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[ddmckee54]

Several weeks ago I stumbled across the files for an RC version of Benchy on Thingiverse.  This in not your normal 3D printed Benchy, but his much BIGGER brother, about 7-9 times bigger.  After I quit laughing I told myself that "I GOTTA  build me one of them."  So I started printing parts, there were several parts that were in the 20+ hour print time range.


The first attachment is is what I had printed up a little over a week ago.  I discovered that the blue hull section had been printed with the wrong scaling factor and was too big.  This was the 2nd attempt at that section, both attempts took 15-18 hours and they both had a layer shift about 80% of the way up the section.  On the 2nd attempt I heard the printer making a ticking sound periodically and finally tracked it do to an overhang that was curling up.  I let it continue and hoped for the best, but it still had the layer shift.  I also noticed that on both attempts the port side railing had come loose from the print bed.  Both of these attempts were made without support, because the instructions said it wasn't needed.  I ran out of the blue filament so I switched rolls, and had to recalibrate the scaling factor.  I was previously scaling the model to 104.5% to allow for shrinkage, the new roll only needed 103%.  This time I bit the bullet and used some support, I also printed a with a brim to keep the part attached to the print bed.  The print time went from 15-18 hours to somewhere between 28-30 hours, but the brim and the support worked like a charm.  There was no layer shift, and the hull had a nice smooth curve to it.  The first 2 attempts had a definite kink in the hull.


One of the engineers that I work with christened this the Dreadnought Benchy, and the name kind of stuck.  I designed a gun turret/turrets for Benchy.  I print in PLA and I ran out of Weldon #4 for gluing it together.  I got my order last Friday so over the weekend Benchy started coming together, and as you can see in the 2nd attachment now he's got some TEETH.  (That's an empty 12oz can for size reference.)  The hull is now in one piece, it's not water-tight yet and there's a LOT more sanding to be done before it's ready for paint.

Don

[Martin (Admin)]

  How much PLA did that take to finish?!

[ddmckee54]

Counting my screw-ups, or not counting them?


If you don't mess anything up multiple times like I did, you could probably get the job done with a 1Kg roll, and that includes a LOT of wasted support material.


I'm probably at about 1.5Kg to 1.75Kg.  Like I said, I printed that forward hull section 3 times before I got it right.  Along with printing the bow section, the 3 deck sections, and the lower cabin section - TWICE.  (Wrong scaling factor 1st time around, they were all too big and didn't fit the hull.)  I also had to print the turret mounts that attach to deck twice.  The front mount is angled to correct for the deck angle, and I got the angle wrong.  I was off by 3° and the turret looked funny.  The rear mount I measured the existing deck part at 65mm.  I then drew my walls at 65mm apart in my 3D model and proceeded to extrude the walls - outward instead of inward.  The part slipped nicely OVER the existing cabin part.  Not good when the rest of the part is designed to clear the existing structures when sitting on top of said structure - not slipped over it.


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

[RST]

Hi Don,


As a fellow printer I'm intrigued about "Weldon  hash 4".  It's available over here though I can't see anything in the TDS or the web that suggests it will bond regular PLA.  That said, if memory serves I have used Tamiya extra thin solvent to smooth very small PLA prints (it kind of works-ish but won't "bond" them).

Rich

[ddmckee54]

RST:


I stumbled across that little tidbit of information on the Interweb somewhere.  I was searching for "solvent bonding PLA", and I was looking for something that wasn't a known carcinogen.

Weldon #4 is listed as a solvent for bonding hard acrylics.  Apparently PLA is chemically close enough to that material that this stuff works.  If I remember correctly, both Weldon #3 and #4 will work.  #4 is the thin stuff, it's like water, and I think #3 is thicker.

It definitely dissolves PLA, I made a thicker trowel-on type glue/filler by cutting up some left-over PLA support material and putting it in a SMALL glass jar with a non-plastic lid.  Then adding some Weldon #4, enough to cover the PLA bits, I wanted to see how well the Weldon #4 would work.   I actually did that before I tried gluing the hull parts together.  When the PLA bits had started to dissolve after only a few minutes, I knew I had a winner of a glue.  By the next day I had a thick glue/filler that I could apply with a small artist's trowel/spatula.  (Styrene modelers use the same trick by cutting old model kit sprues and dissolving them in acetone.)  You can make your glue/filler as thick or thin as you want it.  Be in a well ventilated area when working with this Weldon #4 stuffthough, it stinks to high-heaven.

I use either a small natural bristle brush, or a small hypodermic applicator, to apply the glue to the joint.  The brush gives you better control for small parts.  But if you've got a bigger joint to glue, like gluing hull parts together, the hypodermic applicator is the way to go, it's MUCH faster.  If I've got a gap to fill I get out my glue/filler goo and the artist's trowel.  I use a model paint pipette to fill the hypodermic applicator or my glue/filler goo bottle.

So far the only joint to give me any grief is the Deck #2 to Deck #3 joint.  That's a butt joint and the deck at that joint is only about 1mm thick - I can't reinforce it.  When the deck gets installed in the hull, that particular joint will be glued to the top of a shelf.  The joint's only got to hold together long enough to get installed in the hull.

Don

One other thing I did notice, sometimes the Weldon #4 will bleach the color out of the filament - don't know why for sure.  I'm an Electrical engineer, not a Chemical engineer.

