Patterning and casting a boom gooseneck fitting

[Jim Ledger]

know I've covered a lot of this material on my catboat thread already, but there's still plenty more to do. I think that a separate thread would be a good idea so the process is available to anyone interested without having to hunt for it.

Please bear with me here while I get this thread up to speed. I'm finding it a very interesting project and hope it will give others some good ideas.

I'll start with the mast band patterns, because they are already in the finishing stages. The end fitting for the boom is being worked on at present and I will get to that shortly. There will be an intermediate fitting that hinges on the mast bands and connects to the boom end fitting. That pattern has not been started yet.



So, here we go. The mast band patterns will begin with two laminations glued up on a round form. The wood is Alaskan Yellow Cedar, a less than ideal choice for patterning as it turns out due to it's grain structure. Patterns are best made from a very mild, smoothly grained wood of intermediate hardness. Cherry, Spanish Cedar, Honduras Mahogany are all excellent woods to use.

[Canoez]

:::Getting out popcorn bucket:::

[Jim Ledger]

The two laminations, off the mold after a trim and a cleaning up...










Getting some ear tabs and a block glued on...

[amish rob]

It's good lighting. I can't see the shadow of your wizard hat anywhere. Seriously, your patience, and skill, and care are inspiring.

Peace,
Robert

[Jim Ledger]

It's good lighting. I can't see the shadow of your wizard hat anywhere. Seriously, your patience, and skill, and care are inspiring.

Peace,
Robert

Thanks, Rob, I'll do my best to live up to your expectations...not really a wizard, yanno.




You can start to see the final form of the mast bands in this picture. There will be two sets of each pattern cast.

[Pitsligo]

Definitely a popcorn thread. I'm in for the duration.

Nice job, with those laminations. Why did you choose that instead of a glue-up of solid chunks, maybe of basswood, with a lot of bandsaw work and wasteage?

Alex

[amish rob]

Jim,
I'm not necessarily sure wizards were all that genius, just that they were experimenters, and thinkers, and doers.
No illusions here that you are anything but a man, but isn't that what makes your work so magical?

This type of work speaks to me, because I'm the savage to weld up some mild steel, have it dipped, paint it, and call it a day.

Peace,
Robert

[Jim Ledger]

Definitely a popcorn thread. I'm in for the duration.

Nice job, with those laminations. Why did you choose that instead of a glue-up of solid chunks, maybe of basswood, with a lot of bandsaw work and wasteage?

Alex

Thanks, Alex. The wastage, the first round of wastage, using sixteenth inch laminations is 200%, figuring an eighth inch kerf. But since I was using scrap anyway it hardly mattered. Laminating the half rings makes a strong structure with no short grain or butt joints to make any later shaping difficult. I suppose I could have bricklayed it, but I didn't consider doing so.

You do some casting yourself, I understand?


Jim

Jim,
I'm not necessarily sure wizards were all that genius, just that they were experimenters, and thinkers, and doers.
No illusions here that you are anything but a man, but isn't that what makes your work so magical?

This type of work speaks to me, because I'm the savage to weld up some mild steel, have it dipped, paint it, and call it a day.

Peace,
Robert

I like to do a bit of welding myself, Rob, not an expert by any means but I did manage to get some gear together in a past life and use it at every opportunity.

Jim




Here are the mast bands after some shaping. The inside face, where the bands contact the mast, have been given a slight roundness and the inside corners radiused. The hope is that the shaping and rounding will prevent any severing of the fibers of the mast. The ear tabs have been rounded...

[stromborg]

That is going to be a nice looking bit of bronze. Looking forward to seeing how you set it up for casting.

[amish rob]

That is going to be a nice looking bit of bronze. Looking forward to seeing how you set it up for casting.

I agree. I will recede into the shadows to watch and learn. I may add an occasional word of praise, or question, but I am going to enjoy watching this. Thanks.


Peace,
Robert

[Pitsligo]

Laminating the half rings makes a strong structure with no short grain or butt joints to make any later shaping difficult. I suppose I could have bricklayed it, but I didn't consider doing so.

Makes good sense to me. I'm still new enough at laminating that it doesn't yet come to mind so quickly that I use it very often.

