Choosing a new corexy or markforged printer

3D Printing
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@GeoffS’s New printer - corexy or not? post was so good, I’d like to do it again, but differently.

I gave up on my Cantilever printer design based on leftovers and have decided that I’d like to buy a printer that someone else designed. I’m sure I’ll start modifying it soon, but I want to start from a tested design. I want to spend my design energy elsewhere right now. (If I get another working printer, I can afford to try out new experiments on my existing self-designed corexy, which is currently my workhorse.) I want my kids to be OK printing with it.

Desiderata

  • Full printer or well-tested complete kit (something my kids could help build from instructions with me, for instance)
  • Not completely new to the market, around long enough to know its weak points
  • Corexy kinematics (alternatively, markforged, especially if I go with an IDEX)
  • Linear rail, no wheels running in aluminum extrusion on any axis
  • Cast aluminum bed
  • AC bed heater
  • Able to be enclosed even if it doesn’t ship that way
  • Not depending on structural printed plastic parts (enabling high-temp plastic printing)
  • At least an option of direct drive (even if bowden available)
  • Fully-supported bed, not cantilevered
  • Prefer single Z motor with sync belt connecting them, or three motors with auto-tram; not two Z motors and I really don’t like four Z motors.
  • No proprietary components, open source firmware and standard parts that can be extended
  • Not required to join Facebook to get support

Possibilities

The least expensive printer I’ve found that is even close to meeting my requirements is the Creativity ELF at about $450. That has a wrought bed with 24V DC bed heating, is not easy to enclose, might be a pain to extend due to using “VGA” cable to the hot end, and uses two Z motors; not enough to truly auto-tram, too many to automatically stay in sync; the worst option besides the four motor designs. Slightly cheaper but not as good (e.g. neither synchronous sides nor auto-tramming) is the Two Trees Sapphire Plus for $420. With neither bed sensing nor a bed I trust to be flat, I’d expect it to be as frustrating as the Tronxy X5S was for me earlier.

An SK-Tank, which looks easy to enclose, is about $1500 shipped fully kitted out with all the options, including genuine hiwin linear rail, except a raspberry pi (which I can better source locally), but will take an indeterminate time to ship; it’s one guy. Would be about $300 less with LDO rails.

The Vivedino Troodon moves the X/Y stage up instead of moving the bed down. It is available to ship now and comes fully assembled including enclosure, for a similar price as the SK-Tank. It runs on linear rails but probably not true hiwin… Includes air filtration, so maybe I could print ABS in it, at least if I use a carbon filter. My family says no ABS until I’m doing air filtration! It does use 4 Z motors. I’m concerned about racking if one fails, but the U-shape flying X/Y stage probably has enough flex that it makes at least a little sense to have 4 motors. Can’t tell whether it has a cast bed.

Railcore is a bit over $2k which is a lot more than I want to spend but would ship more quickly. Not clear that it’s easy to enclose (it has doors available but the top is open).

Not sure exactly how much I’m willing to spend but I doubt it’s over $2k. Still thinking about this.

Not considering

  • Creality Ender 6 has a cantilevered bed, and still uses delrin wheels in V-slot.
  • Anything Tronxy after my previous experience (not just poor quality, but also ghosting me when I asked them for GPL source code), and also wheels in slot.
  • The E3D toolchanger and motion platform would be awesome and it’s probably worth the $3K or more it would cost me, but it’s just way more than I want to invest right now.
  • The Hevort is not available as a complete kit.
  • Muldex since there’s no “everything” kit. Not sure how much it would cost all together. Also, I’d prefer not having two X motors; I can’t figure out why that’s actually necessary.
  • Rat Rig — too many plastic components for my taste, not clear it has any benefits to me over the SK-Tank which would cost less.
  • Various other Voron-derived printers with 4 Z motors; it’s hard enough to consider hanging an X/Y gantry from four belts; driving a bed with four screws seems to me like trying to create a potato chip.

I’m sure I missed listing some desiderata I’ve considered as I have looked at printers. Any printers that mostly meet my desiderata that I haven’t considered?

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Voron trident looks promising. Good documentation and bill of materials to self-sourcing for cost.

It has a 3-point bed.

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The Hevort ticked most of those boxes for me. Having to assemble it and get it going is part of the fun. If I just wanted a relaible printer, I could have bought a Prusa for less than I paid for parts.
I expect I’ll spend as much time fiddling as I do prinitng once the Hevort is going. :grinning:

I still have the Ender 5 which, afer some modifications, works very well, if slowly.

