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Messages - Harold Downey

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136
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 20, 2015, 09:13:38 PM »
Pattern progress:

This pattern seemed to go really fast at first.  The back portion was large but relatively straight forward, so it went together fast.   The two side wings are taking a lot of time.

Over the last couple of days, I have cut out all the pieces to stack laminate the two sides.  There were a total of 36 pieces required.   In the picture below, you can see where I have glued up two stacks, which will make up one side.   In the foreground are the two templates that I used to generate them.    After I glue up the pieces for the other side, I need to do a lot of hand work to fill the voids exposed in the plywood, smooth the surfaces, then cut to final height.   I am debating whether to cut out the large oval holes for the clean out plug access before final glue up, or do it in each individual piece first. 

137
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 18, 2015, 09:01:55 PM »
Rear extension casting pattern:

Sorry, no pictures today.    Progress is not quite so visible.   All four of the flanges for the two sides were cut out, cleaned up to their lines, then tapered by hand on both sides to achieve the required draft.  I then made a full size template for the inside of the "U" to use to fine tune the fit of the flanges to the back portion of the pattern.  They are now all tuned up and ready to go.

Next I need to make the vertical portion, the web the connects the top flange to the bottom flange.  I am going to stack laminate them from plywood, so each layer has the shape of the cross section.  I am preparing two templates to use for these, since I will need to cut out and stack 16 pieces of 3/4" thick plywood for each side.   It is really amazing how much plywood a pattern can eat up.  Just the four flanges took almost a 1/4 sheet of 3/4 ply. 

138
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 16, 2015, 10:32:55 PM »
I didn't have too much time to spend today, but I got a start on the top and bottom flanges of the two side wings.  I printed out the drawing full size (it took four pieces of paper to fit), glued it on the wood stack for both the left and right flanges, then cut it on a band saw.

The second photo shows how it fits on the main back portion of the pattern. 

Each of these I will need to taper to get the required 2 degrees of draft. I can't think of a way to do it with power tools, so I will mark the finished width along the outer edge, and use a hand plane to taper it from the inside down to the final outside thickness.  Since there are four of them, it will take a while.

139
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 10:35:45 PM »
Daily progress update: 

I glued up material for the top and bottom flanges of the side wings.  I cut the 40 degree separation line where the back will join to the sides, and also made the flanges that stay with the back portion, and glued them on.   

The 40 degree cut was interesting, since I could only achieve 45 degrees on my table saw with the pattern laying flat.  I then used a hand plane to bring it down to the line. 

The flange sections started as glued up plywood to the thickness I needed, then planed to get a 2 degree draft on both sides (using the planing jigs that Alan came up with).  I printed out full size patterns for their shape, glued it on the surface, cut them out on a bandsaw, and used my hand plane to flatten the mating/gluing surface.  Note the dovetail feature which will interlock with the corresponding flanges on the sides (once I make them).


140
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 07:08:45 PM »
James,  the back side of the pattern will be filled completely at first with a wooden construct called a follow board.  It will be flush with the back surface, where the mold will split, and extends out top and bottom a few inches.    After sand is rammed up over the outside of the whole thing, the follow board is removed, the sand is dusted with parting compound, and more sand is rammed up in place of the follow board, forming a core.  The core comes out; then the pattern is removed in three pieces, then the mold is put back together for pouring. 

See Alan's sketch below; the follow board is the red part:

141
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 12:44:52 PM »
To answer Bernie's question, I will explain how we decided to make this pattern.

If you look at the picture, we are creating a split line on the pattern along the dashed line B-B, so that the sides with the washout holes are separate, and can be withdrawn from the sand at the angle of the washout holes.  Then the back portion comes out perpendicular to its plane.  That way we get all the holes without cores, and the amount of draft required is minimized. 

142
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 12:34:33 PM »
Here is an image of the solid model that Alan did in Solidworks.  It gives a pretty good idea of the complexities of this casting.  There are washout holes in the corners that are at 40 degrees -- how can this be pulled from the sand if these are to be cast in? 

