Aluminum

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Will Winder
Posts: 435
Joined: Fri Apr 20, 2012 2:40 pm
Location: Hudson, MA
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Re: Aluminum

Post by Will Winder » Mon May 06, 2013 5:06 pm

I'm usually able to get the chips out as they are cutting with a shop vac held right next to the endmill.

Lately I will also squirt some oil into the cutting path periodically using a generic oil can (kind of like this one). I'm sure there is a special type of cutting oil, but I just use some motor oil that I had on hand.

Before I would just cut it dry and sometimes I don't even bother sucking up the chips. Here's the biggest aluminum part I've made so far, I think this piece was about 4" wide by 11" long, there are lots of holes and those were by far the most difficult operations for this part. As you can see I haven't even bothered upgrading the tool holder, the stock mounts still work great! Also you can see I'm using tabs in this picture, I make them pretty big then knock the stubs off with a file after the job finishes.
Image
Ord Bot Handle by WillWinder, on Flickr
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

LTMNO
Posts: 172
Joined: Sat Mar 09, 2013 2:56 am

Re: Aluminum

Post by LTMNO » Mon May 06, 2013 5:51 pm

Very Cool, what were you making? Do you have standard y-axis.. single rail? or doubled.
ShapeOko #1508, TinyG Controller, Dual Y, ACME Z-Axis, MeanWell(S-350-24v), NEMA 23's, 1m Squared t-slot table, OpenRail and the Original Z Makerslide and all Motor Plates...

pourcirm
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Location: Saint Louis, MO
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Re: Aluminum

Post by pourcirm » Mon May 06, 2013 8:06 pm

Will,

What endmill did you use for that and what kind of speed/feed were you using?

I'm also curious about your extruder carriage. How much aluminum did you take off in that slot to bend the piece? What's the strength and rigidity like on that piece?

I'd like to do something similar for a few brackets I want to make, but was worried removing material in the bend might weaken it too much.

- Ryan

danimal
Posts: 332
Joined: Wed Mar 13, 2013 5:53 pm
Location: Colorado

Re: Aluminum

Post by danimal » Mon May 06, 2013 10:29 pm

Will Winder wrote:I'm usually able to get the chips out as they are cutting with a shop vac held right next to the endmill.

Lately I will also squirt some oil into the cutting path periodically using a generic oil can (kind of like this one). I'm sure there is a special type of cutting oil, but I just use some motor oil that I had on hand.

Before I would just cut it dry and sometimes I don't even bother sucking up the chips. Here's the biggest aluminum part I've made so far, I think this piece was about 4" wide by 11" long, there are lots of holes and those were by far the most difficult operations for this part. As you can see I haven't even bothered upgrading the tool holder, the stock mounts still work great! Also you can see I'm using tabs in this picture, I make them pretty big then knock the stubs off with a file after the job finishes.
Image
Ord Bot Handle by WillWinder, on Flickr
It looks like your setup is exactly the same as mine. I went ahead and made custom mounts for the 660 because its body it tapered and I was having a hell of a time getting the tool to align with the z axis. So then I built HDPE mounts for it and they were not stiff enough about the y axis and I could see way too much play. So now I built the main mount and I am going to use the stock mount to shim in behind it to adjust for rotation about the x axis and then I built a shroud that has x and y orientation screws so that I can fine tune the position based on mill face measurements and a bubble level on the machining surface. It is as stiff as could be. Now all that I need to do is add two more V-wheels to the z axis and tighten everything down.

I am planning on making PCB's as well so I have some extra makers slide, so I might just make another entire z axis with a higher accuracy spindle. Here are some pictures of how mine is configured now. The upper mount is just shimmed in there to line everything up, but it is not tightened down or mounted. I might try to make another mount for the outer top piece so that it can breathe a little better, but as it sits it does not cut off too much air flow.

Image

Image

Image
Shapeoko # 1458

RT0701C Spindle || dual y motor || x axis nema23 with custom carriage 1000mm length || z axis nema23 linear rail upgrade with 1/2-10 ACME

Will Winder
Posts: 435
Joined: Fri Apr 20, 2012 2:40 pm
Location: Hudson, MA
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Re: Aluminum

Post by Will Winder » Mon May 06, 2013 10:35 pm

LTMNO wrote:Very Cool, what were you making? Do you have standard y-axis.. single rail? or doubled.
I cut out all the custom parts for an OrdBot, I have a few more pictures up here: http://www.flickr.com/photos/39069226@N ... 084880443/

See my signature for machine upgrades, I think I have one of the least upgraded machine of the people posting in this thread (no doubled up X axis). I was cutting aluminum with an old dremel tool, and would still be using it if it hadn't died on me.
pourcirm wrote:Will,

What endmill did you use for that and what kind of speed/feed were you using?

