Dunbrody by Mahuna - FINISHED - 1:48 - Cross-Section - Irish Famine Ship

[Jim Lad]

Beautiful work, Frank - she's coming along very well.

 

John

[Mahuna]

Beautiful work, Frank - she's coming along very well.

 

John

 

Thanks John.  Not as well as I wanted, though - as detailed in the following post.

[Mahuna]

Part 17 – The Keelsons

 

Dunbrody has a single Keelson, and numerous Sister Keelsons.  The central Keelson measures 14” x 14”.  I rounded all scale measurements to the nearest 64^th for accurate milling, so the Keelson scale size is 9/32 x 9/32.

 

The sister Keelsons are arranged as two Inner Sister Keelsons, installed on each side adjacent to the Keelson, with two additional Outer Sister Keelsons on each side.  On the hull cross-section in the plans, the Inner Sister Keelsons measure 6” square.  This seemed too small, so I increased it to 8” square (11/64 square on the model).  Next to the Inner Sister Keelsons are two smaller Sister Keelsons on each side, called the Outer Sister Keelsons (Crothers would call these the ‘Cousin Keelsons’, but what’s in a name?).  These Outer Sister Keelsons are 6” x 8”, or 3/32 x1/8 on the model.  The following is the cross-section from the plans.

 

                        

 

Since the length of the all of the Keelsons on the sectional model would be 48 feet, and since available timbers generally were less than 40 feet, each member of the keelsons would require a scarf joint.  The scarf for the main Keelson is a horizontal hooked scarf.

 

                        

 

This scarf joint would be bolted for extra strength, using 1.5” bolts, so a series of bolt holes was drilled.

 

                        

 

I used 22 gauge copper wire, unhardened but pulled straight.  After these bolts were installed in the scarf joint they were filed flush using a riffler, and then were blackened using Liver of Sulphur.

 

                        

 

In addition to glueing to attach the Keelson to the frame floors, I decided to use functional bolts for additional strength.  Since these bolts would be visible on the model they needed to be properly arranged.  I used a compass to draw lines parallel to the sides of the Keelson.

 

                        

 

The small metal piece was reversed so that the flat side, rather than the tapered end, rode on the side of the Keelson.

 

                        

 

The Keelson was then temporarily pinned to the model so that the bolt holes could be marked.

 

                        

 

I marked the bolt holes, alternating them between the fore and aft sister frames.

 

                        

 

The holes were then drilled while the Keelson was still off model. 

 

                        

 

The Keelson was then glued to the frame floors, using pins with spacers to secure the Keelson while the glue set.

 

                        

 

                        

 

When the glue set, the bolt holes were extended into the frame floors by drilling.

 

                        

 

The bolts were then inserted through the keelson and into the floors, then nipped off.

 

                        

 

The bolts were filed flush using a riffler, and then blackened.

 

                        

 

                        

 

Moving on to the Sister Keelsons, the same process was followed, except for the use of functional bolts.  All bolts in the Sister Keelsons are simulated and do not penetrate the frame floors.  The bolts in the Inner Sister Keelsons are all 1” bolts (22 gauge copper wire that was work-hardened).  The bolts in the Outer Sister Keelsons are .75” bolts (26 gauge copper wire, unhardened but pulled straight).

 

Since each Sister Keelson required a scarf joint, I made nibbed scarfs in each, using the setup shown in the following photo for glueing the joints.

 

                        

 

Of the three central clamps, the two outer clamps ensure that the joint is tight, while the central clamp ensures that the joint pieces are properly lined up.

 

The bolts were inserted into the Sister Keelsons before the timbers were installed.  The copper wire was inserted into a drilled hole from the side which would show, and was extended a short way.

 

                        

 

The protruding end was then dipped into a small puddle of medium viscosity CA glue, and the bolt was then pulled back into the timber and the bolt was nipped off.  This avoided any CA stains on the visible side of the timber.

 

                        

 

The bolts were then filed flush and blackened – all before the Keelson was installed.

 

Installation of the Sister Keelsons was accomplished by using screw clamps where they fit.

