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Cherry Pi III Is Available

Posted by AndyCart 
Re: Cherry Pi III Is Available
April 11, 2015 02:23PM
Andy,

The sensor has a 4mm trigger distance, how do you ensure the 4mm between the hot end tip to the sensor? Also have you had to change the sensor offset in the firmware config?

Thanks

Matt
Re: Cherry Pi III Is Available
April 11, 2015 03:38PM
Quote
AndyCart
...

Hi Mike

The probe is from Ebay [www.ebay.co.uk]

It's the most accurate system I have used to date (microswitch in effector, microswitch with Allen key & FSR all tried previously) the inductive sensor gets the same reading from just two tries about 99% of the time.

No problem manually calibrating with the probe attached.

The only doubt I have about it is the added weight on the effector. Time will tell. So far so good.

Andy

I checked the page and apparently it weighs 46g, I am not sure how much that represents in relation to a complete print head.
Re: Cherry Pi III Is Available
April 11, 2015 04:18PM
Quote
Matt,Wheatley
Andy,

The sensor has a 4mm trigger distance, how do you ensure the 4mm between the hot end tip to the sensor? Also have you had to change the sensor offset in the firmware config?

Thanks

Matt

The sensor body is threaded along most of its length, and it comes with 2 nuts - you just set the hot-end nozzle to the desired height, then adjust the nuts until the sensor triggers at the right point (obviously a bit more fiddly than that, but it's the essence of the process).

You will find these adjuster wrenches very useful...

Edited 1 time(s). Last edit at 04/11/2015 04:20PM by David J.
Re: Cherry Pi III Is Available
April 11, 2015 04:26PM
Quote
Matt,Wheatley
Andy,

The sensor has a 4mm trigger distance, how do you ensure the 4mm between the hot end tip to the sensor? Also have you had to change the sensor offset in the firmware config?

Thanks

Matt

That's 4mm when approaching an iron or steel plate - it's less than 2mm for my aluminium heat-bed. Still perfectly usable though.
(Sorry - should have attached this to my last post... smiling smiley )

Edited 1 time(s). Last edit at 04/11/2015 04:27PM by David J.
Re: Cherry Pi III Is Available
April 11, 2015 04:37PM
So at less than 2mm is there enough clearance from the bottom of the probe to the print? I suppose with even 1mm you will be clear. Sounds like getting auto cal to run then moving the print height down with the paper test.

Thanks
Re: Cherry Pi III Is Available
April 11, 2015 05:06PM
On the circular MK3 heat beds that I use (3mm aluminium) the trigger distance is 2mm so these would be unsuitable for a machine with a glass bed. The glass would be too thick to allow it to trigger. The tip of the sensor misses the print ok but as its 32mm in front of the nozzle you need to be careful with bed fixings to avoid a crash. Ive ordered a couple to experiment with. It may be possible to remove the orange plastic tip and gain a few more mm. I'll keep you posted. I tried a piece of 1mm stainless steel and got a full 4mm distance with that so it may be possible to incorporate something similar under a 3mm glass bed but this would only leave 1mm of clearance. It would be great to find a similar size probe, or even a smaller one, that triggers at a greater distance but I can't find anything.
Re: Cherry Pi III Is Available
April 11, 2015 05:07PM
Yes - even if the extruded plastic rises a little bit after being deposited, it won't end up 2mm above the current layer - if it does, you have other problems to fix!

UPDATE: As Andy said - this is when printing onto an aluminium plate (maybe with kapton or PET tape on top, or blue painters' tape). It can't sense through a glass plate. I've often wondered how it would work if there was a steel plate under the glass...

Edited 1 time(s). Last edit at 04/11/2015 05:10PM by David J.
Re: Cherry Pi III Is Available
April 11, 2015 05:12PM
Quote
AndyCart
It would be great to find a similar size probe, or even a smaller one, that triggers at a greater distance but I can't find anything.

I have done some investigation in the past - the only sensors I've found with a greater range have either had much bigger bodies, or an awkward shape, or too heavy - or all three at once.

As for the probe being some distance away from the nozzle - on my Prusa I declared the 9 test points in Marlin so that I could be sure that the probe was always over the metal bed when it was doing each auto-levelling probe. I'm not sure if you can do the same in RC's version of Marlin?

