Options for auto leveling? March 05, 2015 11:50PM |
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Re: Options for auto leveling? March 06, 2015 12:30AM |
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Re: Options for auto leveling? March 06, 2015 03:04AM |
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Re: Options for auto leveling? March 06, 2015 03:41AM |
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Re: Options for auto leveling? March 06, 2015 04:19AM |
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Re: Options for auto leveling? March 06, 2015 05:40AM |
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Re: Options for auto leveling? March 06, 2015 07:23AM |
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Re: Options for auto leveling? March 06, 2015 10:12AM |
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Re: Options for auto leveling? March 06, 2015 10:31AM |
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Re: Options for auto leveling? March 06, 2015 10:33AM |
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Quote
ggherbaz
Capacitive proximity sensor instead of inductive, simple to set and will detect any material.
Re: Options for auto leveling? March 06, 2015 10:34AM |
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Re: Options for auto leveling? March 06, 2015 11:37AM |
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Re: Options for auto leveling? March 06, 2015 12:41PM |
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Re: Options for auto leveling? March 06, 2015 01:38PM |
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Re: Options for auto leveling? March 06, 2015 03:39PM |
Registered: 11 years ago Posts: 30 |
I mean the traditional of the 4 screws with tension spring on each corner, and use the paper leveling technique. But I think that would be really frustrating considering the large bed area.Quote
DRobs86
Whatever you go with, I would avoid using bed springs and a mechanical probe. Perhaps I had weak springs, but I found that the force required to press the switch caused the springs to compress on the edge which was being probed. Obviously not good.
Re: Options for auto leveling? March 06, 2015 03:41PM |
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Re: Options for auto leveling? March 06, 2015 03:42PM |
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Quote
TheBoilingDumpling
I mean the traditional of the 4 screws with tension spring on each corner, and use the paper leveling technique. But I think that would be really frustrating considering the large bed area.
Re: Options for auto leveling? March 06, 2015 03:42PM |
Registered: 11 years ago Posts: 30 |
Re: Options for auto leveling? March 06, 2015 03:51PM |
Registered: 11 years ago Posts: 30 |
So does that mean, if I were to use Blue Painters Tape on top of the bed, a leveling system that would make contact to the actual bed would be more preferred?Quote
dc42
Quote
ggherbaz
Capacitive proximity sensor instead of inductive, simple to set and will detect any material.
Not so. If you print on a glass bed as I do, it senses the distance to the material under the glass (aluminium in my case), although putting tape, glue etc. on the surface also affects the reading. Not only does this make it less repeatable because of the greater distance, but I use several glass plates, and I can't guarantee that they are all exactly the same thickness. The same considerations apply to inductive sensors. So I only consider sensors that measure the distance to the top of the printing surface, such as contact and IR.
If you print directly on to an aluminium bed (perhaps with a thin coating on top), then both capacitive and inductive should work well.
Re: Options for auto leveling? March 06, 2015 03:53PM |
Registered: 11 years ago Posts: 30 |
That's pretty cool, I will think about it!
Re: Options for auto leveling? March 06, 2015 03:54PM |
Admin Registered: 17 years ago Posts: 7,879 |
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TheBoilingDumpling
Hmm, I'm not quite sure about that!Quote
ggherbaz
Capacitive proximity sensor instead of inductive, simple to set and will detect any material.
Re: Options for auto leveling? March 06, 2015 03:56PM |
Registered: 11 years ago Posts: 30 |
I haven't seen a EZ3D in a while, nice to see it working well!Quote
normw
I have two printers that work fine with the inductive probe. The inductive probe requires a aluminum bed to work properly, one printer has a 1/8" aluminum bed and the other has a MK3 aluminum heated bed. They both detect the bed at about 2mm from the surface of the bed. The cost of the probe and resistors necessary for the correct signal voltage was about $5 each. Then all that is needed is a mount for your specific printer.
