Formed cab roof angle 16 ga. steel

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DaveD
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Re: Formed cab roof angle 16 ga. steel

Post by DaveD » Tue Jun 12, 2018 6:25 am

Jack, I will try forming the angles per your reply above. This will be an easy attempt since I already have the formers. All I need is a rawhide mallet.

I did this in much the same manner using 303/4 (I forgot which) 16 ga. when building the trailer truck wheel relief notches in my ash pan. Much smaller parts, but exactly the same method, and they turned out well (photos attached).

And Dave, yes, I will anneal it. If none of this works, though I believe it will, I will also try some extruded brass angle. Thanks again.
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Ash Pan 23_edited-1.jpg
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Dave Dalton

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JBodenmann
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Re: Formed cab roof angle 16 ga. steel

Post by JBodenmann » Wed Jun 13, 2018 9:54 am

Hello. My Friends
Hi Dave, if you anneal the steel try soaking it in Ospho. This will remove any scale. This will also take the scale off of hot rolled steel.
By the way your work is excellent!
Jack

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Re: Formed cab roof angle 16 ga. steel

Post by Fender » Wed Jun 13, 2018 6:18 pm

DaveD really does fine work. The bronze color on the SS ashpan is from heating it in a heat-treating oven until a light brown is achieved, as I recall.
Dan Watson

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Oxidizing stainless steel for color

Post by DaveD » Sat Jun 16, 2018 8:14 am

Fender wrote:
Wed Jun 13, 2018 6:18 pm
DaveD really does fine work. The bronze color on the SS ashpan is from heating it in a heat-treating oven until a light brown is achieved, as I recall.
Dan, thanks for the compliment and for reminding me about this. I thought I had posted something in chaski on this technique, but I guess I forgot to.

The ash pan is made of mostly 304 stainless and the bronze color is an oxidation coating. I got the idea to color it from some stainless steel art work that had been heated to different colors at various temperatures. It had been placed outside and the color had stood up well to the elements over a several year period, so I thought I might be able to apply this to my ash pan. My primary reason was to tone down the silver SS color and have the ash pan disappear quietly into the background. I have a programmable furnace, but small (9x9x9 inches), and I did some testing on small pieces of my 304 0.060 sheet. I tried various temperatures and various soak times and came up with the optimum temperature of about 600 degrees F (if I remember right) and a soak of 1 to 1.5 hours. Soaking at a higher temperature would have gotten it to that color more quickly but I believe the long soak made for a more durable coating. Going beyond this bronze color will take it to a purple and I did not want that color (note in an earlier photo the ash pan dump lever is slightly purple--it is 416 stainless and colors more quickly than the 304. Keeping the temperature down to around 600 also prevented too much oxidation of the copper rivets.

I then abused the resulting sample pieces and found they held up very well to scuffing, light sanding, and so forth. I then applied some high temp flat black Rust-Oleum spray paint to half of a sample, masking it from the unpainted portion. When cured, the paint is almost impossible to remove, even when scraping from the masked margin. So it appears to me that this is a good way to color stainless and to provide a good base for painting. Since I will be running the loco on propane I am not concerned about further coloration. I could have applied some high temp paint but didn't feel that there was a need.

When the ash pan was complete I took it to a heat treating firm and had it treated in an atmospheric oven. They had never heard of doing this to stainless and were surprised when it turned out like I told them it would! It is now permanently installed on my P7 and with all of the stuff being added to the boiler it is indeed disappearing nicely into the background. Note on the attached photo that you hardly notice the ash pan.

I hope this may be of some use to chaski members!
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2017 12 progress.jpg
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Re: Formed cab roof angle 16 ga. steel

Post by DaveD » Wed Jan 16, 2019 4:13 pm

Hello All,
I finally got to the angle fabrication and tried some of your suggestions. First I took 0.045 or so off the back end of the top roll in my slip roll, shown in slip roll detail.jpg in an earlier append above. That increased the clearance, against a hard stop thrust washer behind it all, to about 0.065, enough to allow one edge of some extruded brass angle to pass through. I annealed a test piece of this brass angle and started bending. It didn't work very well, as the brass tended to warp as I rolled it through on many successive passes, and the angle sharpened from 90 degrees to about 100 degrees. It would have been difficult to straighten out the warp and impossible to restore the 90 degree angle. Not good. See photo 1.