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Yeah, if I wanted to self-source this one it would open up a bunch of options. Right now I want kit or assembled; unusually for me, I’m interested in exchanging money for services. :roll_eyes:

The SK-Tank has the option of self-sourcing lots of parts to reduce price. I don’t mind self-sourcing a few things, but for this one I’m generally looking for something that works out of the box, where that could include following assembly instructions with one or more of my kids… The more self-sourcing I have to do, the less true that is.

Once I have a reliable printer that others in the family can reasonably use (there are at least two with some interest), I can go back to the fun of design and redesign and various experimentation on my first corexy printer, when it doesn’t have to be doing workhorse duty.

The Voron Trident kits I’ve seen aren’t complete. They are frame, or some of the parts, but not all.

I’ve since seen video showing the Troodon stage being moved by hand when it is powered off, and it didn’t rack, which increases my comfort with its 4-motor configuration. Also it comes with low-mass direct drive with an orbiter, which interests me.

I guess I could effectively discount the price of the Troodon by the cost of all the ABS filament I have sitting around unused!

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I would have put the Folger Tech FT-5 R2 on my list of possibilities but:

He might come back some day but for now has closed up his store.

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Don’t know what your time-frame is for getting and completing it, but Ryan over at V1Engineering is working on a new CoreXY machine. 3 Z motors, belt driven, linear rails, Marlin firmware, pretty much checks all your boxes.

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Thanks!

I don’t think I’d care for one with wood panels… Also, like the Rat Rig, lots of plastic components; I want to be able to print high temp plastics confidently so I’d rather not use printed structural components. I should have listed that, I guess I’ll go back and edit that in!

I should also add to desiderata a design that’s been tested for a bit, the point being to set it up and start printing, so I can go back to experimenting on my mostly-self-made corexy. I’m OK with some build time with good instructions, but (unusually for me) I don’t want to be solving puzzles before printing. Every other printer I’ve had has been an opportunity to learn from failure, and… I’ve learned a lot. But this one I’d like to set-up-and-go.

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Who provides support only over facebook, so I can skip them from day 1?

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Oh, I don’t know of any for sure. I’ve seen references to joining facebook groups. SecKit has one, for example. But they also have a presence on github and I think it’s a convenience not a requirement.

But if there were one, it wouldn’t be for me!

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It looks like the Vivedino Troodon is a variant of the Voron 2.4 which they also carry as a kit:

That has a 5/16" / 8mm cast aluminum bed.

I think that the Troodon is basically an assembled version of that with an orbiter extruder, and metal parts instead of plastic. I don’t like that the heat bed on the Troodon sits above an acrylic plate, so the Voron 2.4 kit looks better in that regard. On the other hand, the Troodon has (I think) all metal components in the build chamber where the kit expects you to print plastic. But I can’t find anywhere whether the Troodon has a cast build plate. Probably? I hope so at that price?

Part of my problem here is that my family won’t let me print ABS right now due to smell. So I’d need to buy Voron 2.4 printed parts at $100-200, which gets me closer to the cost of the Troodon — and just printing out of the box.

I found a video that shows that the gantry is definitely flexible enough that it can rack, which I guess means that I guess four belts for X might be not actually over-constrained. :stuck_out_tongue:

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The Flyingbear Reborn doesn’t look easy to enclose at the top, and I can’t see enough technical detail on it to evaluate it well according to my desiderata.

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As I see it, SK-Tank mixes the advantages of the Voron Trident motion platform (three points determine a plane) and the Troodon metal parts for everything under stress (I think, and hope). The Troodon is either 300x300 or 400x400; the SK-Tank is 350x350. I have been repeatedly happy that my other corexy is about 330x330, so going up to 350x350 rather than down to 300x300 seems good; 400x400 seems huge to me. I don’t like that I can’t find any information on what the bed material is on the Troodon.

I asked SecKit and it turns out that it can ship next week. That’s good enough for me! Hopefully in a few weeks I’ll be putting it together.

It does require some printed parts, but I have a few days to print before it arrives. They are not supposed to be temperature-critical; even PLA is supposed to be OK. I’ll print in PETG. Or maybe ABS if I think I can get away with it. :grin:

I’ll see what duties are assessed; reports vary.

I’ll still have to enclose it and add filtration. I think, though, that for filtration I really want to return to the bottom of the printer rather than sucking in colder outside air, so even with the Troodon I would have been eventually modifying it before printing ABS.

