Milling frames to add speaker

[Shaggy170]

Hey All,

So I had quite the experience this past Sunday. Tried to remove some metal from a Kato N Scale E-unit chassis to make room for a speaker using a drill press. Didn't go well. Ended up snapping the frame and hit my thumb with said frame because I did not secure it properly (no one was injured physically, just some bruised pride). So, lesson learned there. Now to the internet to learn. Hopefully I'm posting on the right forum.

My question is this: short of a spending hundred on a milling machine, is there an easy way to remove the metal? Or is a drill press an easy way to get rid of most of the metal and then cleanup with a Dremel/file, when secured properly? If so, what's the best way to secure it so I don't repeat my first try?

Thanks all in advance.

[Steveruger45]

I just use a junior hacksaw and files and patience.
The knack with this approach is to fully secure the frame or frame half.  For this I make a wood form to support the frame from the forces applied. Usually out of scrap of 2x1 that I have whittled to suit.
To help stop a file gumming-up so quickly rub chalk on the file and have a file card to clean the file.

To get a recess where a through cut can’t be done I use a dremel.
Don’t try to rush.

Good luck.

[peteski]

Unfortunately as I see it, there are no shortcuts.  Kato E-units have very hefty solid-metal frame.  I assume you were trying to remove metal from the rear, correct? That is the best place for the speaker and enclosure.

Using a drill press as a milling machine can (as you experienced) end badly.  Coincidentally, just last night I have made room for a speaker in half a dozen of Kato PA frames. Those are very similar to the E-units (which I have also done in the past).  I did that for a friend.

For the cheapest way you can clamp the frame securely in a vise on a solid workbench surface, take a metal hacksaw, and make a horizontal and vertical cut to remove a slab of metal. It will take some time, but still safer and faster than using a drill press "mill".

I can do this in about 2 minutes per frame. My secret?  Small inexpensive band saw with a metal-cutting blade, and a machinist's vise.  The vise is heavy and stable.  I clamp the frame in the vise, and make those 2 cuts.  It is much more efficient than tryign to mill out all that metal in a milling machine.

My Skill Saw 9" band saw was about $100, and I got the machinist's vise (don't recall the price) from Micro-Mark (probably could have found a cheaper one). I also had to buy a metal cutting band, but that was not too pricey either.

[nightmare0331]

sounds like a clamping issue.  From what your description sounds like, you were holding the frame by hand, something dug in and whipped the frame around.    Make sure you are clamping close to where you are machining...not just in a vice attached to where the fuel tank fits as where the trucks fit and worm gear bearings sit can easily get twisted and snap.

were you using an endmill in a drill press or drilling holes then cleaning them up with say a dremel and a hacksaw blade and files?  Certainly with light passes and clamped to an XY table and a vice it will work but drill presses really arn't designed for lateral pressure (Kato frames are soft however so if you're only doing the occasional frame...).

When I was cutting and machining E unit frames by the hundreds, I'd use a metal cutting bandsaw to take the large slug out then chuck into my mill to finish mill to correct depth and side clearance for an 11x17 speaker.  No real need to hog all of that material out one pass at a time.

You are wearing eye protection, right?

Hope this helps!

Kelley.

[ednadolski]

Using a drill press as a milling machine can (as you experienced) end badly. 

Very badly. For example, the chuck can fly off the spindle if a bit binds on anything. My equivalent experience was with a kickback on a table saw. Since then I have learned to respect what these tools can do. I do not need spontaneous projectiles in my work room.

Ed

[CRR Chase]

Thanks for mentioning this, I was intending to use the "dremel press" and an xy axis with clamp to do some milling.... i havent done much, so I'll be learning... If for some reason I decide to "do more' ill get a small mill. speed control should be doable with the dremel, but i also have a hack saw. (learning)

[mmagliaro]

I would suggest that this thread be moved back to the main N/Z scale thread.  I know it was originally placed here because the goal was to mill space for a DCC decoder and speaker, but really, this topic is about the physical milling of engine frames.

And second, I held off about this because people are already discussing the dangers of using a drill press to mill, and of
trying to hold the workpiece in one's hands while doing it.   But I don't think the seriousness of this has been adequately presented.

Drilling straight down under a drill press is NOTHING like trying to cut sideways with it.

When you hold a workpiece in your hand against a milling cutter, whether it be in a drill press or a mill, that cutter is going to either:

a) kick the piece out, which will at the very least make for a mangled mess of a cut, or more likely, send the piece flying across your workroom. 
OR
b) pull the piece in, possibly taking off your fingers or a chunk of your hand

It will happen in an instant.  You won't be able to stop the machine or get your head or hand out of the way.

