What Tools to Cut Metal Underframes

[ai5629]

I am thinking about attempting to lower some Athearn / MDC 52' mill gondolas.  I want to get them down to the same height as the Atlas 52' Evans gondolas.  To accomplish this, I want to go the route of cutting off the bolsters and fabricating new ones from styrene.  My question is, what do you suggest I use to cut the underframe?  If I use a Dremel, what cutoff wheel or cutter would work?  Could I use a razor saw and miter box?  What type of razor saw blade?  I searched for guidance here and on the web, but I could not find any.  Thank you for the help.

Jeff

[nkalanaga]

I use a razor saw and a pair of locking pliers.  Once you've cut most of the way through, across the piece, zinc alloy will often snap along the cut line.  Hold the end of the underframe in the pliers, and saw away.  If you mangle the end a little it doesn't matter, because you're tossing it anyway.  I don't even use a miter box, just cut along one of the crossbearers, far enough in from the bolster to clear the wheels.  If the end is a little rough you can file it, but it won't show after the car is on the track.

The Dremel might be faster, but there's also a greater chance of it slipping and damaging the underframe, or you.

[BCR 570]

I have cut and spliced metal underframes successfully using a razor saw and mitre box as I did not own a Dremel tool.  Dremel would be faster but the razor saw would offer more precision ie. easier to check your work and adjust as you go.  If using a Dremel to cut metal, there are some obvious safety precautions to be taken.

After cutting, parts were cleaned up with files.


Tim

[randgust]

I'd use a dremel and abrasive disk, with the required safety goggles, and if holding anything to be cut, a heavy pair of leather gloves for heat and hand protection.    Metal can get absurdly hot while cutting with a disk.   And to keep the dust contamination down, take it outside.

Oh, and extra disks for the one's you'll shatter.

I've made a real mess out of hacksaw and zona saw blades cutting underframes, easier to replace dremel disks.

I cut down split frame diesels a lot too, and it's a messy if necessary undertaking.   I really don't care to do them in January in the snow, sitting out on my deck, but I have!

The good news is that I think its really worth the effort to lower flats and gondolas.  What a difference in appearance.  I make up a very simple, no-frills evergreen styrene bolster that's more like an extension of the center sill, no sides on it at all.  It gets glued to the carbody, with the original frame bottom only between the original bolsters.   Probably have done 20 of them now.  Way more beneficial results than changing to low-profile flanges because if you lower the car where it belongs you can't see the flanges anyway.

[robert3985]

I just use my mill.  Sure makes it both precise and easy.

Although it's an expensive investment, a small mill is something you'll always be glad you have.  If you've got a lot of metal underframes to cut and rebuild, you might consider looking for a used Sherline or Micro Mark mill, with tooling.  Sometimes you can get a helluva deal.

[bbussey]

Ditto on the mill.  It's not my primary use of it, but it does come in handy for this type of job.

[DKS]

I'd use a dremel and abrasive disk, with the required safety goggles, and if holding anything to be cut, a heavy pair of leather gloves for heat and hand protection.    Metal can get absurdly hot while cutting with a disk.

I've had relatively poor results using cutoff discs on metal underframes. The discs are thick for the job which adds heat, takes time, and results in cuts that are not especially clean, since you're essentially grinding through the metal, instead of cutting it. And the disc will sometimes get "gummed up" with zinc. Not to mention it takes a bit of effort to remain true with a hand-held motor tool. Much prefer a Zona saw and a miter box. It takes longer, but with patience you wind up with a clean, accurate cut.

Now, if you're terminally impatient and want to buy a very useful tool, but aren't made of money, a MicroLux micro table saw will do the job--plus a lot of others. Be sure to wear eye protection, and possibly even ear protection. Also have spare blades on hand as they'll get dull pretty quickly if you have a lot of frames to cut. And do the cutting in the garage or outside; otherwise you'll have granulated metal everywhere. Set the fence to the right dimension, and you can rip through frames like there's no tomorrow.

I just use my mill.

Seems sort of like driving a Mercedes to get the mail from the mailbox at the end of the driveway. Just sayin'... 

[peteski]

Seems sort of like driving a Mercedes to get the mail from the mailbox at the end of the driveway. Just sayin'... 

Well, but it the Mercedes is just sitting there on the workbench, not being used (and you never bothered to buy that Ford Pinto), then why not! 

