The 2-10-0 project

[peteski]

I saw in that thread that you had several 00-90 cutter bits that were 00-90 width for a good length, not with a tapered shaft.  I need to tap some threads through about .25 inches, so I can't use one of the tapered bits.

You must have missed what I wrote (and showed in the photo) in https://www.therailwire.net/forum/index.php?topic=48950.msg650921#msg650921

Here is the relevant text: I also cut the end of the third tap from the bottom (in the photo) to use it for blind holes.  And, as others have mentioned, I use one or two sizes larger drill bit in metal when I use the thread forming taps.

I made that tap by cutting off most of the tapered end.  So, it will tap a shallow hole.

[Lemosteam]

If you purchase real taps, you don't have to make one.  There is a tap called a bottoming tap for blind holes with only a chamfer at the end, but you till must start the threads with a normal tap ensure perpendicularity and a few full threads to engage initially.  the small chamfer makes it difficult to start new threads in a tap drilled hole.

[mike_lawyer]

Built a jig for the 5th driver installation.  Used 3/16 square styrene strips and sanded them down to just fit inside the wheel bearing blocks.  Then shifted it down one so that I could make a slot for a 5th driver.

[mike_lawyer]

The finished jig:

[mike_lawyer]

One of two chassis with rear blocks glued in place:

[mmagliaro]

Wow, does this bring back memories (little tears!... LOL!  )

Keep up the good work, man!

[mike_lawyer]

Hardest part of the project is filing and making the 5th driver slot.  I spent the last two days getting two frames completed:

[mike_lawyer]

Getting back to this project after a hiatus.  I am having trouble getting the 5th driver alignment just right.  I have tried doing it twice on two locos, but I can seem to get the driver situated in the slot such that it will smoothly spin with the side rods.  I wish I remember exactly how I did this a decade ago!

I have been using my caliper for everything and I feel that my alignment is still somehow off. 

Anyone who has done this have any tips or tricks to get this just right? Thanks!

[PiperguyUMD]

Is it out of quarter?

[mmagliaro]

Can you show a photo of how you are adding the rods for that 5th driver?  Are you just overlapping two Kato
rods, or did you somehow splice two together?  The whole problem could be the rod extension, not the slot spacing at all.

As for checking the spacing with a caliper, that really ought to be good enough if you are measuring carefully.
I put the jaws right down into two of the factory bearing slots, and clamp inward.   Only push the jaws down into the slow about 1/2 way, because the bottom of the slot has some radius to it and that can throw off your measurement.
Call that the "inside distance".  Make sure you get that same number when you measure between #4 and #5 (your new slot).  Then use the outer "reverse" jaws and measure outward, and make sure that matches too.  You need to be within .005" at worst.  Better to get it within .002 or .003". 
Assuming the driver set is a standard Mikado set, it can't be out of quarter because those things are indexed on an octogonal axle end, so wouldn't expect it's that.

[mike_lawyer]

Max -

Thanks so much for the reply, I think I figured out where I went wrong.  First, I was putting my caliper all the way down in the slot for the first measurement.  I did not realize there was a small radius at the bottom!

Second, I like your idea for the second measurement. I was measuring back the width of the slot for the second cut.  Your method of measurement is more precise.

As for siderods, I am doing the overlap method.

[mmagliaro]

Max -

Thanks so much for the reply, I think I figured out where I went wrong.  First, I was putting my caliper all the way down in the slot for the first measurement.  I did not realize there was a small radius at the bottom!

Second, I like your idea for the second measurement. I was measuring back the width of the slot for the second cut.  Your method of measurement is more precise.

As for siderods, I am doing the overlap method.

Yeah, I remember just noticing that the measurement I would get about halfway down the slot was always different than measuring at the dead bottom, and I figured "halfway down" was the best guess.   They might even have a slight taper to them as they go down.
 
The other important thing is your slot DEPTH.  Have you been checking that?  All drivers have a hair of wiggle up and down so they can negotiate uneven tracki.  But if the driver is able to lift up too much as it goes around, it's going to cause rod jams.   When this engine sits on the track, how much can you lift up your 5th driver with the point of an Xacto blade?  If it's more than .005", I would put a .005" styrene sliver in the bottom of the slot to limit this.

[mike_lawyer]

Good point about the depth.  On my I1 I built years ago, I had it so the 5th driver was just below the traction tire driver.  You could not tell the difference at track level.

[mmagliaro]

You just need to make sure the 5th driver isn't free to move up or down in the slot very much.  When the rod pushes that driver to rotate, if the driver can push vertically, it will.  And it will do that instead of rotating.  Then, for a moment, it will be out of sync with the other 4 drivers and you can get quartering jams.  It essentially makes the circular motion of the rod hole into an egg shape.

[mike_lawyer]

Measured with a digital caliper tonight, looks the the distance between the driver slots is right at 7 mm.