 

                        

 

                        

 

                        

 

Where the distance was too great to use these small clamps I needed to use pins with spacers.  The pins were inserted into bolt holes that were left open until installation was completed.

 

                      

 

So all Keelsons are now installed.

 

                        

 

                      

 

The keelsons have added strength to the lower level of the model, and will allow me to continue fairing the interior of the hull to the approximate level of the Accommodation Deck.

 

 

 

Unfortunately, I discovered a MAJOR error after the Keelson had been fully installed:  I had positioned the hooked scarf to be located in the forward third of the model’s hull, since the Mast Step would be located between Frames 30 and 31.  This would give me sufficient clearance for the scarf joint.  Unfortunately, I lost track of the fore and aft ends of the Keelson, and installed it the wrong way.  This positions the scarf joint at almost the same point as the Mast Step.

 

Since the Keelson is now held in place by glue and by functional bolts, any attempt to remove and reposition the Keelson would likely tear the model apart.  So, it appears that I have two options –

 

Try to reposition the Mast Step further back in the model to separate it from the scarf joint.  This would cause a redesign of the deck structure for both the Accommodation Deck and the Main Deck, resulting in a model that is not true to the Dunbrody plans.

 

Continue on with the build in its current state.

 

Needless to say, I’m very disappointed with this turn of events.  My goal, in addition to the primary goal of showing the living conditions of the emigrants, was to build a faithful replica of the Dunbrody while following traditional construction practices.  I think my best alternative is to continue according to the plans, and hopefully extend the length of the mast step base to cover the scarf joint.

 

Oh, well.   

 

I’ll be out of the shop for the next couple of days on personal business (maybe that’s a good thing!).  My next work is to continue fairing the hold area in preparation for the installation of the remaining hold timbers.

 

Thanks for following!    

 

 

[GuntherMT]

Frank,

 

I think you should just continue, as when it's done, the only person in the entire world that would know (if you hadn't posted this) would be you.  I doubt if even expert judges at a wooden ship show would pick up on that mistake (I could certainly be wrong, but I'd be willing to put money on it if you didn't point the error out to them).

 

It is still looking great.

[mtaylor]

Frank,

 

I agree with Brian.   However, if this is something that's going to haunt you, maybe drill out the bolts from the keelson, de-bond the glue might leave the frames salvagable.  I'd hate to see you starting over.

[AON]

Thank you for teaching me a valuable lesson.  

[druxey]

I'm sure that this is a disappointment to you. However, none of us reach perfection. Somewhere in every model, lurks an 'oops'. 

 

One possible (non-destructive) solution might be this: the actual scarph will be hidden under the mast step. As the bolting pattern is regular, could you scribe a scarph in the correct position and slightly darken this with a fine pencil point?

[tkay11]

I agree with Druxey. But let's have a hypothetical to see if that helps any further.

 

Suppose you were to dismantle everything, start all over again, correctly place the scarf, etc.

 

Then, a few weeks down the line, oh no! You find yet another mistake of the same order that only you have noticed. AAAARGH!

 

Would you then yet again dismantle the whole thing and start again?

 

I don't think I have ever seen any build without a booboo somewhere. But indeed, yes, some people do go and start again -- but generally once lots of others comment on the difficulty, or when it makes future progress impossible.

 

Then you have to think about how accurate it all is. Was that treenail 0.01mm out? Are the frames exactly spaced as the original? (Well, no, they're the wrong size to start with since they're at scale, and you then worry you can't get the grain to scale, and you haven't seen how the original plans were interpreted fully).

 

Of course, only you can decide on your level of acceptance, and, as others have said, along with the great unlikelihood of anyone else ever noticing whilst standing in awe at the beauty of your craftmanship.

 

Tony

[EdT]

Very nice work, Frank - very precise, very clean.  Don't beat yourself up over the mistake.  We all make plenty of them - and some even see the light of day.  I would consider Druxeys solution or ignore it.

 

Ed

[Mahuna]

Thanks everyone for the encouragement, ideas, and 'forgiveness'.  I'm going to try to disguise the scarf under the mast step.

