Cutting Slots in Brass Bar and Sheet Stock

Discussion in 'Camera Building, Repairs & Modification' started by middlecalf, Mar 29, 2006.

  1. middlecalf

    middlecalf Member

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    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
     
  2. bobfowler

    bobfowler Subscriber

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    Take a look at this...

    I'm going to get one of these soon.
     
  3. John Bartley

    John Bartley Member

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  4. Greg Davis

    Greg Davis Member

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    If you try to hand feed brass into a milling bit you will certainly lose at least one finger. The workpiece will either fly out at high speed or catch on the bit and become a whirling fan blade. I bought a micro mill/drill from Harbor Freight Tools a couple years ago. I was about $200 plus a few accesories, but it cuts slots wonderfully and is relatively small. You are limited to pieces smaller than 4x6 inches. And it doesn't cut hardened steel.
     
  5. Charles Webb

    Charles Webb Member

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    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.....................................
     
  6. rbarker

    rbarker Member

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    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. :wink:

    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.
     
  7. John Bartley

    John Bartley Member

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    Tsk, tsk, tsk - c'mon guys - a bit of imagination here eh? :smile:. 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 :smile:
     
  8. middlecalf

    middlecalf Member

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

    middlecalf Member

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    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.
     
  10. John Bartley

    John Bartley Member

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    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.
     

    Attached Files:

  11. paul ron

    paul ron Member

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    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.
     
  12. Charles Webb

    Charles Webb Member

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    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". :smile:

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

    middlecalf Member

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    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.
     
  14. John Bartley

    John Bartley Member

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    Hehehe - no worries on this end Charlie :smile:

    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.
     
  15. John Bartley

    John Bartley Member

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    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
     
  16. rbarker

    rbarker Member

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    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.
     
  17. Mark Layne

    Mark Layne Member

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

    AZLF Member

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    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.
     
  19. epatsellis

    epatsellis Member

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    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
     
  20. middlecalf

    middlecalf Member

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    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.
     
  21. barryjyoung

    barryjyoung Member

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    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.
     
  22. Johnr0836

    Johnr0836 Member

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    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.