Eulachon Mark II


#1

I've finally been able to dedicate a bit more time to ROV building, and it's been an exciting week.

I've got the electronics and pressure hull for the next version of my Eulachon ROV (which draws heavily from the OpenROV design) all wired up and working.

There's still some work to be done: I have to build a set of thrusters, but my magnet supplier (supermagnetman) has decided to stop selling one of the sets of magnets that I had planned on using, so I'm working out what to do next. Hopefully I can find someone else who sells magnets that are the right size.

Anyways, here's some build pictures:

Pressure hull, after some mill and lathe work:

Moving to something else for a while: Here's the camera, lights, and battery assembly, sans batteries. the white parts were printed on the Makerbot that my work just bought (which is pretty awesome to play with). This holds nine 18650 li-ion cells, wired into three batteries - so I get approx 12 volts, with roughly 9000 mAh. I have room to add an additional 6000 mAh inside the pressure hull, and if the final assembly is positively buoyant, I will probably do it. Unfortunately, I won't be able to confirm this until the thrusters are installed.


I'm a little concerned about glare from the lights, but my backup plan is to replace the Digitron with an Adafruit NeoPixel light ring (more on this later, if I decide that it's worth pursuing - I have to make sure that the NeoPixel works with the controller board, AND is bright enough)

Back to the pressure hull. I decided that a paint job was in order. Here, the pressure hull has been sandblasted and prepped for painting:


For the record, powder coating is like magic.


That finished up just as Techshop was closing, so I just had time to pull this out of the oven and hang it on the rack to cool before I left for the evening.

The next morning we can see the final results. I love the color, and a couple of stickers completes the look. Here, I'm ready to move all the innards into the pressure hull:


Everything assembled and ready to go!


The black spots you can see in the middle of the fins are "Subconn" connectors, which will allow quick attachment and removal of thrusters, so the whole thing can be packed into a small box, and still be assembled and deployed quickly.

Now it's time for an "in-water" test:


The final test: can we find Nessie?


Yes! Victory! No leakage detectable, which is always a plus. The pressure hull is slightly negatively buoyant in freshwater, so there'll probably be some adjustment of total mass and balance once the thrusters have been attached. It's likely that I'll tune it to be neutral in salt water and make a couple of floats that can be strapped on for freshwater use.

So there's the current state of affairs. It's likely to be a while before I get magnets for the thrusters - possibly up to 2 months, but hopefully I'll have something done before that.

Happy ROVing,

Ben


Additional Thruster option idea?
#2

Hi Ben:
Quite a nice work ¡¡
If you want any hydro-Static/Dynamic analisys, just ask. I’ll be glad helping you.
May be this link could be of your interest:

http://www.robotronica.com/joomla/

It’s said to be the best European robotics shop. May be they could supply your magnets.

Regards


#3

Ion,

If you are willing, I'd love to have someone with experience run an analysis. I've got some software that can do it, but no experience using it yet. What file formats can you use?

Also, thanks for the pointer to robotronica, I looked through there for a few minutes this morning, but didn't see any arc magnets listed - perhaps I'm not looking in the right place.

Thanks,

Ben


#4

For the lighting, you could add lights to the tips of the thrusters. That would remove and in tube glare, and it would move them outward from the camera move which will reduce the amount of backscatter.

I guess it would mean redesigning the thruster housing, which would be crazy at this point. heh.

Or you could retro-fit some little led flash lights to the side with velcro!

Your ROV looks amazing by the way. :D


#5

We should all consider an OpenROV conference to show off all the variations and payloads.

Nice work!


#6

An OpenROV conference!?! That's a great idea!


#7

I would totally be there.


#8

Have you tried http://www.magnetictech.com/prod_magcoup_coax_sae.htm for magnets

Dave Hinton


#9

Dave,

I talked with the Magnitech folks, and the one coupling they have that would fit in my thruster costs ~$250 in small quantities. Given that I'd need three of them, it's probably better that I keep looking for other options.

-Ben


#10

Correction: they have another part (MTD-0.2) that is about as strong as the MTC-01, is much cheaper, and at first blush, looks workable. I've ordered some of these for testing and will see how things go! Thanks for the tip, Dave!

-Ben


#11

Magnitech coupling are carried by McMaster-Carr and will supply any models that are not currently in thier catalog. I needed a larger size and they were able to get it for me. We potted them in our silicone resin for a food grade machine.

I have a source for custom made magnets (Tengam).

-Dan, Alumilite


#12

Dan,

That's good info to have. For the record, the McMaster PNs are: 9199T1 - 9199T4, and they are listed under "Shaft couplings", subsection "Noncontact Magnetic Set-Screw Shaft Couplings".

I did end up using the Magnetic Technologies units, and they seem to be just about perfect. My in-water test of the final unit got postponed, but hopefully I'll have more information soon!.

-Ben


#13

Hi Ben:

I've received an Email notification about a new comment from you, but cannot find it.