Pennsylvania A3 Switcher (Kozo)

[Kim]

Thanks Roger and Don! 

Yes, a bit more work with the brown stuff then I'll get on with the copper (and rereading Mr A.Neils book!)

Kim

[Kim]

My plan was to finish up the formers today.  But as we all know too well, things don’t always go according to plan!   

Things started out good though, with centering the Backhead Formers on the rotary table and milling the round part to the correct dimension.  I had to shuffle the clamps a few times to get all the way around, but that's doable!


Then I rounded over the outside edge of the former.


I’ll come back and finish up the straight parts of these formers later.  For now, I wanted to complete all the RT work while I had that centered up.  So it was on to the Throat Sheet Formers.  A couple of things here; first, I decided to add a couple of screws through the whole stack to make sure the formers stayed in place during the milling.  And second, I realized just in the nick of time, that the inside former and the outside former have DIFFERENT radii for their curved portions.  Duh… That’s what I get for doing the layout work and then taking a 2 month hiatus!  But luckily, I realized it in time and just did the top former first.  The bottom one has a larger radius, so I’ll be separating the two before I do that one.  Here I’ve just completed cutting the radius of the top Throat Sheet former.


As with the Backhead Former, I’ll come back and do the straight edges on this one later.

Now, on to the larger of the Throat Sheet Former.  But here’s where I discovered my rookie mistake!  I hadn’t given any thought to the direction of the grain on the wood. The top piece was accidentally oriented correctly.  But the bottom piece – well, you can see what happened when I tried to cut the arc there.


I've done enough wood work to know this.  Guess it's just been long enough since I've done any significant work with the brown stuff that I've forgoten my woodworking chops. Well, nothing for it but to try again.  So, raiding my stash of old well-cured cradle wood, I cut another piece for the larger of the Throat Sheet Formers.  This time, I cut it with the grain running in a more optimal direction, and I made it a bit larger in both dimensions.  Now I’ve got the new piece set up and in place on the rotary table.  But I’m going to leave the cutting till tomorrow.  It’s past my shop witching hour, and it never goes well if I stay out in the shop past the witching hour!


Here’s where I’ll pick up my tale tomorrow. 
Kim

[crueby]

If you continue to have problems with the wood splitting, see if you can pick up some white oak - it has a much more interlocking grain, a lot harder to split. I was lucky to have some left over from a boat keel/stem project.  Red oak has a linear/tubular grain, white oak would be better.
Fun fact with red oak - if you  have a straight grain length of it, dip one end in water, and blow in the other end, bubbles will come out in the water! The tubular grain is a lot like a bundle of straws. Yes, this really works!


Or, if you are more comfy with metalwork, you could always make the formers out of some big chunks of steel!  (Just kidding - doubt it would work that well, it would tend to squish the copper with the hammering rather than giving/rebounding like the wood does).

[Kim]

If you continue to have problems with the wood splitting, see if you can pick up some white oak - it has a much more interlocking grain, a lot harder to split. I was lucky to have some left over from a boat keel/stem project.  Red oak has a linear/tubular grain, white oak would be better.
Fun fact with red oak - if you  have a straight grain length of it, dip one end in water, and blow in the other end, bubbles will come out in the water! The tubular grain is a lot like a bundle of straws. Yes, this really works!


Or, if you are more comfy with metalwork, you could always make the formers out of some big chunks of steel!  (Just kidding - doubt it would work that well, it would tend to squish the copper with the hammering rather than giving/rebounding like the wood does).

Good point on the oak.  I'm hoping the well-aged maple will be fine, but I guess we'll see tomorrow.

Interesting fun fact, too! 

Kim

[internal_fire]

I usually make the former for the forward flange (around the boiler tube) wider to avoid the breakage problem. There is no limit other than the amount of wood used. The side former needs to be the correct width, of course, but the interior shape is mostly unimportant. I have never had any problem with the side former, but it could be made sturdier by creating a smaller cutout.

Gene

[Kim]

I usually make the former for the forward flange (around the boiler tube) wider to avoid the breakage problem. There is no limit other than the amount of wood used. The side former needs to be the correct width, of course, but the interior shape is mostly unimportant. I have never had any problem with the side former, but it could be made sturdier by creating a smaller cutout.

Gene

Thanks Gene,
Very good point!
Kim

[Kim]

Today I was able to complete my plan of finishing the formers for the boiler.  Yay!

Continuing on with the front Throat Plate:
This time around, I decided to try something different.  I chose to use the chain drill method to make the arc in the front Throat Plate Former.  This was a great idea and made the whole thing go quite fast.  You can drill holes in wood very quickly compared to metal!


Then I cleaned up the arc with an endmill and widened it to the specified size.


Before I took it off the rotary table, I did the 1/16” round-over.


Using the bandsaw, I separated the upper part, which is scrap, from the lower part, which is what I want to keep!


And finally, I trimmed it to the specified height.  I’m not sure how important the height is, but since Kozo specified it, I did it.  Guess I’ll find out in a bit if the height is important.  As Gene mentioned in his above post, the width for this former is not critical, so I made it wider to help keep the tips from breaking.  And orienting the grain the right way also helped.


