Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 29047 times)

Offline rklopp

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #285 on: April 03, 2019, 12:50:48 AM »
I love form taps for making threads in softer metals like 1018 even when hand tapping. I avoid cut taps whenever possible. I am surprised yours broke, especially if going for 60% thread. Did you use the tap drill size for 60% thread based on form tapping or cut tapping? My form tapping charts say to use a #43 drill @ 0.089" to get a 70% thread. A 2.3-mm drill would get you to 60%. I would expect to feel the driving getting really hard before you reached the tap's limit. The only time I have broken one is in the CNC by rapiding into the work after fat-fingering a bad Z value.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #286 on: April 03, 2019, 05:16:07 AM »
Thanks for the reply Rklopp,

Yes, this has been my experience (limited though it may be), that the tap gave me very clear signals when it was at the bottom.  It wasn't hard to feel the difference and to know when to stop.  Even in the 1018.  I'd done quite a few holes in 1018 in the past, and 7 others in these pieces just that same day.

But you're right - I was using a #43 drill and that results in a 70% thread, not the 60% that I claimed.  I don't have a 2.3mm drill.  Maybe I should get one though.  60% should be plenty for anything I'm doing here.

Well, I did order a nice Union Butterfield cutting tap to try out (it just arrived today).  It's surprising the difference you can feel in the sharpness of the tap compared to the import cutting taps I have.  I will likely give that a try on some of the steel too.

But it's nice to hear that you use the form taps in 1018 too.

I'm leaning toward the theory that I was getting careless in my excitement to finish the job and I likely moved my tap guide.  There was a bit of a wiggle between the two jaws of the vice. That's one of the reasons I was clamping it down to start with.  Anyway, what's done is done. And I re-leaned a lesson that I have learned before.  Don't hurry. You don't get there faster - take the time to make sure things are secure and won't move about.  It's worth it.  :facepalm2:

Thanks rklopp,
Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #287 on: April 03, 2019, 05:17:55 AM »
I love form taps for making threads in softer metals like 1018 even when hand tapping. I avoid cut taps whenever possible.

Oh, and I meant to ask... Why do you avoid cutting taps?  Inquiring minds want to know! :)
Kim

Offline rklopp

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #288 on: April 05, 2019, 04:27:43 PM »
I love form taps for making threads in softer metals like 1018 even when hand tapping. I avoid cut taps whenever possible.

Oh, and I meant to ask... Why do you avoid cutting taps?  Inquiring minds want to know! :)
Kim
Form taps are much stouter and make no chips. The formed threads are typically stronger, too, due to the work hardening that occurs while forming the threads. Form taps do require more care with tap drill sizing that do cutting taps.

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #289 on: April 07, 2019, 12:15:34 AM »
Thanks  rklopp, your reasoning makes sense!

Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #290 on: April 07, 2019, 12:21:12 AM »
I finished up the Side Sill repair today without a hitch, thanks in large part to the great advice from the forum members! :)

I started, as suggested, by using a hacksaw to cut a notch from the Side Sill. I started with the longer cut and it only took a couple of minutes to complete.


The broken tap is out!


And cleaned up the cut on the mill.


I used a 3/4" length of 12L14 square bar for the patch.  This will be just a tad oversized in each dimension.  Here Im squaring up the two sides that will be silver soldered.


I decided to use a #1-72 screw to hold the two pieces together while soldering. This shows me hand tapping the hole on the mill. I used a new Union Butterfield Spiral Point Plug tap and it worked like a dream!


Before soldering, I made several punch marks on the edges to be soldered. This is a Kozo trick (that Chris uses all the time :)) to help maintain a small gap between the pieces so the solder will wick through.


Here it is, all loaded up with flux and a few pieces of hard solder.


The soldering went OK.  Not the best Ive ever done, but not the worst. It took longer to heat up the part due to the large bar. But eventually, I got there.  I had to apply additional solder, but it worked out in the end.


I let it cool, then pickled it for a bit and washed it up.  Then put it on the mill and started to take down the top.


Then the sides and the end.


Heres how it looks after some filing and a bit of cleaning.  Not too bad, though you can still see some black that I didnt get off in my cleaning up process.


Finally, I drilled and tapped it, as Id done all the others (though this time, I used a new spiral point 3-48 plug tap).  All went well with the taping :).

After assembly, heres the repaired corner:


And the whole frame.


