Got A Question About Cutting A Piece Of Brass Tube

Bob, why not make a test piece with a paper or plastic tube? Once you have the angle correct transfer the cut points to the brass.

Chris, I think that's what will have to happen.  I think I can take Bob's template and make it work, but it'll be a trial and error affair with the template.  At least it'll be done with card stock and not brass!!!

Wouldn't it be cool if you could take a laser and etch a line across the place where the cut should be with no mistakes?  Drawing a straight line on a curved surface by hand is no fun.

I have one of those laser levels used in construction work, I wonder if I can positioned it over the brass tube to orient the line then mark/draw/tape the cut line?

Bob Delbridge posted:

Chris, I think that's what will have to happen.  I think I can take Bob's template and make it work, but it'll be a trial and error affair with the template.  At least it'll be done with card stock and not brass!!!

Wouldn't it be cool if you could take a laser and etch a line across the place where the cut should be with no mistakes?  Drawing a straight line on a curved surface by hand is no fun.

I have one of those laser levels used in construction work, I wonder if I can positioned it over the brass tube to orient the line then mark/draw/tape the cut line?

Bob, long before there were lasers there were profile gauges. This along with a protractor square should alow you to layout a line on that cylinder.

http://www.woodcraft.com/produ...tandard-5-width.aspx

Pete

Why not stick with the PVC?  Once it's painted and weathered, who would know! It's so much easier to work with.  I have fabricated many oil bunkers to convert coal tenders to oil and have always used some type of plastic with rivet decals.

Peter

Pete, The only problem with using the protractor is it only touches a single spot when laid on the tubing, a laser would hit all points along the cut line.

Peter, the PVC pipe was actually larger than what the diameter should have been.  The brass tubing is smaller, but not as small as the PVC was larger (say what?!?!?)

The brass tube is 2" OD and the PVC pipe is 2" ID and was 2-3/8" OD.  The Vandy tank was 8'-4-1/2" diameter so the brass is a bit closer in size.  I could (I think I actually did on the 1st one) cut down the OD of the PVC a bit, but thought I'd give the brass a try.

This new tender may end up a brass and styrene hybrid.

Here's 2 photos of SAL #266, notice the difference in the tenders:

I think the water tank was extended in the SAL Portsmouth shops.

Any idea what type of trucks those are?  The trucks on the 2-8-2 tender (1st post photo) are way different (Ron Dettmer sold me some of those large truck side frames he had cast).

The engine I'm converting is a Lionel Southern 4-8-2:

And here's Bob2s SAL version (hopefully I can come close to Bobs efforts):

The Lionel tender is a USRA I think.  It's diecast and VERY heavy, heavier than the brass will be I believe.

I have to remove/move a couple of pieces of walkway along the boiler, and remove/replace the sand dome and lines.  Also need to relocate the bell and do something with the cast-on air reservoirs and piping.

It'll be close, but not THE cigar.  I'd like to find some of those spoked pilot wheels too!

Bob,
This is where your "Mechanical Drawing " class in High School is useful. There is a way to project the lines unto a flat plane so that it can be easily cut out, then rolled. This would probably be the easiest thing for you to do.

Sir, the one draw back to a construction laser is that it is self leveling. You would have to angle the brass to mark it.

There is another way to cut it, but would probably be costly, and that is to use a Water Jet.  

Bob Delbridge posted:

Pete, The only problem with using the protractor is it only touches a single spot when laid on the tubing, a laser would hit all points along the cut line.

 

Bob, The protractor is only used to set the angle. The profile gauge is set against the tube and will conform to the curve to allow you to scribe a line. The red in the picture below is an array of plastic rods which move independently up and down. Early profile gauges used metal wire rods. Either would work in this application.

Pete

Bob,

I'm trying to remember if you had a friend or associate that did solidworks 3d modeling for you a year or so ago.  It may have been somebody else on the forum.  At any rate, you could model the the skin of the tube in 3d in solidworks with the proper angles and then unroll it in the program.  Print it out on a sheet of paper and you that for a template.

In 3d AutoCAD I could probably do that in ten minutes.  Although I don't know if AutoCAD can unfold or unroll things.  But it should be similar in solidworks.

Why not use a styrene wrapper on the brass tube.  That way you could get the proper diameter AND the finicky work is all in styrene with the brass rough cut.

Thanks guys!

Pete, I have one of those too!

I took another look at what Bob had done in his article.  I copied his template and enlarged it a bit.  But the flat sides of his template form a convex curve when placed on the tubing.

I drew a 12" circle on a piece of card stock, cut it out, then traced it onto his template (so the straight line looks like a concave curve on the template).

It worked, making the concave curve a straight line when looked at from the side.  Only problem was the bottom of the curve was higher (from the bottom of the tubing) than what I need.

The solution (I think) is to change the 12" diameter circle to something like 30" diameter, giving it more shallow curve.  When placed on the tubing the template should appear more flat when looking from the side.

Big Jim, Not only did I take 3 years of mechanical drawing, I went thru an 4 year apprenticeship at a machine shop then worked another 4 years.  Of course that was from 1969-1976 so things are a tad fuzzy, but are coming back .  Wish I still had my Machinery's Handbook, they're going for big bucks these days.

I could make the cut using Bob's template as is, then whittle the sides down until they mated with the coal bunker.  Taking away material is easier than adding it back

Here's my...

worth...

I think I'd take the brass tube (uncut, adequate length) to a reputable metal shop having a horizontal band saw for cutting metal.  If you know the angle of your cut, simply tell them to make the cut at one end.

