Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 25055 times)

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #255 on: March 10, 2019, 04:48:22 PM »
Thanks Achim, Cnr and Bill!
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #256 on: March 10, 2019, 04:54:35 PM »
Sills look great Kim.  :ThumbsUp: :ThumbsUp: :ThumbsUp:Re your lineup marks - maybe not strictly required in this case, but I think it's a good habit to get into to "think precision" in all ops. The easy ones are still easy but the tough ones are less tough, with this approach.

Standing by with  :popcorn:!
Yeah, you're right, it may not make much, if any difference in this case.  But since I machined them together this way I just want to be able to keep track of that. Sometimes it does matter, so I just try to maintain good habits :)
Kim

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3774
  • Springfield, Tennessee. USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #257 on: March 10, 2019, 05:10:49 PM »
Excellent work Kim. Might be time to think about a powder coating setup ( wonít chip as bad) BTW, a truck is also the adornment on top of a flagpole  8). Following along  :popcorn: :DrinkPint:

Cletus

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #258 on: March 10, 2019, 05:15:38 PM »
Interesting thought, Cletus!  I may have to look into that.  Do you know if powder coating is ok with getting hot?  Like around a boiler or fire box?   :thinking:
Kim

Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3774
  • Springfield, Tennessee. USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #259 on: March 10, 2019, 05:18:42 PM »
Donít really know. Check out Eastwoodís website. Iíve been seriously thinking about it what for the chipping reasons. I know KVOM and Stan both use theirs.

Cletus


Offline Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3774
  • Springfield, Tennessee. USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #260 on: March 10, 2019, 10:14:12 PM »

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1119
  • The "Naki" New Zealand
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #261 on: March 12, 2019, 05:06:13 AM »
Hi Kim,
 Coming on nicely!

Check out Nelsonís site for using hi temppowdercoat, I got inspired by this & got my kit about well way to long ago, still to be used!

http://www.nelsonslocomotive.com/

Oh if nothing else itís a great site to spend several hours reading!

Cheers Kerrin
Get excited and make something!

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #262 on: March 31, 2019, 04:09:02 PM »
Yesterday, I completed the Front and Rear End Sills and attached them to the side sills.  It was a pretty good day, but ended in frustration.  :wallbang:

Chapter 4.2 Ė Front End Sill and Rear End Sill
These will go on the front and back of the side sills to make a complete rectangle for the tender frame.

The Front End Sill and Rear End Sill both started as lengths of 5/8Ē square 12L14.  Cut to length and squared up to size.
These are not really very remarkable in any way. They just have a few through holes and tapped holes.

So I set to work on the Front End Sill first.  These are #3 clearance holes for the screws that will hold the Front End to the Side Sills.  And this shot is just after completing the 82o countersink in each of them.


There are a bunch of #3-48 tapped holes too, but apparently, I didnít get a picture of those.

On to the Rear End Sill.  This is very similar to the Front End Sill, but its 1/8Ē longer. The Rear End sill will stick out from the side sills by 1/16Ē on each side. The #3 countersink clearance holes are the same but the #3-48 tapped holes are all different.

There are also some holes for the rear coupler.  These will need to be drilled when I get that assembly completed.  But now that I have it all dialed in on the mill, I chose to leave a few marks on Ďaboutí where they should go so that it's easier to position when I get to that point.  I scribed these with a small engraving bit I have.  It did the job nicely.


The Rear End Sill also has a couple of #8-36 tapped holes. These will be for rail posts down the line.


Here are the completed Front End and Rear End Sills.


Now for the fun!  I hadnít quite figured out yet how I was going to drill and tap the holes in the ends of the Side Sills.  These things are over 15Ē long and even with my new big mill I donít have the Z height to stand them up on end and still get the drill chuck and a bit in there. So, I worked out this method.  I awkwardly clamped the two pieces together, like this.  I had scrap pieces on the back and the side to help with alignment. You really can't make out what I did in this picture, can you?  Well, it seemed to work regardless.  :embarassed:
I used the clearance bit through the End Sill just to make a center hole.  Then I switched to the correct size for taping and continued to use the End Sill as a guide to help me keep the hole straight.  You can see the cordless drill sitting there on the vise waiting to do his job.


With the hole drilled, I took away all the fixturing, and making sure to clamp the piece at 90o to the vice jaws, I used a tap guide to help me tap the hole.  Again, this seemed to work pretty well.  Notice that I clamped the guide in place for added stability.


Unfortunately, this is where calamity struck.  On the LAST hole, I must have gotten a little careless, because I heard the dreaded crunching sound.  :o :'( :Mad:  I donít know exactly what happened. Iíd swear I was doing exactly the same thing as the other 7 holes Iíd done this way. But clearly, I did something wrong.  Well, actually, I do know that I didnít clamp the tapping guide in place.  Iíd stopped doing that for the last several holes, just depending on my other hand to hold it in place.  That had worked for several holes.  But then this. Clearly, I let it shift or did something wrong.  Because here I am now with a two-piece tap, with one piece embedded firmly about 3/8Ē down in the hole. :wallbang:


There was no backing it out.  It's still there:


Iím considering what to do. While the tap is HSS, the part is also steel. So I donít think the Alum trick will work (though Iíve only had marginal success with that in the past anyway).  Iím trying to think of a way to cut the tap out, but thereís so little material to work with.  The hole is centred 1/8Ē away from the top edge. And to make it worse, I donít really have a way to get it in the mill to work on it.