You'll never see the repair after it's painted (or powder coated, most likely - that's the direction I'm headed :) )

Thanks for stopping by and taking a look,
Thanks,
Kim

Offline b.lindsey

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #291 on: April 07, 2019, 12:33:03 AM »
Looks great Kim, and as you say, once painted no one will ever know. Nice save.

Bill

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #292 on: April 07, 2019, 01:40:11 AM »
Excellent repair!!
 :whoohoo:

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #293 on: April 07, 2019, 05:14:46 AM »
Thanks Bill and Chris! :)
I'm quite pleased with it!
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #294 on: April 07, 2019, 07:51:30 AM »
Top notch fix Kim! well done.  :ThumbsUp: :ThumbsUp: :ThumbsUp:

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #295 on: April 14, 2019, 03:25:27 PM »
Thanks Cnr!
Kim


Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #296 on: April 14, 2019, 03:27:46 PM »
Chapter 4.3 Front and Rear Bolster
These pieces connect across the frame and hold the front and rear trucks for the tender.

The Bolsters started as chunks of 5/8 square 12L14.  They were milled to final length (5 5/8) on the mill, then I found the center and drilled a D sized hole for the pins that will hold the trucks on.  This is not a through hole and only goes 3/8 deep.


Then drilled and tapped a 3-48 hole for the screw that will retain the truck pin in place.


To position the bolt holes for holding the bolsters to the frames, I needed to find the right vertical position.  To do this, I made a little scratch mark through the holes on the frame onto the ends of the bolsters:


Like so:


The horizontal positions I was fine using the DRO.  They just needed to be 0.375 apart.  But the vertical position was critical to making the frame line up flat.

Mounted it in the mill and found the vertical position (Y, in this case).


This is a shot of tapping the holes.
This shot also shows my setup for drilling the bolster ends. I actually used 2 Kant-Twist clamps on this setup (kept it more solid), but I started taking it down before I remembered to get a picture!


Finally, I drilled two holes for #3-48 CSK screws in the Rear Bolster. These will be used later to attach the Tank Floor.


And heres the beauty shot of the two bolsters.  Not really much to look at, eh?


And bolted into place with the rest of the Tender Frame Family!




Thanks for stopping by to take a look at my progress.
Kim

Offline Ye-Ole Steam Dude

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #297 on: April 14, 2019, 03:42:28 PM »
Hello Kim,

Still following along and enjoying your work.

Have a great day,
Thomas

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #298 on: April 21, 2019, 01:00:32 AM »
Thanks Thomas!
Appreciate all the support I can get :)

Next up is the Drawbar that will connect the tender to the engine.

Chapter 4.4 Drawbar Pocket and Drawbar

I start with the Drawbar Pocket, which will hold the Drawbar.  This was made from a short length of 5/16x5/8 1018 bar.  I cut it and trim it to width.  Then mill a dado in the middle where the drawbar will fasten. (Do you call grooves like this a dado in metal work?  Or is dado just a woodworking term?)


I drill three holes one in the center for the Drawbar Pin, and the two on the outside for the 3-48 screws that will hold it to the frame.  Here Im adding the countersink to the holes for the fastening screws.


Next, I remove the Front End Sill from the frame assembly and connect the drawbar pocket with two 3-48 screws.  Using the hole in the Drawbar Pocket as a guide I can now drill the frame so the holes line up.


With the drawbar Pocket completed, I move to the Drawbar itself.  The drawbar is specified to be 3/32 thick.  I couldnt find any 3/32 thick steel bar, so I used 0.090 steel plate (4130a).  I cut a piece (slightly oversized) by putting my HF horizontal bandsaw in vertical mode.


Then milled it to the correct width of 5/16.


Next, I drilled 2-56 clearance holes (#43) at the correct locations for the ends of the drawbar.


Then used some 5/16 filing buttons to round the ends of the Drawbar.


After rounding, I drilled them out to the specified size of 0.161 or a size #20 bit.  The reason I did the holes in two steps is because I already had some 5/16 filing buttons with a #43 sized hole. That made the re-use easy, and drilling the holes out afterward didnt take very long at all.


And here are all the pieces I made (or modified) today:


Here we are with the Drawbar pocket assembled onto the Front End Sill.


And now, in situ with the whole frame.  You can see Im using a #8 screw to hold the drawbar in place.  Eventually, Ill get around to making the actual Drawbar Pin :).


That ends my story for today. Thanks for stopping by and taking a look!
Kim

Offline b.lindsey

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #299 on: April 21, 2019, 02:21:05 AM »
Great update Kim. It's all looking great!

Bill