Large corexy mechanical kit options
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@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
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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.
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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.
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.
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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.
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@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.
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@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.
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.
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@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.
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@Corexy said in Large corexy mechanical kit options:
............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.
Yup - that's how mine is and it's so nice to be able to turn on the printer, select a file and hit print. My slicer start code calls a macro which heats everything up and runs home all but that's all I ever do. I've never used any form of firmware levelling or flatness compensation - being a mechanical engineer (retired) I always prefer the mechanical solutions. At the last TCT show, I took the XYUVAB assembly off the base which is the Z axis, put the bits in a van, transported it 60 odd miles, carried it to the stand, put it back together, set the Z offset (because I have to remove the Z axis switch when I take the the printer apart) and started printing. Didn't even bother to check that the bed was level. Did the same in reverse but when I got back home I did re-check the bed level - no adjustment required. Job's a good 'un.
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Yep, and for those who doubt the V slot rollers, these prints have come off a dead stock Ender 3 Pro. The only mods on this printer are 4x M4 nyloc nut on the bed leveling screws, and the ABS printed (which burned into my magnetic build "mat"....doh) fan shroud.
$311AUD delivered for the printer, plus $0.50 for nuts/plastic.
It's all about the mechanical setup and adjustment first. Software compensation should be the last and subtle resort.
Edit: Hope you don't mind, I fixed your image tags. @droftarts
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No worries at all. How do you do that, it's just started happening?
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@Corexy Nice prints!
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@deckingman said in Large corexy mechanical kit options:
@Corexy Nice prints!
Cheers mate.
I did just want to demonstrate the potential of the v slot wheel system, and to be honest with me being so crap on the keyboard I wanted to show that us old "mechanics" still have a place in the hobby lol.
@chas2706 said in Large corexy mechanical kit options:
Excellent print quality.
Any chance you can share your config.g?
Mate...I don't know how to tell you this, but that's a bone stock E3 Pro, with all it's 8 bit goodness.
The only things fitted to that printer are 4x M4 nut and a plastic fan shroud. I do have a few tricks up my sleeve in my S3D profile, but nothing too fancy.
I hope to demonstrate to new players that buying a printer and modding the hell out of it straight away is not necessary. Software compensation will not cover a multitude of sins either.
It needs to be assembled and adjusted correctly from the start.
I ran the same print on my Duet/Zortrax in ABS, but I've got a bad Z wobble that seems to be built into it when it reaches the top of its range. I've got to work out some sort of Z isolator for that one.
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Back on point,
I've spoken to the Rat Rig guy, and he's been right on it with the responses and advice.
I did mention the lead time, and he said they got behind a little at one stage, but they were right up on it now.
For me the decision is to go with their 400x400x400 V slot model with the 3rd Z screw option, just need the money which will likely push the order date out to June.
I've really had enough of Z screws I must admit...I'll look at the belt option harder in the meantime.
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Hi all.
Looks like my birthday's coming early, as I've squirreled away enough money to pull the trigger on a V-core kit.
I've been in touch with them with a million questions, and I must say the responses have been excellent, even including a call direct to my mobile in Australia from Portugal last night.
I was going to go with the 500x500x500 model, as it only costs a little more, but funnily enough the Keenovo mats almost double in price from 400 to 500mm, and it seems build surface options become much more limited as well.
They have offered that if I buy the 400mm model but pay the 500mm price (only about 20 euro more), they will extend the Z height to 600mm. I'm wondering if that will be worthwhile, or should I just go with the 400mm all round size?
I'm going with the triple Z axis leadscrew option, but without the motors as I plan to run a single belt/motor. I do wonder about their Z setup as they run 4 upright V slot channels with rollers, which may defeat the purpose of the triple leadscrews, but I'll look at that when the time comes. I'm still open to the possibility of a belt driven Z axis.
It comes with the 400mm build plate, but it's only 4mm thick. If it's flat that will be fine, if not I'll go with 10mm cast ally precision plate.
I've got a ton of gear here including a Duet wifi/paneldue, E3D V6, Meanwell supply, plus/wire...all sorts of goodies.
It'll probably take a long time until it's done, but I'm quite excited to get started. Also glad I didn't go the Tronxy route, as it seems they are a pile of junk for almost the same money. Cheers to those who advised against it.
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@Corexy congrats and happy birthday! An extra 200 mm in Z for 20 bucks or so, sounds like a no brainer if you can physically accommodate that height. Ref the linear guides, you only need 2 - maybe 3 depending on how they are arranged. The more you have, the more difficult it is to get them all aligned (although Vslot and wheels are a little more forgiving in this respect).
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@deckingman said in Large corexy mechanical kit options:
@Corexy congrats and happy birthday! An extra 200 mm in Z for 20 bucks or so, sounds like a no brainer if you can physically accommodate that height. Ref the linear guides, you only need 2 - maybe 3 depending on how they are arranged. The more you have, the more difficult it is to get them all aligned (although Vslot and wheels are a little more forgiving in this respect).
Cheers Ian,
Not literally my birthday, I just managed to accumulate the funds a little earlier. This might mean that I can get that Bondtech BMG I need for this project as a pressy....
That's how I'm thinking...they've got 4 vslot z rails and 3 leadscrews. I'm of the mind to make it a vslot rail with each leadscrew, possibly with the delrin backlash nut mounted mounted on the actual roller carriage plate.
I'm also considering a water jet cut all floor to mount the bearings/pulleys for belt driven z axis screws/pulleys. IF I don't go with a Digitaldentist style reduction gear belt drive for the Z.
But I won't get ahead of myself, as Ratrig seems to have gotten by just fine without my advice/assistance/opinions so far. I'll have a look at the thing first and take it from there.
As for accommodating this thing, I think it's own small table or roller trolley will be the way to go. It certainly won't fit on the workbench.
Cheers all.
**Order placed. Let's see how they go.
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@Corexy Yeah, I guessed that it was either a "metaphorical birthday", or an "official birthday" like the queen has.
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@deckingman said in Large corexy mechanical kit options:
@Corexy Yeah, I guessed that it was either a "metaphorical birthday", or an "official birthday" like the queen has.
Ha ha!
All my birthdays are metaphorical in a way, and it's hard to be happy on a day when you've just added another number to 5__.
I'm tipping the Queen gets more cards and a nicer cake too!
