CNC Machining Discussion (Cont.)

[CoolHand]

So, you actually have to load the block in by hand? Or do yhou just need to calibrate, then have the machine laod the block at the right speeds, and in the right positions? By the way, if you don't want to clutter your thread with this, we can talk through pm or email, I'm really interested. I would like to go into these classes next year having some clue about the basics.

You have to load every billet by hand, find the edges, and run the programs. For example, these frames have to be refixtured (Taken out of the machine and put back in, in a different orientation) four times, and have the edges found four times to produce a finished part.

They make machining centers that can orient, and change billets on their own, but they cost more than all the assets I will ever own, and are really only viable in high volume production environments. Even though we like to think that paintball is a big sport, the volume of parts required to supply the demand is very tiny compared to some other industries. There just isn't the volume of parts to justify the cost of the uber cool machines.

The chips can be recycled, but you don't get much for them (about 1/3 the amount you would get for alum cans, or less), since they have to be sorted due to possible tool steel and coolant contamination.

[greg]

Gosh Darn.... you work alot....

btw.... a little more work... you never responded about doing a custom mill job on my micromag.... whats up???? lmk

[Branchvillian]

Re: CNC Machining Discussion (Cont.)

Few quick questions. Defenititon for billet, is it the starting piece of aluminum? what exactly do you mean by "finding the edges". You have to feed it in so that the machine knows where the piece of aluminum ends?

Originally posted by CoolHand


You have to load every billet by hand, find the edges, and run the programs. For example, these frames have to be refixtured (Taken out of the machine and put back in, in a different orientation) four times, and have the edges found four times to produce a finished part.

They make machining centers that can orient, and change billets on their own, but they cost more than all the assets I will ever own, and are really only viable in high volume production environments. Even though we like to think that paintball is a big sport, the volume of parts required to supply the demand is very tiny compared to some other industries. There just isn't the volume of parts to justify the cost of the uber cool machines.

The chips can be recycled, but you don't get much for them (about 1/3 the amount you would get for alum cans, or less), since they have to be sorted due to possible tool steel and coolant contamination.

[FactsOfLife]

Billet is usually referring to a block of forged aluminum.

Finding the edges means placing the material in the fixturing, and touching off the edges with a tool held in the mills collet. When you do this, you zero out each axis in turn until the mill knows where the datum or reference point is. Then you can start the program and mill the part.

Machine doesn't have a clue as to where the edges of the part are until this is done. BAsically you're telling the machine the location of the material in 3 axis, X Y and Z.

[Branchvillian]

I see.

[melster]

I see about the contamination bit. Seems like a huge waste of aluminum though.

OK then...why don't people cast parts (such as frames) in generally the proper shape, but just slightly oversized? That way they can mill them down just a little bit to get to the exact dimensions with the least amount of waste and work?

[CoolHand]

+1 for FactOfLife, he hit it right on the nose.

As for casting, it is done with a different alloy of aluminum than is used for forging. It is generally lower in magnisium, and much higher in silicon. This produces an alloy that flows well (to fill the die or mold correctly), but doesn't machine or anodize worth a crap. Ever wonder why Kingman still paints their frames? Its because they are die cast, and they don't ano very well at all.

It also produces a half step where you have to first make a square or flat area to start from, which is just another way to induce error.

That waste alum is one of the reasons why machined parts are so expensive.

[athomas]

Also, billet aluminum is usually pressed or rolled stock. This makes it more dense and also "aligns the molecular strands" (for lack of a more in depth explaination), which makes it a stronger metal.

[CoolHand]

Almost all billet grade alum is rolled, but it is worked hot, due to the high hardness (for aluminum) already present in 6061 or 7075 alum.

The rolling will actually cause dislocations in the crystal structure of the metal, which makes it harder, and stronger (its called "work hardening"), but since they are doing it hot, (at around .4 of the melting temp, like 520'ish degrees F) the work hardening is kept to a minimum.