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I bought an orbiter extruder to eventually mount on this printer. Chose one with an official LDO motor and made of molded glass-filled nylon. It arrived today. I don’t yet have the printer to test, but wow it’s small and light. I love it.

It was a really tight race between the SK-Tank and the Troodon (which comes with the Orbiter out of the box; Vivedino has credits for supporting its development). I could imagine that if I were making the decision over again, it could have gone the other way.

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My kit arrived yesterday, just a week after placing the order. No duties were assessed in my case. It was well packed. It came in two boxes; one for the frame components and one for everything else. DHL pestered me by text and email to sign up to waive signature (and of course liability) and I didn’t take them up on that. I was home for the delivery, but they just dumped it on my porch and ran without even ringing the doorbell.

It’s not clear to me that the HIWIN rails were worth the premium, as one of them appears to have some bad bearings (it hesitates from time to time as I slide it on the rail). If I had it to do over, I would not pay the $290 premium for genuine HIWIN. SecKit offers a single replacement of HIWIN rails within the first 7 days, so I hope the replacement is an improvement. But I could buy a lot of replacement knock-off rails for $290 if a couple were imperfect!

The steel frame is 2.5mm / 3/32" so it’s very heavy duty.

The seller has been extremely responsive to my emailed questions. However, the user community appears to be only on facebook, so I am a little bit isolated from that community when it comes to building and augmenting it. There are only two posts on r/seckit on Reddit…

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The orbiter is a nice little unit.
I did have one installed on the Ender 5 but took it off when I got the PrinterMods XChange tool changer. It will now go on the Hevort.

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I had cleaned out the hesitating/catching rail three times alternating corrosionX and WD-40 and carefully wiping out the grooves each time, and it still caught. He said it was probably still a piece of metal, not a damaged bearing, and suggested I keep cleaning it; that I could send it back for them to clean or replace if necessary — but that every other case had required only cleaning. So I twice filled it with sulfur-bearing, sticky way oil and then flushed it with WD-40, running it across the ralis and cleaning them out each time. And so far, that seems to have done the trick. I’ll keep an eye on it, but so far so good. :crossed_fingers:

The parts aren’t labeled, and some of them are similar to each other. Also, some look very similar end-to-end. However, he has designed it so that if you put it together wrong, the holes don’t line up. There was one case where they seemed to fit but the flanges on flanged nuts overlapped a little, and turning the apparently-symmetric part around resolved the problem.

The instructions are a bit sparse. I’ve run into a few order of operation things so far. It’s a bit more of a puzzle project than the average kit. I wish he shipped a STEP model of the whole printer so I could just reference it as I went along.

Last night I assembled the frame loose. This morning I carefully snugged all the screws in an alternating pattern and checked squareness, and then my youngest and I removed and replaced with loctite 242 all the screws, again in an alternating pattern, fastening them tight. We used bits of tape to mark each screw we did this to. At the end, it still appeared to be square.

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I’ve done almost everything now except finishing the wiring, and printing a few final pieces. It does live up to its name. Solid steel frame components; stiff and plenty of mass. Still satisfied by my purchase.

I’ve run into a few problems since my last post. The instructions have been sparse in places. Order of operations is not always clear, so I’ve had to re-do some things. For example, after using loctite on all the frame screws, I discovered that some of them had to be removed and replaced for later steps. Glad I used 242! :relaxed:

The seller has been quite responsive by email. I have been asking specific questions and providing feedback on how to improve it. However, I suspect that buyers willing to sign up for Facebook and are thus part of a community of builders are better off than I am here—and that’s probably most of them; I know I’m in the minority not signing up for Facebook. For anyone who has never assembled a 3D printer from loose components before, you might need lots of patience while figuring things out, and joining the SecKit Facebook group is probably a good idea.

It turns out that his supplier sent him the wrong spec of constant-force springs (too short), so he is trying to source the right spec and sent out the right ones. The perils of being a small manufacturer!

One of the XY joiners had sloppily-drilled holes that were out of square by over 1mm. I ended up using a 3mm endmill in the mill to elongate one hole in order to attach everything. Otherwise it would have taken some patience with a needle file I suppose. (I suspect he would have sent me a new one if I had asked, but I didn’t want to wait that long.) This was tricky, if you look specifically for it you can see it, but it would be easy to overlook otherwise. So hard to be too annoyed that he missed that supplier mistake.