My top thought at the moment is to see if I can chip away enough of the end of the tap to get a few threads exposed, then I can just make a VERY short screw to go in on top of it.

Iím open to suggestions.

So, ignoring that issue for the time being, I assembled the frame:

I was very careful in setting up which end of which sill went together.  But in the end, when I went to assemble it, I realized Iíd completely forgotten to take into account that the Side Sills are NOT symmetrical. They middle bolsters are in different places from each end.  And of course, I can never accidentally orient things correctly, so had done it backwards.  But, on the bright side, my holes were uniform enough that even with turning things around, all the edges still line up beautifully!  So thatís one positive!  :)

Now I just need to deal with the half a tap thatís embedded in the frame thereÖ


Thanks for taking a look at my trials and tribulations,
Kim

Offline Dave Otto

  • Full Member
  • *****
  • Posts: 3596
  • Boise, Idaho USA
    • Photo Bucket
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #263 on: March 31, 2019, 04:46:24 PM »
Bummer on the tap Kim, you will probably invest more time in trying to remove it than just remaking the part.

Not sure if you mill has enough travel that would allow you to hang your part off the front of the table, while clamped to an angle plate. Rotate the turret of your mill off center to be able to reach the part.
On the Bridgeport style mills being able to extend the ram helps with getting the spindle centered over the part. I don't think your mill has a ram? 

I have drilled cutting taps out using a center cutting 4 flute carbide end mill taking very small bites using the depth stop on the quill to control that. With a roll form tap you would need to use a large enough end mill to remove all of the tap followed with a thread insert (Helicoil). Oh and it usually takes more than one end mill to get through the tap.

Dave 

Offline Florian Eberhard

  • Full Member
  • ****
  • Posts: 432
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #264 on: March 31, 2019, 04:46:40 PM »
Hey Kim

I would either try using a "plug drill bit" (selfmade from some kind of tool steel) to drill around the broken tap, then cut a bigger thread into that beam and put a threaded sleeve into it.
Or you cut off a short piece, machine a step onto it and then make another part which is being screwed, silver soldered (would be my favourite) or riveted to the original beam to make it long enough again.

To machine the end of the beam, you could probably use your lathe and clamp the bar in the toolholder while the tool gets put into the lathe spindle (ideally with coolets)

Florian

Online crueby

  • Full Member
  • *****
  • Posts: 8888
  • Rochester NY
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #265 on: March 31, 2019, 05:17:11 PM »
Last couple of times I had that happen I used a small pointed diamond-coated dental bur in the high speed  rotary tool to grind out the center of the tap, then could wiggle out the outer teeth/flutes with tweezers. Care is needed to keep from damaging the threads, but it works.

Online b.lindsey

  • Global Moderator
  • Full Member
  • *****
  • Posts: 13647
  • Dallas, NC, USA
    • Workbench-Miniatures
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #266 on: March 31, 2019, 05:31:04 PM »
Bummer on the tap Kim, but the frame is looking good none the less. I would probably just remake, the one with the broken tap. Likely quicker in the long run.

Bill

Online cnr6400

  • Full Member
  • ****
  • Posts: 357
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #267 on: March 31, 2019, 06:21:56 PM »
Hi Kim, do you know any mouldmakers? or any other local shop with EDM? If you were on this side of the continent you'd be welcome to drop by my shop to use my home-built EDM machine based on the Ben Fleming design. I would use a hex shaped brass electrode a little smaller than the thread and blow a hole a few mm deep into the tap. Then a normal allen key can be used to ease the tap out. For your next tapped holes, can I recommend a nice new sharp tap, and a few drops of some some good cutting oil?

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #268 on: March 31, 2019, 06:27:17 PM »
Thanks Dave, Florian, Chris, and Bill,
Appreciate the commiseration and the advice.

Dave, actually my mill does have a Ram head, and that a great idea!  I've got to learn how to use the capabilities of my new tools. I have to learn to think differently...

Florian, another good idea.  I've seen people do this - put the part on the cross-slide and the tool in the spindle.  I don't have T-slots in the tool holder platform on my lathe, so I'd have to come up with some way to hold things, but that's probably workable.

I like the Dental burr idea too, Chris.  May have to try that before I abandon the part.

Bill, I may remake the part.  Unfortunately, this is a large piece and I don't have enough to make a new one without ordering more.  The steel is cheap (
Its 1018) but the shippings a killer...  but probably still cheaper than a couple of carbide end mills!

Thank you all for helping me to think of options.  I really appreciate it.
Kim

Offline Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3667
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #269 on: March 31, 2019, 06:31:03 PM »
Thank you Cnr,
I didn't see your post till I'd replied.

The EDM sounds magical! I think I need one of those :)

Yeah, new tap seems in order for sure  :)
Kim
« Last Edit: March 31, 2019, 10:38:09 PM by Kim »