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  1. #1
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    Aug 2016
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    97

    Cutting Brass

    Well, I finally decided to have a go at making the brass hardware for a project I am working on. Thought I'd share as a reference for others. I did a lot of research. Seems as though there is a pretty wide variation in speeds/settings/tools/etc. to get this done. So, this is just what worked for me. For reference, I am using a CNCRP 24x48 Standard machine with a Bosch 1617 router. I created the drawing in a very old version of IntelliCAD, saved it as DXF, then imported into VCarve Pro. The material is 360 Brass - 6x12x0.032.

    My first thought was to mill the outline of the pieces with a 1/8" O Flute, then come back with a 1/16" O Flute to get more detail, then add a chamfer. To hold the material down, I tried double stick tape (woodworking/turning). That didn't work. The part popped off. Next was 5 min. epoxy. Same thing. The parts popped off in various places/bits - not consistent. My epoxy may have been bad. It felt rubbery after it cured (bought fresh today!). Next stop was super glue. The first one popped off too. Gosh darnit - I'm pretty frustrated now! I broke my 1/16 bit - user error - setting Z - I was at zero and hit the Z down button (page down) by accident! Then, I broke a 1/8" bit - not sure why - it happened mid cycle. Chucked up a 1/4 bit and no breakey. However, when I then tried the chamfer, the part popped off. Now, the chamfer tool was an Amana 60° with two carbide cutting edges. At this point, I was pretty frustrated and wondering what to do.

    I then thought why do I need to do a rough cut? Why not just use the chamfer tool? I had another chamfer tool (Whiteside 60° - 3 cutting edges -solid carbide) that I use for inlay, so I tried that. I also changed my cut depth to 0.008" and slowed the travel speed to about 15 ipm. And just for the heck of it, I spread paraffin wax on the surface of the brass (no idea if that helped?). I held my breath and gritted my teeth and low and behold, it worked. Yay! I had been making 0.020 cuts or so before this. Oh, what I'm calling a chamfer tool is a V tool. Sorry. I'll be ordering a replacement since this one is probably not as sharp as it used to be and sharp is important for inlay.

    Here is a pic. You can see where one part popped off. I haven't removed anything yet. I want to use a small engraver to mark the positions of the brad holes. I'll drill those on the drill press later.

    Anyway, thought I'd share my ignorance/experiment/experience!

    Tony

  2. #2
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    Mar 2017
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    148

    Re: Cutting Brass

    When doing brass, the two times I have, I've taken a piece of mdf and cut in a pocket that was the same size as my stock. Then I pushed the brass into that. Then I clamped the wood and cut.

    Sent from my SM-N950U using Tapatalk

  3. #3
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    Aug 2005
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    187

    Re: Cutting Brass

    When the parts in a design are cut from thin sheet and include holes, sometimes it helps drilling the holes first, then securing a screw in each hole, then cutting the outlines. Be sure the rapid height is set to clear the screw heads.

  4. #4
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    Jan 2007
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    36

    Re: Cutting Brass

    diecutter has the right solution. Add the screws then the parts can be cut without being thrown about and no end of cut burrs. I do this all the time myself.

  5. #5
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    Apr 2015
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    9

    Re: Cutting Brass

    Hi Tony

    If nothing else your info makes some of us feel better in that we are not the only ones who go through this :-D

    Cheers for that, just about to have another go at brass this week if i get time so good timing

    Bernie

  6. #6
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    Aug 2016
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    97

    Re: Cutting Brass

    So, will everyone pitch in on a kickstarter to replace my two bits!?! Ha! That really hurt my feelings! They were brand spanking new. I chipped one of my V bits too. I won't be cutting a lot of brass.

    Yesterday, I used an engraving bit to mark the holes. That went well. I then proceeded to remove the bras from the MDF backer. I used spackling knives to slowly lift it. That worked fine, but I accidentally hit a corner of the small keyhole plate and messed it up a little. I can salvage it though. Tried various mechanical techniques to remove the glue and MDF residue from the back. What worked best was soaking them in acetone for about 15 minutes. That turned the glue into a gel that was fairly easy to rub off with a cloth. Now I have to drill the holes, polish, and bend.

    Please let us know what you figure out. I really don't plan on working with metal much, but it is handy when needed. I'd like to make some small ID plates and such.

