Northern 4-8-4 Build 3/4”

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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Rotary table proves invaluable
Rotary table proves invaluable
Looking sharp
Looking sharp
Envision the future
Envision the future
Success! Setting up the milling operation and then returning a week later to actually do the work was fun. I had a chance to imagine how to coordinate the order of operations. The astute will notice I have yet to fabricate the center plate which holds the actual block. That will hopefully be Monday’s project. Progress is being made. I sure wish I knew when this Northern was last worked on and by Whom? Casualties yesterday….a #1 center drill and a 5/32 reamer.
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Bill Shields
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Re: Northern 4-8-4 Build 3/4”

Post by Bill Shields »

Looks good...
Too many things going on to bother listing them.
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Valve spool and spindle
Valve spool and spindle
Wahooo! Good outcome on my project last night and this morning. I initially tried turning a 5/16 rod down to 1/8 while leaving the required shoulder. Scratched that plan. Ended up using 1/8 rod and silver soldering a shoulder on the rod. Excellent result.

The excitement is building as I am able to begin confirming the plan dimensions match the chassis.
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Building 3/4” 4-8-4 Northern &
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Laying them out
Laying them out
Starting on inner link plate
Starting on inner link plate
Milling work
Milling work
Not finished yet
Not finished yet


I started on the inner link plates today. Laying them out for sanity check was first step. I had the DRO coordinates I had plotted but a visual layout keeps me from doubting myself. For the slot I plunged the end points and slowly milled from to end to end to full depth the actual slot. Strangely the plunging created a 3/32” larger hole than the milled slot. Not sure why but half the diameter of these holes are covered by outer plates so I don’t think it will matter. I am just claiming the flared ends of slots are for dirt removal! My area where the forked reversing rod inserts into the link is not quite wide enough. So tomorrow some more filing and shaping to finish them up.

Posting pics on this forum is tough. I’ve had to turn them and re-save for each picture unless I use my IPad turned ninety degrees to take the pictures.
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Building 3/4” 4-8-4 Northern &
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Bill Shields
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Re: Northern 4-8-4 Build 3/4”

Post by Bill Shields »

Drills almost always drill oversize.

Drill undersized then shove a reamer through or work your way up in drill size until you get where you want.

Are you going to file the corners out?

Photo documentation is more work than you realize

Try writing an article about building a loco...🤪
Last edited by Bill Shields on Thu Dec 08, 2022 9:47 pm, edited 1 time in total.
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Yes. I have started the file work but ran out of energy at 6 pm. They’ll take on the final shape tomorrow.

It was the four flute end mill that created the oversized holes when I plunged it. I’ll have to research that issue a bit.
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Bill Shields
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Re: Northern 4-8-4 Build 3/4”

Post by Bill Shields »

Have you made the link block yet?

I generally make the block then gently file the corners until it fits
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NP317
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Re: Northern 4-8-4 Build 3/4”

Post by NP317 »

bushav wrote: Thu Dec 08, 2022 9:44 pm Yes. I have started the file work but ran out of energy at 6 pm. They’ll take on the final shape tomorrow.

It was the four flute end mill that created the oversized holes when I plunged it. I’ll have to research that issue a bit.
If your mill cutter was not a new center-cutting tool, it will flex and wallow out the holes.
BTDT.
RussN
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Greg_Lewis
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Re: Northern 4-8-4 Build 3/4”

Post by Greg_Lewis »

NP317 wrote: Thu Dec 08, 2022 10:53 pm
bushav wrote: Thu Dec 08, 2022 9:44 pm Yes. I have started the file work but ran out of energy at 6 pm. They’ll take on the final shape tomorrow.

It was the four flute end mill that created the oversized holes when I plunged it. I’ll have to research that issue a bit.
If your mill cutter was not a new center-cutting tool, it will flex and wallow out the holes.
BTDT.
RussN
You can drill a pilot hole and finish it with an end mill.
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Dick_Morris
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Re: Northern 4-8-4 Build 3/4”

Post by Dick_Morris »

For the slot I plunged the end points and slowly milled from to end to end to full depth the actual slot. Strangely the plunging created a 3/32” larger hole than the milled slot.
This is how Baldwin did it for the circa 1942 War Department Consolidations. Note that the radii at the ends is slightly larger than twice the slot width. The link blocks have sharp corners.
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Harold_V
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Re: Northern 4-8-4 Build 3/4”

Post by Harold_V »

bushav wrote: Thu Dec 08, 2022 9:44 pm It was the four flute end mill that created the oversized holes when I plunged it. I’ll have to research that issue a bit.
No real need to do any research. It's very common for an end mill to wing when it's used as a drill, which is generally caused by chip loading. When it's excessive, it is able to move the slides from their desired location if they're not locked and the gibs are loose. If you hope to avoid that problem, simply start with a smaller drilled hole, or use an undersized end mill instead of the one used for size. Opening the hole to the desired size will then be pretty much guaranteed.

Bill's comment about drills cutting oversized is a common occurrence, too. Same solution. Open the hole(s) with an undersized drill (one size smaller for fractional drills), then take the hole to size with the desired drill (or reamer, if required). By removing the web area, the drill will usually cut size, assuming the lips are not damaged or dulled badly.

H
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bushav
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Re: Northern 4-8-4 Build 3/4”

Post by bushav »

Thanks for comments guys. I only started learning machine work a year ago. I’ve got so much to learn. This locomotive is my teacher and that’s what I wanted it to be. It’s also my excuse to buy more starrett :)
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
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