143
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 12:14:46 AM »
I started this on Saturday, laminating up most of the material for this part of the pattern.  Today I got this far:  I added the two large wings that stick up vertically, and the small horizontal connectors between the rings around the holes.   The two large wings are glued, but also backed up by some 2 1/2" screws to reinforce the joints.  I will have to plug the holes from the screws.   Eventually all the outside corners need to be rounded over, and inside corners need fillets. 

Stay tuned, more updates to follow.



144
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 15, 2015, 12:03:54 AM »
Then I added two thickeners on the ends,  as well as the top and bottom flanges.  These flanges are laminated up, then tapered with the appropriate draft.   I glued these on, and put in some screws from the back to make sure they stay on. 

145
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: January 14, 2015, 11:59:27 PM »
I am going to start a short series of posts on the pattern for the rear frame extension casting.  This is the second largest pattern for the locomotive.  Overall it is 56 1/2" wide by 15" tall and 20 3/4" long.  Estimated weight of the finished steel casting is 521 lbs.

The function of this casting is to connect the forward frame to the rear frame just in front of the firebox.  If you recall for #9, it needed a similar casting when it was rebuilt. 

The first thing I did was take the CAD drawing and add machining allowance and draft.  Then I scaled it by the expected shrinkage of 1/4" per foot.   

The plan that Alan and I worked out for this casting is to break it into three parts, and to back it up with what is called a 'follow board'.    This allows the pattern to serve as its own core box (to form a core), and to be able to extract the pattern from the sand mold.    This will become more clear as the build progresses.  Just follow along and see. 

I started with the largest piece, a rectangular piece of plywood, laminated up to 1 1/64" thick, 2 degrees draft on all sides, and three 8" holes.  The holes are reinforced by a 3/4" wide ring, which also gets 2 degrees draft on both sides.



146
Work and Events / Re: WW&F No. 9 - Official Work Thread
« on: November 13, 2014, 03:15:49 PM »
Here is a better comparison, both from a similar oblique view:

147
Work and Events / Re: WW&F No. 9 - Official Work Thread
« on: November 13, 2014, 03:14:51 PM »
A new pattern for Number 9 number plate that reproduces the plate used by the WW&F.    Compare with the historical photograph from the WW&F roundhouse machine shop.

148
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: October 07, 2014, 09:16:56 PM »
Finally the nearly finished core box for the main core.  Since it is so big and complex, I tried something new:   I made a positive of the core (shown to the left of the core box), and used that to make a plaster mold.  The plaster mold is the core box.  It took nearly 50 pounds of plaster, and I had to do some repair work after making the casting to fill voids.  Then I sealed it with a few coats of polyurethane.  Finally it will get a nice shiny coat of orange as well. 

Thanks go to Alan for helping me figure out how to do this, and also all his helpful jigs and fixtures for making 2 degree draft features, and many other tricks and shortcuts. 

149
Work and Events / Re: WW&F No. 11 - Official Work Thread
« on: October 07, 2014, 09:16:19 PM »
I am nearly finished with my first pattern for #11 - the lead truck center casting.   It is pretty complex -- there are three cores, one of which is very large.   

First a sketch in isometric view of the casting as it should look when finished.

Then two views of the main pattern with the two small core boxes.  Orange in this case indicates where cores go on the pattern (called core prints), and the core boxes, which are similarly color coded.

150
Work and Events / Re: WW&F No. 9 - Official Work Thread
« on: August 16, 2014, 01:25:32 PM »
Much work has been done this week, especially with the injector piping.  Please go to the museums' facebook page for photos and to find out who put in A LOT of time on the project.  Hint: His name begins with J but it's not Jason  ???

Stewart,

Could you please post some of the photos here as some of us don't have a face book account and with out one they will not let look at the photos.

Andre

Andre,

Writing as a member of the facebook illiterati <grin>, I can understand why you think you need an account.  I first tried to find it on facebook and it did seem to insist that you sign up before letting you in.  Fortunately, that is not the case.  My best method to view the WW&F facebook page is to go to the official WW&F website, and click on the facebook icon (the lowercase white f in a blue circle), and it takes you right there.  Click on any picture to view the whole album. 

Harold

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