The rear Throat Plate Former and the Backhead Former are the same width (in the bottom half, that is) since they will define the front and back of the outside of the fire box.  So I did these formers together by double-sticky taping the rear Throat Plate former to the top of the Backhead Former stack. The width needs to be centered on the boiler, and since I already cut the arc for the boiler I need to keep that centered.  To do this I clocked in on the center hole using a gauge pin and drilled another 1/4" hole in line with it on the center of the formers.


Now I could use a couple of 1/4" drill bits to suspend the formers in the vice and mill each side down the same amount till I’d reached the desired width.  I did this in several steps, flipping the parts each time and taking the other side down to the exact same level (without moving the depth of the mill).  This worked quite well, though was somewhat tedious.  I also worked carefully to avoid chipping out the sides of the formers along the grain.


Now my next problem was getting the formers apart.  I don’t think I’d have had ANY problem with them separating.  I began to wonder if I’d ever get them apart without breaking them, but eventually, I did.  I usually take some old (dull) razor blades and pound them (carefully) between the two parts and eventually the tape will let go.  But this time it took a LOT of persuading.  You can see I even broke one of my dull utility blades. Glad I had my safety glasses on!


And finally, I put the Backhead and rear Throat Plate formers together (end to end) and rounded over the straight edges.  This gave me a continuous roundover on the Bakchead former and just the sides on the rear Throat Plate, which is all that is needed.


And there they are, the whole happy Former Family:


I'm happy to be done with the wood!  Not that I mind it too badly, I've done a lot of woodwork in the past, but I forget how far and wide wood swarf travels!  Metal swarf tends to spread in line of site from where you're working.  But sawdust goes EVERYWHERE!  What a stinking mess!  Before I packed in for the day I vacuumed up all my wood swarf so I'd have a clean place for my meat swarf to land.

And tomorrow is copper day!  Yipee!
Kim

[crueby]

Nice!  Going to be shaping copper soon, got my popcorn ready!

What are you going to be using as a hammer? Do you have one of the plastic forming mallets? You don't want to use a metal head hammer or it will dent the copper too much.

[Kim]

I've got a couple of options on mallets.  I have a rubber mallet, a wood mallet, a plastic mallet, and a brass hammer.  Then we get to the ball peen hammer and your basic claw hammer, plus a small sledgehammer.  I'm sure something in there will work! 

When I was shaping the copper for the tender tank I used the plastic mallet and the brass mallet a little, which seemed to work quite well.  So I'll likely do the same here.

Kim

[cnr6400]

 

[Jo]

I've got a couple of options on mallets.  I have a rubber mallet, a wood mallet, a plastic mallet, and a brass hammer.  Then we get to the ball peen hammer and your basic claw hammer, plus a small sledgehammer.  I'm sure something in there will work! 

In the UK we have a book "Model Locomotive Boiler Making" by Alec Farmer - It is considered to be the Bible on copper boiler making.

Alec recommends using a large 16oz flat-faced planishing hammer. This is one of those hammers with a large flat steel face that is used for shaping sheet metals. Looking at the pictures in the book I suspect he is using a couple of the hammers that you find in the cheap car body repair hammer sets  as I also spotted a cross-face hammer being used for the internal curves.

When years ago  I made my two boilers I followed Alec's recommendations and it worked for me   

Jo

P.S. Alec does say do not use a wooden hammer as the copper will quickly destroy it 

[Kim]

Alec recommends using a large 16oz flat-faced planishing hammer. This is one of those hammers with a large flat steel face that is used for shaping sheet metals. Looking at the pictures in the book I suspect he is using a couple of the hammers that you find in the cheap car body repair hammer sets  as I also spotted a cross-face hammer being used for the internal curves.

When years ago  I made my two boilers I followed Alec's recommendations and it worked for me   

Jo

P.S. Alec does say do not use a wooden hammer as the copper will quickly destroy it 

Yeah, I can see avoiding the wooden hammer

But using a steel hammer seems surprising to me since it seems it would leave marks on the copper.  But maybe those flat, smooth-faced planishing hammers wouldn't?  I don't have one, so likely won't use it. But who knows?  maybe I'll pick one up at Harbor Freight! Always need a new tool, right?

Kim

[crueby]

I've always used the rounded end plastic hammers for boiler work, like Kozo shows in the books. Works great. When I took a copper bowl making course they taught using the planishing hammers, but there we were  just gradually stretching the metal into curves, not putting in tight corners and shrinking the metal like on the boiler flanges. The rounded plastic one won't dent in the edges of wavy sections like you'll get on the forms.

[john mills]

i have always just used a normal hammer the thicker copper for boilers don't hit on the corner radii more around the edges .
how thick is the copper for this boiler .
when at tech school from form one doing copper and brass work we only used a normal hammer engineers ball pien just make sure it has not got bumps  and sharp burrs or nick's which will leave similar marks in the copper you want the face smooth .
john

[Kim]

The boiler is made from 0.080" thick copper sheet.  I think that's fairly hefty copper!

My plan is to use the plastic (round end, as you describe, Chris) for most of the forming operation.  Though for some places a ball peen hammer may be used (Kozo says this is OK in his book, as long as you don't dent the copper).  While forming the rounded parts of the tender tank I also used a piece of wood to help apply pressure on specific areas.  I'd hold the wood like a punch to focus on one area and whack the other end of the stick with a hammer. I found this helped me get to some more recessed areas that the flat plastic hammer had a difficult time reaching.  And if my piece wood was destroyed in the process, I didn't much care.  I could just find another one

Lot's of annealing steps helped too!
Kim