If you are very lucky, sure, "maybe" you'll just get a bumpy ragged cavity made by the cutter.
But this is truly a horrible, dangerous practice.  It think it's even more dangerous than the possibility of the drill chuck pulling out of its arbor and flying across the room (which is the other dangerous thing about this practice)

I am truly glad and relieved that the OP was not injured. 

[Cajonpassfan]

This! What a great post!
Thank you Max.
Otto

[Maletrain]

Thanks for mentioning this, I was intending to use the "dremel press" and an xy axis with clamp to do some milling.... i havent done much, so I'll be learning... If for some reason I decide to "do more' ill get a small mill. speed control should be doable with the dremel, but i also have a hack saw. (learning)

If by "Dremel press" you mean the drill press attachment that holds a standard Dremel tool so that it can be raised and lowered with an arm, like a drill press, then I think you will find that the cutter position is not held rigidly side-to-side by that rig, and milling with it will chatter a lot.  Very fine cuts might get you through, but it will probably be very tedious.

[thomasjmdavis]

I've trained dozens of people to work in cabinet shops and theatrical scenery studios. That's woodworking (mostly) rather than metalworking, but...
AMEN TO EVERYTHING MAX SAID

[Spades]

Southern Digital has a number of milled frames. https://sodigi.com/product-category/digiframe-kits/kato/   Alas no E8's.  They might be able to machine your frame,  It cost money but no deformity or destruction of the frame.

[robert3985]

Having modified several Kato E-8's and E-9's for speakers, I don't "mill" the speaker holes (even though I have a vertical mill), I use my big ol' Craftsman Drill Press to do the job, holding the chassis in a drill press vice that's bolted to the slots in my press's table.

I use round speakers, and at first I drilled completely through the large chunk of metal on the rear of the chassis, first with a smaller bit exactly in the center of the larger hole I wanted, then another bit about 1/16" smaller than my final hole, then a finish hole with the correct sized bit stopping about 1/8" from going completely through...which creates a small ledge so the speaker doesn't fall out.

I found that the final hole was a tight press-fit for the speaker, so the ledge was unnecessary.

I then turned a brass plug to fit the top of the hole with a small hole drilled into it for the wires to come out of, and press fit this into the top of the speaker hole...then sealed the hole with the two speaker wires with silicone caulk to make it an air-tight, dense, speaker enclosure.

One thing that I learned is that whatever metal Kato is using for their E-8/E-9 chassis, it's difficult to drill, and to mill...much more difficult than solid brass or even steel would be...because it wants to gall, even with my brand new sharp drill bits and carbide end mills.

On my later speaker hole-drilling Kato E-unit projects, I used the same setup on my drill press, but drilled a small pilot hole from the top first...clear through so the bit comes out the bottom, then I tipped the chassis over and drilled it from the bottom just deep enough for the speaker to fit in, the speaker wires coming out of the small pilot hole on top of the chassis and after I pressed the speaker into the hole I sealed the pilot hole with the wires coming out of it with silicone caulk...making it, once again, an air-tight enclosure, with the speaker firing downward.

The press-fit is tight enough so that the speaker isn't going to fall out.

Not drilling the big hole completely through the chassis minimized weight loss by removing much less metal and I didn't have to turn a brass plug...and took less time.

Photo (1) - Four Kato E-9's with my first hole-drilling endeavor before turning the brass plugs for the top of the holes:


For these speakers, which are from Digitrax, you'll note that the hole has to be drilled very precisely because there isn't much "meat" on the four sides of the metal "cube" after drilling the full-sized hole in it.

There's no way I could have drilled these without securely clamping them down with my drill-press vice.

Since I did these, I've kept the speakers, but changed the sound decoders to ESU Loksound boards.

Cheerio!
Bob Gilmore

[Shaggy170]

Thanks all for the responses.

I am truly glad and relieved that the OP was not injured. 

Yes, I was very lucky not to be injured. Nothing went flying (other than some small bits of removed material). I should have mentioned that my thumb hit the outer faming of the workbench as I reacted to turn off the drill press, not the frame of the engine. It stayed put where it was after snapping. Only the rear section was moving freely on the drill bit but it also did not go flying.

Kato E-units have very hefty solid-metal frame.  I assume you were trying to remove metal from the rear, correct? That is the best place for the speaker and enclosure.

Using a drill press as a milling machine can (as you experienced) end badly.  Coincidentally, just last night I have made room for a speaker in half a dozen of Kato PA frames. Those are very similar to the E-units (which I have also done in the past).  I did that for a friend.

