pretty much nonexistent.

Also nonexistent is tech support. Not just from the company, but there is no real active user group online. Sure, there are thousands of us who use this brand, but reddit is crickets, and has been since about a month after they started shipping. With millions of Creality customers, the failures of that brand are very common, very debugged, and very easy to find answers, not only in old threads, but in realtime reddit if you are too lazy to search older threads. My alternative brand? Not so much, anywhere. No reddit threads.

Also rare are open source upgrades, like parts to print to improve your printer. I have made a few parts for the ender 3, but others are invalid for mine. The hot end mounting plate does not match, so aftermarket fan ducts, probe mounts, etc...all of those need to be "remixed" yourself.

The firmware is closed source, so to upgrade it, I have to either port a firmware myself or spend the money on a Duet. That either takes a lot of time, or kills a lot of the affordability.