You do some casting yourself, I understand?

Some design and patternmaking, but almost no casting. Once the shellac goes on, I'm in terra incognito.

The inside face, where the bands contact the mast, have been given a slight roundness and the inside corners radiused.

That's a good idea, but how are you managing your draft? Are you keeping it as a one-piece, carving into your drag to release it once it's rammed up, and then doing a cope-down arrangement?

Alex

[Jim Ledger]

That is going to be a nice looking bit of bronze. Looking forward to seeing how you set it up for casting.

Thanks, Steve, I'm very interested to see how it's going to work myself.

I agree. I will recede into the shadows to watch and learn. I may add an occasional word of praise, or question, but I am going to enjoy watching this. Thanks.


Peace,
Robert

Your comments and questions are always welcome, Rob.

That's a good idea, but how are you managing your draft? Are you keeping it as a one-piece, carving into your drag to release it once it's rammed up, and then

doing a cope-down arrangement?

Alex

I think that this next picture will answer your question, Alex. If you look at the piece in the vice you can see how it's been bandsawn in half lengthwise, so it's a two-part pattern. For those unfamiliar with the casting process this means that one half of the pattern gets molded in the bottom half of the sand mold and the other half gets molded in the upper half. This will become clear when we get further along.

It's difficult to do a thread about casting without throwing around a few terms specific to the casting process. Draft, in relation to casting, refers to a slight taper worked into a pattern so that the pattern can be withdrawn from the sand mold without ruining the impression we're trying so hard to make. This pattern has a few examples of draft. The previously mentioned softening of the inside surface acts as draft. The rounding of the outer surface provides draft. The rounding-off of the ears provides draft. If you look closely at the ears you can see that they're thicker along the split than at the outer edge...draft again.

The ears have had a Bondo fillet, sanded and overlaid with a wood putty fillet. The fillets have draft as well.

The ends of the bands, where they bear against the mast, have been rounded and shaped so that there's no sharp edge to dig into the wood when pressure is applied by the bolts.

[PeterSibley]

That's a good idea, but how are you managing your draft? Are you keeping it as a one-piece, carving into your drag to release it once it's rammed up, and then doing a cope-down arrangement?

Alex

I didn't see the split line either Jim. Edited to remove questions.

[JimConlin]

Is the easing of the inner edges sufficient draft on the inner face or are you going to core the bore?

[PeterSibley]

Vertical on the inner face and draft outside should pull OK but a core is a good idea too.

[Jim Ledger]

I didn't see the split line either Jim. Edited to remove questions.

There's a good reason you didn't see the split, Peter...it wasn't there in Post#8. I had to apply the fillets before sawing the pattern in half.

Is the easing of the inner edges sufficient draft on the inner face or are you going to core the bore?

Hi, Jim, you actually need very little draft, so long as there's some outward slant it should be OK. I'll do a test mold before I start to melt anything.

Vertical on the inner face and draft outside should pull OK but a core is a good idea too.

A core is a good idea, Peter, but I think this will work well just as a split pattern.







Here's where we are today. The patterns have been sprayed with some automotive primer. I know that shellac is the traditional pattern finish, but I find that a solid color shows up rough spots and unfairness, especially when the piece is rotated in front of a light bulb. The red material is automotive spot putty, a fine grained filler that dries quickly and sands easily. Good for filling in small imperfections. Sand it out and shoot some primer over it.

[Pitsligo]

If you look at the piece in the vice you can see how it's been bandsawn in half lengthwise, so it's a two-part pattern.

There's a good reason you didn't see the split, Peter...it wasn't there in Post#8. I had to apply the fillets before sawing the pattern in half.

I feel better, now, about not having seen the split.

It looks really good, both technically and aesthetically. I like how softening the inside surface both reduces damage to the wood of the mast and provides draft. I'd be doing just as you are. (Peter and Chuck are the Gods of Coring; I'm an apostate, and avoid cores if I can. )

It looks as though the "ears" are somewhat thinner where they join the band, rather that thicker and tapered away from the mast, as I would have expected. Is that an optical illusion from the camera angle, an intentional feature, or something I shouldn't have noticed?

