Author Topic: Barge for my springer tug  (Read 14707 times)

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Calimero

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Barge for my springer tug
« on: March 25, 2014, 17:29:48 »
My springer tug is almost complete. And while my springer has already rescued a few boats (and soccer balls) a "real" barge would be nice.

A I'm getting a 3D printer this project is as much about getting some basic 3D modeling skill as it as about a barge. I'm learning SketchUp a simple modeling software. I also need to learn about barges obviously. My current designs are just wild guesses based on pictures of actual barges and models mostly found in this very forum.

My barge will be relatively simple. I neither want nor can spend too much time building it. I'll go the easy route with a simple (crude) shape, some plywood and that will be it.

Dedicated page on my site
« Last Edit: March 25, 2014, 17:47:14 by Calimero »

Calimero

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Re: Barge for my springer tug
« Reply #1 on: March 25, 2014, 17:34:59 »
I started last week with SketchUp. 3D modeling is actually quite interesting: object must be seen as surfaces and volumes instead of "parts". Extrusion is a powerful "process" but is at first no "natural", not your go-to solution.

I've barely scratched the surface of 3D modeling but it's really something different (and sometimes puzzling if not downright frustrating).


Overall view (bow)


As basic as it can be


Three skeggs from bow to stern


Square skeggs


X-Ray view


Flat rendering


Cross section


Overwall view


Overall view

Well now that I look at it a week later, my first "barge" looks actually more like a sled. Especially with those "forward skeggs"  :D
« Last Edit: March 25, 2014, 17:45:54 by Calimero »

Calimero

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Re: Barge for my springer tug
« Reply #2 on: March 25, 2014, 17:44:34 »
I started over and went through another iteration. Saturday I took a look at the wood panels offered at the local home improvement store. Found some 120cm * 40cm plywood pre-cut panels. 5mm thickness looks decent while they also offered 8mm and 10mm (10mm looks like overkill).


Overall view (stern)


Overall view (bow)


Hull bottom (bow)


Hull bottom (stern)


X-Ray view


Cross sections

Barge is 50% longer than previous design (120cm vs 80cm) with the same beam (40cm).

Design is still rather crude both because my 3D modeling skills are still close to nil and because I want to keep construction as simple as possible.

Skegs still project 10mm from the hull. Instead of the bulky "front skegs" of the previous design, this one only has a streamlined taper.

Structural beams are still obviously missing.

Let's consider the inside of the hull is 110cm by 40cm and we want the barge to go down by 4cm. This amounts to 110*40*4 = 17600cc, that is to say 17.6kg (39lb).

1.5L water bottles are around 33cm high with a diameter of 9cm. Soda 2L bottle are the same height and are more "box-shaped" with a base around 9.5cm*9.5cm. Current design above has 11cm of inner "headroom" which might be on the short side once you consider the structural beams that will be added to the bottom (inside) of the hull.

With three rows of four bottles (4 bottles side by side, pointing at the bow), I should be able to get at least 12 bottles of either type in the hull. If beams are carefully placed 100mm apart bottles would actually rest on the bottom of the hull in between the beams.

12 bottles would give me 18kg (39.5lb) or 22kg (48.5lb) depending on bottle type. Might even be able to squeeze an extra bottle ... Bottles would of course be filled with water from the pond to keep barge as light as possible during transport.

Next I'll try to model the basic shape of my springer to have an idea how the barge scales compared to the tug.

Any comments welcome because when it comes to barge design ...



 :D ;D

Model Tug Man

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Re: Barge for my springer tug
« Reply #3 on: March 26, 2014, 04:15:32 »
Have you considered ice and beer rather than pond water. Infinitely more refreshing.

Nice job on the design--by the way.
« Last Edit: March 27, 2014, 06:31:26 by Model Tug Man »
VGJQ

Calimero

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Re: Barge for my springer tug
« Reply #4 on: March 26, 2014, 06:31:59 »
Quote from: Model Tug Man
Have you considered ice and beer rather than pond water. Infinitely more refreshing.

Ha ha ! Indeed a tempting idea. But I suspect that as the afternoon would go by, ballast would somehow vanish ...

It would also require thermal insulation.  :D

Quote from: Model Tug Man
Noce job on the design--by the way.

SketchUp has a companion tool called Layout which would let me print out "plans". Well not exactly blueprints as Layout is more a presentation tool, but at least help sheets with dimensions and everything for when you move to the shop and actually start building.

I need to think all that ballasting through.

mike_victoriabc

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Re: Barge for my springer tug
« Reply #5 on: March 26, 2014, 06:37:19 »
Interesting stuff!

Thanks for showing the various views.

Mike

Calimero

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Re: Barge for my springer tug
« Reply #6 on: March 27, 2014, 16:55:02 »
Quick update for tonight : Barge and springer 3D models

To get an actual view of my springer tug with the barge prototype, I decided to create a basic 3D model of my springer.

Measurements are probably off by a few millimeters on all three axes. Hull curvature is probably a bit off too but overall appearance is good enough.


