Cutting Slots in Brass Bar and Sheet Stock

middlecalf · Mar 29, 2006

I need to cut small (1/8-inch or less in diameter by 1/4 to 1/2 inch in length) slots in 1/8 to 1/4 inch thick brass bar and/or sheet stock. I have a drill press, but not a dremel. What options are out there? I currently drill several small holes along the desired mark, then file out the holes to connect them into a slot (using small files, which takes a while). The resultant slots never look very good, but are functional. Other than stamping (which I don't have means to do), I haven't found a bit or tool small enough to do these cuts cleanly. Thanks for any info. Paul

bobfowler · Mar 29, 2006

Take a look at this...

I'm going to get one of these soon.

John Bartley · Mar 29, 2006

If your drill press will hold a 3/8 shanked tool, then you might be able to use a bit like this : http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=0118

and a guide fence to mill the slot. Start with a hole the correct diameter, lower the mill into the hole, lock the plunge and then hand feed ?

Charles Webb · Mar 29, 2006

Take what Gregdavis says about hand feeding brass to the bank! Sooner or later it will get you! Having more than two cutting flutes on the cutter might help a bit, but the idea simply is not safe! Milling slots in thin brass sheet stock is always a coin toss, even when secured to a heavier base in a good vice, it can still grab and tear.

Charlie.....................................

rbarker · Mar 29, 2006

I disagree with Greg. Sort of. The fact that you lost a finger in the first few milliseconds of the operation will be of minor concern compared the being skewered by the bar when it flies off the bit and penetrates your chest.

I have a little Unimat machine, a combination micro-lathe and mill, that I bought years ago that is ideal for small work like this. Unfortunately, they ceased production back in the '80s, but units might be found on the used market.

John Bartley · Mar 29, 2006

Tsk, tsk, tsk - c'mon guys - a bit of imagination here eh? . A hardwood board with a dado groove cut the same width as the metal and twice the depth. Use a featherboard to keep the metal from lifting and a push stick to keep your fingers out of the way. Clamp the guide board securely to the drill press table and Bob's your uncle.

BTW - at 48 I have all my fingers, all my toes, both eyes, both ears and some of my hair

middlecalf · Mar 29, 2006

bobfowler said:
Take a look at this...

I'm going to get one of these soon.

Can't tell how big the files are. I need something pretty small (1/4 inch or so). Any ideas?

middlecalf · Mar 29, 2006

middlecalf said:
Can't tell how big the files are. I need something pretty small (1/4 inch or so). Any ideas?

To answer my own question:

Dear Micro-Mark Customer:

The cutting portion of the file measure 0.051" thick, 0.230" wide, 0.949" long. The mounting portion of the file measures 0.044" thick, 0.160" wide, 0.280 long.

Micro-Mark Technical Service

This might work for my application.

John Bartley · Mar 29, 2006

Just for the heck of it, I went out to the garage, found a chunk of scrap brass, 1"w x 1/4"thick x 4" long. I took out a 5/32" 4-flute end mill and then headed in to the basement to dado out a groove in a chunk of scrap pine. Here's the results.

The pictures are :
1) the setup - metal can't lift or fly out of either end
2) milling bit and workpiece are securely clamped in a sandwich and in the spindle
3) the finished milled slot - 1/2" long - took about 30 seconds in this 1/4" thick stock

I didn't bother to research cutting speed, but the press was set at 480rpm for a circle cutter bit and it "seemed" about right. It cut very smoothly and left nice cool clean shavings.

paul ron · Mar 29, 2006

I sliced up a finger pretty good on an end mill in the drill press. It doesn't work adn don't try it, it happens so fast you don't even feel it till the blood is running down your elbow and you see the ribbons of flesh.

The best solution for your drill press is to get an X/Y vise for your drill press, bolt it to the table and then start cutting perfect slots without any danger. They aren't that expensive. Be sure not to try to cut the full depth on the first pass, do a bit at a time working the vise one side to the other side using the control screw.

Charles Webb · Mar 29, 2006

John Bartley said:
Just for the heck of it, I went out to the garage, found a chunk of scrap brass, 1"w x 1/4"thick x 4" long. I took out a 5/32" 4-flute end mill and then headed in to the basement to dado out a groove in a chunk of scrap pine. Here's the results.

.

Excellent, I learned to do that in high school shop class! Now show us the pictures of this device working with 22 ga. sheet stock.

The jig or fixture you used disqualifies your results, as what you did is not considered "Free Handing".

Just having a bit of fun at Johns expense.
Charlie..............................

middlecalf · Mar 29, 2006

John Bartley said:
Just for the heck of it, I went out to the garage, found a chunk of scrap brass, 1"w x 1/4"thick x 4" long. I took out a 5/32" 4-flute end mill and then headed in to the basement to dado out a groove in a chunk of scrap pine. Here's the results.