 

This has been another valuable lesson about planning and double-checking.  I'm learning something new every day that I work on Dunbrody, whether it's about ship construction, processes, or techniques.  Overall, a very enjoyable and challenging experience, even with the boo-boos!

[GuntherMT]

Maybe time to put a giant label on the building board - "This is the Front!"
 

[Mahuna]

Maybe time to put a giant label on the building board - "This is the Front!"

 

 

LOL!!  Yesterday I started labelling every sister keelson in light pencil with the side (P or S) and end (F or A) since they all looked the same and I wanted the scarfs in particular places.  Seems like something I'll continue doing.

[Canute]

Gee whiz, I thought I was the only dullard who needed to mark directions and sides.    Sounds like an orthopedic doctor I had for joint replacement surgery. Asked me to mark the leg he's supposed to work on, just before they knocked me out.

[captainbob]

LOL!!  Yesterday I started labelling every sister keelson in light pencil with the side (P or S) and end (F or A) since they all looked the same and I wanted the scarfs in particular places.  Seems like something I'll continue doing.

That's what I do. But then I forget to look.

 

Bob

[HIPEXEC]

Thank goodness, Frank. You are human after all.  I have been discovering glued and pinned errors that can't be fixed since I started building model boats. It's good to have an esteemed builder in your class as a member of our can't-fix-it club. Your work is magnificent!

[Omega1234]

Gee whiz, I thought I was the only dullard who needed to mark directions and sides. Sounds like an orthopedic doctor I had for joint replacement surgery. Asked me to mark the leg he's supposed to work on, just before they knocked me out.

Haha! I had three knee operations in 5 months (on the same knee). On each occasion, I was asked to do the same thing. Gees, you'd think he'd know which knee to operate on after the first surgery!!!

 

In all seriousness, Ken and Frank, I'm one of those dullards who feels the need to mark everything...still get things wrong, though!

 

Cheers

 

Patrick

Edited May 18, 2016 by Omega1234

[Mahuna]

Part 17 – The Lower Accommodation Deck Clamp

 

I had a medical procedure done on Tuesday, and as a result I was NOT PERMITTED to work in the shop (by my live-in nurse).  While I was being good I decided to draft the planking for Dunbrody.  I measured the cross-section provided by the plans and converted it into plank sizes for the model.  I used these measurements to tune the Table of Scantlings that I had prepared during my planning exercise.  This will prove useful when I’m milling the individual planks.

 

                        

 

                        

 

Now I’m back to work in the shop, and I’m focusing on the lower deck clamp for the Accommodation Deck.  Once this clamp is installed I’ll feel a lot more confident that the hull will retain its shape and the individual frames will stay perpendicular.

 

As in all other longitudinal timbers, this deck clamp has a scarf.  Since the clamp will also be bent to conform to the hull, I decided to use some ‘bolts’ to keep the scarf from separating during bending.  I’ll probably use this approach for all of the major longitudinal timbers.

 

                        

 

I made an arm for the height gauge that would fit between the frames and was long enough to reach the inside of the hull from the work table – there isn’t enough room on the shipway surface for the base of the height gauge (another lesson learned).  I will adjust all heights by adding the height of the shipway surface from the work table surface.

 

                        

 

Using measurements from the drawings I had prepared above, I marked the height of the Lower Clamp for the Accommodation deck.

 

                        

 

The internal surfaces of the frames needed to be faired to accept the clamp, so there was a lot of time spent in Checking the fairness from frame to frame

 

                        

 

Marking high spots

 

                        

 

and sanding the frames.  When I was satisfied with the frames I soaked the clamp in boiling water.  I use a length of PVC pipe with a cap on the end as a container, so I can fit a fairly long timber in my soaking pipe.

 

                        

 

Since the wood wants to float to the surface, I use a small spring clamp to weight it down.

 

                        

 

I had made some small planking clamps using the design EdT has in his Naiad Vol 1.  Since I only had 6-32 knurled nuts I made the clamps somewhat smaller than Ed’s, and needed to solder 3/64 brass rod as the cross-pieces.

