Large corexy mechanical kit options



  • Hi all,

    I was thinking about buying a Tronxy X5SA kit and speccing it up a bit with Duetwifi/Bondtech/E3D V6, but I've been talked out of it and have been shown better kits, in particular the D bot and Rat Rig V core.

    To be honest I like the V Core 400x400 most, as I like the build size and it doesn't come with a build plate. I'd much rather spend up on my own design good cast tool plate ally bed, than pay for their 3-4mm thick thing and throw it away.

    Either way I want to do my own wiring and component selection, so the mechanical kit is the way for me. I am well and truly capable of cutting up my own frame, but to be honest it's loud and messy with all the shavings etc, I'd rather the "meccano" approach on this one. Whatever frame I get I would have it all squared up and tightened perfectly rigid.

    Has anyone had much to do with these V-Cores? There doesn't seem to be too many in the wild.

    I would NEVER have said it until I got a little Ender 3 Pro, but I'm going with the V slot rollers whichever printer I chose. If I can get the unbelievably good prints I'm getting out of this little E3, I'm sure I can do better with some engineering and a cube frame. I always imagined the rollers were rubbish, but I'm well impressed with how they work actually.

    I would have like 400x400x600 even...I guess I could ask RR if they'd do it.

    Again, I'm not getting into cutting up a frame for this one. I would certainly look at mods to suit my needs, and a triple Z axis on single motor/timing belt springs to mind, even a geared belt drive Z axis possibly.

    Can anyone offer their experiences with this kit, or an alternative?



  • @Corexy I would suggest you look at the BLV the details on the link give you lots of sources for the parts/kits.



  • I too had an Ender3 Pro as my first Printer.
    Within a month it had a Duet Maestro. Then a E3D V6 hotend, then a Titan DD Extruder, Bl Touch.

    I then fancied the idea of building my own printer.
    After looking at everything about including the BLV which I really liked, but I settled on the RailCore 2 ZLT, 300x300x600 build, running on Duet.
    The BOM is very detailed and there is a brilliant community on Discord if you need a hand with the build. Obviously there is this forum.

    Being in the UK, some parts like the Misumi extrusions were hard to get, but since I built mine there is a guy who sells the extrusions in the EU.

    US, you would have no issues in getting the extrusions.
    Your profile does not say where you are based.

    Overall it is fast, exceptional print quality, lots of bling bits are available like aluminium motor mounts, different idler arrangements, the list is endless.

    If you need anymore info, let me know.

    Regards,
    Paul.



  • @Corexy There have been a couple of other threads on here from people who have built RatRig kits so I'll let them jump in. As I recall the general impression was that delivery was a pain in terms of time but otherwise OK. I think I recall one user saying that the holes were not tapped square in the ends of the extrusion but AFAIK that was juts a one off.

    For info, my machine (CoreXYUVAB with 6 extruders) is built using OpenBuilds V slot and I love the stuff. Mind you, it ain't necessarily the cheapest way to make a linear guide. At the last count, I had 60 plus sets of wheels at an average cost of about £10 per set including spacers (I always use an "axle" supported both ends so I have to double up on spacers).

    The carriages tend to be bulky compared to other linear rails but in general, V slot stuff is easy to align and somewhat forgiving. Take especial car in tensioning the wheels. If you get it right there should be zero "play" and they will last pretty much forever. If you have them too tight, they will scrub and wear out. I found that once or twice there wasn't enough adjustment to back them off sufficiently but that was easily remedied by opening up the smaller, fixed wheel holes by half a mm or so. When it's right, there will be no "play" and if you tilt a rail with carriage attached to about 45 degrees, the carriage should slide under it's own weight.

    HTH



  • @PaulHew said in Large corexy mechanical kit options:

    I too had an Ender3 Pro as my first Printer.
    Within a month it had a Duet Maestro. Then a E3D V6 hotend, then a Titan DD Extruder, Bl Touch.

    I then fancied the idea of building my own printer.
    After looking at everything about including the BLV which I really liked, but I settled on the RailCore 2 ZLT, 300x300x600 build, running on Duet.
    The BOM is very detailed and there is a brilliant community on Discord if you need a hand with the build. Obviously there is this forum.

