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Removing Dolphin Tension Bars for 3d print righting coupling
http://www.hobie.com/au/en/forums/viewtopic.php?f=14&t=54611		 Page 1 of 1
Author:  paragon1970 [ Sat May 02, 2015 5:08 am ]
Post subject:  Removing Dolphin Tension Bars for 3d print righting coupling
Hi Folks,

I do not have access to my H16 at the moment to check what is required so thought I would ask here.

I wish to temporarily remove the tensioner bars that connect the front crossbeam and the dolphin striker.
Any Ideas what is involved, please?

The reason for doing so is to gain access to the dolphin striker (note do not wish to remove this) so as to slot the following (orange) item over it. See Pics
Incidentally this was printed on my 3d printer an Orion Delta as was the the over half that links to it (Blue)
This was the second print I have attempted but I think it cam out ok. The orange part is much better quality and stronger than the Blue part since I playing with slicing option and still learning about the printer software so I may reprint the blue part that connects to the pole.
The pole itself is an old boom I found laying around on the rubbish pile after a storm caused some damage at my sailing club.
This is kind of a universal joint for a righting pole system I am fabbing up.
In hindsight I should have split the orange dolphin striker component across the hole that dolphin striker goes through and then used four cap screws to mount it but thought this current incarnation would be a much stronger proposition.

Dolphin Striker Mount:
Image

Righting Pole Mount:
Image

And in case your are interested in the 3d printing aspect here is a link to a short video, apologies for the shaky camera :-)
https://youtu.be/51feYlP6hTI

Thanks Folks!
Author:  paragon1970 [ Sat May 02, 2015 7:11 am ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
Edited Subject Line.
Author:  MBounds [ Sun May 03, 2015 12:55 pm ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
Disassembling the dolphin striker enough to slip the orange piece over the post is a major production, that will probably entail removing at least one corner casting, the mast step and maybe both. Depending on how old the boat is, a lot of the parts could be corroded together, making it even more "fun."

I think you're better off running that orange piece through a band saw to split it in half and connecting it back together over the post with cap screws the way you mentioned (run a drill in a press through the hole to regain your clearance) - or just print another one that's split in half.
Author:  paragon1970 [ Mon May 04, 2015 2:38 am ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
Thanks for your reply Mbounds

I started to suspect that may be the case.
One of the issues I have is that the part is not solid but rather filled with a 30% infill honeycomb, this save on printing time as well as material usage, but drilling four holes will produce a thread that is not 100% in contact with the cap screws and thus may be too weak in operation causing the two parts of the clamp to separate.
I was thinking of drilling slightly oversized holes and filling with J-B Weld or epoxy steel and then re-drilling and tapping that.
The JB Weld should seep into the sidewall cavities of the drilled oversize hole allowing for a strong bond once cured.

I think this should work.
The alternative is to reprint but this part took around 10 hours to complete so would prefer to salvage.

The video link shows the honeycomb infill being printed.

Thanks
Author:  thehazards [ Fri May 29, 2015 6:51 am ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
Isnt 3D printed stuff really brittle and your's has a honeycomb centre too? If you stick a 1.7m lever arm on there and hang off the end with a bodyweight of 90 kilos, then the force moment applied to the part will be massive.

And you risk striking more dolphins with it in place!
Author:  Whatsisname [ Fri May 29, 2015 10:47 pm ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
That depends on what 3D printing process you use. Many of the commercial stratasys machines can print ABS, which can be as strong as you need it to be, provided you make your parts thick enough and align the layer stack normal to your major forces.

thehazards wrote:
Isnt 3D printed stuff really brittle and your's has a honeycomb centre too? If you stick a 1.7m lever arm on there and hang off the end with a bodyweight of 90 kilos, then the force moment applied to the part will be massive.

And you risk striking more dolphins with it in place!
Author:  paragon1970 [ Sat Jun 13, 2015 7:22 am ]
Post subject:  Re: Removing Dolphin Tension Bars for 3d print righting coup
Sorry Folks haven't been around for awhile.

As Whatsisname mentioned depends on the material.
In this case I employed a plastic called PLA (https://en.wikipedia.org/wiki/Polylactic_acid)
This is a thermal plastic that is extruded from a heated element on the printer.

One can tweak option for print quality including choosing infill shape and percentage and external layer depths.
By doing so one can make a very strong part indeed.
The parts produced here should be very strong in fact I would be more concerned about the ally tube I used (old spa) but to be honest there should be no issue with that.

Took a good few hours to print though ;-)
Part was printed on my newly arrived Orion Delta.
http://seemecnc.com/products/orion-delta-3d-printer
Hope that's ok to post that link, I have no other affiliation with this company other than owning this printer.
Its great to watch in action. Not quite as soothing as an open fire but memorizing all the same ;-)

Cheers.
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