They do have a very solid frame. I was trying to remove some of the metal from the rear to fit the speaker. I was trying to use the drill press as a way to remove a majority of the material, not as a true milling machine (no lateral movements, only vertical). I did move the frame slightly, when the drill press was off, to get a second press (plunge, pass, not sure of the proper term here) to make an 8 shape in the frame. The first went find so I thought the second would be okay but I thought wrong.

sounds like a clamping issue.  From what your description sounds like, you were holding the frame by hand, something dug in and whipped the frame around.    Make sure you are clamping close to where you are machining...not just in a vice attached to where the fuel tank fits as where the trucks fit and worm gear bearings sit can easily get twisted and snap.

were you using an endmill in a drill press or drilling holes then cleaning them up with say a dremel and a hacksaw blade and files?  Certainly with light passes and clamped to an XY table and a vice it will work but drill presses really arn't designed for lateral pressure (Kato frames are soft however so if you're only doing the occasional frame...).

When I was cutting and machining E unit frames by the hundreds, I'd use a metal cutting bandsaw to take the large slug out then chuck into my mill to finish mill to correct depth and side clearance for an 11x17 speaker.  No real need to hog all of that material out one pass at a time.

You are wearing eye protection, right?

Hope this helps!

Kelley.

It probably was a clamping issue. I did not use a vice, only a clap and some screws that I though would counter the rotation of the frame. As I experienced, it did not work as I thought. Must invest in a vice if I try this method again. And yes, eye protect was used. As stated above, I was only looking to remove material using vertical movements to make an 8 shape. Looking back, I think one issue was too big of a drill bit. I think the cutting edge of the bit caught part of the frame rather than cutting it, which caused a lateral force that snapped the frame.

Having modified several Kato E-8's and E-9's for speakers, I don't "mill" the speaker holes (even though I have a vertical mill), I use my big ol' Craftsman Drill Press to do the job, holding the chassis in a drill press vice that's bolted to the slots in my press's table.

I use round speakers, and at first I drilled completely through the large chunk of metal on the rear of the chassis, first with a smaller bit exactly in the center of the larger hole I wanted, then another bit about 1/16" smaller than my final hole, then a finish hole with the correct sized bit stopping about 1/8" from going completely through...which creates a small ledge so the speaker doesn't fall out.

I found that the final hole was a tight press-fit for the speaker, so the ledge was unnecessary.

I then turned a brass plug to fit the top of the hole with a small hole drilled into it for the wires to come out of, and press fit this into the top of the speaker hole...then sealed the hole with the two speaker wires with silicone caulk to make it an air-tight, dense, speaker enclosure.

One thing that I learned is that whatever metal Kato is using for their E-8/E-9 chassis, it's difficult to drill, and to mill...much more difficult than solid brass or even steel would be...because it wants to gall, even with my brand new sharp drill bits and carbide end mills.

It sounds like you had some success using a drill press, only for a round speaker whereas I'm using a rectangular one. As stated above, I didn't use a vice but you did. If I try this again, that will be the main difference.

You all have given me a lot to think about if/when I try again. The goal is to mill out 4 frames over time for the 4 E units that I have.

[GGNInNScale]

Hi Bummer about the experience... I use a drill press, with different Dremel carving bits, and the belt set to the highest bit speed.  I bought a heavy drill press vise (Harbor Freight, of course).  Then, I make balsa faces to pinch the engine frames in the vise jaws without damaging the little shell positioning buttons on a lot of frames.  Align the frame with 6 inch level, Then, by slipping shim sheets under the vise to change the height, the metal can be removed a bit at a time without grabbing or chattering.  Finish is smooth, just touch up the edges with a tiny flat file.  I also bought a set of some tiny endmill bits (suggested by another N scale denizen).  10 bucks on ebay, work like a charm for small parts or precision material removal.  You have to be careful as they are a bit fragile.

[peteski]

Hi Bummer about the experience... I use a drill press, with different Dremel carving bits, and the belt set to the highest bit speed.  I bought a heavy drill press vise (Harbor Freight, of course).  Then, I make balsa faces to pinch the engine frames in the vise jaws without damaging the little shell positioning buttons on a lot of frames.  Align the frame with 6 inch level, Then, by slipping shim sheets under the vise to change the height, the metal can be removed a bit at a time without grabbing or chattering.  Finish is smooth, just touch up the edges with a tiny flat file.  I also bought a set of some tiny endmill bits (suggested by another N scale denizen).  10 bucks on ebay, work like a charm for small parts or precision material removal.  You have to be careful as they are a bit fragile.

In most bench-size drill presses the chuck is attached to the spindle by Jacobs taper.  Basically it is press-fit, relying on the friction alone to keep it attached.  Lateral force (like during milling) can (and will) eventually loosen the chuck so it will just drop off the spindle. 



Some really small drill presses might have threaded spindle onto which the chuck screws on, In those presses, the thread holds the spindle attached, and those would be less likely to loosen and fall.  But the drill chucks themselves are also not designed for lateral  forces and can loosen while milling

Sounds like you have been lucky so far (likely because use small mills and milling slowly).   Or maybe on your drill press spindle has a threaded end.