Thread: A Lighthouse Keepers Cabinet

Originally Posted by auscab

The top piece under the glass is constructed in cast iron . You can see the Pattern makers joinery work in the casting near one of the doors up there in the picture on the right. That's interesting because the pattern maker would have needed either a reverse moulding plane to do that or he may have used a scratch stock ?

Edit . I just checked on this and spindle moulders were being used at this time . So moulding planes and scratch stock were not needed in the big industrial workshops of the time that could afford the new machinery.


He had to make a reverse of the pattern in timber so that the casting would show it the right way . If it were moulding planes then he had to go to a plane maker and order a reverse plane , which the plane makers made for themselves to produce moulding planes with . The company who made the light house was making and shipping them where needed I'm pretty sure I remember reading . So numbers of them would have been made . How many I have no idea?

Hi Rob

I'm a little confused by your comments.
At the time carriage maker's molding planes, routers (and another specialist tool I can't recall the name of but in use it was used in a manner similar to a croze) would have been available as either a "make your own" tool or for purchase from a merchant.

But, I'm thinking that the pattern maker would have made a wooden original (with draws, etc) which would then be used to make the sand mold.
Am I missing something?

Hi Ian . I dont know a lot about pattern making . Which is why I’m changing from one thing to the other a bit later . I read about it and have books on it and am even lucky enough to have an old pattern maker friend to ask if I want . A lot of it can be hard to grasp because you have to think in reverse sometimes . What I am guessing at and find interesting is the woodwork panel and frame look in the cast iron . I’m guessing the pattern placed in the sand is wood as normal and , oh hang on ! You don’t need a reverse if it’s done like that with the mould . Another correction is due ��.
What I was getting at was though was it’s not planes or hand tools because spindle moulders were around then. For either way the moulding was done , normal or reverse . It’s normal though . Sorry .

I didnt understand what you meant by Draws , do you mean draw shaves and knifes or something like that to mould the timber pattern ?

Originally Posted by auscab

I didn't understand what you meant by Draws , do you mean draw shaves and knifes or something like that to mould the timber pattern ?

If I am correctly describing the terminology, a "draw" is a reservoir of molten metal that is drawn into the casting as the molten metal cools and contracts.
I think it also refers to the channels left in the mold that allow molten metal to get to all parts of the casting while the melt is still very hot and runny. (How's that for a technical term "runny"? )

Again, as I understand the technology, part of a pattern maker's core skill set is the sizing and placement of draws in the pattern.


as to how the curved panels were made. My thinking is that moldings on curved surfaces were the bread and butter of carriage makers and those craftsmen had the specialist tools required. Meaning that pattern makers also had access to those tools.

I am a patternmaker and have no idea what you guys are talking about.
You can see the Pattern makers joinery work in the casting near one of the doors up there in the picture on the right. That's interesting because the pattern maker would have needed either a reverse moulding plane to do that or he may have used a scratch stock ?

Originally Posted by artful bodger

I am a patternmaker and have no idea what you guys are talking about.
You can see the Pattern makers joinery work in the casting near one of the doors up there in the picture on the right. That's interesting because the pattern maker would have needed either a reverse moulding plane to do that or he may have used a scratch stock ?

Lol ..

Forget what I said there . I had it the wrong way around.

Rob

I was talking about these cast iron panels. The round structure is just made of cast iron panels bolted together I think. I didn't take pictures of that and its been over ten years since I was there.
Some of it looks like normal woodwork joinery . I would assume the pattern was just made close to what it would be if the piece were just being made of wood and not being cast? What I got mixed up with is the mouldings , thinking they may have to be made in reverse so it could be cast . Pretty sure I got that completely wrong . Wouldn't it be made as normal and that just used as a pattern ?

IMG_0667b.jpg

When I first read Ian’s comment re draws I thought he meant draft ie the taper wot allows the pattern to be with-drawn from the sand.
But I agree as another pattern maker that I have no idea what they are on.
Its probably good stuff if you know where to get it
H.

Originally Posted by clear out

When I first read Ian’s comment re draws I thought he meant draft ie the taper wot allows the pattern to be with-drawn from the sand.

OK, so I haven't used the right terminology.

when you cast a large thin object -- like the curved wall panel in Rob's post -- how do you ensure enough hot melt gets to the points furthest from where the melt is poured into the mold and how do you ensure a relatively constant rate of cooling so the panel and far corners don't warp through uneven contraction.
I thought the process to minimise uneven contraction was to include reservoirs of melt in the mold and for some shapes these reservoirs were crafted as part of the pattern. (The core box plane being one example of a tool used to shape these reservoirs.)

I have zero experience as a pattern maker. It was a trade I was interested in as a school leaver.

As an improvisor and maker of "do", I propose that the following is possible with regard to the issues with casting thin, large panels cast in metal.

Might it be that the mould would be put near the furnace for quite some time so as to be as hot as possible when the pour happens? Post pour, I suppose It would be wise to leave the mould where it is, next to the furnace for some time so as to encourage slower cooling and less chance of cracking and breaking? That may be days to move the item to where the next lot of work takes place.

Like I say, I'm just guessing. Fun to speculate.

Cheers

as you say fun to speculate.

one of the things I'd like to know is did the pattern maker build an entire light house or just two or three panels.
Building a limited number of panels implies that the designer and his pattern makers were sufficiently skilled that they could cast multiple copies of the same shape and use them to assemble the completed light house. Building a pattern that represented the entire light house is an interesting comment on the then extant foundry skill skills.

To be honest i would suggest there would have been a limited amount of moulds that would have been used to make the "whole".

It is, and always has been, not much more than measurements, allowances and tolerances to make an item like that. Work it out, draw it, make it.