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RC Benchy

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ddmckee54:
Some time ago I stumbled across the fiies for an RC Benchy on Thingiverse.  Anybody who's into 3D printing knows what a Benchy is, it's a smallish, 2"-3" long, old-timey tugboat that is used to benchmark how well your printer performs - hence the name Benchy.  Also included was a video of the boat in operation with one of the Mario brothers as the captain.  After I quit laughing I decided that I gotta print me one of these.  I'd REALLY like to get the file to print Mario or Luigi to use as the captain, but I haven't found anything suitable yet, and I'm not that much of an arteest.

This sucker is JUST a little bit bigger than its' little brother and needs to be printed in multiple parts.  I haven't got it put together yet so I'm not really sure how big it will be, but it's looking like it will be close to, if not over 20" long, and at least 6" wide.  it will print on a 200x200x200mm printer, but the hull is printed in 4 pieces to do that.  I've got MOST of the big parts printed.  The aft portion of the hull finished printing this morning, that was probably close to a 30 hour print.  Most of the rest of the parts are for the cabin and shouldn't take nearly as long to print since they aren't THAT tall.

Reading through the comments written about the Benchy I found that it tends to want to roll in a turn.  One of the upgrades is a set of "fins" that are glued on to form bilge keels.  I drew up my own bilge keels and extended them into the hull where I could strengthen the joint.  I decided to see if I could print them at the same time that I printed that part of the hull - didn't work out to well.  I tried slicing the two STL files at the same time and the slicer didn't know how to handle that.  I thought it would try to double print where the parts intersected.  Nope, it left air where the parts intersected.  I had the hull, and 2 barely connected separate parts of the bilge keel on each side.  They snapped off easier than most support does.  At least it'll give me nice openings in the hull to insert the bilge keels I printed to correct that little issue.

When I was discussing this project with one of the other engineers I work with, he christened it the "Dreadnought Benchy".  I MAY just have to arm this thing.  It looks like something out of a cartoon anyway, why can't it have a couple of turrets with big guns to defend itself?

No pictures yet, maybe tomorrow?

Don

JamesC:
If I need to work on STLs I import them into Tinkercad.  You can join them together and then export as a single STL

ddmckee54:
The first time I tried it, that is what I thought I had done in my 3D CAD software, it did the same thing when printed.  So I tried something a little bit different this time, but still got the same result.  I know that's awfully close to the definition of insanity, but what can I say?
 
The attachment is a group shot of almost all the stuff I've got printed so far.  There's an empty 12oz can included for a size reference.  I say almost all because I KNOW there's one more part someplace.   I remember stepping on the little sucker in my stocking feet - don't remember where it went after that though.

I was off in my size estimate.  This Benchy will be about 15-16" long, and it's about 7-1/2" wide.  From the STL files you can decide if you want to build the fishing boat version, or the tugboat version.   I'm seriously considering building Option 3 - the Heavily Armed Tugboat version - The S.S. Dreadnought Benchy.

I started another part on the printer last night, the bottom of the cabin for the tug version.  The part on the printer was about half done when I left for work this morning.  It'll either be done and waiting for me when I get home, or I'll have a mess to clean up when I get home.

Don

ddmckee54:
Well, it was done when I got home, just one little problem...  IT DIDN'T FIT!!! It was too small and wouldn't fit over the deck opening.  It was a 15 hour print and I apparently didn't scale the part to allow for shrinkage.  I tried printing new deck parts to match, but they were too small for the hull.  Oh well, nothing for it but to re-print the lower cabin - properly scaled this time.

I started fitting the parts together and the attachment is is what I've got.
 

The more I looked at it, and the fit of that blue hull part, the more I didn't like it.  That's the second time I printed that part and I got a layer shift both times at about the same height both times.  Also both times I printed the part, one side had started to lift off the print bed.  I started printing it for the 3rd time about 5:00 yesterday afternoon, it should be getting done about the time I get home from work.  This time I added some support, and a brim to keep it attached to the print bed.  When it started printing I saw that I wasn't getting good adhesion in the area that let go on the other 2 prints.  I canceled the print and got out the glue stick.  That seems to have done the trick, I'll find out for sure when I get home.

Don

ddmckee54:
The reprinted hull section printed with the brim and the support worked perfectly.  When I printed the blue hull section it has peeled loose from the build plate in same spot, at the portside railing.  You could see a gap between the part and the build plate for about 25-30mm down from the railing.  As the part was printing I would hear a ticking sound periodically.  It was printing an overhang, and the overhang was shrinking and curling up as it cooled.  This was at about the height where the layer shift occurred.  My theory was that the printhead hitting this curled up plastic made the ticking sound, and eventually caused the printer to lose steps, giving me the layer shift.  Along with the layer shift, the bow curve was definitely not a smooth curve .

I reprinted this part, for the third time, only this time I added a brim to keep the part stuck down to the build plate.  I also had concerns about the unsupported side of the part wanting to pull inwards as they cooled, this was a 25 hour print after all.  So I supported the sides in several places.  The part would print without support, that's how both of the blue parts were printed, they only took about 18 hours.  If I had used all of the automatically generated support it would have been a 33-34 hour print.  Anyway the brim and support worked and the part fits about as well as you can expect from an FDM printer.

Over the last few nights, I've designed the fore and aft gun turrets, barrels and turret mounts.  My PLA glue is arriving today, I think, so I can actually start gluing this thing together.  I'll get some more pictures then.

Don

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