    Being in the UK, some parts like the Misumi extrusions were hard to get, but since I built mine there is a guy who sells the extrusions in the EU.

    US, you would have no issues in getting the extrusions.
    Your profile does not say where you are based.

    Overall it is fast, exceptional print quality, lots of bling bits are available like aluminium motor mounts, different idler arrangements, the list is endless.

    If you need anymore info, let me know.

    Regards,
    Paul.

    Sorry, no I've been printing for almost 10 years now.

    I only bought the E3 Pro as a backup after my Duetwifi converted Zortrax got fried in an electrical storm.

    My point was that I've always looked down my nose at v slot rollers as inferior, but am coming around to them.

    I'm in Australia, by the way.

    @deckingman said in Large corexy mechanical kit options:

    @Corexy There have been a couple of other threads on here from people who have built RatRig kits so I'll let them jump in. As I recall the general impression was that delivery was a pain in terms of time but otherwise OK. I think I recall one user saying that the holes were not tapped square in the ends of the extrusion but AFAIK that was juts a one off.

    For info, my machine (CoreXYUVAB with 6 extruders) is built using OpenBuilds V slot and I love the stuff. Mind you, it ain't necessarily the cheapest way to make a linear guide. At the last count, I had 60 plus sets of wheels at an average cost of about £10 per set including spacers (I always use an "axle" supported both ends so I have to double up on spacers).

    The carriages tend to be bulky compared to other linear rails but in general, V slot stuff is easy to align and somewhat forgiving. Take especial car in tensioning the wheels. If you get it right there should be zero "play" and they will last pretty much forever. If you have them too tight, they will scrub and wear out. I found that once or twice there wasn't enough adjustment to back them off sufficiently but that was easily remedied by opening up the smaller, fixed wheel holes by half a mm or so. When it's right, there will be no "play" and if you tilt a rail with carriage attached to about 45 degrees, the carriage should slide under it's own weight.

    HTH

    Mate your machine is spectacular. That was just me on YT, complimenting the use of a ball joint on the bed (love that by the way, total alignment).

    While I'm total crap on the coding, building things rigid and square, correctly tensioned rollers, good wiring...absolutely my thing. I went over this dodgy little E3 Pro meticulously, which has built my confidence about the whole v slot system.

    I've sent RR an email asking for a firm(ish) shipping lead time.



  • @PaulHew

    Sorry mate, late down here and I'm tired. Didn't read all of your post.

    The problem I see with a lot of these linear rail printers is that they are using MGN12, which is minature rail, and they are bolting it straight onto out of spec surfaces. Those rails are meant to be mounted on machined surfaces and clamped against a reference edge. This never happens in the world of Chinese printers. Most likely the Railcore does it right, but that's a pretty expensive printer compared to what I'm talking about isn't it?

    I'd have to look at the prices and compare, but I'm getting some pretty good prints off these rollers....

    [img]https://i.imgur.com/0lQlahM.jpg[/img]



  • No Prob. Original HiWin Linear rails and carriages was about £450 about 880AUD



  • @PaulHew said in Large corexy mechanical kit options:

    No Prob. Original HiWin Linear rails and carriages was about £450 about 880AUD

    Cheers. If I was going that way I'd go the V core pro, as it uses MGN15's, but it's a kick up in price.

    When people complain about flat spots on these rollers, they must have something wrong when adjusting, or just watched a seized bearing run for a full print or something like that. It shouldn't happen.

    Then they talk about wear and dust (like you see in my pick), but to me that just looks like molding release agent and a bit of shiny surface wearing down as they bed into their channel.

    But I'd better be careful not to open a can of worms... each to their own.



  • @Corexy said in Large corexy mechanical kit options:

    Either way I want to do my own wiring and component selection, so the mechanical kit is the way for me. I am well and truly capable of cutting up my own frame, but to be honest it's loud and messy with all the shavings etc, I'd rather the "meccano" approach on this one. Whatever frame I get I would have it all squared up and tightened perfectly rigid.

