RC Benchy

[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

[ddmckee54]

No PLA solvent glue, my sample of COEX Green Bay yellow got here instead.  The PLA glue is actually Weld-on #4 and does pretty fair job of solvent bonding PLA.  The last time I used it though, it bleached the color out of the red filament I was using it on, we'll see what happens this time.

I got done redesigning the turret and its' internal parts last night.  I also designed both the fore and aft the turret pivots.  I grouped them all together and started them printing.  S3D says it's a 19 hour print.  That print should be done an hour or 2 before I get home tonight.  It's not the parts themselves that take so long to print, it's the support.  The hull parts that I printed a couple of days ago would have only taken about 2/3 the time they actually took if I hadn't used support.

Don

[ddmckee54]

Friday night when I got home, my Weldon #4 order was waiting in my mailbox.  So Benchy is starting to come together - literally.  Benchy's hull is now in one piece, it's not water-tight yet, but it's in one piece.

As you can see in the picture, Benchy had his V8, and in the process he grew some TEETH.
 
The turret's kind of like a cartoon version of the deck gun on a USN destroyer, that or a cartoon Imperial Scout Walker.  Either description would be appropriate.

There's a WHOLE lot of sanding to be done to smooth out the layer lines to get the hull ready for paint.  And almost every other printed part as far as that goes.

Don

[ddmckee54]

I talked to the Captain last night and he informed me that because of the height of that damned bow railing, the forward turret can't depress as far as it should be able to.  This leaves us dangerously exposed to a frontal attack by a small craft.  He recommended a Close In Weapon System placed up high, maybe on top of the pilot house.  I told him I'd take it under consideration. 

Hmmm... Maybe it's time to dieselize Benchy.  The CWIS could replace the smokestack, and I'll add a couple of exhaust stacks on the corners of the pilot-house - beside the rear turret.  (Twin turbos on the diesel dontchaknow.)  Then I could add that diesel sound system that I've got.


Don

[ddmckee54]

I made some progress on Benchy in the last week.  But if I showed you a picture you'd think just the opposite, since he's almost completely disassembled.  The hull is sanded and sealed, I've got 3 coats of semi-gloss varnish on it so far.  Even thought it's plastic, there are still pinholes in the surface, I discovered that while wet-sanding the hull. 

There were several spots where I could dry the area off, and when I checked those areas a couple of minutes later they would be darker, like water was seeping onto them.  I decided to just varnish the hull to seal it.  For a while I was debating whether I should fiberglass the hull, or just give it a sealing coat of epoxy.  Since I don't have the materials to do either of those options, I went with varnish which I do have.

I've been trying to find a suitable figure to place at the helm.  Where I work they think I should use Cap'n Crunch, but they might be just a little biased.  I couldn't find any Cap'n Crunch STL files, but I could find an 11cm tall Mario, and a Luigi, about the same size.  I downloaded the files for Mario last night, all 35 of them.  It's designed to be printed using the correct color filament for that part.  That's makes Mario look more realistic, but I'm pretty sure a realistic Mario is an oxymoron.

I don't have any pink or brown filament, and I'm not going to buy a roll just for this one print.  I'll print everything in one color and paint the parts the correct color.  I printed out some of Mario's major parts at 100% to see if he needed to be scaled.  I'm pretty sure he'll need to be scaled up to 110%-120%, maybe more to look right when he's at the wheel.  I'm going to print out the neck, the shoes, and the hat, then glue him together - to get a better idea about the scaling.

Don

[tom osselton]

Well there is always Steamboat Willie.
 

[ddmckee54]

Take a look at this and see what you think, has Benchy got a Cap'n?   (I think so.)
 

Here's a slightly blurry side view.
 

 

I printed Mario out at 100% and stuck him in the wheel-house, he was just too small.  I reprinted this version at 120%, which I think looks a LOT more better.  I think he's going to have to go under the knife and have a little surgery on his right arm though.  To make it look more like he's holding the wheel, and less like he's just standing there like a Dork.

Benchey got several other modifications.  He got his Close In Weapon System, his smoke-stack was modified to be a radome, and he got his diesel exhaust stacks.  I originally had a really neat set of barrels designed for what was supposed to be a Mini-gun.  I took one look at the printed version, realized that they were WAY TOO SMALL, and said - "Nope, not gonna happen."  The Mini-gun then got replaced with the chain-gun seen in the picture.  As you can see this is not just a Close In Weapon System, it's a REALLY Close In Weapon System.  In fact it could be used to pick-off the seagulls and keep them from crapping on top of the turret.  I've got some seagull figurines on order to set up just such a scene.

I've got to get some more hardware, motor, ESC, prop, bearings, prop-shaft, rudder-post, and all the other Bit's and Bob needed to make a functional boat - that I haven't already got stashed away somewhere.

Then Benchy will be almost ready for the test pond, and his weights and balance testing.  Painting will be done after that.

Don

[ddmckee54]

Just did that.

[ddmckee54]

Mario is out of surgery and recovering nicely.  His time spent under the knife wasn't too drastic.  I just bent his arm a little, and twisted it a bit.  Just enough so that he doesn't look quite so much like he's the Fonz going Heyyyyyyy.  I'll get a little filler on his arm, enough to cover the scar and give him a bit of an elbow.

Don

[vtsteam]

Did you use physical tools for that?

[ddmckee54]

Did you use physical tools for that?

Oh yeah, I don't have the software tools to do it any other way.  I just amputated his arm at the elbow and then reattached it.  I think it turned out OK.  Here's a couple of views of the wheelhouse, this first one is from forward looking into the wheelhouse.
 

