CoreXYNZ build

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the_digital_dentist
I'm not being negative, just trying to understand how you can use such a device to align a printer with the required accuracy and precision. If it works I'll buy a laser leveler, but every laser I've ever seen produces a relatively wide beam with indistinct edges - suitable for hanging pictures or framing a deck, but precision alignment?. Between that and the basic +/- 4 degree spec I can't see how it would be possible to perform an accurate alignment. If you have a technique that works I'd love to hear some details about it.

It's pretty easy. I'll do a detailed write up with pics and maybe a video some time. The important thing is that being a beam if light, it's straighter than any straight edge. So if you can get it square, you have a giant square, not just one that's a few inches long which is just what you want if your frame members are 500mm or longer. Like any beam of light, a laser will spread a bit. It does depend on the quality of the diode (and that's where the price makes a difference), but yes when viewed at a distance they can look fuzzy but close up even the really cheap ones should be pin sharp. Calibration is easy (well checking it is - adjusting it is another thing but even that is no big deal as I'll explain). It's the same principle as you'd use with a spirit level where you simply turn it 180 degrees. If the bubble is level both ways, you know the thing is accurate. If the bubble is level but when you turn the thing through 180 degrees it's high on one side, then you know it is out (but, you can still hang your picture straight by having the same bubble offset either way round). Same thing with a laser level. You set it up in the centre of a room and mark the left and right walls where the horizontal line touches. Then you turn it 180 degrees and do the same. They should line up. If you room is 5 metres wide and they line up within 1mm (mine does) then you know the horizontal is good for 0.1mm at 500mm. The vertical is done the same way. If they don't line up, and if you can't find a way to adjust it, all is not lost. For one thing you could measure the error and allow for it but that's a pain - e.g if it's say 5mm at 5 metres, you'll know it's going to be 0.5mm at 500mm.

Hopefully you'll end up with a calibrated laser level. If not, all is not lost and proceed as follows. To see if a corner is square, set up a work surface that is horizontally level with the laser. Then put your frame on the surface and check the vertical. If its out, measure the distance between the top of the frame and the vertical laser line. Say the frame is 1mm to the left of the line at the top when it;'s touching the line at the bottom. Then turn the frame 180 degrees and check the distance from the other side. If the gap is 1mm to the right of the line then you know it's square. If not, adjust the frame as necessary until the error is the same (but mirrored) from both sides. Obviously, it's much easier if the laser is known to be square to start with but it's always good practice to double check (just as you would with a spirit level). One other thing you get with a laser, that you don't get with a square, is an immediate check and measurement of how straight the frame members are. So, although you might get a frame square by other means, the rails could possibly not be parallel because something is slightly bowed.

I don't know if I've explained that very well - pictures will be easier if and when my extrusion ever gets here.

Interesting discussion. I have a cross line laser a laser pointer a digital level on my phone a couple of decent bubble levels and some dial gauges. Dial gauge over a piece of granite would probably work well.
Open and closed belts arrived. Had to buy 10 1220mm closed belts.

For me the laser does not sound precise enough unless you have some of the expensive Leica stuff.

It can probably work, but if you have a dial gauge then I believe this is the best method by far:



I am not even sure you need the counter weight because the specs on the linear rails are pretty amazing when you actually start looking into details.

Well whatever guys. It was just a tip which I have found works for me, at least for the initial build. Very fine adjustments will always have to be made by other means. I was just passing on something that I have found works well for me. Sorry if that was the wrong thing to do.

80 tooth pulleys arrived. Trial fitted them along with an 8mm ID flanged bearing. I might use one of these pulleys to make an extruder like this [www.thingiverse.com] Still looking for a light extruder option. I know a Flex3drive is an option but would prefer a light weight on board extruder.

Pretty much finished up drawing the XY axis. Just a bit of editing or maybe a change of mind

I recently installed an E3D Titan extruder on a Taz 2 printer. It seems to work well, though at the moment I'm struggling with a firmware problem on that machine. It is a very light weight extruder.

I prefer geared extruders in general because they are capable of pushing the filament harder than ungeared direct drive extruders. The BullDog XL and E3D V6 on my own printer have suffered exactly one jam in almost two years of operation, and the filament has never been stripped by the extruder.

Edited 1 time(s). Last edit at 07/04/2016 09:27PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks for the input DD. I am currently using the Bulldog/E3D too. No problems there except weight. The Titan looks good, what length motor did they end up using? Am still considering a variation of the Itty Bitty belted extruder.

It doesn't come with a motor. I've seen claims (not by E3D) that it reliably drives filament with just a 20 mm long pancake motor, but I have my doubts about it. I'm just using the old extruder's motor and it seems to work fine. I think it's a 35 mm motor.

Edited 1 time(s). Last edit at 07/04/2016 09:31PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

2020 hardware arrived.



M3 and M4 T nuts.
[www.ebay.com]

Corner blocks
[www.ebay.com]

Are those the 2020 or 2028 corner blocks?

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Mikk36
Are those the 2020 or 2028 corner blocks?

They are 28 mm. I wish I had got some 20mm as well.

I have never used 20mm extrusion but may give it a try at some point. The 1 1/2" or 40 mm stuff I use is industrial surplus that I buy at scrap yards for $2/lb, but it isn't always available when I need it or in the quantities that I might need. Does using all those corner blocks and hardware plus 20 mm extrusion cost less than using 40 mm extrusion without all the extra stuff?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
It doesn't come with a motor. I've seen claims (not by E3D) that it reliably drives filament with just a 20 mm long pancake motor, but I have my doubts about it. I'm just using the old extruder's motor and it seems to work fine. I think it's a 35 mm motor.