That strength is gotten back with a Heat Treatment. (thats what the T6, in 6061-T6 means.) In this case it is a solution hardening (exposure to an element rich atmosphere at an elevated temp.), followed by an atificial ageing (time spent in an inert atmosphere at an elevated temp.), and a light tempering to stabilize it (reheating to grain growth stage, and then a quench to stop it at a stable point).

[greg]

you dont respond to my emails... you ignore all my messages... and you dont return pm's..... do you now want my business or soemthin???? ive been askin bout your doing custom work on my micromag for foreva...

[CoolHand]

Originally posted by greg
you dont respond to my emails... you ignore all my messages... and you dont return pm's..... do you now want my business or soemthin???? ive been askin bout your doing custom work on my micromag for foreva...

Whoa! Be calm dude.

I thought you were gonna send me a pic of what you wanted done, so I've been waiting on that.

I can do the work, but its not gonna be cheap (nothing ever is it seems ).

I have been uber busy, but things are starting to slack up, so I might be able to sneak you in.

I still owe a single trigger frame to a fellow from here, and I am still working on my EMag rails, and a new Impulse vert frame.

My suggestion is to send it in, and I will sneak it in when I have some free spindle time. I will take a look at it, and get you a price quote before I start, if you don't want to do it, I will eat the shipping back to you.

That's the best I can do.

Sorry for the mixup.

Thank you for your interest.

[greg]

o ok... well i cant really draw... or design stuff on computer... pretty much i have the old( i think) left feed boy with the slide in feed neck....i understand its impossible to make it a centerfeed..??? so possibly i would want just to have the body shaved flat... or curved instead of the things on the sides and then.... a 4 leaf clover a ace of spades and one of those chinese symbols... most likely power one inside another

[steveg]

Coolhand can I ask what kind of milling machine and control
you have, perhaps I'm misreading/misunderstanding why you
are reindicating every time you reposition the part because
fixture offsets are a wonderfull thing

the aluminum used in cans is almost 100% pure with no
alloys or additives so it's a "known" metal, while 6061
is the most common alloy used it's definately not the only
one, this lead the posability that the recycled metal becomes mystery metal

[CoolHand]

Originally posted by steveg
Coolhand can I ask what kind of milling machine and control
you have, perhaps I'm misreading/misunderstanding why you
are reindicating every time you reposition the part because
fixture offsets are a wonderfull thing

I'm using a Moog A-22 with a HydraPath III control on it, circa 1993 or there abouts. It has a machining cube of 22in x 18in x 18in, and a 22 position ATC.

Fixture offsets are indeed a wonderful thing, but since my fixturing is really only good to +- 0.003 to 0.005, they do me little good. Plus, if you look at the tolerances of rolled barstock, they are mindboggling. +- 0.040 in width, and +- 0.010 in thickness from my supplier. My machine is repeatable to +- 0.0001 , so I reindicate to take advantage of this.

No steps, or misalignments for me.

I am currently using two 6" vises for my workholding (square and parallel to .0003"), with fixtures that I load into them, to allow for more flexability. This is where most of my error shows up.

I could drop some serious cash on fixtures that would allow me to use the offsets like they were designed, but I really don't sell enough stuff to justify that expenditure. At least not right now.

[FactsOfLife]

Originally posted by CoolHand


I'm using a Moog A-22 with a HydraPath III control on it, circa 1993 or there abouts. It has a machining cube of 22in x 18in x 18in, and a 22 position ATC.

Fixture offsets are indeed a wonderful thing, but since my fixturing is really only good to +- 0.003 to 0.005, they do me little good. Plus, if you look at the tolerances of rolled barstock, they are mindboggling. +- 0.040 in width, and +- 0.010 in thickness from my supplier. My machine is repeatable to +- 0.0001 , so I reindicate to take advantage of this.

No steps, or misalignments for me.

I am currently using two 6" vises for my workholding (square and parallel to .0003"), with fixtures that I load into them, to allow for more flexability. This is where most of my error shows up.

I could drop some serious cash on fixtures that would allow me to use the offsets like they were designed, but I really don't sell enough stuff to justify that expenditure. At least not right now.

I'd LOVE to have that setup to complement my wood shop.