Edited 2 time(s). Last edit at 04/11/2015 05:15PM by David J.
Re: Cherry Pi III Is Available
April 11, 2015 05:20PM
What connections do you use for probe and does it just connect straight to board like the old switch.
Re: Cherry Pi III Is Available
April 11, 2015 05:26PM
Quote
mrorange26
What connections do you use for probe and does it just connect straight to board like the old switch.

This may help: Tom on YouTube. He explains how to connect one of these up - you'll need 2 resistors and a soldering iron. 2 wires go to the existing end-stop pins on RAMPS (0v and signal) and the third goes to 12v. Not difficult to set up. He's talking about auto-levelling on a Cartesian printer like a Prusa, but the sensing part is just the same as Andy's describing.

Edited 1 time(s). Last edit at 04/11/2015 05:27PM by David J.
Re: Cherry Pi III Is Available
April 11, 2015 05:27PM
Ok thanks.
Re: Cherry Pi III Is Available
April 11, 2015 06:00PM
Quote
David J
Quote
AndyCart
It would be great to find a similar size probe, or even a smaller one, that triggers at a greater distance but I can't find anything.

I have done some investigation in the past - the only sensors I've found with a greater range have either had much bigger bodies, or an awkward shape, or too heavy - or all three at once.

As for the probe being some distance away from the nozzle - on my Prusa I declared the 9 test points in Marlin so that I could be sure that the probe was always over the metal bed when it was doing each auto-levelling probe. I'm not sure if you can do the same in RC's version of Marlin?

In Rich Cattell's fork of Marlin you can specify the distance between the probed points. The auto-calibration sequence (G30 A) probes 7 different points only.
Re: Cherry Pi III Is Available
April 14, 2015 12:51AM
I edited [forums.reprap.org] Pointys design to fit Open Builds V slot extrusions and fit a 10mm ball bearing.

The design has a nice cable tightener also a little more build space
Link -> [www.thingiverse.com]


Hope this helps some one building a Cherry PI from the USA
Re: Cherry Pi III Is Available
April 14, 2015 02:50PM
Just updated my firmware to Update v1.04 RichCattell and now my lcd just lights up and lots of squares where the numbers and letters go.Is it a setting in config h I have to change.
Re: Cherry Pi III Is Available
April 14, 2015 04:17PM
Sorted it had to pick right lcd in config h file.
Re: Cherry Pi III Is Available
April 15, 2015 06:46AM
Whoopie! My round aluminium heated bed has arrived from China.

It doesn't seem right to just sit it on the base's extrusions - should I put it on something non-conducting? I have some 2mm thick cork sheet, so I could use strips of that, couldn't I?

Opinions?

David
Re: Cherry Pi III Is Available
April 15, 2015 07:12AM
#David

I cut out a cork sheet and glued it to the underside of my aluminium bed, it helps keep the heat from going down. It also stops you transferring some heat to the frame.
Re: Cherry Pi III Is Available
April 15, 2015 07:21AM
Matt,

What sort of thickness was your cork?
Re: Cherry Pi III Is Available
April 15, 2015 07:25AM
David,

I'm using 4mm cork.
Re: Cherry Pi III Is Available
April 15, 2015 07:27AM
Thanks!
Re: Cherry Pi III Is Available
April 15, 2015 10:28AM
I'm supporting my round aluminium heated bed on 3 standoff pillars screwed in to the horizontal extrusion. These provide firm support without conducting much heat away. They also provide more room to fit put insulation underneath the bed, which I need in order to keep the heat away from the PSU and SSR that are mounted in the base.

Edited 1 time(s). Last edit at 04/15/2015 10:28AM by dc42.



Large delta printer [miscsolutions.wordpress.com], Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Cherry Pi III Is Available
April 15, 2015 10:58AM
I use 6 printed standoffs on mine (printed in ABS) and this works very well.





I can post the STL files if anyone wants them but these are done for a 400mm diam 5mm thick Plate.

Doug
Re: Cherry Pi III Is Available
April 15, 2015 11:11AM
Doug,

I was wondering about designing something like that... they would also provide a bit of an air gap to help with the excess under-bed heat. I'll have to have a think! winking smiley
Re: Cherry Pi III Is Available
April 15, 2015 11:16AM
A question for Andy: I've just received a heated ali bed that is the same as the one you recommended a while ago. Surprisingly it came with a thermistor on a length of cable - did yours come with one as well, and have you worked out what sort it is?

I'm guessing that it's the usual generic EPCOS-style 100Kohm job, but there's no way to tell unless I measure its resistance at various temperatures and see which table it matches!

