That's a lot of heat! Conventional wisdom would be that the feed is too slow and or the speed is too high; Are your chips coming off as spirals or flakes? Ideally, you want spirals, indicating that you are only cutting the material once. If you have flakes, particularly small ones, you are cutting the cut material, and recutting the sides of the cut, generating much more heat.

I always find this counterintuitive and scary, but you want to be very close to overfeeding to get the best cut and temperature control.

This is my first try with aluminium. I used 4mm Carbide TiAlN coated bit, spindle 12k rpm, feed 1200mm/min and 0.5mm stepdown.

It machines beautiful and the finish is extra smooth.

http://www.cnc.rs/mechmate/alu1.jpg


bit is from ebay : carbidechiu

Hi Roos, i thing yuo dont use coolin liquid http://www.limpieza-empresas.com/cat...na-blanca.html and is posible the tool is olso not de best for aluminium http://www.belintools.com/Catalog.pdf ....

For aluminum it's best to use non coated tools. And try lubricating it a with a few drops of lampoil every now and then.

lampoil=kerosene=parafin

As you can read on wikipedia or any other search trough internet I found that TiAlN is ok for aluminium

Thanks everyone for your input.

Aluminium is type is unknown.
Cutter was a 3mm Carbide End Mill.
Pass Depth .3 mm and Stepover 1.25
12,000 RPM and 10mm/sec feedrate.
Feedrate was dropped by 50% after I saw the bit flex on contact.

The chips were flakes not spirals and towards the end (as the workpiece got hotter) they were obviously rewelding to the bit and the work.
With respect to the cutter size I have been considering using a larger end mill as 3mm is fairly weak even by comparison to a 4mm cutter that Danilo has used.

Cheers
Ross

Aluminium Milling
 

Better this time.

Attachment 11773

A video of part of the process - http://www.youtube.com/watch?v=qnMIMSP-LWc

Details...
6mm 2 flute HR45 Carbide End Mill at 1200RPM
0.3 mm Depth of Cut
20mm/Sec Feed Rate

I also periodically stopped and used some welding anti spatter grease on the bit if the aluminium was starting to stick to the bit (you can hear it when it is starting to go wrong).

Not perfect but better. Note I cleaned up the outside top edge with some 400 grit wet and dry.
Thanks everyone for your help.

Regards
Ross

Instead of simple plunge , do a ramping plunge, and you can go deeper than 0.3 with 6mm bit.

Ahh of course, that makes perfect sense Danilo.

Ross

As usual, Nice work Ross!!

Cheers
Tony.

You should be able to increase your feedrate at least 50% with the same rpm.

I agree with Ger, you can keep upping the feedrate. Look for spirals!

Now I'm tempted to have a go....
Good job!

Will definitely give the faster feed rate ago and watch for the spirals.
Can't help but thinking lots of coolant and lubricants will make cutting aluminium all that much easier.

Regards
Ross

I just don't like the BIG MESS that ALU leaves. Wood shavings are much more pleasant. ;)

Agreed Kobus, still finding metal everywhere.

Ross

Even the dust foot didn't help ro contain the metal chips?

Ken that is the reason they use flood coolant while milling most metals - except for some

Hi Ken
I was not using it as it prevented me using the spatter grease on the work and cutter every now and then.

Infran
You got that right, with a coolant system in place cutting metals would be significantly easier.

Regards
Ross

Demonstrating how the CNC machine works is so much better than just telling esp when it comes to the kids.
A visiting 10 year old future engineer got his name cut out and was very happy with his new possession.
The timber was reclaimed from a broken piece of furniture and the capital letter "A" is around 100mm high x 10mm thick.

Attachment 11851

Regards
Ross

Greetings All

Recently it has all been about tidying up my work spaces and getting my older tools back into shape.
Dare I say it but I killed my favourite 1100 Watt grinder last week, something not to be taken lightly on the MM forum as we all know !!

The welding skills I learned building the Mechmate have come in handy as my ageing box trailer had finally passed the 50 percent mark - that is 50% steel and 50% rust.
The ladder section base and the A frame have now been nicely re-fabricated so it rolls on for a few more years yet.

As part of getting some sanding drums chucked up into my drill press I thought it might benefit from a retrofit with some of those crazy looking but very effective Power Twist belts from Fenner.
As promised the belts reduce vibration a treat and have eliminated a harmonic at low speed (160 RPM) and smoothed out the 3000 RPM performance.
Fenner belts are appearing on anything that turns in my place after they turned my beast of a table saw into a purring pussycat.
Attachment 12011

Once my restructuring and repair of all the support gear is over it will be back to the Mechmate and hopefully a few new and interesting projects.

Some of the newer builds on the forum are speeding along and I am totally impressed with the support some of the senior members continue to give.

Regards
Ross

I lke those Fenner belts as well but they are VERY expensive here.