[RST]

Hi thanks for the info.  Google is a strange thing, I've not seen any hits on solvent welding PLA until you mentioned that stuff. Now I find plenty!


Rich

[ddmckee54]

Rich:


No problem.  As well as the Weldon #4 works for bonding the PLA parts together, now I'm starting to wonder if it could be used to vapor smooth PLA parts.  I'm thinking that this might work something like the acetone used when vapor smoothing ABS parts.  I might have to take a stroll through either Goodwill, or some of the 2nd hand shops to see if I can find a suitable smoothing chamber.


Most of the vapor smoothing that I have seen done used a rice steamer.  As big as the Benchy parts are, I'm thinking maybe an electric roasting pan?  I know my grandmother used to have one that might have worked.  It's LONGGGG gone now though, she died in the late 60's.  Might have see if I can find a rice steamer first to test this theory - THEN look for a roaster.


Don

[JimG]

Looking at some of the online articles it looks like these products contain Methylene Chloride (Dichloro methane). Best to have a read of the MSDS for this as it is highly toxic. From working in a school chemistry department this could only be used in a fume cupboard with a suitable organic filter or direct vent to the outside away from any windows. Always stored in a well sealed bottle in a well designed vented store room. The filter had to checked yearly and replaced when it no longer removed all solvents from the exhaust. I would have doubts about using it indoors. Your right it stinks and if you smell it you are being exposed.

Jim

[ddmckee54]

Jim:


You're right, no vapor smoothing with this stuff.


And I'd better break out the respirator the next time I need to glue anything together with this stuff.  All in all, since I will not be exposed to this stuff on a regular long term basis, I think with a little PPE, common sense, and a well ventilated work area I'll be OK.


I'd be more concerned if I was 18 and I was going exposed to this on a daily basis for many years, than I am at 68 and using it once in a while for hobby purposes.


Don

[RST]

Looking at some of the online articles it looks like these products contain Methylene Chloride (Dichloro methane). Best to have a read of the MSDS for this as it is highly toxic. From working in a school chemistry department this could only be used in a fume cupboard with a suitable organic filter or direct vent to the outside away from any windows. Always stored in a well sealed bottle in a well designed vented store room. The filter had to checked yearly and replaced when it no longer removed all solvents from the exhaust. I would have doubts about using it indoors. Your right it stinks and if you smell it you are being exposed.

Jim

Dichloromethane is a well known "modelling" solvent  and perfecty safe to use in rasonable quantities if you heed the warnings.  It doesn't work on my preferred filament from Fiberlogy but given the fact PLA itself is almost passing a century since invention now, all the modern PLA printing filaments I've had behave sligtly different so whatever works for you.

[ddmckee54]

Rich:


I know that all PLA is not "created equal", but so far the Weldon #4 has worked to bond the PLA from 2 different manufacturers - filament that I probably got off of Ebay.  One of the spools was from WYZworks, I've always had good luck with their filament.  I can't remember the name on the other roll right now, I'll check when I get home.  I think it was from Color3D, or something like that.  Again, they are a supplier that I've always had good luck with.


You'd think that the chemistry of the PLA from different manufacturers wouldn't be THAT much different.  The different dyes used to color the filament would change the chemistry between manufacturers a little, but the basic PLA pellets used to make the filament you'd think would be pretty much the same.  When they start tinkering with the recipe to make PLA+ is where I'd expect to see the major changes in chemistry.


Maybe we should start a thread listing the types of PLA that Weldon #4 will, and will not bond?


Don

[ddmckee54]

Take a look at the 1st attachment and see what you think, has Benchy got a Cap'n?   (I think so.)




The 2nd attachment is 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]

Mario survived his surgery and is doing well.  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 attachment is from forward looking into the wheelhouse.


This 2nd attachment 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 attachment 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

[Martin (Admin)]

 Looking good!   

[ddmckee54]

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

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

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

[ddmckee54]

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

[ddmckee54]

The seagull figurines showed up yesterday.  When I ordered them, 3 poses were shown, one with the bird sitting on a piling, one with the bird standing, and one with the bird taking off.  I just ASSUMED that I'd get one of each pose - not so much.  I got 3 copies of the bird on the piling - OH Well, I can work with it.


I couldn't resist trying it out, only to check if the scale was correct though - I definitely wasn't playing around.  Check out the seagull attachment, I think it's about the right size.

[MirabileVisu]

How interesting to see your project.  I did the giant Benchy from Thingiverse to pass the time during the first lockdown in England, only I made it a Pirate Boat.  I even put a Mario in it too, like yourself.  I cheated though and bought a toy Mario instead of printing him.  I'll see if I can work out how to put photograhs on here.

[MirabileVisu]

Wow, the security on this site is very high - eight questions to answer before you can post a comment.  Dose this requirement stay forever, or is it only for new members?

[MirabileVisu]

Here (hopefully) are the Mario Pirate photographs.

[Martin (Admin)]

Wow, the security on this site is very high - eight questions to answer before you can post a comment.  Dose this requirement stay forever, or is it only for new members?

... only for your first 5 posts!   

[MirabileVisu]

My photographs haven't arrived, so I presume that is a restriction until I have posted five times.

[MirabileVisu]

.... and here is another post to make it up to five posts......


Best regards,


Trevor


PS Apologies to the the original poster of this thread, Mr ddmckee54, with me filling it up!

[MirabileVisu]

Second go with the photographs!

[MirabileVisu]

I'm not going to give up.