Dual CoreXY setup that uses LME12UU and 12mm shafts
by Thump2010, published
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This is a modified CoreXY setup I have been working on, I have to do the corner bearing holder and the motor mount yet, this is for a printer I am creating, it uses LME12UU bearings and 12mm shafts, I went bigger as this is also used in a much larger printer also, that and I like tanks, I don't like things that are flimsy and flex.
It does not cross over it runs at two different levels so everything stays straight.
I used 686Z bearings on the ends and the flanges I made are designed to be paused then the bearing added then printing to continue so they are encased in plastic (a blast of a heat gun before hitting resume makes a strong bond for the continuing layer.)
I made it around this hotend that I got from amazon:
Signswise Assembled J-head Hotend 0.4mm Nozzle Printer Head for 1.75mm Filaments
It shouldn't take much to change the clamp to fit your hotend.
Things to do:
Corner bearing mounts.
Spot for a small magnet on the Y carriage for the X carriage home and another for Y homing.
Spot for a hall effect sensor on the X carriage to line up with above
Spot for a Z probe.
I had to redesign the X carriage, when I went to put it together it wasted almost 2 inches of space so I flipped the Y axises upside down to lift it up higher and to put the belts above the printer on top of the frame which solved the problem of no where to mount anything.
it is functional now, I was going to put new picks but I am almost done mounting everything and running the belts I just need to print out some more bearing flanges, on those I stop at height with cura, and pop the bearing in and resume printing.
I have made a motor mount that mounts to the outside on the sides with the belts passing through, I will have picks up hopefully by tomorrow as soon as I get the rest of the bearings done everything else is mounted, lines up and is ready to go.
I finished assembling the mechanical parts, all seems to look good and moves as it should, I could have brought the corner bearings in more and use a t-nut in the slot and had them in line but I wanted more support than that offered and tapped the corner holes of the extruded aluminum and used nice long 1/4" bolts to hold it together, so it causes the belts to angle out to the corners but it shouldn't matter as it gets pulled away on one corner it gets pulled tighter on the other so there is never any slack and the other thing look at the serpentine belt on your car, it does not make a perfect square. ;-)
Pictures added, I just need to wire the motors to the smoothieboard now.
I worked out where to put the endstops, I made them separate to glue on (acetone for the win) now that I have how I want them designed and best placement for them I will put them in the design of the parts so that they are built in.
I have everything hooked up but the hotends and the extruders and told it to print, told it to do a print speed of 150mm/s and a move speed of 300mm/s and it didn't blink an eye, I cranked it to 999% and it flew, I doubt it could push the plastic out that fast especially as I normally use a 0.3mm nozzle but the mechanism handled it just fine and flew, it was a glorious sight.
This is fully operational now.
Endstops were added, print and enjoy.
Raised the bottom of the X carriage (hotend holder) by 1mm to give more space at the bottom of the hotend heatsink.
Uploaded the fan shroud, it is designed to use blower fans for the plastic active cooling and a 40mm x 40mm x 20mm normal 12v pc fan to cool the hotends, a standard 10mm fan does not move enough air to cool both heads at a time but the 20mm fan works great.
Uploaded a in progress fan duct, I have printed it a couple times for fit and am printing the final version of this style now for testing tomorrow.
I thought about using two fans on the hotend one to push one to pull, the ones I found though blow a lot of air and with both nozzles at 220c you can barely feel a warm breeze at the bottom and quite cool at the top, but it is getting cooler now, the test will be in the middle of a hot summer.
I have decided to do a dual Z lift system with a hardened linear shaft in each corner, that should eliminate all Z wobble and issues, and I am switching from a 1/4" thick aluminum build plate to a 1/8", the 1/4" would probably be fine with the dual Z but might as well lighten the weight and help the build platform to heat up faster.
I expected to have it all done last weekend but I forgot to get more M5 nuts and bolts as I ran out and in the US it costs me $1.50 for 2 bolts/screws from the hardware store since they are metric. :-(
I was looking at everything and have decided to change the XY parts, right now they clamp the LME12UU bearing in place, sometimes that can throw the bearing out of alignment, I found that to be the case on the Z axis, it was bad. I decided to make a circular mount like you would get if you bought the brackets in metal, the metal ones you slide the bearing in and put a locking clip in, my new ones is completely encircled in plastic and you put two stop screws in the corners to keep the bearing from coming back out.
I left the v5 clamp ones posted and included the new v6 as a separate item for those that may not like that style, I printed it out and it aligned perfectly and worked really well, I am working on the X axis part now.
Uploaded all the new parts, it is working so much better, I will get pics up soon, just really busy.
I gave up on the bearing flanges, they were more trouble than they are worth, unless your printer prints perfectly which my original one didn't then you have imperfections in the inside of the flange where the belt rides and I had them pop apart and then the belt fall off several times, maybe PLA wouldn't pop apart but I was concerned about the temperature issues if I enclosed it.
What I did was to just do a bushing that the bearing sits between so the belt sits right on the perfectly round, and smooth bearing itself.
changing that has changed my prints to perfectly aligned perimeter layers, I am extremely happy with the prints.
I am going to tweak the XY motor mounts so that the bearings are a bit further in, finish the active cooling ducts, and I may add a z probe but lack of space it will probably be a switch driven probe and then I am going to consider this finished. (until I remember something else)
All of the new parts are installed and everything is working beautifully.
