Pennsylvania A3 Switcher (Kozo)

[matthew-s]

Those pins have some crazy tolerances. You can imagine me reading the drawings, then looking at my 7x16 mini-lathe, then back to the drawing, then frowning at the mini lathe ....

I made it work by doing the last few tenths with hand files!  In the end it not sure that level of tolerance was really necessary. But here we are.

I think with your skills and tooling it may not have been such a big deal for you!

[Kim]

Those pins have some crazy tolerances. You can imagine me reading the drawings, then looking at my 7x16 mini-lathe, then back to the drawing, then frowning at the mini lathe ....

I made it work by doing the last few tenths with hand files!  In the end it not sure that level of tolerance was really necessary. But here we are.

Yeah, it was pretty interesting - one of the few parts where Kozo specifies down to tenths of a thousandth! But I'm not really sure if it would make any difference if you left the entire length of the pin at 7/32" - a close fit for the 7/32" reamed holes in the wheel (glued) and in the bearings (a sliding, but not-slopy fit)!

Regardless, I 'tried' to follow his tolerances.  Not sure I really made it, but I'm guessing it would pass the Close-Enough quality check of my shop!

Kim

[cnr6400]

 

[Kim]

Thanks CNR! 


Not a lot of shop time lately.  I thought it would take longer for all that doom and gloom prediction about not having any time when you retire!  Boy, was I wrong! I’ve had so much stuff come up in the last week it’s unbelievable!  And yesterday I thought I’d get some shop time.  But I remembered I’d taken the hitch out of the back of the truck to help with a move (some of that stuff that came up that I mentioned) and we’re hoping to do some traveling soon.  Plus, I wanted to get that big hitch out of the middle of my shop.  So I loaded it back into the bed of the truck.  But it didn’t fit where it came from – took me hours to get it back in.  Well, at least that “simple” job got done!  Plus, while I was at it, scooting things around to get at my shop hoist, etc., I came across a part that I’d dropped a year or two ago!  I remember looking for it for a LONG time – longer than it took to re-make it of course.  But here's the lost little sheep (after 2 years AWOL).  Guess I found one of the shop gnome’s hiding spots!


Anyway, today I did get some time to play.  I continued on making the crankpins.  Last installment finished up with the crankpins – but those were just the rear crankpins.  The front crankpins are much shorter and they will have a small pin going through them that will attach the side rods.

These were also turned from the 5/16” 12L14 round rod.  Turned it down to 7/32”, drilled a 1/8” hole all the way through, and reamed:


Cut it off, turned it around, and faced it off to the specified length.





Chapter 12.5 – Side Rod Pins

Next up are what Kozo calls the Side Rod Pins.  These will go through the front crankpin to hold the side rods to the front wheels.

The side rod pins have a very big head, so they are made from 7/16” diameter 12L14 steel rod.  Here I’ve turned down a short length to the required 1/8” (actually, Kozo specifies 0.123” – so it rotates easily in the 1/8” hole of the front pins) and cut a narrow groove in the end for a retaining e-clip.


With the groove in the end cut, I completed bringing the pin down to a uniform 0.123”.


After cutting it off from the parent stock, I flipped it around in a 1/8” collet and faced off the top side of the pin.


And here are all crankpin pieces I made today.


The next activity will be to make a quartering Jig!
Thanks for checking in,
Kim

[crueby]

Maybe the shop gnomes sent that part back as a retirement gift. Though, hopefully they didn't take two others...




Great progress, very well done!   

[Kim]

 Thanks Chris! 

A retirement gift!  How thoughtful 
If only they'd be as thoughtful 2 years ago when it would have done me some good! 

Kim

[kvom]

For future powder coating, I suggest buying the set of silicon plugs Eastwood sells.  Use them to plug holes that shouldn't get powder inside.  For tapped holes, a screw works just as well.

[Kim]

Thanks for the pointer, KVOM, appreciate it!
I'll have to look into getting some of those, though it really wasn't too hard to re-ream the hole.  Keeping it out in the first place is probably the best idea.
Kim

[Kim]

Chapter 12.6 – Quartering

To make the quartering jig, I pulled out all my latent woodworking skills.  I cut a couple of blanks to be the ends for the jig, nice and square, double-sticky taped them together, then, with some packing to hold them off the face of the RT, I milled the 90^o shape in one end of the blanks.  I milled the required ‘lump’ right into the shape.  The lump had to be 7/64” up from the main ‘V’ shape.  That’s because the Axle is 7/16” diameter, but the crankpins are only 9/32”.  So, I made up for that diameter difference in the shape of the V.  This is what Kozo shows in his book and I’m sure is standard practice, but all new to me.