I'm also curious about your extruder carriage. How much aluminum did you take off in that slot to bend the piece? What's the strength and rigidity like on that piece?

I'd like to do something similar for a few brackets I want to make, but was worried removing material in the bend might weaken it too much.

- Ryan
I believe this job was done with the 1/8" 2 flute endmill from drillman1, I use this bit for just about everything.

Looking through a few of my old cambam files, here are some of the settings:
speed: 300 mm / min
depth: 0.6 mm / pass
-----
speed: 500 mm / min
depth: 0.3 mm / pass
-----
speed: 450 mm / min
depth: 0.3 mm / pass
-----
Looking at the parts, all of the settings worked fine. I'm sure there were different amounts of cleanup required once the job finished, but I don't recall how much.

The extruder carriage works flawlessly, it is very strong. Much stronger than it needs to be for this application. I didn't do anything special to bend it, just clamped the short side in my bench vice and folded it down by hand. The relief cut takes away a little over half of the 1/8" aluminum. My exact settings were... total depth of cut = 3.5mm (cutting into the spoil board), relief cut = 1.65mm (eyeballing it, starting as close to the material as I could get it).
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

Will Winder
Posts: 435
Joined: Fri Apr 20, 2012 2:40 pm
Location: Hudson, MA
Contact:

Re: Aluminum

Post by Will Winder » Mon May 06, 2013 10:37 pm

danimal wrote: Image
You may want to move the top bracket down a smidge, covering up over half the vent may explain your overheating problems. :shock:
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

Tom Smith
Posts: 297
Joined: Mon Apr 09, 2012 9:55 pm
Location: North Vancouver, British Columbia

Re: Aluminum

Post by Tom Smith » Mon May 06, 2013 10:44 pm

Will Winder wrote: I cut out all the custom parts for an OrdBot, I have a few more pictures up here: http://www.flickr.com/photos/39069226@N ... 084880443/
The OrdBot looks great!

Nice to see I am not alone in wearing a headlamp while working :)

Tom
_______________
ShapeOko1 191

danimal
Posts: 332
Joined: Wed Mar 13, 2013 5:53 pm
Location: Colorado

Re: Aluminum

Post by danimal » Tue May 07, 2013 1:44 am

Will Winder wrote:
You may want to move the top bracket down a smidge, covering up over half the vent may explain your overheating problems. :shock:
The overheating problems were with my old mounts that were not on the vent at all. I just put that mount on there today after I trued up the 660 to the z axis I am still looking at other solutions for the upper mount, but I just fit it in there to where it will support the tool in the correct position in alignment. I think that I will just file the stock mount down a little at the contact points until it moves down below the vent, but I just wanted to get everything together to see how sturdy it felt and how it aligned. I have not had a chance to run it since I cut out the new mount.
Shapeoko # 1458

RT0701C Spindle || dual y motor || x axis nema23 with custom carriage 1000mm length || z axis nema23 linear rail upgrade with 1/2-10 ACME

mikegrundvig
Posts: 2
Joined: Thu May 08, 2014 12:50 pm

Re: Aluminum

Post by mikegrundvig » Thu May 08, 2014 4:07 pm

It's really nice to see the ShapeOko cutting aluminum this well. It's a really cool machine and it's neat to see it being used for metals. I apologize for the really long post but I hope it helps some people out.

Coolant and chip removal are absolutely critical for your edge finish, end mill life and your ability to use the machine reliably. Chip welding and ultimately breaking your end mill will occur if things heat up or you don't remove chips fast enough. A squirt of WD-40 along with an air nozzle actually works pretty well, but at higher RPMs and feeds you need to get the chips out of the cut and keep things cool from the moment the bit touches the material. On my big mill, I use full flood cooling and it makes a horrible mess but does a great job keeping everything ice cold and washes all the chips to the sides of the tray where I can just dispose of them. For a small machine like this, I bet a mist system would be perfect. The big router I've used did well with careful feeds and speeds choices along with mist. You can see a lot of small mist systems at Little Machine Shop:
http://littlemachineshop.com/products/p ... 2122081959
Many of those are good products and will work well. It's probably worth a call to LMS to talk to them about coolant volume needs - they are real experts and very nice to boot.