    Misumi USA custom cuts at VERY reasonable prices and delivers in a few days. The most recent two coreXY I built, I did the basic frame this way, and am very happy with the results.



  • @Corexy said in Large corexy mechanical kit options:

    When people complain about flat spots on these rollers, they must have something wrong when adjusting, or just watched a seized bearing run for a full print or something like that. It shouldn't happen.

    IMO, that's always the case (incorrectly adjusted). My printer has been running for about 4 to 5 years and although it has evolved during that time, the wheels on the XY gantry are all original. In fact, there are no problems with any of the 60 plus wheels although the UV gantry has only done about 3 years and the AB about 18 months or so. Oh, and I throw around about 2 to 3 Kgs on each gantry. These are standard Delrin wheels. Having said all that, I've heard bad things about the mini wheels but I've have no personal experience of using them. I'd think it likely that problems might be due to poor adjustment but can't say for sure.



  • @deckingman said in Large corexy mechanical kit options:

    @Corexy said in Large corexy mechanical kit options:

    When people complain about flat spots on these rollers, they must have something wrong when adjusting, or just watched a seized bearing run for a full print or something like that. It shouldn't happen.

    IMO, that's always the case (incorrectly adjusted). My printer has been running for about 4 to 5 years and although it has evolved during that time, the wheels on the XY gantry are all original. In fact, there are no problems with any of the 60 plus wheels although the UV gantry has only done about 3 years and the AB about 18 months or so. Oh, and I throw around about 2 to 3 Kgs on each gantry. These are standard Delrin wheels. Having said all that, I've heard bad things about the mini wheels but I've have no personal experience of using them. I'd think it likely that problems might be due to poor adjustment but can't say for sure.

    Absolutely.

    As a field service fitter in the mines and oil rigs I saw similar mechanisms rolling submerged in coal slurry, etc for years. Mind you they did throw a few bearings in that aggressive environment.

    I adjusted all mine so that they could just still be spun on the track with my fingers while holding the carriage stationary, which gave an even(ish) tension across the board. Then I expect a little scuffing on the surface of the wheel as mentioned above.

    I totally agree that mini wheels may be more prone to problems just due to the smaller diameter. I wouldn't want those miniature bearings for a start.

    @Danal said in Large corexy mechanical kit options:

    @Corexy said in Large corexy mechanical kit options:

    Either way I want to do my own wiring and component selection, so the mechanical kit is the way for me. I am well and truly capable of cutting up my own frame, but to be honest it's loud and messy with all the shavings etc, I'd rather the "meccano" approach on this one. Whatever frame I get I would have it all squared up and tightened perfectly rigid.

    Misumi USA custom cuts at VERY reasonable prices and delivers in a few days. The most recent two coreXY I built, I did the basic frame this way, and am very happy with the results.

    I'm in Australia, so shipping from Misumi would be expensive. There is Misumi SE Asia, but they do seem to have a complicated website. Regardless, I don't want to do it that way this time, but it's certainly a consideration for the future.



  • So do we have any V core 2.0 owners out there?

    And do we have any experts on belt driven Z axis? Is it better in any way? I understand there's a little reduction gear of sorts, and I see the V king designer singing its praises. I just wonder if it wouldn't be a bit quieter and "softer" running than lead screws.

    And then I see some issues in the forums about toothed belts running over smooth idlers. Is that a problem? I'd have thought it would be OK if the diameter was a bit larger and the belts were tensioned correctly, but have had no experience with Corexy yet (despite my username lol, had big plans once).


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  • @Phaedrux said in Large corexy mechanical kit options:

    @Corexy said in Large corexy mechanical kit options:

    And do we have any experts on belt driven Z axis?

    https://drmrehorst.blogspot.com/search?q=z+axis @mrehorstdmd Paging Doctor Rehorst.

    @Corexy said in Large corexy mechanical kit options:

    So do we have any V core 2.0 owners out there?

