Northern 4-8-4 Build 3/4”
Moderator: Harold_V
Re: Northern 4-8-4 Build 3/4”
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.
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
- Bill Shields
- Posts: 10589
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Northern 4-8-4 Build 3/4”
The excitement is building as I am able to begin confirming the plan dimensions match the chassis.
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
Re: Northern 4-8-4 Build 3/4”
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.
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
- Bill Shields
- Posts: 10589
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Northern 4-8-4 Build 3/4”
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...
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.
Too many things going on to bother listing them.
Re: Northern 4-8-4 Build 3/4”
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.
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.
New to live steam
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific
- Bill Shields
- Posts: 10589
- Joined: Fri Dec 21, 2007 4:57 am
- Location: 39.367, -75.765
- Contact:
Re: Northern 4-8-4 Build 3/4”
Have you made the link block yet?
I generally make the block then gently file the corners until it fits
I generally make the block then gently file the corners until it fits
Too many things going on to bother listing them.
Re: Northern 4-8-4 Build 3/4”
If your mill cutter was not a new center-cutting tool, it will flex and wallow out the holes.
BTDT.
RussN
- Greg_Lewis
- Posts: 3021
- Joined: Wed Jan 15, 2003 2:44 pm
- Location: Fresno, CA
Re: Northern 4-8-4 Build 3/4”
You can drill a pilot hole and finish it with an end mill.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
- Dick_Morris
- Posts: 2851
- Joined: Sat Jan 04, 2003 2:09 pm
- Location: Anchorage, AK
Re: Northern 4-8-4 Build 3/4”
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.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.
Re: Northern 4-8-4 Build 3/4”
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
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Northern 4-8-4 Build 3/4”
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
Building 3/4” 4-8-4 Northern &
1” 4-6-2 Pacific