Overall view


Top and bottom views


Hull bottom


Side view OA length would be 165cm / 5'5"  ;D

Bonus: 360ish view/animation:

<a href="http://www.youtube.com/watch?v=bOzC1PKOnvA" target="_blank">http://www.youtube.com/watch?v=bOzC1PKOnvA</a>

Tug and barge with ballast would displace around 30kg (65lb). Might have to upgrade the prop from 40mm to 45 or even 50mm ...  :o

Calimero

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Re: Barge for my springer tug
« Reply #7 on: April 14, 2014, 16:23:28 »
More 3D modeling and off to the home improvement store ...

My previous 3D models of the barge were solid models which can be seen as a single "mold" in which material would be injected.

Essentially a hollow "inside" constrained by surfaces. That's how models should be created for 3D printing.

Except that this barge won't be 3D printed but built from plywood sheets ...

As I'm learning 3D modeling for 3D printing I went that way (to a hammer, everything is a nail, right ?).

What I need is actual "blueprints" of the various parts I'll have to put together. The previous 3D models were not a complete waste as I've been able to "draw off of them".


Exploded view


Exploded view


Assembly "helper"

Here's a short animation on YouTube.

<a href="http://www.youtube.com/watch?v=_QbW7nHTldo" target="_blank">http://www.youtube.com/watch?v=_QbW7nHTldo</a>

All the various parts (sidewalls, frames, bottom, transom ....) are individual components which can be modified, duplicated (draw one frame, all other will reflect changes). Individual components can be moved as "units". Or can be hidden.

You can also make sure you end up with something you can actually assemble ...(altough SketchUp has no "mechanical" processing abilities; it's not a CAD engieering software)

Sharp eyes will have noticed that two notches are missing on the deck beams. I missed them and will be easily added (didn't want to re-process the video, lazy me).

Extra "open frames" will be added every 200m (or maybe less) and have been accounted for.

Once everything is designed that way, it's easy to get measurements and ... get to the local home improvement store !

I decided to go with 5mm plywood. Just basic ply, not the marine type which is significantly more expensive and much harder to find around here.

Castorama (think Home Depot, only more expensive ...) has actually two policies when it comes to cutting wood to custom dimensions:


  • Lumber: Pay a full board (usually 227cm by 240cm or 7' by 8') and then pay one per cut (you'd better carefully plan how you instruct them to cut it up)
  • Engineered wood (ply, MDF ...): Cuts are free of charge and only actual board surface is billed

That essentially meant I could get them to cut my plywood parts for free and not even pay for any leftovers. There was just a 250mm by 100mm (10" by 4") lower limit. No big deal.

I handed over the measurements for all my 15 parts and went my merry way. 24 hours later I collected all my plywood parts (and gave a little extra to the guy for all the dust my apartment never saw).

Cost for ply (excluding tip): 23.30

I also go some oak and beech (took whatever I found dimension wise ...) square dowels as beams.

Dowels will be added to most corners (not shown above) to strengthen them. I think I'll nail and epoxy everything together. Or maybe use simple white wood glue (which is easier to work with than epoxy) and then add epoxy fillets all around. Not sure yet.

Considering my views on epoxy ...



... I see where this is going.

I'm also 3D printing some helpers to hold parts together during assembly and curing.

But before assembly starts I'll have to figure out all the deck stuff: bollards, bitts, ...

Now that the ply sits in my dining room I can't chicken out.  :D
« Last Edit: April 14, 2014, 16:28:35 by Calimero »

Calimero

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Re: Barge for my springer tug
« Reply #8 on: August 03, 2014, 12:53:45 »
Final design & first milled parts

After stalling for a few weeks (or months ...) I got back on track with my barge project. I finally managed to meet with the airplane guys to get a quick introduction to the 2.5-axis CNC milling/cutting machines we have a the MCCR's workshop.

I also reworked some details in my 3D model. Instead of using water bottles to ballast the barge down, I got four 5kg (11lb) lead ingots. This will obviously take much less volume. I decided to add extra frames to make the whole thing stronger.

Not shown below: I'll use metal brackets on all four corners and also to secure the hull bottom and the deck to the sides. I'll bolt them (with countersunk bolts) and epoxy them in place.

I also diagnosed a tiny error ... The wood I got from the home improvement store is 14mmx14mm and not 9mmx9mm. Absolutely no idea how I got that 9x9mm dimension in my mind. Well ... It was quickly fixed in what is now the latest iteration of my 3D model.

First parts were milled from 5mm plywood: one of the "closed" frames and the front plate at the bow.


General view


Deck off - Deck will be expoxies in place, of course


Side view - With frames


Exploded view


Exploded view - From below


CNC milling in progress


CNC milling in progress


From 3D model ...


... to actual parts

Here's a video of the CNC cutter in action
<a href="http://www.youtube.com/watch?v=3lHpMTXCh9Q" target="_blank">http://www.youtube.com/watch?v=3lHpMTXCh9Q</a>

Two fellow members of the MCCR introduced me to CNC milling on the club's machines. This particular machine was built from scratch. It is still driven by an old DOS version of Step Four Pro.

First step is to set the absolute/machine zero and then the origin/zero of your drawing.