This next one is looking at the port side.  I plan to attach a chain to Mario's left hand to make it look like he's going to sound the horn.
 

This last one is looking at the starboard side.  I didn't get too crazy with how much I bent his arm, wasn't exactly sure where his hand would wind up in relation to the wheel.  I think it looks OK.
 

Don

[ddmckee54]

Benchy's temporarily on the back burner while I wait for parts to arrive.

You know, the unimportant stuff like the motor. ESC, prop-shaft and bearings, prop, more servos - little stuff like that.  I got the motor yesterday, and the servos a day or two ago.  The prop-shaft and bearings isn't supposed to get here for another week or two.

I'll have to find something else to do, probably yardwork.  It is getting to be that time of the year again.

[vtsteam]

I guess a fair amount of weight low in the hull will be helpful, as there's a lot of top hamper and weight above the waterline. Can't see the underbody, but form stability doesn't look like a strong point. She'll like lots of batteries, maybe even, dare I say it, NiCads for weight. Might be a good (unintentional) sailboat with Lipos. Actually there are some compact 12V sealed lead acid cells that might fit. I use one for my depth sounder on my rowing and fishing boat, Flier. I think it was under 20 bucks from Runnings.

[ddmckee54]

The instructions on Thingiverse said it needed around 1Kg of ballast.  One of the upgrades on Thingiverse were glue on "fins" to keep him from rolling so much in turns.  I printed my own version as bilge keels.  I'm not sure if the ESC that I've got coming is 2S/3S, or just 2S.  I should have an old 6V SLA battery from my first boat.  I changed it to a 12V, probably wasn't a good idea since the boat now sits a little too low in the water.

I can kind of relate to the unintentional sailboat bit.  I converted my first boat, a "Dickie's Workboat", to use a real RC system instead of the POS it originally had.  I was playing around with it one evening and I realized that I couldn't turn any direction other that to the right.  I was alone and had NO way of getting to the boat.  After a few minutes I realized that the boat didn't turn as sharply to the right in reverse and it did going forward.  After about 10 minutes of see-sawing back and forth I was able to get the boat close enough to the bank that I could grab it.

Since that day part of the gear that goes with me when I take a boat out is a collapsible fishing rod with some line, some sinkers, a bobber, and a blunted treble hook.  I try not to sail any farther away from the bank than I can cast the line.  The boat might get a little banged up if it gets hit by the sinkers, but the way I see it that's better than losing the boat.  Haven't needed it yet, wonder if I need a special fishing license for RC boats?

Don

[vtsteam]

Well I used to fly seaplane models and the same thing can happen. Also capsizes. I remember one guy made a retriever seaplane to hook onto a disabled one.

If you have a rod and reel with a line and a sinker and treble hook on it, you might have a hard time convincing a game warden! But if it works, let me know, and I'll bring a model boat with me next time I go fishing in New Hampshire!

[ddmckee54]

I don't know, I'd be fishing FOR a model boat - I don't think there's a limit or a season on them.  And if there's an RC boat sitting there dead in the water... 

If you're planning on fishing with a model boat in New Hampshire, that's a whole 'nuther kettle of fish - might just require a special license.

Besides, the treble hook has had the points ground off from it.  It's more of a small grappling hook now.  Maybe I need to get a BIG treble hook, the kind used for deep-sea fishing and do the same thing to it.  Something big enough that it can't be swallowed by the fish around here, that'd make it easier to hook the boat anyway.

[vtsteam]

Or just wire three pieces of coat hanger or other stiff wire together with some thin copper wire and bend them  to shape. A little solder or epoxy at the joint to hold it permanently......and you can make it any size you want. And/or shape. If you go the solder route, you can even weight it if you want and get rid of the sinker.

Actually, I use steel nuts as sinkers here in Vermont. Lead sinkers are illegal, so skip the solder.

BTW even a small largemouth bass can swallow a hook that would choke many big saltwater fish.

[ddmckee54]

I've got some uncoated 1/16" brass brazing rod sitting on the shelf - somewhere.  That should do nicely. 

The parts have started arriving.  I got the motor and the prop shaft earlier, and last night I got the ESC.  I got the motor installed, and the shaft fitted ready for installation.  The connector was a 3mm x 3mm, I needed a 3mm x 1/8".  It was a solid coupler anyway, so I've got a Huco U-joint ordered.  The ESC had NO connectors, so now I've got to source some connectors, get them ordered, and installed.  The prop shaft came with a useless, too small, 2 blade prop - which I knew about.  So I ordered a 3 blade in the size I wanted.  The 3 blade prop is apparently on a different slow boat from China.

I've got to find my 3mm brass rod and my 4mm brass tubing, they're stashed SOMEWHERE.  I can get the rudder installed when I find them.  When that's done all the holes in the boat should be plugged.  Then it'll be weight and balance time?  (And checking to see if all the holes in the boat ARE plugged.)

Don

[vtsteam]

I've got to find my 3mm brass rod and my 4mm brass tubing, they're stashed SOMEWHERE.

So familiar!

[ddmckee54]

My seagull figurines showed up yesterday.  When I ordered them there were 3 poses of bird in the ad, so naturally I ASSUMED I'd get one of all 3 poses.... Not so much, I got 3 copies of the same pose.  Oh well, I can work with it.  I had to try it out to see if the birds were about the right scale.

 

Whatcha think, I think it looks about right.  They're resin, so they'll be fairly easy to modify into a sitting down bird and get rid of the pilings.

[tom osselton]

Those should look good on it. Maybe contact them and say WTF and get all three.