When I set about designing and patterning Bucephalus's gooseneck, I started off on a similar line of design as you're doing, but then went with a more compact pad-style design, as much because I didn't feel I had a full grasp of all the variables with a mast-band as because I didn't have enough room to do what I wanted with the band. So I'm definitely taking notes on your approach.

Alex

[Jim Ledger]

It looks as though the "ears" are somewhat thinner where they join the band, rather that thicker and tapered away from the mast, as I would have expected. Is that an optical illusion from the camera angle, an intentional feature, or something I shouldn't have noticed?.

Alex

That's an optical illusion, Alex. Think of the ears as having draft on both sides, now consider the rounded shape of the ears. What appears to be a thinning is actually the draft increasing around the perimeter of the ears.

When I set about designing and patterning Bucephalus's gooseneck, I started off on a similar line of design as you're doing, but then went with a more compact pad-style design, as much because I didn't feel I had a full grasp of all the variables with a mast-band as because I didn't have enough room to do what I wanted with the band. So I'm definitely taking notes on your approach.

Alex

Is there any chance you could post a picture of the gooseneck here? You really can't have too much information, and who knows where the next idea will spring from. I'm really interested to see other ways of handling the problem.


Thanks,

Jim






So much for the mast bands for now. I'm now working on the boom end fitting. I'll walk you through what's been done so far.

This is actually the second iteration of the boom fitting. Originally I was going to use two tangs, one on each side of the boom and bolted through. This ended up looking clunky, so I put the project aside while I worked on other project. There's something to be said about leaving a project for a while if you're dissatisfied with the way it's turning out. You can mull things over without pressure and see things with fresh eyes when you return. You soon enough forget the effort spent, which makes it easier to scrap a portion and start fresh. It's not all a waste, though, as even effort spent on the wrong track gives you a foundation for new ideas.


The new boom fitting will be, essentially, a cup over the boom end connecting the two tangs running down the sides of the mast. There will be a projection from the center of the front of the cup that will become the pivot for the boom. Don't worry, it will all become clear. The boom will be round all the way to the end, with no additional tapering or flat spots. The boom will maintain its normal taper all the way to the end.


I turned a glued-up block of pine to the diameter of the boom end. This will be the template, around which the pattern will be fashioned. It will eventually become part of the pattern itself.

[Pitsligo]

That's an optical illusion, Alex...

Yep; got it now. Easy to see, once it's pointed out. Thanks.

There's something to be said about leaving a project for a while if you're dissatisfied with the way it's turning out. You can mull things over without pressure and see things with fresh eyes when you return. You soon enough forget the effort spent, which makes it easier to scrap a portion and start fresh. It's not all a waste, though, as even effort spent on the wrong track gives you a foundation for new ideas.

AMEN!!

Is there any chance you could post a picture of the gooseneck here?

It's by no means a revolutionary design. I don't have photos of the patterns, as they're now owned by Port Townsend Foundry --I had an arrangement with them for a while where when I built a pattern for Bucephalus, if it was a broadly-applicable piece of hardware, they'd trade me the finished casting for the pattern-- but here's a photo of the gooseneck itself:



Very basic three-piece: a pad on the mast with two tangs, a knockle that serves as a U-joint, and a two-tang boom-end fitting, rivetted in place. The eye-nut for the tack is a standard, off-the-shelf PTF eye-nut.

Her original gooseneck was much the same, but brazed up out of fairly light silicon bronze plate, and it had started to deform and was heavily worn. I patterned the new one a lot heavier, and had it cast from aluminum bronze (insanely strong), so I don't think it'll go anywhere anytime soon. The original was also pretty clunky, so with the new one I added some curves here and there and made sure all the edges were nicely bevelled.

The mast band I originally envisioned incorporated little wings as bases for halyard turning blocks, to replace the ABI cheek blocks you can see here. It was also a one-piece, Herreshoff-style, like a big hose-clamp, with a pair of bolts on the forward face to tighten the whole thing down around the mast. I changed approach, back to a pad, because I realized that I was trying to make a single piece of hardware do too much, and it was getting clunky. Your approach, quite happily, does not show such tendencies.

