Posts made by mrehorstdmd

@gwatson90 I don't know if the belts expand significantly at elevated temperatures. Most belts have glass cores and glass tends to be pretty stable over temperature. I would think that since both belts will be at the same temperature there won't be any tension differential causing the X axis to tilt relative to the Y axis, bit I'm just speculating. It shouldn't be too hard to test it. You could always tension the belts at the print temperature to make sure the X axis is square. Make sure you buy belts that are specced for high temperature operation.

The most critical thing about setting up CoreXY is to ensure that the pulleys are positioned accurately to keep the belts parallel to the linear guides. Any error in that will result in belt tension varying with extruder position in the XY plane and will lead to distorted prints, especially as the extruder gets closer to corners of the build space.

You will also want to use quality drive pulleys that have properly sized and centered holes, and quality idler pulleys. Don't buy the cheapest crap that is marketed to 3D printer hobbyists. Gates makes quality drive pulleys that you can buy from Filastruder. I recommend stacked ball bearings for idlers. The cheap, crappy 3D printer idlers have too-tiny bearings that wear out quickly.

Finally, don't stand pulleys up on posts. The belt tension will cause them to tilt. Make sure pulley shafts are supported solidly at the top and bottom.

See: https://drmrehorst.blogspot.com/2023/07/corexy-x-axis-wobble-revisited.html
and https://drmrehorst.blogspot.com/2020/12/x-axis-wobble-in-ummd.html

@fcwilt said in My Second build (in progress):

The flatness spec is based on an entire sheet (4'x12' or so) of tooling plate. Typical flatness over a smaller piece is usually much better. In my printer, I would guess the varying thickness of the PEI and adhesive sheet under it are likely to contribute more to the unflatness than the plate itself. I have never tried to print a 100um first layer- I'm not sure why that would be needed - but I do print with 200 um first layers once in a while without any trouble.

The purpose of tramming/mesh compensation is to get the first layer to stick for the duration of the print, not to get a flat bottom on the print. If you move the Z axis up and down to compensate for bed unflatness or tramming error, you're not going to have a flat bottom on the print - it's going to be the shape of the bed, whatever that is. I can't imagine any application for a plastic 3D print where the flatness of its bottom, beyond what comes off the bed, would be critical to the function or appearance of the print. If flatness down to micron level is needed, a 3D printer is the wrong way to make the part in the first place.

Auto tramming and multiple screws/motors to lift the bed are a chicken and egg sort of thing. A lot of people think they want auto tramming so they use multiple screws/motors to lift the bed. But if you use multiple screws/motors, you have to use auto tramming because the bed is going to tilt every time you cycle power to the printer. I think what people really want is a reliable printer that they don't have to mess around with, but youtube videos showing corners of beds going up and down have made them think that auto tramming is the only way to achieve that.

If you use a single motor to lift the bed, regardless of the number of screws or belts, the bed won't tilt when you cycle power. If the bed plate is on a stable mount, it won't require tramming every time you print. You won't need bed sensors, multiple motors, drivers, and cables. And you'll never experience the joy of troubleshooting it when it fails.

I enjoy starting prints and not waiting for the machine to tram itself. I also enjoy not having to worry about whether the print is going to stick or whether I'll be able to to print at all if auto tramming fails. There's less to go wrong with a flat bed plate on a stable mount that doesn't require tramming before every print.

@fcwilt And if you do it right, there's no need for mesh compensation or auto tramming.

I use a single NEMA 23 stepper with a 30:1 worm drive gearbox to lift the bed on two linear guides in my printer. It has an 8 mm thick cast tooling plate bed on a kinematic mount. There's no autotramming or mesh compensation. The last time I trammed the bed was at least 2 years ago, and it took less than a minute. It just works every time I turn it on. The bed doesn't move when power is cut, so theoretically I can resume printing after a blackout, though I've never tried.

@Dad003 That looks like a piece of cast tooling plate. That means it is flat. 3 points define a plane, not 4, so trying to tram with 4 screws is not a great idea.

You might want to look into a kinematic mount for that bed plate. As it heats it will expand. That means something is going to have to flex and that means it will shift out of tram. A kinematic mount has 3 bed support points and just two tramming adjustments. It allows the bed to expand without causing anything to flex so doesn't go out of tram.

Several lamps, a bread box, bicycle disc brake sanding tool, bicycle fender mount, Nespresso capsule dispenser, Pax Plus vaporizer handle, Ikea Frakta bag handles, physical therapy rubber band handles, incandescent lamp replacement for microscope illuminator, camera and cell phone mounts for telescopes, microscopes, and 3D printer, in-drawer knife block, wire twister tool, Wago lever nut mounts, several furniture feet, a Van de Graaff generator, 3D printer spool holders, coin and wallet holder for Prius console, replacement for failed Prius trunk release cover, stand for S&B Mighty vaporizer, bottle cover for Uberlube, parts for my sand table and 3D printer, parts of a 20 liter soda syrup tank agitator, replacement pushbutton caps for an old preamp, brackets for a "cat ladder", cat puzzle toy, aperiodic tile array pieces and storage box, cutting board drying rack, dental x-ray sensor wall mount, brackets for mounting curtain rods,
racks for torx and hex screwdrivers, bicycle air horn bracket, coasters, cable hold-downs, bicycle chain guard, One Wheel electric skateboard car stand, ear-savers and bias tape making tools for COVID masks, compartmentalized refrigerator storage box, binaural mic earpieces, manual coffee grinder electric drill adapter, antique radio dial belt, Audi and BMW jack pads, white board marker and eraser holder, and many more.

