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Messages - Harold Downey

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61
Work and Events / Re: Coach 9 - Official Work Thread
« on: August 03, 2018, 08:06:53 PM »
Here is the current progress.  Most of the edge pieces had to be made the same way.   Everything is just loosely placed at this point.  I will glue everything down once all the pieces are done.   All that remains on this part of the pattern are the edges to the legs, the feet, and the lettering. 

62
Work and Events / Re: Coach 9 - Official Work Thread
« on: August 03, 2018, 08:04:37 PM »
It goes on the left side, as shown:

63
Work and Events / Re: Coach 9 - Official Work Thread
« on: August 03, 2018, 08:03:51 PM »
Then the part I want is here.

64
Work and Events / Re: Coach 9 - Official Work Thread
« on: August 03, 2018, 08:03:03 PM »
Then the cube is separated into the three vertical stacks.   (the part I want is in the center of the middle stack).

65
Work and Events / Re: Coach 9 - Official Work Thread
« on: August 03, 2018, 08:02:00 PM »
I am adding all the details to the top side mold.  I thought this would be easier.  But many of the edge pieces have 3-D curvature, and I couldn't just bend them out of thin pieces.   For example, here is one of them.  I start with a cube that contains the part I want, and glue paper patterns to two sides.  I cut it on a bandsaw in one plane, then keeping the stack together, cut it in the other axis.   Here is the cube with all the cuts done.

66
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 10:08:50 PM »
Quote
In the Top Side Mold picture we see the lattice work, but don't you need the negative of that?

James, the pattern is a positive shape.  A sand mold gets made from this by packing sand around it, and then extracting the pattern.     Similarly, for the bottom side core box, it is packed with a special chemical curing sand, and extracted from the core box.  This sand core then drops in the sand mold made from the top side pattern.  The resulting space between the two will be the seat frame once filled with iron. 

 The way I am building this is --  that right now, if a mold and core was made from these two as shown, the net space is exactly zero.   So I add material to the top side pattern on the baseline form that exists now.  The lattice work is like that - I just set it on there for the picture.   I know this may not make a  lot of sense.  I keep having to make sketches to keep it all straight in my mind.    Maybe I should post one of those to better describe it. 

So - the lattice is a positive shape.   


67
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 08:07:58 PM »
Here is another view of the bottom side core box, with the seat frame sitting on it, so you can compare.   As you can see there are lots of features to be added to this. 

But the hard parts are done, and the rest will just take some time.    I promise to show the completed versions. 

Harold

68
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 08:05:46 PM »
This is the core box which will form the bottom side of the seat frame

69
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 08:04:46 PM »
Then I finally was ready to separate the two halves.   Shown first is the mold half, which will form the top of the seat frame.   Since this mating assembly as I constructed it, splits on the back surface of the seat frame, this mold will get built up by the thickness of the frame (about 3/16"), and also the side webs and other features will be added. 

70
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 07:59:59 PM »
Then I attached 4 sides to the top half, to form the core box. 

71
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 07:59:11 PM »
After the glue dried (actually its epoxy, so it was an overnight cure), I cut 5 degree angles on all four sides.  This was not as simple as it looks, but I did it on a large bandsaw after a couple of different setup attempts. 

72
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 07:57:03 PM »
Now a side view of the same assembly.

73
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 07:56:25 PM »
Now this frame is placed on the assembly, with glue to attach it to the pieces it touches.   

(I assume everyone knows to click on the picture to embiggen, not the hyperlink below it.)

74
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 11, 2018, 07:54:34 PM »
This will be another update on the seat pattern.  I will do it in a series of posts, so that I can upload pictures and stay under the limit. 

First picture:  This is the frame or skeleton that will become the core box.  It is ready to be glued to the 17 pieces that mate with the top side mold parts. 

75
Work and Events / Re: Coach 9 - Official Work Thread
« on: July 06, 2018, 10:33:34 PM »
Here is what the seat side frame pattern is looking like so far.  This will be the top side pattern.  There are 17 separate pieces here, all loosely assembled on a base plate.  Many of the pieces required curves to be cut in two different dimensions.   Once this is glued up, all the features get added, such as the lips along the edges, the lettering and the feet. 

There will be a corresponding core that will form the underside of the seat frame.   There is a corresponding piece to each of the 17 pieces which will form the same parting line for the core, but looks like an impression of this top side pattern.  You can see the pile of them just to the left. 

This is the most difficult pattern I have done.  It has been a crazy amount of time so far -- over a hundred hours.  A lot of the time is set up, measuring and creating drawings.  I am trying to make it as robust as I can, since this will be used for more than a couple of seats -- 24 just for Coach 9. 

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