Alex

[Ben Fuller]

Catboat that I had, had a double band gooseneck with a rod running between the two bands. This was not uncommon in the big old cats.

[amish rob]

Okay. You guys have convinced me I need to try this. I've never cast metal, but I do know some sculptors that cast bronze all the time, and I have molded and cast many things in many other materials. I can't think of a piece I need, but when I do, I just have to try... Right?

Really amazing knowledge being shared here in the form of questions and answers. I'm not knowledgeable enough to ask some of the questions posed here that have taught me the most.

This may eclipse the catboat thread for quality!

Thanks all.

Peace,
Robert

[Jim Ledger]

It's by no means a revolutionary design. I don't have photos of the patterns, as they're now owned by Port Townsend Foundry --I had an arrangement with them for a while where when I built a pattern for Bucephalus, if it was a broadly-applicable piece of hardware, they'd trade me the finished casting for the pattern-- but here's a photo of the gooseneck itself:



Very basic three-piece: a pad on the mast with two tangs, a knockle that serves as a U-joint, and a two-tang boom-end fitting, rivetted in place. The eye-nut for the tack is a standard, off-the-shelf PTF eye-nut.

Her original gooseneck was much the same, but brazed up out of fairly light silicon bronze plate, and it had started to deform and was heavily worn. I patterned the new one a lot heavier, and had it cast from aluminum bronze (insanely strong), so I don't think it'll go anywhere anytime soon. The original was also pretty clunky, so with the new one I added some curves here and there and made sure all the edges were nicely bevelled.

The mast band I originally envisioned incorporated little wings as bases for halyard turning blocks, to replace the ABI cheek blocks you can see here. It was also a one-piece, Herreshoff-style, like a big hose-clamp, with a pair of bolts on the forward face to tighten the whole thing down around the mast. I changed approach, back to a pad, because I realized that I was trying to make a single piece of hardware do too much, and it was getting clunky. Your approach, quite happily, does not show such tendencies.

Alex

Thanks for posting that, Alex, it's a nicely thought-out and executed design. That's the finish I'm aiming for, smooth cast, but not polished. I like the pin with the eye for the tack, and if you don't mind I'll copy that for my own purposes. You often see the wings for turning blocks, or belaying pin holders incorporated into mast bands, but I won't be doing any of that because the mast hoops chafe the halyards if they are too close to the mast.





Here's the beginning of the boom end fitting. A glued-up block of maple turned round and hollowed to match the end of the boom pattern. The block has a sheet of newspaper glued in the center joint which will allow the turning to be split later on. The hose clamp keeps it from splitting earlier than needed, which it attempted to do several times. To get the match, the boom pattern was shoved, carefully shoved, into the spinning blank. After a short while the points of contact burned slightly and were then shaved off. After repeating this process a couple of hundred times it stated fitting pretty close. In truth, the black smudge you see is from carbon paper, the burning idea came later and worked better.

[PeterSibley]

There's a good reason you didn't see the split, Peter...it wasn't there in Post#8. I had to apply the fillets before sawing the pattern in half.

Thanks Jim. I tend to make split patterns as one piece, 2 sections glued together over a paper gasket along which the 2 halves can be split easily ....then the paper residue scrapped off. I guess I assumed you did something similar. I've tried cutting patterns in half post finishing and messed things up with an imperfect cut.

I don't have your tool skills.

[Pitsligo]

I've tried cutting patterns in half post finishing and messed things up with an imperfect cut.

I don't have your tool skills.

Same here. If I tried that with a bandsaw, it would not have gone well.

Thanks for posting that, Alex, it's a nicely thought-out and executed design. That's the finish I'm aiming for, smooth cast, but not polished. I like the pin with the eye for the tack, and if you don't mind I'll copy that for my own purposes.

You're welcome, and you're welcome to the pin-with-eye approach, too --I was hardly the first person to think of it. Just remember that it needs to match whatever gap exists between your mast and your sail. Tack down your sail too close to the mast, and your mast hoops can bind up. It can also be a bit of a chore, while bending on sail, balancing your foot tension against your luff tension, as the two different force vectors act dynamically on the eye: i.e., you need to allow that your foot will be further tensioned as soon as you sweat in your throat halyard.

