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New Sensor Idea

Posted by Mickyblueeyes 
New Sensor Idea
February 07, 2014 04:51AM
I am putting this idea out there because I think its possible to print most of the parts required and modify ormerods existing parts to accommodate it.

As far as I can see there are still a few drawbacks to the existing arrangement in particular:-

Affected by ambient light
Affected by the table material and reflectivity
Needs to be placed only where the foil is present

My idea is to create a lever or moving part one end is presented to the IR sensor, the other end of the lever is used to probe the table and depending on the ratio can be used to amplify the distance to the table, this provides a more accurate reading and because the sensor is reading the same lever end in any table positions it will be consistent.

Other advantages are that it can be shrouded to keep out ambient light and it can probe anywhere on the table without need for foil.

The major problem is being able to retract the lever when you want to print, one idea I had was to make a similar action to a retractable biro such that when it is returned to the x axis it either stows or releases the lever, the sensor can then be checked to see which position it is in.

The lever action will unfortunately invert the signal produced by the sensor so either a hardware or software change will be needed to use it.

This is only the outline of an idea and I'm sure better minds than mine can either find a way to create / improve it or provide a better solution.

Thanks

Mike
Re: New Sensor Idea
February 07, 2014 05:14AM
Well since we are putting ideas out there... here's mine smiling smiley

I would love to try adding a piece of foil under the ducts. That is one plate of a capacitor. The other is the aluminium sheet on the bed. Then it becomes just a problem of measuring the capacitance ...

regards
Andy


Ormerod #318
www.zoomworks.org - Free and Open Source Stuff smiling smiley
Re: New Sensor Idea
February 07, 2014 05:26AM
Hi Kwikius, yes that could work, but I wonder what the possibilities of having 2 plates on the ducts and using the metal plate under the bed to just proved capacitive coupling between them, that way the sensor would be self contained attached to the hot end.

regards

Mike
Re: New Sensor Idea
February 07, 2014 05:39AM
Quote
Mickyblueeyes
Hi Kwikius, yes that could work, but I wonder what the possibilities of having 2 plates on the ducts and using the metal plate under the bed to just proved capacitive coupling between them, that way the sensor would be self contained attached to the hot end.

regards

Mike

Sounds good. The only problem is actually implementing it. I've got too much on my plate at the moment (So should probably be getting on with work rather than be on here smiling smiley )

regards
Andy


Ormerod #318
www.zoomworks.org - Free and Open Source Stuff smiling smiley
Re: New Sensor Idea
February 07, 2014 05:49AM
Another solution I was looking at is to integrate a force sensor into the part of the x-carriage that supports the 9mm or 10mm x-runner bearing. As the print head is lowered, it touches the bed, which takes some of the weight, therefore the sideways force on the bearing is reduced, which is detected by the force sensor. Then the head itself can be used to probe the bed at any point. It would be necessary to remove any residual plastic from the outside of the nozzle first.

I have a FSR400 force sensitive resistor (http://www.steadlands.com/data/interlink/fsrdatasheet.pdf), so if anyone would care to design a modified x-carriage to accommodate it, I'll give it a try.

Edited 1 time(s). Last edit at 02/07/2014 05:49AM by dc42.

Ormerod hot end board with differential modulated IR Z-sensor, fan control and lighting: [miscsolutions.wordpress.com]

Ormerod dual nozzle conversion howto: [miscsolutions.wordpress.com]

Tools and services for developing mathematically-verified critical embedded software: [www.eschertech.com]
Re: New Sensor Idea
February 07, 2014 06:14AM
Me Too Kwikius, I dread to think what the cost would be if I added up the hours I have already spent modifying the printer and checking the forum. I guess its a good job I married the company secretary LOL
But seriously I could have bought a high spec ready made model and saved money but the experience gained by going through this process is worth it.


@ dc42 I have seen your thread elsewhere regarding the strain guage on the printer x axis, it would work apart from the clogged nozzle problem, maybe we need a built in nozzle cleaning station and g codes to run it, something like the brass wool things used to clean soldering irons.

Regards

Mike
Re: New Sensor Idea
February 07, 2014 07:07AM
Quote
Mickyblueeyes
@ dc42 I have seen your thread elsewhere regarding the strain guage on the printer x axis, it would work apart from the clogged nozzle problem, maybe we need a built in nozzle cleaning station and g codes to run it, something like the brass wool things used to clean soldering irons.

Or just heat the nozzle to 180C, retract the filament, and wipe the head either on a designated corner of the bed or on a pad at the start of the x-axis.


Ormerod hot end board with differential modulated IR Z-sensor, fan control and lighting: [miscsolutions.wordpress.com]

Ormerod dual nozzle conversion howto: [miscsolutions.wordpress.com]

Tools and services for developing mathematically-verified critical embedded software: [www.eschertech.com]
Re: New Sensor Idea
February 07, 2014 08:41AM
@dc42 - i'm working on an x-carriage mod for this sensor, i also thought about trying a modified nozzle-mount to take the pressure sensor also, i'll do both and we can see what function best.

I like the idea of a nozzle wipe routine also =)

Matt


Owner of RS Ormerod #144 - now Custom Blumerod
Creator of the New Ormerod Web Interface - [github.com]
iamburnys Ormerod Upgrades Github
Re: New Sensor Idea
February 07, 2014 11:30AM
Hi Guys,

See attached, initial first (dirty) concept of x-carriage mod to accept an FSR 400 - force sensing resistor, i have successfully printed a 10mm slice of this modded x carriage, i'm still unsure if its going to be function as planned.

github STL viewer

Thoughts?

Matt


Owner of RS Ormerod #144 - now Custom Blumerod
Creator of the New Ormerod Web Interface - [github.com]
iamburnys Ormerod Upgrades Github
Attachments:
open | download - x-carriage-v3.stl (460 KB)
Re: New Sensor Idea
February 07, 2014 11:39AM
Looks interesting. However it will be necessary to get the slot width exactly right, because the FSR will be compressed by being in the slot, and the compression will be alleviated by the force applied by the weight of the print head. I imagine it may be rather temperature sensitive. I would prefer to put the FSR in a slot on the other side of the bearing. That way, the FSR can be a loose fit in the slot, but (with careful design) will have to support almost the full sideways force on the bearing caused by the weight of the head.


Ormerod hot end board with differential modulated IR Z-sensor, fan control and lighting: [miscsolutions.wordpress.com]

Ormerod dual nozzle conversion howto: [miscsolutions.wordpress.com]

Tools and services for developing mathematically-verified critical embedded software: [www.eschertech.com]
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