 

                        

 

These clamps work OK, but I intend to make larger clamps that will be able to use round toothpicks as the cross-pieces.

 

When clamping the timber, I started by clamping the ends of the timber to the position markings using spring clamps, then installed the planking clamps at intervals.

 

                        

 

When the timber was fully clamped I removed the spring clamps.

 

                        

 

Both Lower Clamps for the Accommodation Deck are now temporarily in place for drying.  I intend to install them over the weekend and hope to get some other key longitudinal timbers installed.

 

                        

 

It feels good to be back to work on Dunbrody after the short enforced break.

 

 

[Omega1234]

Very nice progress, Frank and it's great to see you back at work.  She's a little beauty, for sure!

 

Cheers

 

Patrick

[EdT]

Outstanding and lovely work, Frank.  I will be interested to see how your lighter version of the clamps work out.  I often had to put a lot of stress on these, but better preforming of the planks - especially the curved, twisted, heavy ceiling planks - may alleviate this.  Of course,  with only the mid-section to worry about, you will avoid many of the problems found at the curved ends of the hull.  I used 6d nails instead of toothpicks.  If you do that I recommend coating them first (I used shellac) to avoid staining the wood if you wash glue off with water.

 

Ed

[captainbob]

Looking good Frank, that should really stabilize things.

 

Bob

[Mahuna]

Part 19 – The Lower Accommodation Deck Clamp – Cont’d

 

The Lower Accommodation Deck Clamp is a key structural component for the model and needs to be bolted through the frames as well as being glued.  In addition to being functional bolts, these bolts also need to be properly positioned and uniform for a good appearance.  Since my last post I’ve been trying to decide how to drill for these bolts. 

 

At first I thought I’d lay out and drill all of the bolt holes on the clamp before gluing the clamp to the frames.  Then after gluing I would use the pre-drilled holes as guides to drill through the frames from the inside of the ship.  The problem with this approach is that my rotary tool won’t fit inside the hull, so this would require using a pin vise to finish the drilling.  I could do this, but the clamps aren’t the only timbers that need to be bolted through the frames.  This would be a lot of manual drilling.

 

At our ship modelers club meeting on Saturday I described my issue to the other members, and several of them suggested using some kind of a jig to align the holes.  We discussed a few approaches, and I decided to make a metal drilling fixture – a wood fixture runs a greater risk of the holes becoming deformed by the constant drilling.

 

I have a brass bar that is 1 inch wide and half an inch thick, so I decided to use a piece of that for a drilling fixture.  I milled tabs on one end.  These tabs would allow me to hold the fixture against the deck clamp.

 

                        

 

I milled a groove in the fixture that would fit over the frame.

 

                        

 

I drilled four holes in a square format using a #72 drill for 1.25 inch bolts.  Even though I will only drill 2 diagonal holes per frame, having the four holes would let me change the diagonal on opposite sides of the ship.

 

                        

 

Making the fixture took a little over an hour, and I had calculated that manually drilling 52 holes in a single clamp would take more than that.  If I can use this fixture for the eight clamps in Dunbrody I’ll have saved considerable drilling time.

 

                        

 

I didn’t want to use the fixture on the real clamp before testing it, so I used some of the discarded frames from the scrap box to set up set of test frames.

 

                        

 

I think this testing setup will come in handy for more testing in the future – now I feel much better about my scrap bin!

 

My first test was to drill through a single frame.  I was pretty happy with the results.  The first photo is the holes from outside.

 

                        

 

And the next photo is of the holes viewed from inside the hull.

 

                        

 

Using the fixture is fairly simple.

 

                        

 

I drilled the holes in all of the test frames, and was happy to see they lined up pretty well.

 

                        

 

                        

 

So now I can proceed with gluing the Accommodation Deck Clamps in place.

 

 A big Thank You to my fellow club members for getting me thinking the right way – and thanks to everyone for following.

[GuntherMT]

Not what I envisioned, but as usual you came up with a tool that works very well for you.  Nicely done!

[druxey]

Nice result, Frank. You might wish to back up the clamp with a scrap of hardwood to prevent tear-out on the drill exiting.

