Gina's Observatory Roll-Off-Roof Automation

[Gina]

The print was adequate for purpose if not very pretty.

Here are some photos of the rain detector fastened in place.  I have yet to secure the cable.

[Rusted]

Baking paper as backing paper. To avoid adhesion.
Being a layer deposition system, presumably the base is vitally important to topological accuracy.
So baking paper probably isn't flat enough to avoid humps and hollows.
It still seem logical, to me at least, that a cheap, sacrificial base layer is used each time.
Or at least a base which is tough enough to allow repeated mechanical separation of the printed component.
I am probably talking nonsense, as usual, because I haven't really studied the subject of 3D printing.
Just reading between the lines.

[Gina]

Adhesion to the print bed is totally necessary otherwise the print would move about or fall over if tall.  With a warm bed and print the print will usually stick to a glass plate or various things applied to the glass.  As the bed and print cools the adhesion should break and the print be released.  HTH

[Rusted]

Understood. It was a good job you didn't rush out and buy a job lot of baking paper!

[Gina]

I have a roll of it in the kitchen cupboard.

[Dr_Ju_ju]

6 hours ago, Rusted said:

I am probably talking nonsense, as usual, because I haven't really studied the subject of 3D printing.
Just reading between the lines.

Beware, if you start getting into it, it has a habit of taking over a large part of your life, especially if the skies are overcast.....  

[Gina]

Oh yes indeed!  Great fun though and very useful.

[Gina]

Regarding PEI sheet :-  I'm having considerable trouble getting PETG to stick to this and think I shall end up pulling it off again!!  Maybe it needs a higher bed temperature, I'll try increasing it.

[Dr_Ju_ju]

On my Prusa, I use:

                     First layer       remainder

Extruder        240                250

Bed               85                  90

Fan               30%               50%

 

hope you can decode the values.... 

[tekkydave]

For PETG I generally use 250C extruder and 80C bed. No cooling fan except for bridges. I was under the impression that cooling was not good for PETG.

Also dont 'squish' the first layer too much like you would with PLA.

[Gina]

Well...  it took a lot of fiddling to get PETG to stick to the PEI sheet.  Got that sorted out earlier and left it to cool while I went out this afternoon.  Now it's stuck firm!!

Just tried to get the print off with a strong pair of pliers and broke the print rather than getting it off the PEI!!  There seems to be just one way of getting the print off the bed and that's with the PEI sheet as well.

Edited August 21, 2019 by Gina

[Gina]

Levered the print off the glass plate and it's taken some of the PEI with it!  So that's it.

[Gina]

Got the PEI sheet off the glass and now I'm left with a horrible sticky mess - any suggestions??

[Gina]

Guess I should order a new borosilicate glass plate...

[redtail]

Hi i have the same rain sensor and it does not work unless you have a plate etc for rain to run off onto the sensor as it needs some pollutant to activate. https://www.rapidonline.com/Kemo-M152-12V-Rain-Detector-Sensor-Relay-Module-Pre-Assembled-55-2385?IncVat=1&pdg=pla-294357559827:kwd-294357559827:cmp-757438067:adg-44804851896:crv-207912323492:pid-55-2385:dev-c&gclid=EAIaIQobChMI5LO9wr2U5AIVQ7DtCh3P-gLzEAQYBCABEgKE2fD_BwE read the bottom line of text.

Edited August 21, 2019 by redtail

[Dr_Ju_ju]

Paint brush cleaner, white spirit, IPA, will all remove the adhesive.....

[Gina]

Tried IPA - didn't touch it.  Tried acetone - yes seemed to dissolve it but only made it even stickier.  A soak in a bath of acetone might work but that much acetone would probably cost more than a new sheet of glass.  Haven't tried white spirit - will do.

[Gina]

IPA did gradually loosen the adhesive and I was able to scrape some of it away from the glass with the end of a steel rule.  That wasn't the end of it though, it was still hellish sticky and stuck to everything in sight.  I ended up taking the heater pad off the glass and taking the latter out to the kitchen sink where further application of IPA plus water and detergent enabled me to scrape off the glue.  More detergent, hot water and a good wash both sides followed by rinsing in cold water and drying with clean paper towel and I have a clean glass plate again.  I have now put everything back and about to try a print.

Edited August 21, 2019 by Gina
typos

[Gina]

Printing on my Concorde printer is now back to normal with a clear, unadulterated borosilicate glass plate. 

[Bukko]

Hi Gina,

Not sure exactly what adhesive you are trying to remove, but this stuff is pretty good... WOrks well on the sticky lables shops insist on using too.

https://www.amazon.co.uk/STUK-Professional-ASSR200R-Remover-Aerosol/dp/B0071QNB70/ref=pd_day0_hl_60_1/260-5209561-1635909?_encoding=UTF8&pd_rd_i=B0071QNB70&pd_rd_r=0c46efa7-9186-4d7b-aaf5-3ec4f5f01e54&pd_rd_w=EffSr&pd_rd_wg=9KUWU&pf_rd_p=92d624bb-a334-423e-8722-8024dd09667f&pf_rd_r=V2VGN83SR3G2HRQH2WNE&psc=1&refRID=V2VGN83SR3G2HRQH2WNE

(other suppliers are available !!)

Gordon.

 

[Gina]

That looks good - thank you.  I have already removed the adhesive now though.  Worth getting anyway, I think, for other times the dreaded sticky stuff needs removing.

[Gina]

I've ordered some digital panel ammeters and voltmeter for a new power distribution box.  I already have fuses and switches.

Meanwhile, I've disconnected the current box and brought it indoors for servicing.

Edited August 24, 2019 by Gina

[Gina]

I think I may have a little problem with having a separate digital ammeter for each load from the power distribution box.  My observatory wiring has one common earth or Ground connection with a heavy duty cable going from a copper earth rod, to the pier head where the mount and imaging rig supplies are earthed/grounded.  From there it goes through the cable duct with other cables (the supplies to the mount and imaging rig) to the warm room and the power distribution box.  Separate twin cables will feed the all sky camera and ROR motor control unit.  Like the mount and imaging rig, I was planning to use a common Gnd for the other loads.

Now to the problem :-  The digital ammeters need a voltage source as well as the series current measuring resistance (shunt).  No problem you say - connect +ve to the main +ve supply and the -ve to Gnd - but no the negatives are common on the ammeter circuit board as shown below in this circuit diagram of my current power distribution box.

 

[Gina]

This is what I would like to have.  A main ammeter to show the total current and individual ones to show the current taken by mount, imaging rig, ASC and ROR control individually.  The individual digital ammeters would need a supply several volts above the 13.8v main supply if the current shunts are in the +ve rails.  I could use a buck converter to provide a 24v supply, I guess, but this seems ridiculous.  I could put the shunt in the -ve line for the ASC and ROR Control as these are totally separate but the mount and imaging rig share a Gnd line via USB.

[Gina]

This shows one digital ammeter expanded to show the extra supply.