The Z (vertical) axis also has to be calibrated as it depends on the milling bit.

Not having my own bits yet (they run the machines like coffe machines: everyone can use them, just bring your own coffee or ... milling bits). The "teacher" lent me one of his 1.20mm carbide dilling bits.

The 5mm ply was cut in two 2.5mm passes. Less strain on the cutter. With such a small bit corners are quite sharp and just require two strokes with a small file to be perfecly square. The produced parts are almost ready to use/glue. Quite impressive.

Model Tug Man

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Re: Barge for my springer tug
« Reply #9 on: August 04, 2014, 06:43:34 »
Looks professional.

Wish I had one!!!
VGJQ

Calimero

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Re: Barge for my springer tug
« Reply #10 on: August 04, 2014, 07:34:34 »
I'm indeed glad to have access to such machinery. One of the members donated a Stepfour machine with the controlling PC and software.
Another stronger machine was built (the one pictured above) with much stiffer axes, frames, guide rods, still using the same driver and software.

I haven't measured my parts yet, but accuracy seems very good. Apparently < 0.1mm and maybe even less on stiffer material (epoxy plates).

I just have to figure out how to cut larger parts as the cutting area isn't - of course - infinite.

There are nowadays some good DIY kits. Or even scratch builds. Stepper motors aren't that expensive anymore and 3D Printing software has drawn enough geeks to have various free and opensource software available.

Some people also invest in laser cutters which only require 2 axes.

I might ask a quote to one of those online laser-cutting services (targeted at hobbyists or other low volume projects) to get an idea how much it would have cost to "get my kit from the post office".

Calimero

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Re: Barge for my springer tug
« Reply #11 on: January 25, 2015, 16:14:12 »


No this project isn't dead !

The various parts were cut from 5mm plywood on the MCCR's CNC milling machines over the past few months. Assembly has finally begun.


Barge - Top view


Barge - Underside

Calimero

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Re: Barge for my springer tug
« Reply #12 on: February 15, 2015, 17:08:16 »
Assembly continues ...

Back in January most assembly was done with two main units: hull and deck.

Everything was thoroughly coated with Yachtcare G4 primer (FR EN) just like the Sequana. G4 is a single-component polyurethane primer. Although quite thin out of the can I thinned it further with PU-thinner (+100%) for the first coats to really soak the plywood.

A new coat can be applied as soon as the previous coat is tack free (around 2 hours) but before resin has cured. 7 coats were applied with the last three coat being "pure" G4.

G4 has a slightly yellow tint and will darken the wood. G4 will turn even more yellow/dark when exposed to UV but this isn't an issue here as it will be painted over. Yachtcare now has G8 which is insensitive to UV but significantly more expensive.

Both assemblies were then left to cure for three weeks.


Freshly baked bollards - Yes - that's how it's made


Hull and deck - G4 primer and some fiberglass


Deck underside - Bollards epoxyed in place


Deck installation - With epoxy - of course

Bollards

Bollards were made from OD 10mm/ID 8mm and OD 8mm/ID 6mm copper tubing. A simple jig was made from plywood to have a somewhat consistent center-to-center distance. Got some flux and solder and we had a blow-torch laying around. Even on a drill press getting centered holes was quite tricky (and some of the bollards are a bit off ...).

Soot was sanded off and bollards were washed with water and were then dried in the oven (low temp).

I'll 3D-print small "caps" to close the tubes.

Fiberglass

I laid some fiber glass on a few areas I consider "critical". I got some marine laminating epoxy and 100g/m fiberglass cloth. Things turned out decent for a first attempts

Laminating epoxy is very thin which is great for its intended use: laminating. But I had to get filler (#406 Colloidal Silica from West System) to thicken it to make nice fillets on most joints.

Deck was epoxyed in place and is now curing overnight. I'll add extra fillets of epoxy from the inside to strenghten everything up.

And I'll lay some fiberglass from the outside. 100g/m cloth first and then 50g/m for finishing.

But it looks like I might be short on epoxy. When I got that 450g pack (300g resin, 150g hardener) I thought I'd have plenty. But even with minimal waste (I only prepare small < 30g batches) I've probably already spent half to two-thirds of the resin.

tug-arlyn-nelson

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Re: Barge for my springer tug
« Reply #13 on: February 16, 2015, 20:28:43 »
Man you got way more serious with the barge build than did I!  I drew mine out on a pc of paper by hand, did a little scale work with the calculator and started cutting plywood.  The difference between a low tech guy (me) and an obviously high tech guy. You're barge is going to be real nice.

Calimero

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Re: Barge for my springer tug
« Reply #14 on: February 17, 2015, 03:13:38 »
Well it was mostly an "educational project": from 3D model to CNC machining.  And it is "over engineered" for its actual purpose.

Your approach was probably much faster and efficient !

Some more fiberglass was laid on the bottom of the hull last evening. Next is fiberglassing a few more layers of very light glass on the deck and various corners. And then epoxying aluminium U profiles on the skegs and various exposed sharp corners.

Then a few more fillets of epoxy on the underside of the deck and most of the heavy lifting will be complete.