Besides, if I understand Jeff correctly, he wants not to cut a piece of the underframe; he wants to cut off the bolster.  INsted of cutting, it can easily be milled off flush with the bottom surface of the underframe. Or just milled enough to shorten it to correct height.

[bill pearce]

That is what I was typing a reply about when your email came in. Is it possible to simply file a bit off the bolster, as you would do to lower the car to correct ride height and body mount? If so I've done plenty with a big ol' file. Not hard, not expensive, not overthinking.

[Ed Kapuscinski]

Screw filing the bolster. I use a hand held cordless drill. A press would be better, but ain't nobody got time fo that.

[towl1996]

                                 ain't nobody got time fo that.

Here ya go, spend sometime with this...

/>

[Ike the BN Freak]

These mills, can these be used to mill out the sides of a Kato passenger car to then attach brass car sides.

But think it would be pretty expensive to mill out a few Kato cars.

[ai5629]

First, thank you for all of the suggestions.  I don't have the funds for mill (as useful as it would be), so that is out.  I think I will follow Dave's suggestion about a Zona saw and miter box.  My inspiration for this project is Bryan Bussey's Jan 94 N Scale article on lowering MTL gons and flats.  He only mentioned that he used a Dremel to cut the underframes, so I started this thread to expand upon that and explore other options.  I don't feel that simply filing down the bolsters will work.  These cars really need to come down, and I think this would result in the wheels rubbing the underframe.  I want to cut the underframe at the bolster.  Then cut from the outer most cross bearer to the center sill and from the original bolster cut along the center sill to the first cross bearer cut.  Once I do this, I will need to decide on an appropriate bolster thickness that produces the proper ride height with 100 ton Atlas or Athearn trucks with 36" wheels.  I will then figure out body mounting MTL 1015's or Atlas 23015's.  This will most likely require some thickness of styrene to get the coupler to the proper height.  Another variable I am seeing is the center sill hangs lower than the side of the car.  This doesn't look right compared to the prototype, so I may consider replacing the entire underframe with something else.  Who knows. 

Jeff

[robert3985]

Seems sort of like driving a Mercedes to get the mail from the mailbox at the end of the driveway. Just sayin'... 

Well, but it the Mercedes is just sitting there on the workbench, not being used (and you never bothered to buy that Ford Pinto), then why not! 

Besides, if I understand Jeff correctly, he wants not to cut a piece of the underframe; he wants to cut off the bolster.  INsted of cutting, it can easily be milled off flush with the bottom surface of the underframe. Or just milled enough to shorten it to correct height.

What Peteski said...

[robert3985]

First, thank you for all of the suggestions.  I don't have the funds for mill (as useful as it would be), so that is out.  I think I will follow Dave's suggestion about a Zona saw and miter box.  My inspiration for this project is Bryan Bussey's Jan 94 N Scale article on lowering MTL gons and flats.  He only mentioned that he used a Dremel to cut the underframes, so I started this thread to expand upon that and explore other options.  I don't feel that simply filing down the bolsters will work.  These cars really need to come down, and I think this would result in the wheels rubbing the underframe.  I want to cut the underframe at the bolster.  Then cut from the outer most cross bearer to the center sill and from the original bolster cut along the center sill to the first cross bearer cut.  Once I do this, I will need to decide on an appropriate bolster thickness that produces the proper ride height with 100 ton Atlas or Athearn trucks with 36" wheels.  I will then figure out body mounting MTL 1015's or Atlas 23015's.  This will most likely require some thickness of styrene to get the coupler to the proper height.  Another variable I am seeing is the center sill hangs lower than the side of the car.  This doesn't look right compared to the prototype, so I may consider replacing the entire underframe with something else.  Who knows. 

Jeff

Contrary to DKS's assertion that you've got to be "made of money" to own a mill, I traded for mine.  Didn't cost me a dime out-of-pocket.

Jeff, if you're doing a lot of this type of work, thinking about getting a little mill would be good.  I've lowered several modern cars, and being able to hog out metal where the flanges rubbed the underside was invaluable...meaning quick, precise and simple.  Having done the same thing with my Foredom Tool...there's no comparison.

In the thread on workbenches, seems I saw a lot of mills and lathes on those workbenches.  Although there may be some modelers who regret getting some machine tools, I'd venture a guess that most of us are very happy with our investments.

Something to think about and maybe plan for eh?? 

Just sayin'....