[SpacedCowboy]

Hi there,

Having just been burnt with another vendor, I was wondering if the KT1414 (or 1425) models would be sufficient to do some light work in Aluminium, or would I have to go to the KG model ?

The goal is to make some Al moulds for injection-moulding, but I don't actually expect to make too many of these (2 or 3 at most). I don't care if it takes a long time to make the mould, I just want to know if the machine would likely be capable of it. If adjusting the cut-depth and ipm is what it takes, then so be it

Anyone any advice ?

Thanks
Simon

[MA$TER_E]

I don't have any experience with the KT series but I'd suspect that it would do it. You'll need some good motors and drivers and I'd recommend a coolant system of some kind. You'll have to accept that there will be some errors though. The machine wasn't designed to handle that kind of work. The only thing I think you have going though would be that its the 14x14 model. If you try the 14x25 or 25x25 I'd safely say that there just isn't enough support there to really mill on aluminum.

You will also need to think about your spindle/router. Cutting aluminum at 10,000 rpm with a slow feed rate and depth of cut is going to present some issues without some kind of coolant. Even with the KG series machines thats an issue. However the KG series have more support and can handle a heavier load without binding and causing a stall. And again, even in the KG series the 14x14 is going to be your best bet for milling aluminum with reasonable tolerances.

My machine will cut aluminum but if I were to load up a 6x6x1.5 block of aluminum and mill out half of an injection mold, I'm not sure it could do it. I'd have to cut really slow which is bad as my routers slowest speed is 10k rpm and I don't have coolant either so the aluminum welding to the cutter is a very real concern.

I'm still kind of a noob to the CNC world but thats my thoughts based on my experiences thus far. Maybe some other guys will have some additional input.

:cheers:

Eric

[SpacedCowboy]

Thanks for the input

I've been talking to K2, and they seem to think it'll be ok for the light-milling I have in mind. They're recommending air-gun cooling (which was new to me - I was planning on using http://www.fogbuster.com/Machining-S...-Products.html ...)

Let's see what the quote comes back as

Simon

[MA$TER_E]

Thanks for the input

I've been talking to K2, and they seem to think it'll be ok for the light-milling I have in mind. They're recommending air-gun cooling (which was new to me - I was planning on using http://www.fogbuster.com/Machining-S...-Products.html ...)

Let's see what the quote comes back as

Simon

The air-gun is pretty haha "cool" no pun intended. Unfortunately you need a super awesome air compressor to support it which can be pretty expensive. On the up side though there is no real mess, just cold air and chips. I think that the fogger would be a good alternative though. Let us know how that works out. Maybe I'll get one and cut aluminum more if it works out well. My current setup would have to change a bit to handle the mess though.

:cheers:

Eric

[ger21]

I've been talking to K2, and they seem to think it'll be ok for the light-milling I have in mind.

Will they give you a refund if it's not OK?

[MA$TER_E]

Will they give you a refund if it's not OK?

LOL good question

[SpacedCowboy]

Will they give you a refund if it's not OK?

I didn't ask, but I doubt it....

"We have customers using our machine to cut Aluminum. For those who would like to use our machine for mold making, they will have to resort to their own skill sets.

The statements on the cutting of aluminum is generally stating that we do not offer training. Cutting aluminum does require more knowledge than cutting of wood or plastic because it is not forgiving to the end mill or machine."

The 'more knowledge' bit is slightly worrying (me being a newbie and all that), but I do plan to "work up" to Al, starting off with soft wood, so we'll see.

You don't try, you never know. At least that's how I look at it

Simon.

[SpacedCowboy]

The air-gun is pretty haha "cool" no pun intended. