3D Printer (Prusa Bear Mod) Build

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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

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The drive pulleys for the X and Y motors arrived the other day, so I was able to finish installing the belts and install the heated bed. The current Prusa model that this is based on uses "mesh bed leveling" instead of having adjustment knobs at the corners for bed leveling (i.e. tramming the bed to the print head), which is done using an inductive probe to determine the bed height at 9 locations prior to each print. It's much easier than manual adjustments and it means that instead of adjustment screws, the bed is held to the Y carriage by regular screws with aluminum spacers in between.

I had one of the places I ordered parts from go incommunicado after the automated "thanks for ordering" email went out. Not sure if they are a zombie site or what; I posed the question on the Discord for the Bear mod, and the designer claims to be in contact with the owner and offered to help, but by then I had already turned it over to my credit card company and reordered most of the stuff from another vendor. Except for the stupid spacer kit, which that vendor didn't carry. I ended up making them myself on the lathe.

There are a plethora of alternative screen and controller setups but I stuck with the same electronics that the stock Prusa uses mostly for simplicity's sake. The LCD screen/interface board was made by LDO motors which also makes the steppers for Prusa and probably the LCD unit as well. I printed up a "smooth" version of the housing without the Prusa logo. There's several printable housings to choose from since the Bear re-uses the Prusa part with its own printed mounts to the front frame extrusion.

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The mechanical aspects being finished, I am wading into the wiring and electronics. I have the controller board mounted on the left and the steppers (except for the extruder stepper) plugged in. I need to hit the hardware store for 4mm screws to mount the power supply unit on the other side. I would have preferred to use the standard Delta power supply that Prusa uses, but they don't seem to be available anywhere right now, including from Prusa. They are still shipping printers, so I assume they are only able to get enough to use with new printers.

I bought a Meanwell LRS-350-24 which is arguably a better power supply in some ways (higher wattage rating) but it does mean that I had to seek out and print a dedicated lower case and set of mounts to use it with the Bear, since the official mod only has mount options for stock Prusa PSUs. I am still waiting for the switch and plug (which has support for the "power panic" feature that is supposed to let you resume a print after a power failure), and I will need to get some silicon wire and make up my own wiring to the controller board due to the non standard installation.

One thing I really like is the printed parts for the Bear mod include these awesome cable clips that twist into the extrusions. Prusa didn't include anything like that, although I did find some that will fit the 3030 extrusions, so after this printer is up and running, I will go back and clean up the wiring for the first printer a little.

The other thing I am waiting on is some 3mm nylon line which is used as a support for the extruder wiring bundle between the extruder X carriage and the wiring pass through at the controller box. I found limited choices for this... I could buy the replacement part for the Prusa which is cut to the exact length needed in the stock printer, and which therefore is probably too short due to my 100mm extended Z height. I could buy a whole roll of 3mm nylon printer filament and cut off what I need, and then have an entire roll of filament I have no use for since pretty much all printers use 1.75mm filament these days. I eventually found some 3mm string trimmer line on Amazon which I am now waiting on, and which was cheaper. No dice finding it locally at Los Depot.

Anyway, it's progress and I am slowly getting closer to the point where I have to figure out how to set up the firmware for this beast.
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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

The plug/switch/wiring kit for the power supply arrived. A wiring diagram would have been helpful, but for the most part it was fairly self-explanatory except for a lone red mystery wire off the Power Panic board. I asked about it on the Bear discord and also the Prusa forum, and on the latter I was pointed to an older thread where it was explained that was the sense wire, to be connected to one of the 24V+ terminals on the PSU.

Using this guy's case and mounts for the Meanwell PSU:

https://www.thingiverse.com/thing:3111868/files

I don't remember why I chose the version for the side entry power cable and switch over the version he drew with the cable in the rear, but I think I had a reason at the time. I think it had to do with the location of the cable ports on the portable printer enclosure bought but have yet to use.

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I should have taken more pictures of the wiring but to be honest I was glad to get this hooked up and mounted to the printer frame. About all I have left on the physical assembly now is to finish up the wiring, and then mount the access door for the mainboard case.

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HTRN
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Re: 3D Printer (Prusa Bear Mod) Build

Post by HTRN »

Elegoo Saturn is currently on sale on Amazon, for $499.
HTRN, I would tell you that you are an evil fucker, but you probably get that a lot ~ Netpackrat

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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

HTRN wrote: Wed May 04, 2022 5:55 pm Elegoo Saturn is currently on sale on Amazon, for $499.
At some point I may want to get a resin printer but I am not sure how useful they are for functional parts. The RPG crowd seems to love them though.

the 3mm nylon weed whacker string came in, could have saved myself the trouble and bought just the 50cm pre-cut length for the stock Prusa since that would have been plenty long enough even with the 100mm extended Z. I only ended up making the nylon cable support from it about an inch longer than that.

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Here you can see the cable support tail that bolts to the back of the X carriage to provide support for the extruder wiring as it exits the back of the extruder. The stock Prusa extruder has a similar arrangement. This both provides strain relief and keeps the wiring from hanging down and dragging on the print bed and/or the print.

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Another shot with the wiring bundled up. These wiring sleeves are a bit of a pain to work with but they are supposed to be better than standard spiral wrap or flex conduit.

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Almost done now. I am waiting on one connector to arrive and I still have some wiring clean up to do... Unlike the Prusa kit where all the stepper motor leads are the correct length, these were all either too short or too long, so I have some bundling to do and I think I am going to shorten up a couple of the leads too. Tomorrow I am going to print some more of the bear cable clips to tie down the rest of the stepper leads that don't seem to be worth the effort of shortening. These are pretty handy in that they just twist 90 degrees into the extrusion slots and provide an anchor point for zip ties. Would do it now before I go to sleep since they are a short print, but I already have something running on the Prusa.

Could finish it up right now but for lack of a single molex connector. Plus I have all the fun of figuring out how to edit firmware and compile from source due to the non-standard configuration and then flash it. Oh and hope nothing turns into smoke when I switch it on.
Cognosce teipsum et disce pati

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g-man
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Re: 3D Printer (Prusa Bear Mod) Build

Post by g-man »

Non sequitur: I am envious of the tidiness of your clamp collection. My garage is mostly a dumpster fire, with the collection of crap that didn't sell in last fall's neighborhood garage sale day occupying maybe 1/3 of the usable floor space, unorganized chicken/duck/rabbit supplies occupying another 1/3, and a combination of clamps, tools, amazon boxes awaiting shredding for inclusion with the compost, and other random crap fighting with viable walk-throughs making up the other third. Between work, outside chores, and just life in general, it seems like I can never get ahead in there. Made a little progress the weekend before last, only to lose ground again working on duck pond 2.0 this past weekend.


Back on topic... that looks to be coming along quite nicely, and the ability to print parts seems very, very appealing. Might be able to slide it in as an addition to the astronomy habit - "It's so I can print adapters and mounts for the telescopes instead of having to buy them..."
Igitur qui desiderat pacem, praeparet bellum
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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

The garage is a disaster, but yeah the clamps are organized. I built that bench with the overhang specifically so I would have a place to hang clamps.

I haven't added up any costs but I doubt if I saved any money compared to buying a stock Prusa kit and one of the Bear frame kits, and throwing away the stock frame. But compared to buying something like a Caribou with a320mm Z axis I probably did OK. I mostly have done this for the experience. The real question will be whether or not to do the Bear frame upgrade to the stock Prusa at some point; it's a perfectly good printer and one of the first things I did was to print a full spare set of the functional/structural parts for it, so probably not.
Cognosce teipsum et disce pati

"People come and go in our lives, especially the online ones. Some leave a fond memory, and some a bad taste." -Aesop
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HTRN
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Re: 3D Printer (Prusa Bear Mod) Build

Post by HTRN »

Netpackrat wrote: Mon May 09, 2022 6:45 pm The garage is a disaster,
Can you still see the floor? Then it ain't that bad. 8-)
HTRN, I would tell you that you are an evil fucker, but you probably get that a lot ~ Netpackrat

Describing what HTRN does as "antics" is like describing the wreck of the Titanic as "a minor boating incident" ~ First Shirt
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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

Of course one thing that should have occurred to me earlier, is that once I have two printers up and running, my current monitoring solution of a standard baby monitor probably isn't going to cut it anymore. I could buy another one, but as far as solutions go it's not something that really scales.

There's an app called Octoprint for controlling 3d printers, which runs on a raspberry pi, and supports a webcam and a lot of other cool features. The printers have support for adding the pi board but I figured I would get around to it eventually... Maybe sooner rather than later now. One of the cool things Octoprint can do is detect when it thinks a print is going bad, and then message you asking whether you want to discontinue it or not.
Cognosce teipsum et disce pati

"People come and go in our lives, especially the online ones. Some leave a fond memory, and some a bad taste." -Aesop
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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

Image

Flipped the switch and nothing turned to smoke. Now I just need to load the correct firmware and calibrate. 8-)
Cognosce teipsum et disce pati

"People come and go in our lives, especially the online ones. Some leave a fond memory, and some a bad taste." -Aesop
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Netpackrat
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Re: 3D Printer (Prusa Bear Mod) Build

Post by Netpackrat »

Firmware is built and flashed; that was a bit of a pain. It wasn't as easy as just changing the Z_MAX line in the config file; that led to a floating point error based on the new height being out of the default range, but thanks to the help of another user on the Bear Discord, I was able to zero in on the changes that needed to be made to another config file.

Hopefully it works. Can't test it right now because I have to get ready for work.
Cognosce teipsum et disce pati

"People come and go in our lives, especially the online ones. Some leave a fond memory, and some a bad taste." -Aesop
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