The pictures are :
1) the setup - metal can't lift or fly out of either end
2) milling bit and workpiece are securely clamped in a sandwich and in the spindle
3) the finished milled slot - 1/2" long - took about 30 seconds in this 1/4" thick stock

I didn't bother to research cutting speed, but the press was set at 480rpm for a circle cutter bit and it "seemed" about right. It cut very smoothly and left nice cool clean shavings.

I like it! Good job. Now the problem. So far, the smallest mill bit I can find is 1/8" diameter that cuts a 3/16" slot. That's too big. I need smaller (like an 1/8"). Unless I haven't looked in the right places. I suspect the part that I'm trying to replicate (100yrs old) was stamped on a press, that made 10,000 of them. I need one. Oh well.

John Bartley · Mar 29, 2006

Charles Webb said:
The jig or fixture you used disqualifies your results, as what you did is not considered "Free Handing".

Just having a bit of fun at Johns expense.
Charlie..............................

Hehehe - no worries on this end Charlie

I learned about safety at a very young age. Started working on a farm at thirteen and my first full time job, fresh out of college was contract gold mining. I saw first hand my share of the results of unsafe practices including digging my stope boss out of a 45' deep mill hole.

Credit where due - Paul Rons suggestion of a cross feed vise is an excellent one and I second it most heartily.

John Bartley · Mar 29, 2006

middlecalf said:
I like it! Good job. Now the problem. So far, the smallest mill bit I can find is 1/8" diameter that cuts a 3/16" slot. That's too big. I need smaller (like an 1/8"). Unless I haven't looked in the right places. I suspect the part that I'm trying to replicate (100yrs old) was stamped on a press, that made 10,000 of them. I need one. Oh well.

Here you go - 4 flute, TiN coating, 3/8" shank with 1/8" cutter size :

http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=0121

cheers

rbarker · Mar 29, 2006

Nice jig, John. I noticed that the company you linked to for the end mills also had a couple of nice X/Y cross-feed vises, too.

Mark Layne · Mar 29, 2006

rbarker said:
I disagree with Greg. Sort of. The fact that you lost a finger in the first few milliseconds of the operation will be of minor concern compared the being skewered by the bar when it flies off the bit and penetrates your chest.

I have a little Unimat machine, a combination micro-lathe and mill, that I bought years ago that is ideal for small work like this. Unfortunately, they ceased production back in the '80s, but units might be found on the used market.

I have one of these Unimat combos and is hard to beat for simplicity
Mark

AZLF · Mar 29, 2006

You might want to check your drill press to see if it uses a taper fit chuck.If so then there is a good chance you will drop the chuck on the work piece during the process. Taper fit chucks are designed for vertical downward force. Not lateral. If you are going to go for it anyway then for sure use a four flute end mill. If the work piece is a 16th" thick or greater then make a couple of passes rather than trying to hog it all out in one pass. Don't ask me how I know this. :rolleyes:

Some good advice came in while I was typing. Yes! the compound vices work well for this. My first "mill" was a floor standing drill press with a compound vice bolted to it. And yes, it had a taper fit chuck. It became a bigger pita than it was worth. I ended up buying one of the mill/drills from Harbor Freight with about 20" of cross travel. I have cut slots as small as 1/16th" with it in steel.

epatsellis · Mar 30, 2006

middlecalf said:
I like it! Good job. Now the problem. So far, the smallest mill bit I can find is 1/8" diameter that cuts a 3/16" slot. That's too big. I need smaller (like an 1/8"). Unless I haven't looked in the right places. I suspect the part that I'm trying to replicate (100yrs old) was stamped on a press, that made 10,000 of them. I need one. Oh well.

You can get end mills as small as .010 (IIRC), typically 2 flute, solid carbide. My usual source for these is ebay, however wholesale tools (www.wttool.com) as well as enco (www.use-enco.com) have them when I'm getting low and need one right away, look for carbide end mills. I must warn you to be sitting down, they're not cheap.

erie

middlecalf · Mar 30, 2006

I'm now loaded for bear (or at least ordered "stuff"). "Stuff" includes cross slide vise, appropriate end mills and will see about the micro-tek filer after I cut a few pieces and how much clean-up is necessary. Great help and suggestions from all and many thanks.

barryjyoung · Apr 28, 2006

When chain drilling for a slot which is what you are talking about, drill every other hole 1.5 diameters away from each other then come back and drill the in between holes. This will allow you to take a MUCH larger percentage of waste out with the drill bit which means a lot less filing by hand. Make sure the part is clamped to the drill press table. Put a handle on your mill bastard file. Hold the workpiece between hardwood strips in a vise with the finish line about .020 inch above the vise jaw. While filing, keep the file parallel with the floor and rock back and forth on the balls of your feet using your body to move the file, do not use your arms or you will tire quickly. This also works when using a hack saw. You can saw or file all day long using this technique.

Johnr0836 · May 9, 2006

Do be careful when using a drill press for milling. Drill press chucks are pressed on and as a result a side load can cause them to fly off the arbor.

Cutting Slots in Brass Bar and Sheet Stock

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