Hmm I am tempted to get a Titan as I want a volcano block and some hardened steel nozzles. I thought I might seriously lighten this 80 tooth pulley and make an extruder. 4/1 or 5/1 with either a 20 or 16 tooth pinion.

The whole Titan extruder weighs 60 g. It remains to be seen if the nylon (?) gear lasts, but it should be easily and cheaply replaceable.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
I have never used 20mm extrusion but may give it a try at some point. The 1 1/2" or 40 mm stuff I use is industrial surplus that I buy at scrap yards for $2/lb, but it isn't always available when I need it or in the quantities that I might need. Does using all those corner blocks and hardware plus 20 mm extrusion cost less than using 40 mm extrusion without all the extra stuff?

For me it is about availability and freight costs to New Zealand (about as far away from anywhere that you can go) There was a local supplier of 2020 so I got 2x 5.8 meter lengths. The hardware is from China which for me is nearly local . Anyway for me the Tnuts and corner blocks seemed cheap in these quantities and are handy to have for other projects.

Kind of getting there with the XY part of the design. Struggling a bit with parts built within the Solidworks assembly, but it is a good learning curve. Mostly I am an Autocad guy and should really be using Fusion 360.
I am thinking this arrangement is a bit lacking in adjustment to get the 2 Y axis arms on the same plane. Should be rigid though.

Be sure to put the belts into your model and check for clearances at both ends of the Y axis.

I've been working on a coreXY design and didn't realize I had a clearance problem until I was almost finished with the layout. I am using belts on two levels and solved the clearance problem by using larger pulleys at the corners opposite the motors. The pulleys consist of flanged ball bearings, F608ZZ (22 mm dia) and F6903ZZ (30 mm dia). The bearings are 7 mm wide, so I stack two of each type with nylon washers or printed spacers between them, and use 9mm wide belt. The width of the flat area is 11 mm and matches the 20 tooth drive pulleys that go on the motors.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
Be sure to put the belts into your model and check for clearances at both ends of the Y axis

Thanks for the heads up Mark. I will do that, I need to go over the belt tutorial again.
I have been researching surfacing plates to set up the XY axis accurately and have decided on a self leveling epoxy surface on a concrete pad.

[www.precisionepoxy.com]

I do a lot of composite work and have the epoxy. Should only need a few millimeters.

Edited 1 time(s). Last edit at 07/06/2016 01:11AM by RodF.

9mm rails arrived. I will start cutting metal shortly.

I did a quick deflection test on the 9mm rail. It is 400mm long, I put a 347gm load on each axis. With the rail flat it deflected 0.2mm and with it upright it deflected 0.1mm. I'm pretty keen to keep the rails flat for simplicity. Not really sure how much the X carriage will weigh with the extruder, hot end, 2 or 3 fans and the mounting system along with some cable chain. Worst case might be 700gm. Of course the carriage max travel will only be 300mm so I guestimate a deflection of maybe 0.15mm. Probably too much but a couple of aluminium angle strong backs should reduce it to an acceptable amount.

Interesting test!

I think that if you bolt it to some flat plate with all the bolts installed and torqued correctly you'll be fine.

Just my thoughts, I have no expertise to back that statement up I'm afraid.....

Surprised they bent so much with less than half kilo, luckily mine are shorter & thicker, and supported(though have other unsupported setups), I wonder if a plate(about 4 holes worth) joining the rails underneath would halve the deflection or add to it?

Decided to simplify the X axis mounting system. This does move the belt axis away from the carriage axis but should be more rigid and quite a bit lighter. If the X axis needs stiffening it will be easy to screw a piece of aluminium angle to the underside of the X rails.

Take a look at this. When I was looking at datasheets for these rails. I believe the holes are spaced perfectly so you could extend the X Rails a bit and connect them to the blocks on the Y, using 2 screws. That would make it alot more rigid, and you wouldn't need to fabricate the "ears" on the green part.

Quote
FA-MAS
Take a look at this. When I was looking at datasheets for these rails. I believe the holes are spaced perfectly so you could extend the X Rails a bit and connect them to the blocks on the Y, using 2 screws. That would make it alot more rigid, and you wouldn't need to fabricate the "ears" on the green part.

Great spotting. Thanks a lot. That's serendipity. I will rework the design and see how it goes. It looks like no print space would be lost.

24V centrifugal fans arrived. [www.aliexpress.com]



Edited 1 time(s). Last edit at 07/11/2016 07:55PM by RodF.

Looks doable.

What app are you using to model? Are the parts like extrusions, motors, pulley's, etc part of a library?

Edit: ah, Solidworks

Edited 1 time(s). Last edit at 07/12/2016 12:35PM by FA-MAS.

I have pretty much sorted out the basic configuration of the Core XY platform. Still some spacers to model and the belt tensioners on the extruder platform to design. I have ordered a Titan extruder from E3D (and a 1.75mm Volcano setup). I have 3 different size motors ordered for the Titan to see what the lightest setup can be. Also pre ordered a Duet WiFi.

Work in progress. I've managed to order some 1/4" cast aluminium plate from the US, but that will not arrive for a few weeks. Hopefully around the time of the Duet Wifi.