Bread box and cover:

Disc brake sanding tool:

Bicycle fender mount:

Button caps for old preamp:

Lamps:

Another lamp:

Coin and wallet holder for Prius console:

@Dizzwold I used a 7mm thick PVC foam board- I don't recall the product name. It isn't very rigid so I braced it with square aluminum tubing so it wouldn't sag too much.

@developeralgo222 Normally you do not need to know the diameter of the motor shaft as it has nothing to do with the steps/mm. Are you using lead screws? Lead screws will have a spec called "lead" which is the linear distance the nut (your Z axis) would move in one full rotation. For one-start lead screws, lead is the same as pitch. For two-start screws, lead is 2x the pitch, etc. Lead/200 = full steps per mm. If you turn on microstepping you also have to multiply by the microstepping factor.

If you're using lead screws and they are connected with a belt to a single motor, you also have to factor in the pulley size ratios.

@T3P3Tony Thanks! I wasn't aware all these commands existed. I'll give it a go.

My sand table is running a macro that calls out a long sequences of gcode files to run on the table. The macro is very tediously assembled manually and subject to errors. I recently discovered that the sequence currently running must have a typo in one of the gcode file names that make up part of the sequence. When the macro gets to that point, the whole thing just stops. There's no UI on the table, so I don't know exactly where the error occurred, so I will have to manually go into the macro and hunt for the typo.

Is there some conditional gcode that can be included in a macro that will just skip a file in the sequence when the controller can't locate that file because of a typo or other problem?

Thanks!

@dc42 I think so. I don't have the table here, but I'll probably be going to visit it later today. I'll check then. IRIC, the last time I updated firmware was about a year ago.

@stuartofmt I don't try to control the sand table table from my phone, only laptop. The laptop has Mullvad VPN but I shut that off when accessing the table. I have found that using the Mullvad browser keeps the connection to the table working for better than an hour at a time, where Chrome drops the connection every few (5-10 , usually closer to 5) minutes. In the past I had the VPN running with local network sharing enabled. The connection would drop every 30 sec to 1 minute that way. When I disabled the VPN the connection would stay up for 5-10 minutes. I am using my home wifi network, not a direct connection to the Duet board. There's no VPN running on the router, just on specific computers on the network.

In the last couple years I have scoured all the posts about Duet2 wifi connection issues and have tried everything short of replacing the board to no avail -until I tried the Mullvad browser. AFAIK, the Mullvad browser is based on firefox with a bunch of security/anonymity stuff taken from Tor. Maybe there's something in there that makes a difference.

@Phaedrux I don't have access to the table right now- it's over at my brother's distillery tasting room and I don't know when it will be back.

@dc42 There's no Panel Due. This particular controller is in the sand table.

I have gone through all the posts on wifi problems and played with ajax retries, it didn't seem to do much good. I also shut off the VPN when I am connecting to the table. The Mullvad browser just seems to work about 10x more reliably than Chrome.

Is there any possibility that the browser being used to access the web server has some effect on reliability of the connection?

I have had a lot of trouble keeping a Duet2 WiFi board connected to my mixed 2.4/5GHz network for the last few years. About a year ago I switched to a mesh network with no change in the connection behavior. The mesh router has a dedicated 2.4 GHz IOT network that I use for the Duet and things like light bulbs, appliances, etc. The Chrome browser in my laptop would connect and I could access the control panel for between 30 seconds and maybe 2 minutes at a time, then the connection would fail. It got a bit better when I shut off the VPN (even though I had local network sharing enabled) on the laptop, but still not what anyone would call reliable. I gave up on ever getting it to work reliably.

I recently tried the Mullvad browser that is based on Firefox (I think) and Duet board miraculously stays connected for up to an hour, maybe more, at a time, so it seems the browser used plays a part in the reliability of the connection.

Or am I completely wrong?

So sorry to hear it. Rest in Peace.

15 hours at 40 mm/sec, 1mm nozzle, 1.2 mm line width, 0.3 mm layers, vase mode in Cura, 923g of PETG filament, 638 mm tall:

It's going to become a lamp.

@Dad003 I thought you were trying to simplify the design. Never mind.

@Dad003 click on "one of these" in the post above. That guy has been selling the things via ebay for many years.
Your design may work, but look at all the parts and space required. The worm gear box with attached motor is as simple as it gets.

@Dad003 One of these will make your life much easier. The 30:1 reduction enables it to lift very heavy beds, and it doesn't move when the motor is disabled, allowing restart of prints in the event of a power failure. It doesn't require brakes, additional wiring, or additional configuration. Just treat the motor like a normal stepper. I used 60 tooth pulleys on the shaft to get 20 um per full step from the motor. I've been using it for my 695 mm Z-axis about 7 years without any problems. The gear quality is very high, so there are no gear induced artifacts in the z-axis of prints.