Then, you can either have them make the finish vertical end cut to your dimension/subsequent mark, or make the vertical cut yourself...granted a much simpler job for the DIY modeler.

I can't imagine they'd charge much for making a single angle cut, and it's the sort of thing a metal shop does eleventy-seven times a year.

The other alternative would be to have your PVC pipe turned/polished on a lathe to the preferred smaller diameter.  Again, I'd let a pro shop do that, too.  And, BTW, there are plastic tubes in the larger sizes available in polymers other than PVC.  We have a custom plastics shop here in town that deals in all sorts of materials, fabrication/cutting, bonding adhesives, etc., etc..  I've found them to be very helpful, and their price reasonable (when taking into account my own ineptitudes, shortcomings, limited big-box paradigm choices, etc.!).

FWIW, always....

KD

OSN would often take my carefully drawn illustrations and re-draw them with a computer.  No guarantees.

Trial and error is really the only way, but I do have a hunk of 2 1/8" dia. exhaust pipe cut to the proper SP angle.  I can slip a 2" brass tube inside, and cut that way for a more or less good fit.  The SP angle is different from the Seaboard angle.

What I now do is fly- cut two bulkheads to slip over the tube, solder the oil (coal) tank wrapper to them, slide the entire assembly on to the tube, solder, and then fill in from underneath.  If you are given to plastic, that can be easy, and you can fill in gaps with putty.  Even easier with cardboard.  You never see that area, anyway.  I fill in with metal, after making cardboard templates, and solder.

Lots of advantages to this method - squareness is much, much easier.

you could take the pvc,  make your angle,  slip brass tube inside pvc,  cut your angle,  then you have a jig if you do it again

Bob,

If you can get an accurate measurement of the angle, you could cut slots (don't cut all the way through) in two boards with a power miter and then cobble up a miter box (like the cheap all wood versions) and clamp your tube to the box and use those angled slots to cut your tube with a hacksaw. Make the box just big enough to contain your tube.

Simon

Thanks again folks!

KD, the machine shop I used to work for is no longer in business, but they used to charge a minimum for doing walk-in work like this.  That was back in the 70s so prices must have gone up, I may find someone who will do it for cheap but I'm going to give it a go (I have enough material to make another if I mess up).

Simon, I think you hit it...keeping the tube still (and not squishing it) while cutting.

Riki, that sounds like a good idea, thanks!

I have a mini-lathe, but I want to go brass this time around.

Bob, I'm going to read your article a few times until I feel comfortable about working all in brass.  I was going to do the bunker in styrene but I have the brass so why not give it a try.  I think once I get the slope sheet correctly positioned the rest shouldn't be too hard.

I'm in no hurry on this project, it'll probably be my last steam engine.  Other than a 2-10-0 I have all I wanted for Seaboard and too many to run at one time now.

Bob,
Since you are bent on working in brass, forget this wild and crazy gobbledee-goop these guys are trying to pass up on you and do it the way a real sheet metal worker would do it (just like I suggested). Bone up on your latent mechanical drawing skills and plot it out on a flat piece of brass that is easy to cut.   

BTW, have given any thought as to how are you going to make the dome-like end of the tender, anneal some brass and spin work it or pound it out with a hammer?

Big Jim posted:

Bob,
Since you are bent on working in brass, forget this wild and crazy gobbledee-goop these guys are trying to pass up on you and do it the way a real sheet metal worker would do it (just like I suggested). Bone up on your latent mechanical drawing skills and plot it out on a flat piece of brass that is easy to cut.   

BTW, have given any thought as to how are you going to make the dome-like end of the tender, anneal some brass and spin work it or pound it out with a hammer?

He could do that but rolling it up might be an entertaining exercise.

As for the end, I was wondering about that myself, but I'd be willing to loan Bob one of my anvils to save him ordering one from Acme....

The math for that cut is beyond most sheet metal workers and draftsmen.  Having done it both ways, you really should consider my suggestion for bulkheads that slide over the tube.  No cut required, and dead accurate.

The end bell - you do need a lathe if you do it my way and use an automotive freeze plug.  Dorman used to make them with the proper bell shape.  I have a steel die that I use to hammer the bell shape into a flat freeze plug.  The rim has to be machined to fit inside the tube.

You guys REALLY want me to work don't you!?!?!?

Here's what I did on my previous PVC tender:

The gray PVC round stock was 2" and fit inside the PVC pipe.  The white styrene was shaped to match the template.

This enabled me to pop it in/out if I had to get inside.

I think Bob T might have used a brass knockout plug for the one he made in his article (which I still need to read).

I have the mini-lathe so I could make it out of brass easy enough.  Either way (brass or plastic) I have to shape/machine it somehow.

Are the trucks in the SAL photos Commonwealth type trucks?

This is a fantastic thread.  It will help me with a future project. 

Last year I searched several auto stores, Lowe's, and other hardware store for brass freeze plugs-nothing in my area.  Seems most are steel or some other metal now days. 

Summit Racing had them-just an FYI if you find them hard to locate. 

If I had a lathe I could do some much more..

MWB, I am curious how you cut and shaped that. Big band saw or cutting torch or neither?

Lots of ideas here. I am pretty sure I could make that cut in 5 minutes accurately with a couple of hand tools. No computers or drafting boards needed.

Pete

Norton posted:

MWB, I am curious how you cut and shaped that. Big band saw or cutting torch or neither?

 

 

No idea - that was a spontaneous and serendipitous acquisition along with a somewhat smaller and clearly commercial product anvil - I do use the smaller one every so often.  Figured I better keep it since you never know when you're going to need one to put down a roadrunner or one of the Warners,