Aluminum

[coach]

I am going to attempt to cut alum. letters next week. The material is .050 thick.
Any and all input is welcome.
Letters are about 20" so the vac situation won't be too bad.
Thanks, David

[mwpfeifer]

David,
I have cut 0.125 6061T6 on my buddy. Parts for experimental airplanes. I used an Onsrud 65-000 Super O Upcut and took about .05 with each pass. Speed was about 1 ips at 12K. Edge needed a little dressing up and it was done.
Good Luck
Mike

[woodworx]

I have never used these Onsrud bits. Usually when I cut aluminum, I buy them from a metal milling shop next door. I usually buy 2 flute upspiral 1/4". Last week I ran some 5052. It is hard to mill since it just wants to melt. Good milling will usually come from 6000 series aluminum or higher. This last run I ran at 7200 rpms and 24 ipm, taking .0625 on each pass. I used a little silicone for lube, which does help. Just get the chipload and feed rates from the bit manufacturer. If you have a router and not a spindle, getting the right speeds/feeds is harder because you don't have the torque at lower rpm. It is necessary on all alum, and acrylics to surface your bed before you start. Cut your parts with a .01" offset and machine down to .02" from your bed. Then come back with no allowance and machine through. This will give you the needed edge quality to impress your customers, and leave you with less sanding to do.

[bernott]

David are you getting sign grade al(3003)?

[coach]

Bernie, The sign guy is bringing the material to me this week. I am going to phone him tomorrow to find out.
What would you suggest for cutting if it is 3003?
Thank you Bernie, Justin and Michael for your input.
BTW Justin,,I saw your pic in a copy of Wood Magazine.
David

[bernott]

I'm almost sure it 3003 sign grade. if you have tight corners where a .125 bit is needed then use HSS 48-*** down spiral single flute and spray the surface with wd-40 and air cool the bit while cutting, small cuts .025 at a time. then theres not heat build up and rewelding going on speed .8 ips with ramps, if you can get by with .250 bit about the same but you can use a 65-*** down sprial bit. most of my spindle speeds are around 12-13500 rpms. 3003 is tricky to cut but take your time.

[rb99]

Use Alumacut and apply it by hand as it is cutting.

RB

[coach]

Richard,,,Alumacut? Where would I get this? Is it sprayed on? Will it saturate my spoilboard?
Thanks, David