Also notice the soft copper washer under the nut of that pin, for bearing surface; it helps keep everything from graunching.

You often see the wings for turning blocks, or belaying pin holders incorporated into mast bands, but I won't be doing any of that because the mast hoops chafe the halyards if they are too close to the mast.

I had certainly seen such arrangements, but I hadn't enough experience, when attempting to design one for Bucephalus, to really work out the best way to do it. As for chafe, I haven't had any trouble with the mast hoops chafing the halyards --which are held very close to the mast by those turning blocks-- but I have had problems with too much friction between halyards and hoops while trying to lower the sail, so that the sail won't come down. The two later hulls of this design took note of the problem, and they have small wooden pads under the turning blocks, spacing the blocks a little way out from the mast, hoops, and gaff jaws. I'm still trying to decide the best way to iron out that bug aboard Bucephalus.

To get the match, the boom pattern was shoved, carefully shoved, into the spinning blank. After a short while the points of contact burned slightly and were then shaved off.

That's wicked clever. I need to remember that. A real advantage to using maple, too, given how well it burns.

Okay. You guys have convinced me I need to try this. I've never cast metal, but I do know some sculptors that cast bronze all the time, and I have molded and cast many things in many other materials. I can't think of a piece I need, but when I do, I just have to try... Right?

Have a look at the thread Brian (Sea Dreams) started. He's got some good stuff: http://forum.woodenboat.com/showthre...all-metal-bits

Alex

[Jim Ledger]

Catboat that I had, had a double band gooseneck with a rod running between the two bands. This was not uncommon in the big old cats.

It's good to see you again, Ben. My plan is to have double mast bands as well, with a swivel between.




The boom tangs will have a rounded inside to fit directly against the round boom without having to plane a flat. In order to pattern this I coved a piece of Cherry to a reasonable fit. The coving setup is shown in the picture, a temporary fence clamped to the saw table at an angle to the blade. Changing the fence angle and blade height while making test cuts lets you dial in to the proper radius after two or three goes.

I'll chop two lengths and saw out the profile of the tangs, and then somehow plane the tops round to match the cove. Something along those lines.

[PeterSibley]

With the pin in this goose neck may I suggest casting the pivot pin shackle attachment at the tack onto a stainless bolt. It sounds strange but I prefer dissimilar metals bearing on each other, bronze on bronze seems to gall sometimes.

[Jim Ledger]

Okay. You guys have convinced me I need to try this. I've never cast metal, but I do know some sculptors that cast bronze all the time, and I have molded and cast many things in many other materials. I can't think of a piece I need, but when I do, I just have to try... Right?

Really amazing knowledge being shared here in the form of questions and answers. I'm not knowledgeable enough to ask some of the questions posed here that have taught me the most.

This may eclipse the catboat thread for quality!

Thanks all.

Peace,
Robert

That's what I like to see, Rob, a guy ready to roll up his sleeves and give it a try! Check out Youtube, type in bronze casting. You'll find everything from casting huge church bells to pouring molten aluminum into ant holes. The latter make amazing sculptures, depending on the type of ants, I suppose.



I've done several threads on bronze casting that might be of interest.


Here's the one where I made the crucible furnace...

http://forum.woodenboat.com/showthre...nze&highlight=


Casting the rudder hardware for the catboat...

http://forum.woodenboat.com/showthre...are&highlight=


A thread about a casting class with Sam Johnson, who, unfortunately no longer gives classes. Sam wrote a very useful reference and guide to amateur casting. Well worth getting a copy.

http://forum.woodenboat.com/showthre...ass&highlight=



...and my favorite, http://forum.woodenboat.com/showthre...ant&highlight= in which I pattern and cast this...








and make this, the steering quadrant for the catboat...









I think there's a few more but these are enough to be going on with.

Jim

[Jim Ledger]

Thanks Jim. I tend to make split patterns as one piece, 2 sections glued together over a paper gasket along which the 2 halves can be split easily ....then the paper residue scrapped off. I guess I assumed you did something similar. I've tried cutting patterns in half post finishing and messed things up with an imperfect cut.

