[Moondog]

I am sure you can provide advice on this...

I am considering making Metal Plaques from Aluminim (see below for example) that would need to be machined.

The question is: what type of machine would be best suited for production machining ie., Gantry Router Style or CNC Mill. I know the Mill is best suited for precision and heavy duty milling but is it suitable for high feed rates and repitition work. Excuse my ignorance on Mills but I thought because of their machined ways they would be slower than a THK type bearing setup.???

I am probably leaning towards a Fixed Gantry machine with a moving table size around 1200*1200mm, servos, lead screws and spinning Ball Nuts and HD THK bearings/rails. Would this type of machine be suitable for alum maching etc?????

your input appreciated.

cheers

[balsaman]

You want a mill. No they are not slow.

Some cnc routers can cut aluminum but they are best suited for wood.

It's very hard to make a machine that size cut aluminum acurately and you will never build one to cut it quickly.

JMHO

Eric

[nervis1]

I've done signs like that out of 1.5" aluminum plate on a VMC. Looked great.

My 10 year old VMC will move 400ipm feed if I want it to, 100 is the fastest I've dared though.

I've seen a newer Okuma move at ludicrous speed, over 1200 ipm rapid, and 400ipm contouring in aluminum. I've never seen a home built cnc router that can move that fast although I'm sure they are out there somewhere.

The only issues with those signs is that around the corners and where letters meet you need to use a small end mill to clean up, that means generally slow feeds and fast speeds, or be prepared to be replacing cutters mid stride.

I've come to despise any EM 1/8 inch or smaller.

[Ken_Shea]

Nervis1 (Dave) has shown a point here, we get all excited about IPM when in fact most of the things we make we do not approach max IPM because of cutter size, if you are making 1000's of an item then those rapid speeds add up but for most all of us on the zone it will make esentially no difference.

I have seen those ultra fast machines opperate, it is unbelivable and scary all at the same time, chip to chip tool changes in under 3 seconds, better know what you are doing or use OneCNC huh Dave ?


My Haas TM1 max IPM is 200IPM yet in actual cutting I have never been over 80IPM, you got me there Dave ! It is still really cool to watch

If you have 1400IPM or a 30IPM CNC it is still a treat to watch.

[Moondog]

Thanks guys for your replies.

So I get the impression that you believe a Router will not be accurate enough. These things don't need tolerances of a 'Thou' that a Mill is capable of but would surely get accuracy of 10 thou or so.

Then if a Gantry type of router is built 'strongly' surely it would be more than capable of this type of work. Not talking about Precision Machining.

The reason I don't necesarily want to go down the Mill route is that I want the machine to fairly versatile for other tings such as plastics, wooden signs etc...

I agree that speed is not that important. Even though this would be used professionally.

cheers

[HuFlungDung]

Its not just about accuracy. In much of my work, I don't have to attain super accuracies, but the performance of the cutting tool is nonetheless important. In sign work, it has to look nice. The rigidity of a large machine will pay you dividends in appearance. The accuracy is just incidental, so you don't have to charge like a machinist

[Moondog]

I like this discussion.

Now lets talk Machine specs... A fixed Gantry Router about 1200*1200mm moving table. Frame and gantry from 4*4 & 6*6 RHS 1/4 inch wall thickness..

X axis 1 1/2 inch Lead screw rotating ballnut, Y Leadscrew 1" + Ball nut, Z Axis 5/8" Leadscrew + Ball nut. All Ballnuts anti=backlash/pre-loaded.

X axis Alum plates 1" thick.
HSD Spindle 3-5HP.
THK rails.
Servos etc..

Do you think these specs would give me a machine capable of machiining 1/2 to 1" alumiium with reasonable accuracy.

cheers

[balsaman]

What sort of drives, what's your budget?

Have you seen my router? It's pretty beefy and I cut aluminum in .05 deep passes at 4-6" per minute with a 1/4" endmill. It's servo driven and can do 100+ inches a minute. It's a nice machine but it's a router. Routers are for wood, and that's what it does best.

Eric

[E-Stop]

I've cut many a sign, several similar to the one shown. Mostly out of aluminum, some in wood and quite a few out of plastic. All were done on a Fadal 4020 with absolutly no problems. And fast.... you bet! Alot of them were done on the sly between job set-ups so they had to be done before anyone noticed. What I got caught up in for a while was making license plates out of 1/4" aluminum plate with team logo's, names and personalized stuff on them. It was fun but once you make one, everyone wants one.

[jimbo]

Have you considered casting them. Make the mold on cnc from foam or wood.

[Moondog]

Jimbo... good idea.. I'll have to look into casting.. is it difficult?... It does add another process though.. but it may be the answer.

Balsaman...I'll have a look at your machine. Drives would be Rutex... Budget...probably around $10-12K....

E-Stop.. Fadal 4020 I assume is a Mill?.... If you cut something like that sign how long did it take..just trying to get some idea about machining time... so making Licence plates... was that on the inside or outside...lol

thanks for oyur input so far...much appreciated.

cheers

[rolinjunk]

Well now if quanity and speed is paramount hows a about a staming die with interchanable # and char. inserts. Just like the ones at the state prisons.
Of course tooling cost will overcome you unless you have a buddy with access.
who said license plates?.....

later

[balsaman]

for 10-12K buy a nice used bridgeport and have it cnc'ed or do it yourself, then with the leftover cash build a cnc router for your wood projects.

Eric

[Moondog]

Balsaman....a used BP... now that's an idea....I am nearly finished a 8*4 router for panel work etc, but was thinking of a smaller machine for smaller items. From Jan 2005 I will be establishing a business around CNC. A Mill would be suitable if there was lots of contract work for Milling?... I am planning to do some contract work for Cabinetmakers and Signwriters...metal machining may be an additional sevice.....

Is it difficult to CNC a BP...

[E-Stop]

E-Stop.. Fadal 4020 I assume is a Mill?.... If you cut something like that sign how long did it take..just trying to get some idea about machining time... so making Licence plates... was that on the inside or outside...lol

Yes, the Fadal 4020 is a Vertical CNC Mill. The signs I made similar to those shown were about 12" x 16" and they took about 20-25 minutes each to run. The licence plates, done on the outside, take about 6 minutes apiece to make, give or take a little depending on the design.