So I went to Jack's method. First I made a couple forms (jigs?) out of heavy steel plate with the exact profile of the roof radii and aligned them precisely with a couple dowel pins. That done, I laid out the angles so they were a couple inches wide radially and cut the outside end to a bit more than the top flange dimension would be. Then I annealed the 16 ga. sheet metal, bead blasted off the worst of the scale, aligned it in the jigs, put it very tightly in the vise, and started beating it with a plastic dead-blow hammer. Then the metal was fairly bent over, I got after it with my 2-3 pound hammer with a piece of 1/4 inch plate about 4 x 8 inches between it and the sheet metal. That was important, as it prevented me from making a real mess with hammer dents in the angle I was forming. Then I whacked until my arm couldn't take it any more and it all looked good. Finally, I trimmed the flat edges to proper size in the mill, cut off the excess metal on the other flange (carefully, in my trusty 1941 DoAll band saw), and filed that edge down to precise dimensions. Finally, as usual, I cleaned it all up by bead blasting. All the pieces retained the original radii to a few thousands of an inch. There was no spring-back.

Note that the outside radius of 90 degree angle on these pieces is rounded--about 5/64 inch radius. But that will never be seen unless I put my head inside the cab, which I won't be able to do. The inside radius is sharp. The only part of the angles that will be seen from the outside of the cab is about 1/8 inch by 9 inches of the two wider pieces that will be forming a ledge into the opening where the removable roof part will sit, and that is all as smooth as the original sheet metal. You can see the outside radius on the single shorter piece I have turned over.

Again, thanks for all the suggestions. Now on to the fun bending the roof piece to this complex radii!

P1167189 cropped.jpg
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P1167190 cropped.jpg
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Trainman4602
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Re: Formed cab roof angle 16 ga. steel

Post by Trainman4602 » Wed Jan 16, 2019 4:41 pm

That is exactly how I did it 15 years ago for the 1361 there is a video on it

https://www.youtube.com/watch?v=ruf0FJL7--M

ALLWAYS OPERATING MY TRAIN IN A SAFE MANNER USING AUTOMATIC AIR BRAKES

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Re: Formed cab roof angle 16 ga. steel

Post by Dick_Morris » Thu Jan 17, 2019 6:54 pm

Thanks for the inputs to this thread. I've spent the last couple of weeks pondering how to make the same curved angles out of 16 gauge steel for my cab. I'd come up with the same suggestions, as above, but it's nice to be able to take advantage of other's experience. This came at just the right time.

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Re: Formed cab roof angle 16 ga. steel

Post by daves1459 » Fri Jan 18, 2019 9:32 pm

DaveD, I see you had problems with the roll forming of your cab rib. I'm glad you were able to make your rib using one of the other processes. The roll form process will work. But, it does tale some technique. I've seen 3" steel angle iron successfully rolled into arcs. The helix or corkscrewing that your photo shows is the biggest problem to over come. In case you want to try rolling again for a future projects here are a few suggestions to help get better results.
1. All surfaces of the work piece must be guided in all three rolls. Even the forming roll. If the radial flange points away from the form roll then a groove for the width of circumferential flange is needed. Reference my previous photo showing rolling of a piece of "T" section brass trim.
2. Turning the part end for end and passing it back and forth through the rolls will straighten a lot of the helix. In terms of a routine two times back and forth in the rolls, then turn end for end and two passes back and forth, then turn end for and two passes back and forth. and so on. At each end for end turn add a small increment of feed. and always use small increments of feed.
3. Guiding grooves and slots should have just .005" to .007" clearance for the small work we're discussing.

I realize this all sounds rather fiddly. Once you get the routine down the process goes rather quickly and the process is adaptable to many material cross sections.

Dave

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