Milling Machine Recommendation For Lowering Freight Cars

[peteski]

https://www.sherline.com/authorized-sherline-dealers/

If the chuck on the drill press is attached to shaft by a threaded connection then some lateral loads are ok. But f the chuck is connected using a Jacobs taper, I would caution against using it for any lateral loads

[Chris333]

If the chuck on the drill press is attached to shaft by a threaded connection then some lateral loads are ok. But f the chuck is connected using a Jacobs taper, I would caution against using it for any lateral loads

Even for pot metal? MTL frames are like butter to a milling bit.

[peteski]

Even for pot metal? MTL frames are like butter to a milling bit.

Yes I would not put any lateral loads on Jacobs taper mount.  It is basically metal cone wedged in a tapered hole. Nothing but friction is holding the chuck.  With lateral force the chuck can just slip out.  But some inexpensive small drill presses use chucks with threaded mount (like handheld power drills).

[Chris333]

Ah I thought the tapered chucks had a draw bolt that pulled them in and held. I dunno I don't have a drill press. My mill is tapered with a draw bolt.

[wvgca]

dunno ... i have a few drills [1/4, 1/2] , maybe 6 or 7, that have tapered chucks, but they all have draw bolts through the centre that holds it all together  ... some -may- not have the centre bolt i guess ???

[peteski]

Ah I thought the tapered chucks had a draw bolt that pulled them in and held. I dunno I don't have a drill press. My mill is tapered with a draw bolt.

The drill presses I have use Jacobs taper where the male part is on the shaft and the chuck has the female part.  There is no place for the drawbar to screw into (inside the chuck).  Maybe Morse taper mounts use drawbars?

If the taper mounts in your tools include a drawbar then that should be ok for lateral loads (although a standard drill chuck itself is not designed for lateral loads).

Like the bottom chuck in this photo.

[wazzou]

I did over 400 MT cars just using good lighting, magnification a steady hand and my disc sander.
10 per night.   

[jagged ben]

For just lowering cars get an XY table for a drill press.
https://www.micromark.com/MicroLux-X-Y-Table-Attachment

Car frames are soft cast metal so the side load of a drill press will be fine.

Hmm, I think I'd be frustrated without precision on the Z axis.  Kinda valuable for lowering cars.

[mmagliaro]

The drill presses I have use Jacobs taper where the male part is on the shaft and the chuck has the female part.  There is no place for the drawbar to screw into (inside the chuck).  Maybe Morse taper mounts use drawbars?

If the taper mounts in your tools include a drawbar then that should be ok for lateral loads (although a standard drill chuck itself is not designed for lateral loads).

Like the bottom chuck in this photo.

Peteski, I think that is exactly right: The Morse taper arbors can be bought plain or with a threaded drawbar hole in the top end.  I have a Jacobs chuck mounted in my milling machine, but it is on an MT3 arbor with a drawbar, so I have a drawbolt going up through the top and I don't have to worry about the chuck unceremoniously coming loose and flying across the garage.

Folks: Peteski's warning bears repeating.  I wouldn't try to mill anything, even soft aluminum, on a chuck that is not bolted in from the top.   I made the mistake of forgetting to take the chuck key out of the side of the chuck once when I turned the mill on.  Little mill, low speed.... yeah, right.  You only have to see something like that fly past your face once to know it's not worth the risk.  I can't imagine what a Jacobs chuck spinning at 300 rpm would do it if dropped out of the mill head.

[Chris333]

This is how my mill works

/>And my chuck has the same R8 taper
https://littlemachineshop.com/products/product_view.php?ProductID=1396

I have a different draw bolt for my chuck because the threads are different than the regular collets.

[peteski]

Peteski, I think that is exactly right: The Morse taper arbors can be bought plain or with a threaded drawbar hole in the top end.  I have a Jacobs chuck mounted in my milling machine, but it is on an MT3 arbor with a drawbar, so I have a drawbolt going up through the top and I don't have to worry about the chuck unceremoniously coming loose and flying across the garage.

Again, based on my personal experience with Jacobs taper drill chucks. they are friction-fit only. There is no threaded hole in the bottom of the Jacobs-taper hole in the chuck, or a hole through the arbor (for the draw bolt).  The drill press' shaft is solid metal, and has a Jacobs taper "stub"on the end. the chuck (with a female Jabobs taper hole) press-fits onto it. YMMW.

[glakedylan]

elementary question from a guy who has never done any of this lowering:

what part of the car, exactly, do you mill/file/remove to lower it

i picture the frame which would allow the trucks to be attached higher, thus lowering the car?

but, then, i am clueless.

anyone???

thanks
sincerely
Gary

[wazzou]

elementary question from a guy who has never done any of this lowering:

what part of the car, exactly, do you mill/file/remove to lower it

i picture the frame which would allow the trucks to be attached higher, thus lowering the car?

but, then, i am clueless.

anyone???

thanks
sincerely
Gary

The raised circular part of the traditional MT metal frame’s bolster. 
I usually knock them down just a hair beyond flush with the rest of the bolster.

[Maletrain]

I am one of the "bad boys" that has done more milling than I should have with my old Sears Craftsman drill press.  I have sometimes used a cross feed device, and sometimes just slid the piece around the press table by hand, depending on what I am cutting.  I usually am very careful with side force, because the chuck is held only by the friction on the taper.  But, once, milling a large, shallow depression in a piece of aluminum bar, I did dislodge the chuck.  It did not go flying, because it could not drop completely out of the taper, but it did gouge the bottom of the aluminum piece.  It was a large chuck at relatively slow speed, with cutting oil, on a full sized press.  I would not hesitate to use that same press for very light pass cuts in soft stuff like plastic or white metal. 

But, I would be concerned about how to make sure that the amount of material I remove is correct to get the ride height just right.  There is no easy to use feed depth adjustment, although the stop is a coarse screw threaded cylindrical nut.  One big issue for any car height adjustment is the none-standard height of the model parts from the bolster to the upper surface, whether it is the top of a frame that is removed from its car or a glued-on walkway on the roof.  Those parts might be different thicknesses from different model mold eras.  So, I would need to have a reference surface on the bottom of the car frame to adjust my depth of cut for each car frame to get them to visually ride at the right height.

A very fine vertical feed adjustment would really help with that, and drill presses usually don't have those.

Whatever you use, remember to make sure the table surface is perpendicular to the axis of rotation of the cutting tool, or the car will sit cocked on the tracks when you get done.  A piece of wire held by the chuck and bent out to make a large circle on the table can be spun by hand to see when it just doesn't touch the table all the way around the circle of its path when you adjust the table tilt.  If your frill press table tilt adjusts in only one direction, it might not be able to be made perfectly perpendicular to the cutter axis in the direction that does not adjust.

[Ed Kapuscinski]

Just to play devil's advocate: when it comes to shaving down bolsters I've had luck using a cordless drill and the frame solidly clamped to the table.

It's not pretty, but it works.