The Home Machinist!

LVRR2095 wrote: ↑Mon Feb 01, 2021 2:07 pm Dan, those bits are called the “inductors” for the automatic train control.

thanks keith, I appreciate it!

JBodenmann wrote: ↑Mon Feb 01, 2021 3:18 pm Hello My Friends
Thanks Dan. Those are some very cool photos and will be useful when I get to the cab and tender.
Jack

you're welcome jack, always glad to help. would you believe I now have 277 photos of the real 5344 in my collection. 17 years of collecting off the internet.

one more for you from the front, fresh out of ALCO in November 1931.

Hello My Friends
Yesterday I made the steam dome. This is one of them little puzzles that I really enjoy as its mainly just sticking my thumb out, and the main tool is a hammer. It is much easier to make than the sand dome as it's round. But in some ways it's not, as the lip around the bottom is quite a fiddle and takes a good deal of time to form and get fitted to the boiler. First was to make a forming die. This started out as 3" round aluminum and was turned down to 2-7/8". Then a card stock pattern was made to check the shape. It was roughed out with a round nose lathe bit and then finessed with files and sand paper. Then a .030" round steel disc was made and stuck to the top with a heavy disc and small screw. Some heat was applied and it was worked down over the former with a wooden mallet. Used to spin these parts but after making a gaggle of them I think it's easier to hot form them.

After the top portion was made it was time for the side piece. The forming die was plunked down on top of the actual steam dome and was wrapped with some card stock, actually an old file folder. Then it had the boiler contour marked on it with some dividers and a Sharpie. This card stock pattern was then trimmed to shape with scissors and then marked out on some .030" steel. The steel was then trimmed and wrapped around the aluminum dome former. The seam was then TIG welded. When welding something around a form tool like this it should be a little loose on the form, as the process of welding will shrink the steel. I had cut the work piece a bit short but thought it would be OK. Sometimes if something is a bit tight in situations like this you can heat up the steel, it will expand and you can slip if off the former. Well...in this case no soap. That steel ring shrunk on there and it was determined not to come off. I had to band saw it off as you van see in photo 4. So another ring was made, considerably looser than the first and things worked out this time. The weld was smoothed out and it went back on the form tool and had the top edge formed in to meet the top. It's much easier to join pieces like this midway on the radius than where the radius meets the straight portion.

Now we are getting somewhere. Here is the top and sides carefully fitted together. Then the two parts were tacked together, carefully checking the alignment as working around. Once everything was looking good the entire weld was made. The weld was smoothed out with an abrasive wheel and then the work piece was slipped back onto the form tool. It was then chucked up in the lathe, spun at about 150 RPM and smoothed with files and sand paper. This got the top radius very smooth and uniform. Much more so than just with an abrasive wheel. Then it was time to start the flare where the dome meets the boiler. A bit of aluminum was machined to the correct radius, and then a hammer with a rounded head was used to form the lip. This is the fiddly bit. It took several hours to form this lip. Hammer a little. Check the fit. Grind some off. Check the fit again. hammer a little...

The lip around the bottom is where patience and a good eye comes in handy. As I have said before, in my case I think it's more a matter of stubbornness rather than patience. Go with what you got. The top photo shows the dome early on in the process. The dome is still quite a bit too tall. I always start them out too tall, as if it's too short you have to start over, and at this point there are more than a few hours invested. As usual I learned this one the hard way. So hammer, test the fit, grind some off, hammer. All the while testing with a spirit level to make sure things are all lined up. And measuring the height. Finally it gets down to a few thousandths at a time. It was getting late last night and I was getting tired. The dome still needs a little finessing but I will do that this morning after breakfast and several cups of Java when I'm really on my game. One thing I rambled on about in the past is perfect scale versus what just looks right. The lip at the bottom is made to the drawing which scaled out to 9/32" radius. Too me it looks to small. I wish I would have made it perhaps 5/15" radius. I'm not changing it as it is scale.
Jack

JBodenmann wrote: ↑Tue Feb 02, 2021 12:58 pm ...
One thing I rambled on about in the past is perfect scale versus what just looks right.
...

This is so true. Just as physics can't be scaled down, aesthetics often have a similar problem. Something 15 feet tall that has pleasing proportions and balance can look just wrong when reduced to a matter of inches. Trust the eyeball.

Could you give some details about how you did the weld of the top to the sides of the dome? Like metal thickness, electrode, settings, etc... I've never had luck getting thin stock to weld.

Hello My Friends
The weld was done with a Lincoln Precision 185 TIG welder. The material is .032" cold rolled steel. For rod I used .035 solid wire from the MIG machine. The power was set at 45 amps with a 1/16" electrode. Very little rod was used, mainly when tacking. If you fit things carefully you need almost no rod. The dome was positioned so the welding was happening at the very top. A small length of weld was made, and then re positioned. A comfortable welding position always helps. The challenge for me is just seeing what I'm doing. I have very bright lighting over the welding table and this helps. Here is a photo of the backside. It's not too pretty, I'm not the greatest welder but I get by.
Happy Model Building
Jack

so.....the welding arc does not provide enough light to see where you are going?

I must be missing something

I have always worn really dark eye protection when I was welding...but then that was 30 years ago and perhaps things have changed...

giggle....

Hello My Friends
I have trouble seeing when welding. It didn't used to be so bad. I think the bright lights help a bit, but it could just be wishful thinking. I have welded right off the gap into no man's land a time or two. I hate it when that happens. Time to get out the eraser
Jack