Rebuilding the Central of Georgia #408

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Fri Jul 03, 2015 11:24 am

Been a busy couple days, just now got a chance to go down and start TIG'ing the stainless bushings into the outer firebox sheets.

These are for washouts and blowdowns.
408_112.jpg
Washout and blowdown bushings.
Next I'll start putting the bushings in the boiler tube before welding the outer firebox sheets on so it's easier to maneuver the tube around.

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Fri Jul 03, 2015 2:34 pm

All of the bushings except the turret supply are in.
408_113.jpg
Bushings TIG'd into boiler tube
There's another feedwater bushing on the opposite side. This boiler will be fed with two injectors. No pumps of any kind so we're only putting in two inlets.

I'm short a piece of 1/4 pipe for the dry pipe to the turret so I need to wait to put that one in. That dry pipe, from the back to the front, will be an elbow to pipe to another elbow and then a short section of pipe that almost reaches the top of the steam dome. I forgot to tell Mike, the owner, to buy a 12" piece of pipe for this and all I have around the shop is 3/8. Off to the hardware store!

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Sun Jul 05, 2015 12:23 pm

More fun stuff today!

Marked up the steam dome and tapped it into place so I could see where it needs to be ground to match the i.d. of the boiler tube. When I built my mogul boiler I made a paper template and cut it out on a bandsaw -- not the quickest way. This trick worked great.
408_114.jpg
Fitting steam dome.
408_115.jpg
Steam dome fit with dye scratched off.
I tapped the dome back out and simply ground it down where the dye was scratched off.
408_118.jpg
A peek inside at the dry pipe and steam dome test fit.
The fab'd up turret supply dry pipe and the bushings TIG'd into the backhead along with the ground-down steam dome.
408_116.jpg
Dome ground to profile, backhead, and turret dry pipe
Once I got everything mocked back up I realized that the 3/8 ball valve for the throttle doesn't have enough room to make a complete revolution inside the dome when installing or removing it. The dry pipe need to be shortened to allow the ball valve to sit dead center in the dome and have room for the stem to be clear in a full circle.
408_117.jpg
Testing dome and dry pipe

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Tue Jul 07, 2015 10:25 am

Finished all the mock-up work with the turret dry pipe and the throttle ball valve and supply pipe to the smokebox.

Here's a look at the two inside the dome. Note that the throttle valve isn't secured at this point and is just leaning against the inside of the dome.
408_119.jpg
Mock up of dry pipe and throttle valve
Went ahead and made up a stainless baffle for the valve as well.
408_120.jpg
Throttle valve with baffle
I did a 6011 root pass and then a 7018 cover pass on the inside of the boiler tube. I couldn't get a decent photo of it though; heck, it's hard enough getting the stinger, half a rod, and my arm in there all at once!

This is a view of the dome after those inside welds.
408_121.jpg
Dome after doing the welds on the inside of the tube
... and after another root pass and cover pass.
408_122.jpg
Final steam dome welds
Got the turret dry pipe TIG'd in and finished up. Here's a wide view of what's done so far on the tube itself. In the background is the old boiler.
408_123.jpg
Gettin' 'er done!
Next up, side and throat sheets.

Kimball McGinley
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Re: Rebuilding the Central of Georgia #408

Post by Kimball McGinley » Tue Jul 07, 2015 2:19 pm

Just curious about welding Stainless Steel bushings to mild steel side sheets?

redneckalbertan
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Re: Rebuilding the Central of Georgia #408

Post by redneckalbertan » Tue Jul 07, 2015 3:13 pm


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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Tue Jul 07, 2015 3:55 pm

Kimball McGinley wrote:Just curious about welding Stainless Steel bushings to mild steel side sheets?
309L or 312 alloys are perfect for this application. Their makeup results in very good welds. 312 has been working better than 309L for me as I've not had a single weld crack due to the difference in cooling between the two metals.

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Wed Jul 08, 2015 2:17 pm

For quite a while in the shop today I don't have much to show. Spent about two hours tacking together the outer firebox sheets and then fitting, grinding, tweaking, fitting, ... rinse repeat, to get it all lined up correctly on the boiler tube. I had forgotten how fidgety this part of construction is.
408_124.jpg
Outer firebox sheets ready to go
It's all ready to be welded, but I'm done for today as it's in the low 90s right now and I don't feel like sweating it out! Tomorrow morning when it's not tropical outside I'll get it all stuck together with the electric glue gun.

(edit: is it just me or does the throat sheet look like it's frowning? Hah!)

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Fri Jul 10, 2015 10:28 am

Got to it early yesterday and today to beat the heat and got the side sheets and throat sheet all welded up.
408_125.jpg
Outer firebox done
408_126.jpg
Outer firebox done
For those curious, I've already used a few rods shy of an entire 5lbs box of 3/32 7018 and half a 5lbs box of 3/32 6011. Stuff disappears quick!

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Wed Jul 15, 2015 2:00 pm

Like Mayor Goldie Wilson, "Progress" is my middle name!

Got all but the middle row of stay holes drilled. Was waiting for suggestions in my other thread before I did those.
408_127.jpg
Stay hole drilling
Because the boiler tube isn't perfectly round I had to take about .006" off the o.d. of the front flue sheet and then lots of test fit, mark, grind, test fit, mark, grind, etc., until I got it to be a nice interference fit.
408_128.jpg
Tweaking the o.d. of the front tube sheet
I welded on the supply pipe gland and knocked it all in place with a rubber mallet. Luckily it stayed aligned with my top and bottom centerline marks so all I had to do was tweak its distance from the end of the boiler tube.
408_129.jpg
Front tube sheet set in the boiler tube
All welded up! Again, 6011 root pass, then lots of chipping, grinding, cleaning, more 6011 here and there. Then 7018 on top.
408_130.jpg
Front tube sheet welded in

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Thu Jul 16, 2015 1:55 pm

Spent most of this morning cleaning the shop and running around town looking for a couple tools I need and some materials. Spent a few hours cutting up all the material for the stays and the mud ring, and machined up the firebox door ring.
408_131.jpg
Bits and pieces
The door ring will get heated and squished into an oval. The original boiler appears to have had the exact same coupling used for both the steam dome and the door ring, with the door ring pressed into an oval. I'm doing the same with the heavy wall pipe I used for the dome.

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John_S
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Re: Rebuilding the Central of Georgia #408

Post by John_S » Mon Jul 20, 2015 1:17 pm

After debating it a bit, I decided to haul the boiler back out to the railroad to use the big mill there to drill out the middle row of stays.

I centered it with a wiggler, then used a centercutting 1/2 end mill to start the hole. Once I had a good flat, I swapped out to a 1/2 drill and finished them. Nice and quick and no wandering.
408_132.jpg
Endmill to start the stay hole
408_133.jpg
Drill to finish the stay hole
I also stopped by Rich_D's shop to make use of his 50T press to turn a circle into an oval.
408_134.jpg
Firebox door ring, squished with much force

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