At least with the volcano hot end, the nozzle can’t reach approximately the rear 15mm or so of the bed. And it sticks out beyond the front at max extension, which could get in the way of adding a door. I will have to see what I can do about making a compact design for moving to the orbiter, at least when I enclose it.

There are two control board options available. I chose the GTR. Apparently I was one of the first two people to order that option, and mounting holes hadn’t yet been added to the back panel. FreeCAD and the BIGTREETECH STEP file for the GTR to the rescue; I printed a frame that will be not only a drill template but also a mounting frame. :grin:

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I’m thinking about how to make the frame also hold a duct for a fan to blow over the stepper drivers to keep them cool, but I haven’t figured that out yet, so for now I just printed the frame as shown.

There are lots of optional parts to print. Some of them are in the SecKit SK-Tank github repository; others are referenced in a separate section of the manual. I printed a cover for the high voltage terminals for the Mean Well power supply, as well as a set of TPU feet. SecKit warn that this is not a first printer, and this warning is certainly right; key parts require that you already have a 3D printer.

The Troodon would have been running already and enclosed for similar money, but with a smaller print bed. Ultimately, since I’m complaining about losing about 15mm front to back, I must care enough about size that the Troodon, with still a strictly smaller print area than even the reduced available size on the SK-Tank, would have been a bad choice. Similarly, while I think that @Eclsnowman hit the nail on the head—this is closer to a Voron Trident kit than it is to anything else out there—like the Troodon, the Voron Trident kit is also 300mm by 300mm. While I never make use of the full volume of my existing 330x330 corexy I often appreciate having at least one horizontal axis be more than 300mm. For example, it was very helpful when I was printing face shields. So I still think this was the right choice for me.

But if I had it to do over, I think I would not spend extra for genuine hiwin rail. It wasn’t obviously better than the good clone rail I’ve gotten in the past, and the amount of cleaning I had to do before it ran right was more than I had expected from brand-new genuine hiwin.

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SecKit have confirmed that they are intentionally not releasing STEP files because they are afraid of knock-offs. Honestly I have trouble understanding this; first, they built on the work of others in the first place; second, anyone who wants to build something similar could make their own files. A STEP file of bent steel doesn’t actually address the harder problem of designing parts to be formed. So anyone who want to have an accurate model of their printer to help them mod it should probably pass on this one, and start from one of the open source designs instead.

Also, they have confirmed that the default configuration does not actually provide the full build volume, and are considering fixing that in a later revision. In the meantime, we have worked out a possible workaround for the existing components that I plan to explore.

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The workaround parts I have designed get me within a few mm of using the whole bed.

I finally learned that the TMC2225 drivers that are shipped with it are basically a different packaging of the TMC2208.

Here’s the secret decoder ring, it seems:
TMC2225 ~= TMC2208
TMC2226 ~= TMC2209

This means TMC2225 don’t have sensorless homing. It isn’t that I want sensorless homing necessarily, but it turns out that the bed is slightly larger than the maximum travel for the head, and using sensors for X/Y homing will further slightly reduce that. So it seems at least possible that I’d rather use sensorless homing for X and Y — which I also set up for the cantilever printer I abandoned, which worked fine.

To get full bed width, I would also have to design and fabricate a new narrower carriage.

I am ordering a set of TMC2209s as they have lower RDSon; I will either use them from the start or have them as standby units; they support higher power at lower heat and sensorless homing; the tradeoff is a higher possible voltage but I’ll be running them at 24V anyway so there’s no value in the higher voltage support on the TMC2208/TMC2225 vs the cooler TMC2209/TMC2226.

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On the GTR control board, the manual says that the DIAG jumpers do nothing, and that TMC2209/2226 stepsticks require clipping the diag pin to use end stops. Not sure why, if the end stops would trigger first anyway. So I suppose I’ll start with the TMC2225 step sticks that the unit shipped with. I do still need to design a fan duct to print to keep them cool.

The thermistor came (as usual) with bare wire ends. This board uses a JST connector for thermistor, not screw terminals. The kit includes a generous JST pigtail terminated in bare wires. SecKit recommended crimping my own JST inline connectors to join the thermistor wires to the JST pigtail.

I think that this kit should be primarily considered a frame and motion kit with a bunch of wiring. It’s less complete than I hoped. I’ve had to ask enough questions that I feel a little bad about pestering him on email. Not that he has complained, and many questions have turned into improvements he has promised to the manual. But I think that if you have any doubts but are still interested in any SecKit printer, whether you use Facebook might reasonably be a deciding factor.

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