I don't have your tool skills.

Don't be trying that "I don't have your tool skills" on me, Peter Sibley! Rubbish! I've seen pictures of your band mill and bronze winch, among other things.


The mast bands were not paper-splits, instead they were ripped on a bandsaw using a tall home made fence. The boom pattern is a paper-split, as is the maple turning for the end cap.

With the pin in this goose neck may I suggest casting the pivot pin shackle attachment at the tack onto a stainless bolt. It sounds strange but I prefer dissimilar metals bearing on each other, bronze on bronze seems to gall sometimes.

Good point, Peter. I can think of several instances where this is done, turnbuckle clevis pins, the pins in the saddles of gaff halyard blocks come to mind. I suppose if the fitting is not immersed in salt water the effects of contact are mitigated somewhat and the benefits outweigh the disadvantages.



Cheers,

Jim

[PeterSibley]

I still don't have your tool skills, I'm just good at muddling through!

[Jim Ledger]

I still don't have your tool skills, I'm just good at muddling through!

Pretty good muddler myself. Showing up with my shoes on, tape on belt and pencil behind the ear is the best part of what I do.

Gotta go now. There's a hole in my roof.

[amish rob]

Jim and Alex,

Thank you for the links to the metal casting threads. That is a fair amount of staring at a screen.

Jim, as to trying stuff? Well, I only got one shot, that I know of, and the clock is ticking... Seriously, though, one of my colleges (yes, Virginia, I went to a few, and yes, I finished every time) was an art school. I did a lot of time with some people who have gone on to be sculptors, who work in metal.

I have done molding and casting of non-molten things for a goodly part of my life. Plaster, alginate, resin, paper-mache, grp, all that fun crud. Also, I've run a Civil War's worth of round ball and enough jigs for Bill Dance for the rest of his life, to say nothing of the various weighted foils, but lead ain't all in it with hard metals, I imagine.

That said, I do have a few little thingies what I might make. I do got a couple smallish sailboats coming along, a little sailing canoe what could use some fancy hardware someplace, I'm sure, and well...

I will be studying all the linked threads, some of my books, and for sure going to hit up some of my friends about metal casting. I'm sure if someone can cast a human sized chunk of bronze, they can probably help me make some pintles?

Keep up the fantastic work, and I will keep trying to learn enough to stay current. Heheh.

Peace,
Robert

[Pitsligo]

I suppose if the fitting is not immersed in salt water the effects of contact are mitigated somewhat and the benefits outweigh the disadvantages.

Um... yeah! That's *exactly* what I was thinking! (Nope. Galling never crossed my mind. Not even a little.)

With the pin in this goose neck may I suggest casting the pivot pin shackle attachment at the tack onto a stainless bolt. It sounds strange but I prefer dissimilar metals bearing on each other, bronze on bronze seems to gall sometimes.

Fortunately, it's an eye-nut threaded onto a piece of bronze rod, so swapping in a piece of stanless rod will be no big deal if I see that there's any sign of galling --which I will now look for.

...and make this, the steering quadrant for the catboat...

Wow. Just... Wow.

Alex

[PeterSibley]

Robert, may I suggest this forum as a good source of information. http://www.alloyavenue.com/vb/forum.php

[amish rob]

Peter,
You may, you may! Thanks. I don't often wander on the web, so I'm not apt to find such as that.

I should be able to second guess Jim in no time, eh?

Really, thanks. Lots to read and digest. Thanks to everyone. Need I tell anyone here what most people say when I tell them I aim to DO something?

Peace,
Robert

[Jim Ledger]

I look forward to great things from you, Rob. The equipment needed is simple and easily made if you can weld. There's a lot of good furnace designs out there to choose from and simpler is probably better to start. Aluminum has a lot of possibilities and melts easier than bronze. I believe you can melt it in an iron pot, but you'd better check on that first.




Here's the pattern for the end cap. It still has the stub where I chuck it in the lathe, so if I need to I can still do a little refining. It will eventually be sliced of and the knob rounded by hand. The sides of the knob will be sliced off to make two parallel flats.