    There's a few. https://forum.duet3d.com/search?term=v-core&in=titlesposts&matchWords=all&sortBy=relevance&sortDirection=desc&showAs=posts

    Cheers mate,

    Yep, I'm all over Mark's design. It's probably the benchmark today as far as belt drive Z axis' go. It also looks good for being driven by a single nema 17 stepper, which is something I've been thinking about. I'd rather not get into a 23 size stepper. I've also seen it expanded on with an extra "slave" shaft so as to have a belt in each corner, and have wondered about setting it up as a triple belt system.

    I'm thinking of which is better... triple lead screw on a common timing belt or this belt drive Z axis. I would imagine the belt drive would be quieter and no greasing of lead screws required. I will not be running 3 stepper motors on the Z axis, as I'll build a level be in the first place and don't want the wiring/programming complication.

    I've seen some invalid arguments against the belt drive like reduction gear backlash and belt stretch. It's all got the weight of the bed sitting on it, and while the new belt might initially stretch a little as it breaks in I doubt the weight of even the largest print would affect it. Plus the Digital Dentist has demonstrated it doesn't with testing.



  • There are only two real concerns with a belt driven Z axis. You want to keep the bed from dropping like a rock when the Z motor loses power so a gear reduced drive helps. Specifically, a worm gear drive of sufficient ratio will keep the bed from moving at all if you want to be able to resume a print after power loss. Z axis print quality is a function of the quality of the gears used, especially the worm gear, as defects will cause repeating errors in the Z axis of your prints.

    Thoughtful selection of the gear ratio and drive pulleys will allow you to use a nice, round steps/mm value that will get you nice, round full-step-multiple layer thicknesses in your prints, if that matters to you.

    Backlash in the gears shouldn't matter as long as the Z axis guides are aligned parallel to each other and the bed free-falls without the belts attached. If you start monkeying around with counterweights, elastic cords, or springs, all bets are off.

    Belt stretch isn't really an issue, but be sure to keep the working side of the belt loop parallel to the Z axis guide rails (just as you would keep lead screws parallel to the rails).

    Since you're into old-school building techniques, you might be interested in a fine adjusting Z=0 switch I'm working on. The design uses a differential screw to move a flag for an opto interruptor by 100 um per full turn of the thumbwheel over a 2 mm range of adjustment.

    alt text

    The screw is an M5x0.8 mm that I turn down to 4 mm on a lathe and then threaded M4x0.7 mm. With the proper arrangement of nuts for the two screws, the movement per turn is the difference between the two screw pitches- 100 um.



  • Just chipping in here as I literally took delivery of a V-Core Pro last week and began building this evening.

    My experience with RatRig was exceptional. They customised my kit based on the specs I provided (default build volume but an extra Z-axis and rail, plus a few other changes) and from the point of paying to delivery was a little over a week. Everything is cut and tapped correctly and squarely, all packed exceptionally well and so far I've had zero issues assembling.

    If I had any complaint, it's that the rails are really oily and need a good wipe down. I'm tempted to rebuild them using proper grease as I've just done on some other rails, but I'll cross that bridge when I get to it.



  • @NexxCat said in Large corexy mechanical kit options:

    Just chipping in here as I literally took delivery of a V-Core Pro last week and began building this evening.

    My experience with RatRig was exceptional. They customised my kit based on the specs I provided (default build volume but an extra Z-axis and rail, plus a few other changes) and from the point of paying to delivery was a little over a week. Everything is cut and tapped correctly and squarely, all packed exceptionally well and so far I've had zero issues assembling.

    If I had any complaint, it's that the rails are really oily and need a good wipe down. I'm tempted to rebuild them using proper grease as I've just done on some other rails, but I'll cross that bridge when I get to it.

    Mate that's good news!

    Rails and other shafts etc like that are often coated in spray grease etc just to stop it rusting on the shelf. Just wipe off the excess with a cloth or piece of kitchen paper and you're all good.