    Oh, not knowing what might happen, I wore my face shield the whole time! Yes, very Darth Vader like. I'm not much to look at already, so any further damage to this mug would be truly tragic.


    Tony

  7. #7
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    Jan 2007
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    36

    Re: Cutting Brass

    Sneak the wife's cloths iron out to the shop and apply heat to the parts. It may loosen the adhesive enough I would think. I use double sided foam tape to hold parts down when the part has no holes. Using a tapered engraving bit will increase the tool load verses an end mill.

  8. #8
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    Jun 2010
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    3755

    Re: Cutting Brass

    Brass: use a cutter designed for brass. One designed for aluminium will not work too well (too sharp!). The same applies to drilling brass - look it up.

    Epoxy on brass: usually cannot grip. The copper in it repels the epoxy.

    Holes and then screws first: YES! I machine titanium sheet and aluminium sheet that way. The photo shows Ti 6Al-4v being cut with a 2 or 3 mm cutter.
    Attachment 398854

    Double-sided tape: this probably popped because you were using an aluminium cutter with up-thrust (ie the normal sort). Try using a cutter with a down-thrust. Less common but available. The helix goes 'the other way'.

    Pocketing: works well but still needs screws in the parts first. Screws in the spare corners of the sheet works as well.

    Cheers
    Roger

  9. #9
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    Sep 2006
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    229

    Re: Cutting Brass

    One other option for a sheet like you are cutting is to treat it like a piece of plywood and add tabs to each shape. Secure the perimeter with screws. It might also help to add 1 or 2 screws in the center of the workpiece to prevent it from bulging up as you cut away material. Swarf or sawdust often wedges between the workpiece and the sacrificial material.

    The tabs work best if you place them along outside curves so you can sand or file them off easier.

    Steve

  10. #10
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    Jan 2007
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    36

    Re: Cutting Brass

    I use Mach 3 it has a provision for adding tabs to a profile. No holes needed except in the waste stock.

  11. #11
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    Jun 2010
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    3755

    Re: Cutting Brass

    Tabs! Yeah!
    The pointy bits at the ends with screws in them (see photo above) actually get cut off later. Straight cut.

    I don't think Mach3 can add tabs, but maybe you mean LazyCam which comes with Mach3?

    Cheers
    Roger

  12. #12
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    Aug 2016
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    97

    Re: Cutting Brass

    So, what about the feed rates? I was cleaning up my parts this weekend and the edges look like there was a fair amount of chatter. I cut them awfully slow (~14 ipm). But that was because it worked. I have read lots of posts that imply a much faster feed rate and that going too slow is not good. I was only taking 0.008" bites. The cutter that finally worked has three cutting edges. I got the job done, but I'd like to figure out how to do it better. I'm not thrilled with the cut edges. I cleaned them up ok with a Dremmel but they still aren't as nice as I'd like them to be.

    Drilled the holes. Cleaned up the edges. Now I have to figure out a good polishing method. Everything I tried this weekend left fine scratches. But I was doing it all by hand. May try some buffing wheels this week. I have polished lots of brass on my lathe and achieved very nice mirror like results, but that was under lathe power. The parts look good though. Oh, I also have to bend most of them. That might prove exciting! I have done some testing and that went well, so I'm hopeful. Sorry I haven't gotten any pictures to post yet.

    Thanks for all the good discussion. For holding the brass down, I didn't have any holes to use for screws. The holes I am drilling are for brads, so they are too small for screws. I didn't want to use tabs because I wanted the chamfer and I didn't want a lot of post processing. Also, my machine usually leaves a little witness mark when it does tabs. I didn't use a straight bit because I wanted the chamfered edge. My original thought was rough it with a straight bit, then add the chamfer. That didn't go well and the chamfer bit alone made the cut, so I ran with it. I wasn't aware there was a 'brass bit.' The O flute bits list brass as a material that they are good for, so I tried them. I did manage to not break my 1/4" bit! I also didn't know that epoxy wasn't that great for brass. I think my epoxy was not good. It held pretty well though. Might be good enough if the epoxy is not bad. I forget which part, but one of the parts was thick and grainy. I may try some more stuff later. I really don't want to cut a lot of metal, but it is nice to make a few parts now and then.


    Tony

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