Cutting Aluminum letters?

[jhicks]

I didn't find much in my search so maybe its a bad idea but does anyone cut aluminum letters out there? I understand the caution from Brady about hot shavings in a wood dust collection system and appreciate that concern. Just trying to determine if its just not a typical Botters focus of IF someone cuts Aluminum on a regular basis. I'm trying to determine if it makes sense to try aluminum sign letters or not. Looks like the prices are pretty good for routed letters and need to follow that thought or drop it.
IF anyone does and cares to offer speed, feed, etc or even a "STAY AWAY" recommendation, I would appreciate it.

[gerald_d]

Mark Tucker mentioned (http://www.talkshopbot.com/forum/show.cgi?tpc=27&post=35091#POST35091) cutting up 1/8" alu sheet at 1.25ips at 18000 RPM this week. What was the cutter, coolant.......?

[jhicks]

Thanks Gerald, I did see that one but its about router wear etc. Was looking for some more practical "If to" or "how to's" from a botter who is actually doing it. I'll keep searching to see if anyone is actually doing it out there and solicit their speed, feed, thickness, and implementation recommendations. Have spindle so router is not my issue.

[mrdovey]

A couple of weeks ago I cut an NEMA23 motor mount from 3/16" 6061 sheet stock; and this week cut a "beefier" version from 1/4" x 3" x 3" 6061 angle.

It worked out fairly well for a novice effort; but I had some roughness due to chatter. You can see the first effort in progress on a web page here (http://www.iedu.com/DeSoto/JBot.html).

I used a 3-flute 1/8" carbide end mill fed at xy:0.125"/sec, z:0.01"/sec and used 1/32" passes at 4000 RPM.

You can read some discussion of my experience and a number of suggestions for improving the finish of the cut in a current thread on news:alt.machines.cnc (feed and spindle speeds for cutting aluminum and brass).

BTW, I don't run my dust collector while cutting aluminum; and I mist with WD40 and clear the cut with an air hose - I've learned that re-cutting chips left in the cut contribute to the chatter.

[jhicks]

Thanks Morris, Photos look pretty nice. At 7.5"/min, and those thin passes that must take quite a while. No wonder the metal routed letters cost so much. I appreciate the info and will probably just preview a few test files to determine if it makes sense, or perhaps search out a water jet fabricator. Thanks again

[gerald_d]

Onsrud says on this (https://www.onsrud.com/xdoc/metal) page: "If breaking the cycle of time consuming climb cutting with multiples passes at low productivity rates is the goal, Onsrud Cutter LP high-speed router tools is the answer!" The cataloge page says 200 to 300 inches per minute at 18000rpm

Onsrud Alu cutting data (https://www.onsrud.com/xdoc/ChipAluminum)

[paco]

I have tested the 63-606 (1/8" CED, 1/4" CEL, 1 O-flute spiral up) and it's a very aggressive AL cutting tool. BUT, I don't think it's feasible to achieve the pretended 1/8" cutting depth per pass on the Bot at 200 to 300 inches per minute at 18000 RPM. The Bot is not rock solid enough to withstand this kind of working force and will chatter (earth quake) a lot under this load. BUT the bit will hold on without breaking (I've snapped the very tooth once but that's all... re-sharpen to 3/16" CEL to a new tool)! Intense chatter is an enemy to Carbide cutting tool bits.

You need a VERY good hold down (both sideway and vertically {vacuum}) to use this tool to a max. So far, I have achieve 0.065" per pass at about 1.5"/sec. (or so) at 18 000 RPM with lube (WD-40) and air cooling/blowing to clear the kerf from chip. indeed, as Morris wrote, re-cutting chips left in the cut contribute to the chatter.

Maybe the Bench top would be better at routing AL... still, to cut at 200 to 300 inches per minute at 18000 RPM with a 1/8" deep cut pass, the Bot will need to be slow down to maybe 1"/sec. or less I believe...

If you don't need too much detailing on your design, try to use larger CED tools with the shortest CEL possible.

The 63-600 series is quite expen$ive starting at some 27.00$ or so for a 1/8" CED... don't drop 'em on the floor...

Tips, stay away from "utility" grade AL with such RPM as 8000 and up...

[gerald_d]

There are many (http://www.ez.org/aluminum.htm) different grades of alu, and some will cut a lot easier than others. The soft alu's weld themselves to the cutting tool more than the harder stuff.

[wcsg]

Here's my 2 cents on cutting Alum

6061 is Boing Grade and recommended by Belin Tools, it's harder and more expensive than 5052

5052 is softer but I like this grade more. My Bits seem to cut thru this like butter and i'll just mist down with WD-40 every 30 secs or so. No melting with my speeds

I use 1/4" & 1/8" CED's on a Belin Spiral O

1/8" Bit I'll spin 18,000RPM's @ .40 IPS
1/4" Bit 12,200RPM's @ 1 IPS

I get excellent Harmonics with this.

I use double stick tape for hold down. Also I recommend any Alum thinnner than say .080 to use a down spiral bit.

Here's a project I did with 1/8" Alum

http://www.thesignsyndicate.com/forums/index.php?showtopic=445

My feed speeds appear to be much slower than others posted, but this is what works for me.

[wcsg]

I forgot to ask, what's the dealio with not using a standard dust collector for cutting ALum? I haven't had any problems nor my friend locally here who has had the Bot a lot lot longer than me and cuts alum all day.

[paco]

Hey Erik!

Does the 0.08" (and less?!) burr at bottom with a spiral down? And do you hold that stuff with double side tape?!

Your feed are slower because you cut 1/8" thick in a single pass (with a 1/8" CED tool) I believe from a previous discussion... right?!

[wcsg]

Double side tape, Yes this is single pass but 2 passes using 1/8" bit thru 1/8" material

[jhicks]

Eric, If you are referring to my note on dust collection, it had to do with a story Brady related to some of us at last years jamboree. Has to do with wood shops with dust in the system and the potential of hot shavings igniting the dust. I just remember him saying a fellow burned down his shop due with a fire started in his dust collection system.

[wcsg]

Oh lol. My dust collector has both wood and alum shavings in it

[artisan]

I just finished (today) a project for a family emtertainment center that called for aluminum letters. I just saw this thread tonight or I would have posted earlier. I created bartops and letters from .040 aluminum sheet using bits from Hartlauer with no problem. Finding the proper speed to get chips is the most imprtant aspect....or you'll be doing a lot of finishing on your edges.. There is also an excellent product called "Ultraboard" that comes with an aluminum face as well as "Dibond". These products cut like butter because they have a thin sheet of aluminum with either a pvc or foam backing....they make great letters. I shot some pics today....but am too tired to get the camera just now. Hope this helps...Good night....D