[www.youtube.com]
Re: Options for auto leveling? March 06, 2015 03:59PM |
Registered: 11 years ago Posts: 30 |
I think I will be able to print at high speed, because I am using a Core XY system, so the bed won't be moving as much as the hotend will be.Quote
ggherbaz
dc42,
I don't share your opinion about capacitive sensors. They sense any material including water. My 2 printers used this method and one have a pcb board and the other an aluminum bed, both with glass on top.
Repeatability: I test every 5 to 10 prints over 100 prints so far and not once my spacing between hotend and bed have been greater or smaller than 0.01 from the 0.1 I use. The difference between a 70 an a 110 degrees bed it's so small that doesn't require adjustment.
The only issue they have, and I'm willing to live with it is weight, they are heavy and they are not suitable for deltas or if your intentions are to print at really high speeds.
Re: Options for auto leveling? March 06, 2015 04:08PM |
Registered: 11 years ago Posts: 30 |
Apparently from the the graph on [m.machinedesign.com] a Photoelectric can sense Silicon, Plastic, Paper, Metal, etc... Wouldn't it be able to sense a acrylic bed if it was a color other then clear? Because it use a light transmitter to sense a object, and a receiver to catch the beam I think.Quote
dc42
I am both a physicist and an electronics engineer. I can assure you that a capacitive proximity sensor will not sense the surface of a glass bed, or any other good insulator. It can detect a conductive or semi-conductive plate under a glass bed. It can also detect the difference between glass and no glass between the sensor and the underlying conductive surface - but that is of no use for a height sensor. This is all basic physics. And yes it can detect water, because water is a relatively good conductor. I have used capacitive proximity sensors to measure water level. I have tried using one as a height sensing device for a 3D printer. It worked, but not consistently enough for my situation (3mm or 4mm glass on top of aluminium, with interchangeable glass plates and various coatings on the plates to hep the print adhere, temperature range 20C to 100C).
Bear mind that we are not just trying to detect whether the bed is close to the sensor. We are trying to get a trigger height that is reproducible to within 0.05mm over a range of temperature, humidity and bed coating.
It's also entirely possible to make a capacitive sensor that it light enough to use on a delta printer - the one I made for height sensing weighed only a few grams.
Re: Options for auto leveling? March 06, 2015 04:11PM |
Registered: 11 years ago Posts: 30 |
You're talking about this right? [www.openbeamusa.com] I have seen a bunch of variation of auto leveling on Delta bots.Quote
nophead
Capacitive sensors detect insulators at a different distance to conductors. If you have an insulator over a conductor it will trigger at a bigger distance than either on their own. So if you have glass over metal it responds partly to the proximity of the metal and partly to the thickness and proximity of the glass, not to the top surface of the glass as you would want.
Capacitive, inductive, hall effect, and optical are all analogue measurements compared with a threshold. They can be affected by supply voltage, temperature and stray fields.
My preferred solution is a pair of gold contacts, you don't get much more digital than that. Pulled together by a magnet, pushed apart by a rod and pushed further to latch in an up position held by the magnet. The only electronics requires is a digital input pin.
Re: Options for auto leveling? March 06, 2015 04:21PM |
Registered: 11 years ago Posts: 30 |
I wont be using a glass bed over the aluminum bed, if I do decided to go with the aluminum bed.Quote
nophead
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TheBoilingDumpling
Hmm, I'm not quite sure about that!Quote
ggherbaz
Capacitive proximity sensor instead of inductive, simple to set and will detect any material.
Capacitive will detect any conductive surface. It will also detect any insulator with a high relative permittivity compared to air but it responds to its bulk, not its surface. Both increase the capacitance of a single plate capacitor.
Re: Options for auto leveling? March 06, 2015 05:18PM |
Registered: 10 years ago Posts: 14,672 |
Quote
TheBoilingDumpling
Apparently from the the graph on [m.machinedesign.com] a Photoelectric can sense Silicon, Plastic, Paper, Metal, etc... Wouldn't it be able to sense a acrylic bed if it was a color other then clear? Because it use a light transmitter to sense a object, and a receiver to catch the beam I think.