Removing material from GHQ flat.

[wcfn100]

As I go through my fleet looking at what it's going to take to convert to True Scale couplers, the flat cars are definitely the biggest problem (if you also plan to lower the cars).  I may be at the point I need to get a small mill but would like to explore other avenues first.

Basically, I need to make the ends less thick by a bunch.  I'd like to have a clean, flat surface when I'm done.  I can dremel some of it out but can't really file anything because of the tight space. Anyone work with pewter parts like this with any suggestions?



Jason

[mmagliaro]

Can you possibly post a close-up photo of what you are trying to do?  I am not able to picture how there would be tight clearance when trying to file the ends of a pewter GHQ flat car.

[wcfn100]

So in a perfect world, I would have a mill and would just make a slot for a new coupler box, but I don't, so I can't.



It doesn't need to be perfect, but just something that looks presentable and is a nice flat surface for the box.


Jason

[Chris333]

I have a bit that looks like a small end mill (about 1/8" dia.) You could mill that out by hand with a Dremel using it.

You could use the same bit in a drill dress. Without a x-y table you could just set the depth and slowly push the flatcar into it.

[wcfn100]

You could use the same bit in a drill dress. Without a x-y table you could just set the depth and slowly push the flatcar into it.

Then I'd just need a drill press.   

I think I may have to just grind into the floor the best I can with the dremel measuring every 5 seconds.  I can use a pool of glue to secure the pocket if need be.     The plan is to mold and cast new flats out of resin so I just need the box to endure the mold process but would like it to look as good as possible.


Jason

[cjm413]

Would the GHQ flat have the correct coupler height and ride height if you leave off the top plate of the coupler box?

[Chris333]

Just offered the drill press as another way. I'd probably just do it by hand using the end of the bit.

[narrowminded]

Sharpen a tool and scrape it, much like you might do with a sharp chisel in wood.  The nose of a small triangle file might be the blank to start from.  A fine grain wheel and then hand dress on a knife sharpening stone much as you would when sharpening a knife blade.  Slight radius/ rocker underside to register and rock the cutter from and the vertical edge tipped back towards you at about 8 to 10  degrees.  Stone all edges smooth and the cutting edge sharp.  Clamp a fence along both edges and the back side to hold the part while you push against it.  Paint sticks might work for that.  To start it might help to define the perimeter by scoring slightly with an Exacto knife.  That score profile might be just slightly smaller than the finish dimension.  Take slow and steady, controlled strokes rocking the tool up to control the depth of cut, taking a very small amount with each pass.  Just an amount that feels smooth and lets you stay in control.  Watch for squareness and uniform depth as you progress and rock the tool or tip as needed to maintain the pocket.  You may want to scrape from the opposite direction as you progress to keep the floor flat or if a step starts to develop.  Come from the opposite direction to correct it before it gets out of control/ beyond recall.

That doesn't wreck the file either, just makes it more useful.  That can also be used on the side as a deburring knife.  Sharpened to the same general shape as the file is manufactured just smoothing the teeth on the front 3/8" or 1/2" of the file.  Any triangle file I own, nominally 1/4" or less, has the nose dressed that way or will the day it's needed.   Another source of hardened tool steel for fashioning custom cutters of all shapes and sizes are drill bit shanks and pieces of old hacksaw blades. 

[Lemosteam]

You could do what I do when I have to mortise in a hinge in wood.  On a very flat and hard surface turn the car upside down and scribe deeply (as straight as you can and as close to the final depth as you can) the outside edges of the rectangle you want to end up with.  If you use an exacto chisel blade, you can start in the center and shave away from you up to the scribe line near the bolster, parallel to the side scribes. Keep shaving little by little, working from the bolster to the end of the car, at which time you can turn the blade 90 degrees and shave to the side scribe lines. You may have to scribe two or three times and shave the same way till you get to the depth you want.

[wcfn100]

Would the GHQ flat have the correct coupler height and ride height if you leave off the top plate of the coupler box?

No, the coupler box lid is only .012".  There's still .030"+ material to remove to get the deck to a prototype height.


Jason

[narrowminded]

No, the coupler box lid is only .012".  There's still .030"+ material to remove to get the deck to a prototype height.


Jason

Is there enough material in the frame to remove .030" without breaking into the deck or leaving enough for the screw thread?  I might suggest to contact me in PM and just have you send it to me for milling.  Leave the bolster and coupler pocket as is and just mill both, quite precisely, in one setup.  Also drill and tap the coupler screw at the same time. 

[mmagliaro]

Ah, I see now.
The other suggestions in here are all fine ones.  I have been in situations like yours with other cars.

I do what is probably a combination of the other suggestions in here.

- Use an Xacto to cut lines along the left and right boundaries of what you want to remove.

- Then I just use a square ended file and "push" it in there, doing more scraping than actual filing.
  Filing is not such a great idea on pewter because it immediately loads up the teeth.  I use a junker
  file for this in any event.

- Do some cleanup in the corners of the recess with a sturdy Xacto blade (like a #24).  Pewter is soft.
   You can scrape it out of the corners with the Xacto blade point pretty easily.

It takes a little while, but just working it, shaving and filing, you can remove that material and get it flat.

[nkalanaga]

It won't help you, but this might help those wanting "standard" couplers.  I lowered mine, and body mounted Accumate couplers, by screwing them directly to the floor.  Add end sills to retain the centering springs, install BLMA trucks, and they're at just the right height.  The Accumates are offset just a little, so they mount a bit lower than 1025s, even in the same case. 

My first thought was to install 1025s, but that would have required the same work you're trying to do. 

Good luck!

I wish GHQ would rerelease those, and if they did, it wouldn't be hard to modify the ends to accept body mount couplers.  The easiest way would be to cast the top of a 1015 or 1025 box into the end.

[wcfn100]

Well it just so happened that I already had a #17 x-acto blade cut down to about the width of the coupler box so I gave it a try.



All in all, it went pretty good.  The biggest key was resharpening often.  I got it to the point where I would need a box without a top to get the coupler to the correct height.  Otherwise I need to take off another .012".

Thanks for all the help.

Jason

[cjm413]

How does the quality of the N Scale Kits 50T AAR flat compare to the GHQ 50T AAR flat?