Here’s the jig all assembled.  You can see the crisp beautiful job I did with the re-used lumber scraps I had laying around   The “NO” and “USE” labeling are to help me remember which side to hold the pins against while the Loctite is curing.  (Right side leading.)


Here are the rear wheels, sitting on the jig curing.  The trick with the rear wheels was to make sure and remember the eccentrics for the water and lubrication pumps.  You can see the crankpins are inserted so they stick out the back of the wheel.  They aren’t being glued; they are just being used as a guide right now.  I’ll be gluing those in next.  But first, let's get the wheels quartered.


Another shot of the rear wheels curing.


After a bit, I set the rear wheels aside and did the front wheels.   And here they are after quartering.


Once these cure overnight I’ll be Loctiteing the crankpins in place.

That’s it for this update!
Kim

[crueby]

What an elegant jig! Never seen that kind before.

And its nice to see someone else using 'free-range metal' for jigs! Dug out of those surface mines called 'forests'...

[Kim]

What an elegant jig! Never seen that kind before.

And its nice to see someone else using 'free-range metal' for jigs! Dug out of those surface mines called 'forests'...

Gives a whole different meaning to strip mining, eh? 

[matthew-s]

Chapter 12.6 – Quartering

To make the quartering jig, I pulled out all my latent woodworking skills. ....  This is what Kozo shows in his book and I’m sure is standard practice, but all new to me.


....

That’s it for this update!
Kim

Great work as usual!

For the future reference of others  (I hope Kim does not mind) ...  you can make this jig w/o a rotary table. Secure the two ends to one another as Kim did - they MUST be machined together (mine were aluminum so I screwed them together). Then you can clamp this to your milling machine table, angled to 45* (I used a Combination square. This only needs to be close to 45). Be sure to put something underneath them, like plywood, to not mill your table!

Now, you m ill that inside “V” using x and y feed, one axis at a time. This will get you the 90* “v” you need.  There is a jog in the parts that is oriented differently on each side of the jig - so you will need to flip one of the ends before assembly. In a sense, that makes the most critical part of this jig drilling the holes used to bolt each side of the jig to the base such that the ends are perfectly aligned.

[Don1966]

A lot of good stuff happening in this thread, looking good Kim!


 
Don

[Kim]

For the future reference of others  (I hope Kim does not mind) ... 

Kim not only doesn't mind, he welcomes it!  Additional info is AWAYS welcome and encouraged! Thank you, Matthew!

you can make this jig w/o a rotary table. Secure the two ends to one another as Kim did - they MUST be machined together (mine were aluminum so I screwed them together). Then you can clamp this to your milling machine table, angled to 45* (I used a Combination square. This only needs to be close to 45). Be sure to put something underneath them, like plywood, to not mill your table!

Now, you mill that inside “V” using x and y feed, one axis at a time. This will get you the 90* “v” you need.  There is a jog in the parts that is oriented differently on each side of the jig - so you will need to flip one of the ends before assembly. In a sense, that makes the most critical part of this jig drilling the holes used to bolt each side of the jig to the base such that the ends are perfectly aligned.

I was originally going to do that - make the jog on one leg of the "V", then flip one of them over... but at least in my situation, I decided to do a jog on BOTH legs.  That way if my "V" was off-center, it wouldn't matter - both sides remained in the same orientation as they were milled.  I just  made sure to mark which 'jog' I used on which side.

Now my follow-up question for you Matthew -  I considered doing this in aluminum but decided that I could be accurate enough with wood.  Maybe that's not the case?  If I'm off by a few thou, will that cause me problems?  I did try to keep things quite square and accurate, but undoubtedly, it is not as accurate as if I'd assembled it with aluminum.  I'm sure its off a little bit... I was assuming that it would be close enough to 90 degrees, and the front and rear axels are 'quartered' in the same jig, so will have the same misalignment, if any.

Was that a bad call? (he asks in retrospect? - learning for the future.)
Kim

[Kim]

A lot of good stuff happening in this thread, looking good Kim!


 
Don

Thanks Don!