Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 9123 times)

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #210 on: February 10, 2019, 12:33:36 AM »
Thanks Roger! Yes, those bricks are a big help.  I've often thought I should get another set.  I keep wishing I had one or two more!

Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #211 on: February 10, 2019, 12:40:38 AM »
My how time flies!  Not a lot of shop time over the last few weeks, but I finally got some time today. And it was quite enjoyable!

Last time Iíd just started bending the Tie Bars.  I started with them because they were only 1/16Ē thick.  The Arch Bars are 3/32Ē thick! Thatís getting pretty substantial!

After I bent the middle bends, I used the hole jig to drill the two middle holes to attach the columns.


I wasnít very happy with how this went.  It worked, but it just felt squishy to me.  I could wiggle the bar back and fortha bit and it just didnít feel as precise as I would like.


Regardless, I finished up bending the four tie bars.  This wasnít a fast process.  It took 15-20 minutes per bar to get things bent correctly so that it all lined up, wass just the right height, and didnít have any twists in it anywhere.  I just found it took a lot of tweaking.


For the next set of bars (Lower Arch Bars) I used a different technique.  I calculated the location of the center holes and drilled them first.


Then I marked the locations where the bends should go.


The problem with drilling the holes first is that when you go to bend the bars, it wants to bend in the weakest spot Ė right where the hole is!  :Duh: But, as long as I clamped over the hole and bent the other side it worked just fine.  And I feel that the holes came out much more predictably.

Hereís one of the Lower Arch Bar fitted to the bending pattern.  Again, quite the time consuming process.


And this picture shows the set of 12 bars with the column holes drilled and bent to shape.


To drill the outer holes (the ones for the journal boxes) I was going to go back to the drilling jig. But before I did that, I needed to re-make the hole guide.  Turns out that my first attempt had a couple of problems.  First, the cross bar was too flimsy (I used 1/16Ē sheet material).  And second, the holes werenít centered.  They were in the correct positions lengthwise, just not centered.  So, I made a new one using some 1/8Ē 1018 steel. This one turned out much better.  The bottom one is the original one (note the non-centered holes), and the top one is the new one (with the more centered hole pattern).


And hereís how I drilled the holes for the journal boxes.  Attach one of the bars to the jig, like so:


Flipping it over, you can see the template with the hole pattern.


Then I just drilled the holes!  The little brass bar clamp is just to keep the bars aligned with the jig.


And did the same thing with the Upper Arch Bar and the Tie Bar (they are the same, with the exception of the thickness of the bar).


And finally, we have all 12 bars bent and drilled!


By this time it was getting to be the end of my shop time but I just had to get one of the frames assembled:


You canít imagine how happy this little piece here made me!  I still have to cut the bars to the correct length, but thatíll be the next step.

Getting close to having the trucks complete!

Thanks for looking in,
Kim

Offline b.lindsey

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #212 on: February 10, 2019, 12:47:31 AM »
That is a lot of tedious work there Kim, but it sure looks good assembled. One down, three to go  :cartwheel:

Bill

Offline Dave Otto

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #213 on: February 10, 2019, 01:10:35 AM »
Nice progress Kim!

Dave

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #214 on: February 10, 2019, 01:17:07 AM »
Very nice!

Those little brass bar clamps are handy, got a set of those that come out once in a while for holding bits on.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #215 on: February 10, 2019, 05:46:22 AM »
Thanks Bill, Dave, and Chris,

Yeah, those little brass bar clamps do com in handy from time to time.  You can't exert a lot of pressure with them, but for little things like this, the work great!  Those are from back when i was doing some ship modeling.

Kim

Offline Ye-Ole Steam Dude

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #216 on: February 10, 2019, 10:04:00 AM »
Hello Kim,

Coming along quite nicely.

Have a great day,
Thomas

Offline Steve17

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #217 on: February 10, 2019, 01:02:38 PM »
Really taking shape now, it sure is time consuming putting holes in bent bars and getting it all to tie up.

Steve.

Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #218 on: February 10, 2019, 01:04:04 PM »
I hadn't seen that type of bar clamp before.  Looks useful.  Good progress being made.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #219 on: February 10, 2019, 04:26:34 PM »
Thomas, Steve and Kvom,
Thanks for stopping by and taking a look!  I do appreciate it :)

Kim

Offline Admiral_dk

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #220 on: February 10, 2019, 10:01:41 PM »
Very nice build so far Kim  :praise2:

I'm enjoying your progress and parts made  :cheers:    :popcorn:

Offline Tennessee Whiskey

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #221 on: February 10, 2019, 11:33:50 PM »
Really nice Kim. I admire how you try to hold everything to the closet tolerance in the beginning and that pays off in the end. If you have more bending to do, think about hardwood dies. They can easily be cut and shaped, the grain isnít going to split, and, you can easily adjust angles for springback. For thinner stocks, something about the wood makes things slide easier.

Cletus

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #222 on: February 10, 2019, 11:40:37 PM »
Thanks Admiral and Cletus,
Hadn't thought about using Wood for a die for bending... Wonder if it would hold up to repeated use (repeated 10-12 times).  The Aluminum jaws on my vise were starting to deform some on the edges after working over the dozen parts I had to make here!
Interesting idea for sure.  One I'll have to consider in the future :)  Guess its not that much different than using hard wood for forming copper, eh?
Kim

Offline matthew-s

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #223 on: February 11, 2019, 01:24:52 AM »
Nice work! I found the arch bars to be tricky - and that was with brass!

Figuring out where to start the bends, especially on the ends that hold the axle blocks, was particularly fussy - itís hard to get the height right while nailing the position of the bend. Too long and it interferes with the screw heads (especially if using  hex heads). Too short and it does not look right, or at least hard to get them to look identical front to back.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #224 on: February 11, 2019, 05:22:59 AM »
Thank you Matthew!
Yes, those were quite the fiddly bits to be sure!

I'd love to see your Pennsy.  Do you have a build thread going?  Don't remember seeing it.  If not, you should one and post a few progress photos!

Kim