[Mahuna]

Not what I envisioned, but as usual you came up with a tool that works very well for you.  Nicely done!

Hi Brian - I guess I didn't understand your idea.  I'd love to hear it again - always looking for different and better ways of doing things.

 

 

Nice result, Frank. You might wish to back up the clamp with a scrap of hardwood to prevent tear-out on the drill exiting.

 

Excellent point, Druxey.  Thanks, I'll be sure to do that.

[Omega1234]

Hi Frank

 

Lovely work, overall, as always.  The brass jig is a great idea that'll ensure precision and uniformity.  

 

Oh, by the way, they're your 'discarded' frames...I can only wish to do one that good!!!!

 

All the best and keep the tutorials coming.

 

Cheers

 

Patrick

Edited May 23, 2016 by Omega1234

[GuntherMT]

Hi Brian - I guess I didn't understand your idea.  I'd love to hear it again - always looking for different and better ways of doing things.

 

 

I think your execution accomplishes the same thing, but here was what was in my head that I was trying to describe (hopefully my amazing MS Paint skills are somewhat clear):

 

 

It would of course be directional based on the thickness of your deck clamp and the width of your frames, and would work perfectly fine with four holes like you did it.  I was trying to describe it as the posts being long enough that you could put a piece of wood backing between the posts and use that to clamp it with possibly, but not sure if that would even be necessary.

 

[David Lester]

Hello Frank,

This will be a very interesting model. I don't believe I have seen any other models of an Irish famine ship or coffin ship. Have you seen the bronze memorial at Westport in Ireland? It's a moving sight and very interesting artistically. Here's a picture I took when we were there a few years ago. Notice how the "rigging" and other parts of the ship are represented by skeletons. Like many others, I'm of Irish ancestry - County Cavan in my case.

 

I'm looking forward to following your build log.

[Mahuna]

I think your execution accomplishes the same thing, but here was what was in my head that I was trying to describe (hopefully my amazing MS Paint skills are somewhat clear):

 

FrameDrillJig.jpg

 

It would of course be directional based on the thickness of your deck clamp and the width of your frames, and would work perfectly fine with four holes like you did it.  I was trying to describe it as the posts being long enough that you could put a piece of wood backing between the posts and use that to clamp it with possibly, but not sure if that would even be necessary.

 

FrameDrillJig2.jpg

Thanks Brian - now I get it.  It's fairly similar to what I've made, but the four tabs instead of two might make a difference, both good and bad.  On the good side it would be a closer fit with less chance of it moving around.  On the not so good side it might limit where it can be used.  I had to reverse mine in some spots due to the pesky filler blocks (they've now been removed since the clamps are in place and secure).

[Mahuna]

Hello Frank,

This will be a very interesting model. I don't believe I have seen any other models of an Irish famine ship or coffin ship. Have you seen the bronze memorial at Westport in Ireland? It's a moving sight and very interesting artistically. Here's a picture I took when we were there a few years ago. Notice how the "rigging" and other parts of the ship are represented by skeletons. Like many others, I'm of Irish ancestry - County Cavan in my case.

 

I'm looking forward to following your build log.

Hi David - welcome aboard, and thanks for that very interesting photo.  I have been to Westport several times, but haven't been there since the early 90's.  I don't recall seeing this monument - it might be fairly new.

 

The plans for Dunbrody are from the Ships in Scale magazine, and I recall seeing a POB version in that magazine a few years ago - built by a couple of modelers who worked together on it.  Without showing the emigrants experience it's a fairly ordinary ship - that's why I'm doing the sectional model.  I plan to show the living accommodations for the emigrants. 

[Mahuna]

Hi Frank

 

Lovely work, overall, as always.  The brass jig is a great idea that'll ensure precision and uniformity.  

 

Oh, by the way, they're your 'discarded' frames...I can only wish to do one that good!!!!

 

All the best and keep the tutorials coming.

 

Cheers

 

Patrick

Thanks Patrick.  I consider this more a 'diary' than a tutorial.  It describes the way I do things, including all the do-overs.