They are very expensive here as well!:)

Expensive everywhere !!

Here in Australia they are wickedly expensive.
From the USA the belt is 7 USD a foot plus 14 USD for the initial postage so buying a bit makes it cheaper if their is such a thing.
As usual Ebay is your friend.

My tidy up continues - today I reclaimed some bench space by making a mobile sanding station for my disk sander.
My neighbours entertainment unit is reborn !!
No back or doors as the day ran out but should be finished tomorrow.

Attachment 12018

Regards
Ross

Off the Rails
 

I know I run off the rails every now and then... it's to be expected!
BUT when the Mechmate gantry runs off the rails that will never do.

My machine developed a very bad habit of crawling up off the rails and it was just so annoying.

Anyway after a good look, either the LHS motor swing plate bolt had come loose or I had not tightened it properly after some fiddling with the LHS rail.
Realistically probably the latter.
Just a few simple turns to snug up the plate pivot point turned the MM from a out of control beast to a well behaved machine.
Though I might leave a record of the symptom and the fix on the forum for others to stumble across.

Stefan MM #73 is doing some nice stuff and Kobus is also knocking out some great creations on his thread.

Also whoever "stole" :D my 4mm collet better fess up soon.
I mean there is no way "I" could have lost it is there???:)

Regards
Ross

Thanks for posting the off the rails tip. I was wondering what conditions might lead to it.
The person that got your 4mm collet is probably the same one who needed my 8mm one for their set. Definitely time to get the shed in shape!

Hardwood Timber Plugs
 

Thanks to Kobus and his post on using the Mechmate as a plug cutter.
I used my Mechmate to cut a few timber plugs for a friend who is building a recycled timber table (complete with pre-existing bolt holes).

Attachment 12166

Regards
Ross

I am a great FOLLOWER.....the original idea came from Hennie. Nice to see it is used by others.

Hi Kobus

Thanks for the attribution to Hennie - now we got a conga line.:)

Little trick about the plugs I have used.
Set up the 3d profile of the plug to cut a "small cone", with about 2 deg sides. Makes a nice tapered fit (and room for the glue)

Nice Job!

Thanks Sean

Used the "barrel bung" thing before on timber floor and wall penetrations that needed to be repaired but never thought to cut them that way in the first place.
I actually discussed hand sanding the plugs to that shape with my mate.
Will have a play tomorrow and see if I can cut a few as you have suggested.

Regards
Ross

Ross,
It's easier to get the proper shape if you use a BALL NOSE rounded bit. This way, the tangent of the ball shape cuts the side wall. Or, I have used a V-bit (5deg) taper, but not as good of results.

Good luck.
Sean

Longboard Skateboard Deck
 

Hi All

I set my Mechmate a new task today to cut out some longboard skate decks.
Love watching the machine work away but have yet to run a toolpath I am totally happy with :D.
This one was too slow as the experts on the forum will no doubt agree.

This time I played with the idea of cutting at .2mm allowance using a climb path and then coming back with a conventional toolpath right on the vector.
Danilo recently discussed this on Kobus' thread and I like the idea of the cleanup cut.

Also used a 4mm end mill for everything and chained the tool paths together.
It was press start .... wait a little, then a skateboard appears.

Attachment 12173

Attachment 12174

http://www.youtube.com/watch?v=KQNwAW5akeE

Regards
Ross

Nice Ross, and how did the CLEANUP pass work for you on the plywood ?

Hi Kobus

It worked well, particularly on the inside cut out for the trucks.
The two cut method will be my prefered option as I like the machine to do most of the work if at all possible.

Broken one in half already testing to see how strong they are.
The decks require 2 or 3 layers of 4 oz fibreglass cloth on the underside to control the flex if anyone is planning on making their own.

Regards
Ross

Take 2
 

Broken :)

Attachment 12175

Reinforced underside with 3 layers of 4oz fiberglass cloth and white tinted epoxy resin.

Attachment 12176

Regards
Ross

Hi, Next time could you do the underside re-inforcing on your uncut sheet. Save a lot of trimming of messy resin/cloth.

Be interested to see how it cuts as this is something I want to do, when I get my machine finished .

Andrew

A quick google search shows that "dried" epoxy dust is sensitizing, just like the resins themselves. You would need to treat all the resulting dust with the same care (no breathing or skin contact) that you treat liquid epoxy.

Hi Rival and Brad

Rival - exactly right the machine will cut the cured resin and cloth and that is future project. Good advice.

Brad - yep it's nasty stuff. I use gloves, a sanding suit and a respirator to limit my exposure.
Then an immediate shower after the job is done and all up the exposure is minimal.
It is the resin of choice for my boards as polyester resin literally melts the newer EPS foams on contact.
Some of the early users of epoxies in the surf industry were pretty haphazard with the stuff and have paid the price of becoming sensitised.

Regards
Ross