Pennsylvania A3 Switcher (Kozo)

[cnr6400]

 

[Dave Otto]

Hi Kim

The ash pan turned out great!

Yes, sheet metal will always stretch through the bend, this is something that people who work with sheet metal deal with every day. On a press brake with known material and tooling it is somewhat easier to predict, but there is always variables that will change things.
The easiest thing you can do is take a strip of the sheet that you are planning to use, say 1"X 4". Measure the length and then bend it 90 degrees, approximately in the center across the short direction. Use the same method that you will use on your actual part. Measure the outside length of each leg and add them together. Then subtract the original length value from the sum of the two folded legs. This will give you your outside bend deduction. this amount needs to be subtracted from your flat pattern for each bend. Bends less than 90 will take some trial and error to get the proper bend deduction. We have sheet metal software at work that does a pretty good job of this, once you have a good value for the 90 degree bend.

Hopefully this helps some.
Dave

[crueby]

Great info guys! Have not done much sheet metal work, so I would have guessed the opposite.   

[Kim]

Hi Kim

The ash pan turned out great!

Yes, sheet metal will always stretch through the bend, this is something that people who work with sheet metal deal with every day. On a press brake with known material and tooling it is somewhat easier to predict, but there is always variables that will change things.
The easiest thing you can do is take a strip of the sheet that you are planning to use, say 1"X 4". Measure the length and then bend it 90 degrees, approximately in the center across the short direction. Use the same method that you will use on your actual part. Measure the outside length of each leg and add them together. Then subtract the original length value from the sum of the two folded legs. This will give you your outside bend deduction. this amount needs to be subtracted from your flat pattern for each bend. Bends less than 90 will take some trial and error to get the proper bend deduction. We have sheet metal software at work that does a pretty good job of this, once you have a good value for the 90 degree bend.

Hopefully this helps some.
Dave

Thanks, Dave!
That is very helpful!

I've just always tried to make sure I add any features that require accuracy AFTER the sheet metal has been bent to it's final shape (like I did here).  But the problem with that, of course, is that it's harder to hold onto when it's not flat!  If one could learn to predict where things will end up after bending, one could do these ops while the sheet is flat and easier to deal with.  I'll have to try that method sometime!

Thank you for the detailed response.  I really appreciate it!
Kim

[kvom]

The good news is that the ash pan can end up a little narrower without causing a problem.

[Kim]

Very true, KVOM.

Kim

[Kim]

Chapter 22.4 – Ashpan Latch and Spring Hanger
With the major pieces of the Ashpan complete, all that’s left are a few little bits.  But they’re complex bits.

I cut a piece of 1/16” 304 stainless steel sheet for the latch and spring hanger.  After getting it to the required size of 0.240” (just a tich under 1/4") I drilled all the required holes for the parts – one part on each end.


One of the holes is actually the hook for the latch so that needed to be opened up.  I did this with a 1/16” end mill.


With all the major features in place, I cut the part in two and rounded the ends, like so:


On the lathe, I churned out a bunch of little round pins of various descriptions from some small 303 rod.  These will all be silver soldered into their respective holes.


But before I do that, I needed to shape the spring hooks (the center pin on the left, and the lower pin on the right in the photo above.  I did this by holding the little end in a 5C collet and milling the shape, as shown here:


Then drill the hole for the spring:


Then to the hearth where I silver soldered the pins in place:


Here are the two parts after a bit of cleaning.  I left the insertion pin long on several of the parts to ease the silver soldering step.  So now I have to clean those up.


I did that using a combination of belt sander and filing.  And here are the completed latch (on the left) and the spring hanger (on the right).

[Kim]

Chapter 22.5 – Pins
The next item were the pivot pins for the ash pan.

These were also turned on the lathe from 303 stainless rod (1/4”).

[Kim]

Chapter 22.6 – Spring
The final part of the ashpan assembly is the spring.

I made this in the lathe using stainless steel wire. I first stretched the wire to work harden it.  Then wrapped it on a mandrel in the lathe.  I just hand-turned this – it is an extension spring, rather than a compression.  So the winding spacing was easy to do manually.


After bending the ends of the spring into hooks, I assembled all the pieces on the grate support.


Next, I put the ashpan in place and marked the location for the ashpan latch pin (You can see the scratch marks in the ink just behind the latch mechanism on the right).


Lining this up on the mill, I drilled a hole for the pin:


Then soldered it in place:


And there you have it – a completed ashpan!


I took a short video of the ashpan latch in action - it has such a satisfying feel to it!
<a href="https://www.youtube.com/watch?v=oGuYr294iJM" target="_blank">http://www.youtube.com/watch?v=oGuYr294iJM</a>

The next step is the boiler!  It’s a rather intimidating element to launch into but I’m quite excited to get started on it!  Though it may be a few days yet.  I have some household things I need to attend to.  But I really wanted to get to this point before I took a break to focus on domestic activities for a bit.  I’m excited to begin work on the boiler!

Thanks for stopping by,
Kim

[crueby]

Excellent!!  And very nice that you gave your shop elves a way to flush...   

[Kim]

Yes!  Definitely!  Elf hygiene is very important in the shop! 

Kim

[cnr6400]

That's a beautiful latch / unlatch action Kim! Careful you don't get LDEGv* though.     


*LDEGv= latch detent euphoria, Goldilocks variant , commonly caused by machine builders operating mechanisms that are just right  .....   (very common when building Kozo's designs) 

[Don1966]

Outstanding work Kim! Your soldering skills are excellent you should have no problem with the boiler fab and soldering……….I ……….likeeeeeee….



 
Don

[Kim]

That's a beautiful latch / unlatch action Kim! Careful you don't get LDEGv* though.     


*LDEGv= latch detent euphoria, Goldilocks variant , commonly caused by machine builders operating mechanisms that are just right  .....   (very common when building Kozo's designs) 

I may already have LDEGv and not even know it!   

Thanks CNR! 
Kim

[Kim]

Outstanding work Kim! Your soldering skills are excellent you should have no problem with the boiler fab and soldering……….I ……….likeeeeeee….

 
Don

Thanks Don! 
That's very kind of you.  But anything I know about silver soldering, I owe to you and others on this forum who so kindly and patiently walked me through my training for all these years! 

Kim