All I have left on this project is the improve the active cooling ducts for the fans to cool PLA.
Uploaded new pictures.
see some print videos here
Finished the airduct.
I tried many different styles but due to the tight spaces most were too close to the heaterblock and eventually melted and sagged.
I finally hit on a design that did not blow too much towards the bed or too much on the nozzle cooling it down.
I forgot to post the end stop magnet and hall effect holder for the Y axis.
The fan ducts still blew on the nozzle too much I modified it a little, and realized one fan didn't align due to the fact that the fan outlet is offset so I adjusted the duct for that side so print both a and b and then you will know which goes on which fan when the center lines up with the nozzles.
As far as I am concerned this is finalized, it works beautifully.
I just had a scathingly brilliant idea.
Aligning the heads to the same height is an absolute pain in the A** you have to loosen the clamp and twist the heatsink with some needle nosed pliers until the height is obtained, and trust me it is not fun.
I just had the idea of the clamp itself, on one side I will leave the clamp as is, on the other hotend I will shrink the inner part of the clamp by 1mm top and bottom so that you will have 2mm wiggle room, set the bed until nozzle one is touching, let nozzle 2 drop and touch the bed and then tighten the clamp, done.
Simple and easy, I guess there is a reason for the term KISS and trust me, this is so simple I really do feel stupid..... ;-)
With this change it is important to put the clamp in properly now, match thin side to thin side and thick to thick.
I do have some add on features for later but the core is done.
those features being a cable/boden holder and a z-probe.
I am working on a single head version of this setup, the X carriage and Y carriage will be different, I thought about making them universal but with a single nozzle I can squeeze extra build space out of it if I try, like 2" in one direction and 1" in another.
But I will do a Drop in single nozzle X carriage replacement for this setup as well.
Also I will be working on an 8mm version of both the dual and single head version
Version 8 of the Dual Hotend:
I have switched to physical switches instead of hall effect as I was having issues with them and went back to old school.
One head is held snug, the other head can adjust +/- 1mm up and down to help to level the heads, loosen the clamp, bring the bed to just touch the set hotend and let the other hotend drop to the bed and then tighten the clamp, you are now aligned.
Added a BLTouch version.
Added a Inductive probe version with a lock screw to secure it in place. I used an LJ18A3-8-Z/BX
NEW option for the upper motor mounts.
either old mount or new will work but the new motor mount has been extended to hold a bearing to hold the top of the 12mm ball screw stable, I used 12mm x 28mm x 8mm 6001ZZ bearings, the bearing holder is adjustable.
There was a problem with the belt mounts being too loose in one corner, fixed all of them.
I finished the fan shroud, it holds 2 30mm fans to cool the hotends, and 2 40mm fans for part cooling, I used 40x40x20mm fans for part cooling, the more air the better.
I moved the bearing screw holes as they were too close to the bearing throwing off alignment a little.
I modified the inductive probe version to us a clamp, a setscrew was just not cutting it, it would throw the probe into an angle when tightened.
Special thanks to Saldot and his Fan holder/mount for E3D v6 http://www.thingiverse.com/thing:780379 which I butchered into my fan shroud as I have been using his fan holder for quite a while and really like it.
Coming up next will be a tweak to the bearing holder motor mounts to make them a bit smaller and eventually be a single head version.
I used ABS but I think that really is only important for the parts around the nozzle, everything else PLA should work fine.
0.2mm layer height
Set your slicer to pause right before the top flange of the bearing, when the print pauses then insert the bearing and continure printing.
- The number on the left is the total number of that item needed, not the number
of times to order the included link, so if it says 4 - and the part is a 4 pack then
just get one 4 pack -
4 - 688Z Metal Sealed Deep Groove Radial Ball Bearings 8 x 16 x 5mm
10 - 698Z 8mm x 19mm x 6mm Sealed Deep Groove Radial Ball Bearings
8 - LME12UU Linear Motion 12 mm Ball Bushings
2 - Nema 17 Stepper Motors
4 - A3144 A3144E OH3144E 3144 Hall Effect Sensor
1 - (depending on the size of your printer, you do the math)
Thomson QS 12 MM 2000, Quick Shaft
4 - Neodymium Magnets 1/4 x 1/16 inch Disc N48
(That is the size I used but they are not available on amazon, check your local
hobby store or ebay)
2 - GT2 20 Tooth 5mm Bore Pulleys (bought them with belts, it was cheaper than without
and just didn't use the belt as it was too short)
1 - 5 Meters GT2 2mm pitch 6mm wide Timing Belt
1 - Sunon 40x40x20mm 3 pin fan #KDE1204PKVX
2 - 12V 0.13A 40mm Turbo Blower Fan 4020 40x40x20mm
2 - 3D Printer J-head/E3D 0.3mm Extruder Printer Head for 1.75MM Filaments
8 - small m3 screws to hold in the bearings, I used some small computer screws
for holding in cd/dvd drives that I had lying around, they just need a flat
bottom and a big enough head to cover a little of the bearing edge.
22 - 4-40 bolts and nuts, I just got long 1.5 inch ones and cut them down to various sizes with a dremel as I hate hunting for screws
10-14 feet of 3 wire cable for the sensors, fans, thermistors. More if you have a
A spool of ABS plastic in your color of choice to print all the parts.
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Dual CoreXY setup that uses LME12UU and 12mm shafts by Thump2010 is licensed under the Creative Commons - Attribution - Non-Commercial license.
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