Specific Gravity probe

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Captain Starfish
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Specific Gravity probe

Post by Captain Starfish »

Not a rocket...

Image

This is the application which prompted my purchase of the Max in the first place, kinda excited to get to print it at last. Essentially fluid passes in the port visible at the base (it's upside down), down one side of the cylinder which is partitioned into halves, up the other side and out another port opposite the visible one.

In the partition are tubes for sampling pressure and temperature at the base of the column.

Idea is that static head changes with specific gravity and, by measuring that pressure, I can work out the SG of the fluid going through. Think beer, wine and spirits here and you're on the right track.

The rocket fins? Well, you tell me if it's overkill, but I figured that with a tube 20mm wide and 200mm high there was a good chance that the leverage would make it way too easy for the print head to topple it at the top end. So they're stabilisers which I'll cut off at the end of the run. The print is about 2/3 on its way to final height in the photo.

I have some challenges ahead, namely how to vapour wash the inside of the tube effectively and get it all nice and slick for fluid to pass through (without leaking between layers). But this was just going to be wayyyy too hard to machine using traditional methods.

neurascenic
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Re: Specific Gravity probe

Post by neurascenic »

Just posted this on another thread.

Not sure if the stuff itself is food safe, but I suppose you could discard the little bit that you test.

Watch the video

http://www.neverwet.com


It comes in spray form, so the challenge then is how to apply it.
I am a fool entrapped within my own wisdom.

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Captain Starfish
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Re: Specific Gravity probe

Post by Captain Starfish »

Hah, nice!

One of the reasons I chose ABS is it's safe for what's going through it, I think (hope) the acetone vapour bath or wash if that doesn't work will take care of smoothing the surface and tightening up the porosity of the build enough to let it hold water. So to speak :)

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Batteau62
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Re: Specific Gravity probe

Post by Batteau62 »

"Think beer, wine and spirits here and you're on the right track."
Oh yeah! my kinda thinking! Having said that I did a little research in this area. Unless you can make a surface "porosity" free, you will always take the chance of bacteria in the nooks and crannies. PLA is recommended for food(drink :D )rather than ABS, but again-"nooks and crannies" :( http://reprage.com/post/36869678168/is- ... food-safe/
The fix is using fired ceramic with non-toxic glaze, so easy peasy, set your Max up to print ceramics :lol: ...could be a fun mod. Seriously though, depending on how often you use your probe? You could make it a one time use-recycle it-print another one :)
Best of luck on the fementation! ;)
-"Simpler is better, except when complicated looks really cool."
-"As soon as you make something fool proof...along comes an idiot."
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Eaglezsoar
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Re: Specific Gravity probe

Post by Eaglezsoar »

If you make your moonshine strong enough those little buggers wouldn't stand a chance trying to hide in the nooks and crannies.
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Captain Starfish
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Re: Specific Gravity probe

Post by Captain Starfish »

Damn, that will teach me to photo mid-build.

Was watching telly as it did its thing and noticed everything had gone quiet. Finished! Came in to have a look and found the print stopped with about 100 layers (of 1343) to go. DAMN! The steppers had all relaxed, too, just dropping the hotend where it last worked and allowed it to melt a blob into the end of the piece.

What what what? So close and it just gave up? Nothing in the log, all looked fine on the LCD, just nothing doing.

The droopy head reminds me of petty annoyance #13 - in Gene's build instructions the cheapskate tensioning was set so the carriages gently dropped down the rails under their own weight. Add the weight of the head and arms and now the whole lot creeps down when the steppers are powered down. And this happens annoyingly often during bed heatup. Presumably it's an inactivity timeout on the stepper controls but it would be nice if the thing stayed up out of the way.

Is the simplest answer (tighten up the carriages) the best here?

Lol @moonshine. Sadly it's ill eagle to make at home here in Oz. Doesn't stop a few mates from trying.

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Captain Starfish
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Re: Specific Gravity probe

Post by Captain Starfish »

Awww, nuts.

A day's printing and it's scrap :( Just tried to run one of the probes through the tubes and they are a millimetre narrower in the print than they were in the CAD drawing. The external measurements are all fine, but the internals of the main tube AND the sensor tubes are about 0.5mm radius too small, ie the wall thickness has blown out by 0.5mm.

:(

Ah well, I guess I have a dummy piece to play with surface finishing etc on and I don't have to worry about stuffing it up.

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foshon
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Re: Specific Gravity probe

Post by foshon »

Is this an alternative to a hydrometer?
Purple = sarcasm

Please do a board search before posting your question, many have been answered with very time consuming detail already.

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Captain Starfish
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Re: Specific Gravity probe

Post by Captain Starfish »

Not until I can get this wall thickness calibration sorted out it isn't :)

But yes, when it's done the idea is it will replace the hydrometer which needs me to take samples every now and then with a continuous flow monitor.

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