Aluminum Knob

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McMagical Eng.
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Re: Aluminum Knob

Post by McMagical Eng. » Thu Aug 14, 2014 5:22 pm

McOtis wrote:Problems?
Not at first.
However last night I milled a larger knob and long story short, my bit was destroyed at the very end. All "4 corners" of the bit completely sheared off.
I think I know what happened; my dust shoe and vacuum collection got clogged up.
I had several small aluminum piles of debris when I finished and cleaned up.
This may have caused the chatter which then shattered the bit.

Once I mill out some aluminum mounts for my new Makita router, my days of milling aluminum are over.
Messy, problematic and not worth it. Assuming I get that far!
As you can see in the photo above, I had 2 failed attempts already for some test mounts.
Don't quit!
You have shown that the shapeoko is capable of greatness! Even small table cnc mills designed to cut aluminum will take a long time and make a mess. I used to teach shop with prolight mills and students would break parts until they dialed in the right settings!
Keep in mind, good parts take time, especially on hobby equipment. I leave my 3d printer working for hours to get good plastic parts...
Thanks for sharing your pictures, I cant wait to get some aluminum going on mine!
Shapeoko2 NEMA 17s, Custom aluminum baseboard, coroplast sideskirts, 300W quiet cut spindle, 3d printed enclosure, panel on/off, E-stop

"They took from their surroundings what was needed... and made of it something more." -Primer-

RobCee
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Location: Birmingham, UK

Re: Aluminum Knob

Post by RobCee » Fri Aug 15, 2014 12:45 pm

Some things I have learned that will make life much easier are:
  • 1. Use a roughing and a light finishing pass - takes longer to setup and perform, but significantly improves the finish you get
    2. Make the roughing (profile) pass wider then your milling cutter (this forces the CAM software to perform the cut in two stages) - Leaves the cutter somewhere to push the chips and reduces cutting stresses significantly
These two tips help when cutting anything, but are invaluable with aluminium.

Good luck and don't give up!
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

McOtis
Posts: 80
Joined: Sun Feb 09, 2014 12:21 am
Location: Maryland

Re: Aluminum Knob

Post by McOtis » Tue Aug 26, 2014 5:54 pm

RobCee wrote:Some things I have learned that will make life much easier are:
  • 2. Make the roughing (profile) pass wider then your milling cutter (this forces the CAM software to perform the cut in two stages) - Leaves the cutter somewhere to push the chips and reduces cutting stresses significantly
These two tips help when cutting anything, but are invaluable with aluminum.
Good luck and don't give up!
Any easy way to do this via MakerCam?
I am going to attempt to mill some aluminum this weekend; new router mounts.

WillAdams
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Re: Aluminum Knob

Post by WillAdams » Wed Aug 27, 2014 3:21 am

Yes, MakerCAM allows one to do a roughing pass, along w/ a finishing pass.

http://www.shapeoko.com/wiki/index.php/ ... ctionality
Please note that roughing clearance only makes sense when one is making two passes at a given path --- the first pass (the roughing pass) will specify how much material is to be left by setting roughing clearance to a positive value and will typically be done w/ a minimal value for stepover, a faster value for feed rate, while the second pass (the finishing pass) with zero for roughing clearance, will remove the balance of the material w/ a larger value for stepover, a slower value for feed rate and will leave a finer finish.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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criznach
Posts: 220
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Location: Great Falls, Montana, USA

Re: Aluminum Knob

Post by criznach » Wed Aug 27, 2014 8:07 am

RobCee wrote:2. Make the roughing (profile) pass wider then your milling cutter (this forces the CAM software to perform the cut in two stages) - Leaves the cutter somewhere to push the chips and reduces cutting stresses significantly
^ ^ ^ What he said. :) I've been doing this, and while it takes longer, the jobs actually finish with no broken bits, decent edges, etc... Well worth the time if you can bear the noise.

McOtis
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Location: Maryland

Re: Aluminum Knob

Post by McOtis » Wed Aug 27, 2014 4:51 pm

The roughing clearance can be configured for a POCKET operation, not for a simple PROFILE cut.

Would I need to add extra geometry to my drawing?

Usually I tell makercam to generate a simple OUTSIDE PROFILE cut. The part is cut out. Done.

Instead, Should I add some geometry to my drawing and make POCKET operations, and then a quick outside PROFILE cut?

criznach
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Location: Great Falls, Montana, USA

Re: Aluminum Knob

Post by criznach » Wed Aug 27, 2014 5:42 pm

That should work. Offset it by whatever your normal stepover would be or less. Or you could use the same profile operation, but specify a larger tool diameter than what you really have. In cambam you can set the cut width independent from the tool diameter, which creates multiple passes as needed.

McOtis
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Location: Maryland

Re: Aluminum Knob

Post by McOtis » Wed Aug 27, 2014 11:42 pm

I hate to be picky but I mentioned I'm using MakerCAM.
Maybe the steps are clearer in cambam compared to MakerCAM.

criznach
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Joined: Sat Dec 14, 2013 5:28 pm
Location: Great Falls, Montana, USA

Re: Aluminum Knob

Post by criznach » Thu Aug 28, 2014 2:11 am

Yes, I got that. In makercam, you can either add extra geometry as you thought, or pretend you're using a larger bit to create the first pass.

McOtis
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Location: Maryland

Re: Aluminum Knob

Post by McOtis » Thu Aug 28, 2014 10:56 am

Thanks. I will try pretending to use a larger bit on the first pass, and then a final pass on finish. This should give more clearance during the final pass.

I was looking for something to help the first roughing pass be more reliable but this should help the finish assuming the machine makes it that far.

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