As for tooling, I'm not a huge fan of Onsrud as they seem very expensive. I've personally had superb luck with anything and everything from MariTool. On my big mill, I run these 3-flute high-helix end mills almost exclusively and absolutely love em. They never fail on me - anytime I have a problem, It's always my fault:
http://www.maritool.com/Cutting-Tools-E ... index.html

With that said, these small machines are not rigid, have slow feed rates, and high RPM spindles - this combination of factors makes choosing a good end mill kinda nasty. I'd probably shoot for dual flute stuff and probably avoid the high-helix. Some basic rules of thumb that might help newbies - higher RPM and more flutes requires faster feeds. Less flutes is better for high RPM machines unless they are rigid and can move quickly. The faster you move, the more toque and stress you put on things and the rigidity becomes critical. On these small machines, you are going to have to go slow with shallow cuts in metals. These 2-flute endmills might work well:
http://www.maritool.com/Cutting-Tools-E ... index.html
I suggest calling MariTool and asking them. They have helped me several times in the past with tool selection and it's been dead on every time. You want to avoid the high helix as it pulls the bit down (HARD!) into the workpiece and requires you to have really bolted things down. I've seen a Techno-Isel machine rip a 4x4 foot piece of 1/8" aluminum up from the spoil board with a 1/4" high helix end mill because the sheet wasn't secured well enough.

As for calculating feeds and speeds, I swear by G-Wizard. It works amazingly well and was designed by a hobby machinist so it's a good place to start for lots of feed/speed data. It has an "aggressive" slider that you will want to crank all the way down to "turtle" for the ShapeOko that will probably get you in the ballpark:
http://www.cnccookbook.com/CCGWizard.html
Due to the light-weight nature of the machine with a gantry, you will almost certainly want to experiment with depths of cuts to find something that works well. Personally, I've had really good luck on other machines with fast, shallow cuts. It minimizes the torque on the bit which is where these little machines really have to be careful. G-Wizard has a deflection calculator and a few other tools to let you see how much torque is being applied to your machine.

Some other tips that might help - I'd suggest against using drill bits in these machines. The vertical feed rate for drill bits is extremely high and it puts a lot of pressure on the machine. Even just 3/8" bits in 1" aluminum on my big machine make me cringe at how fast it drives the bit into the material. In my experience, I've had FAR better luck using an end mill and carefully cutting the hole with a helical path. It's slower, but makes for good holes (if the machine is accurate/true) and puts far less stress on things. I do use a lot of 1/8" drill bits but I'm pretty careful about the feed rate and cooling. They do gum up more easily than end mills. I always peck drill as well.

Slotting is not as simple as people think with these little machines. They just don't have the horsepower or rigidity to plow through material. This means you have to nibble carefully. Using a .0625" end mill to cut a .250" deep slot works but you are forcing the chips to evacuate up through the flutes unless you make the slot wider than the end mill. You do this by using a smaller endmill than the slot width and have some step over. This gives the chips room to the side of the end mill. Or if you are profiling, you can relieve the cut by having it profile wider than your end mill. I can provide some pictures of what this looks like if I'm not explaining it well. this is a lifesaving tactic with smaller machines and I've found it a good practice when I want to the part to come out reliably every time.

Something else too - ALWAYS ramp in. For instance, if you don't ramp in with the holding tabs, it's plunging at whatever your vertical feed rate might be for every pass. This can be pretty harsh on a little machine. It's best to always ramp in. It will give you a better finish, be easier on tools and machines and generally just work better all around. Ideally your tables will be flat topped with a ramp up and down on both sides.

Whew, that's enough for now but I hope this helps people a bit. I'm self-taught and learned all of these things with the help of others or the hard way with lots of broken bits, swarf and frustration.

-Mike

mikegrundvig
Posts: 2
Joined: Thu May 08, 2014 12:50 pm

Re: Aluminum

Post by mikegrundvig » Thu May 08, 2014 4:08 pm

Gah! Sorry, I've revived a zombie thread. My apologies! This was sent to me by a friend and I assumed it was fresh!

-Mike

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