  • @mrehorstdmd said in Large corexy mechanical kit options:

    There are only two real concerns with a belt driven Z axis. You want to keep the bed from dropping like a rock when the Z motor loses power so a gear reduced drive helps. Specifically, a worm gear drive of sufficient ratio will keep the bed from moving at all if you want to be able to resume a print after power loss. Z axis print quality is a function of the quality of the gears used, especially the worm gear, as defects will cause repeating errors in the Z axis of your prints.

    Thoughtful selection of the gear ratio and drive pulleys will allow you to use a nice, round steps/mm value that will get you nice, round full-step-multiple layer thicknesses in your prints, if that matters to you.

    Backlash in the gears shouldn't matter as long as the Z axis guides are aligned parallel to each other and the bed free-falls without the belts attached. If you start monkeying around with counterweights, elastic cords, or springs, all bets are off.

    Belt stretch isn't really an issue, but be sure to keep the working side of the belt loop parallel to the Z axis guide rails (just as you would keep lead screws parallel to the rails).

    Since you're into old-school building techniques, you might be interested in a fine adjusting Z=0 switch I'm working on. The design uses a differential screw to move a flag for an opto interruptor by 100 um per full turn of the thumbwheel over a 2 mm range of adjustment.

    alt text

    The screw is an M5x0.8 mm that I turn down to 4 mm on a lathe and then threaded M4x0.7 mm. With the proper arrangement of nuts for the two screws, the movement per turn is the difference between the two screw pitches- 100 um.

    @mrehorstdmd Thanks Mark,

    Yes mate, all about the old school! So of course I love your little adjusting jigger there.

    I've followed you work for a few years and we've spoke in the past in other places. I do like how you aim for turns of pulleys/threads/screws to have usable measurements in movement. After all, it costs no extra to do so, so yes please I'll come back to you closer to the time to review my pulley sizes etc when I've finished procrastinating.

    No question about using the reduction gears, can't have the bed dropping. On a printer this size I would have preferred ball screws over lead screws, so the little reduction gearbox you used is not worrying me price wise if it works better. I like the keyed shaft through the center and the pillow blocks at the ends, which looks to keep the belt runs simple and in sync.

    My questions to you are:

    For this particular printer (V Core 2.0) using rollers not rails, is it worth doing compared to getting the 3x lead screw option and running them on a single belt? I did mention I'm not overly keen on lead screws over ball screws, but I guess I didn't like V slot rollers either until I used them.

    On this particular kit, would 3 or 4 Z belts be better for a 400x400 bed, as an extra shaft/pulleys/pillow blocks/belt would not cost much more really, and (I think) would put no more load on the motor.

    Cheers for your replies.



  • @Corexy I haven't looked at Mark's design but I'm sure it works very well. For my own printer, I chose to use 3off 1mm lead, screws (8 X 1 single start) driven by a single motor and continuous belt and can say that works well too. For what it's worth, I'd say that either approach will work well. Maybe the way to decide would be to look at the cost and lead times (no pun intended) for each and see which would be the easiest to source in your part of the world.
    Edit, my bed is also 400 X 400.



  • @deckingman said in Large corexy mechanical kit options:

    @Corexy I haven't looked at Mark's design but I'm sure it works very well. For my own printer, I chose to use 3off 1mm lead, screws (8 X 1 single start) driven by a single motor and continuous belt and can say that works well too. For what it's worth, I'd say that either approach will work well. Maybe the way to decide would be to look at the cost and lead times (no pun intended) for each and see which would be the easiest to source in your part of the world.
    Edit, my bed is also 400 X 400.

    Cheers Ian,

    I'm a strong believer in lifting the Z axis/bed via 3 points, for the same reason I like 3 point bed leveling. I not only want my build plate dead level and true, I want the mount plate it sits on to be close as well. I don't want to build something that's bent like a banana and ask 3 steppers and software to fix it up for me. To be honest I'd like to switch off all leveling, or at least have it that it only needs the mesh updated if I change/move something.

    As the kit comes with the option of 3x lead screw, it's probably a big enough modding job to tie the 3 of them together with a timing belt, by the time I rig a belt tensioner etc.

    I've got to sell something to fund this...Minister for Finance (and war) has hat a gut full of my shenanigans at the moment. been a bit spendy lately.