Edited 1 time(s). Last edit at 04/15/2015 11:43AM by David J.
Re: Cherry Pi III Is Available
April 15, 2015 11:51AM
Quote
David J
A question for Andy: I've just received a heated ali bed that is the same as the one you recommended a while ago. Surprisingly it came with a thermistor on a length of cable - did yours come with one as well, and have you worked out what sort it is?

I'm guessing that it's the usual generic EPCOS-style 100Kohm job, but there's no way to tell unless I measure its resistance at various temperatures and see which table it matches!

David

Most if not all the Chinese supplied Thermistors have a 25/50 Beta value of 3950 which is not the same as the Epcos ones.

as for air gap under the bed to release excess heat I intend to stuff the underside of mine with Fibre roof insulation (I have a ally plate attached to the underside of the lower extrusion's and all my Electronics/PSU etc is under that plate) I think the advantage in doing it this way will

A. speed up the bed heating time (Not that 4 mins to reach 115 deg is slow)
B. mean less heat to get down to the electronics/motors which is my main concern.

Doug
Re: Cherry Pi III Is Available
April 15, 2015 12:07PM
Doug,

I have an EPCOS thermistor - I might use that instead of the Chinese one, as at least I'll be certain about which identity to use in Marlin.

As for the heatbed - I think I've got some heat-proof board in the garage, so I might make a platform under the bed. This will make mounting straightforward and provide good insulation underneath. It's also dimensionally quite good, so shouldn't put the bed on a tilt.
Re: Cherry Pi III Is Available
April 15, 2015 12:14PM
Quote
David J
Doug,

I have an EPCOS thermistor - I might use that instead of the Chinese one, as at least I'll be certain about which identity to use in Marlin.

Sounds like the best bet (Or get some Semitec ones from E3D-Online they deliver in a couple of days and they work type 5 in Marlin and 8 in Repetier)

Quote
David J
As for the heatbed - I think I've got some heat-proof board in the garage, so I might make a platform under the bed. This will make mounting straightforward and provide good insulation underneath. It's also dimensionally quite good, so shouldn't put the bed on a tilt.

Anything to insulate the bottom of the heatbed is a good thing in My opinion (Some have used radiator reflector pads but be careful with them that you don't run the bed to hot else they can melt the polystyrene).

My PiXL is getting very close now just need to wire up my Z Probe from DC42 kapton my glass plates do an auto calibrate and test print with it (getting time to do all this is the issue at the moment SWMBO keeps getting in the way as well as the day job lol)

Dougmoody smiley
Re: Cherry Pi III Is Available
April 15, 2015 12:37PM
My heated bed didn't come with a thermistor. I used a spare 100K item I had. I've designed a mount that I printed in ABS. I use a bit of 3mm cork between the mount and the bed and counter sunk M3 screws to secure the bed down. There is a nut trap in the mount. My bed is 220mm in diameter and has six holes drilled around the perimeter. I countersunk 3 of them to allow the mounting screws to be flush with the surface of the bed. This gives clearance to the inductive probe.



This is the link to the .stl on Thingiverse (it's too big to attach here)

[www.thingiverse.com]

Andy

Edited 1 time(s). Last edit at 04/15/2015 12:39PM by AndyCart.
Re: Cherry Pi III Is Available
April 15, 2015 12:40PM
Quote
dougal1957

Anything to insulate the bottom of the heatbed is a good thing in My opinion (Some have used radiator reflector pads but be careful with them that you don't run the bed to hot else they can melt the polystyrene).

My PiXL is getting very close now just need to wire up my Z Probe from DC42 kapton my glass plates do an auto calibrate and test print with it (getting time to do all this is the issue at the moment SWMBO keeps getting in the way as well as the day job lol)

I've heard of people using MDF under a heatbed - it's usually even in thickness. I don't know if it would cope with 110C - 120C though. The advantage of a board under the bed is that I will be able to run a fan or two to cool the RAMPS board without chilling the heatbed from underneath.

Any more details on the Z probe? Sounds intriguing! smiling smiley

As for finding time - I'm retired, and my wife is pretty cool about my weird hobbies! smiling smiley Still don't find time to do anything though...

David
Re: Cherry Pi III Is Available
April 15, 2015 12:58PM
Andy, thanks for those bed clips. You've been busy!

(I'm now torn between these and a backing board... winking smiley )

David
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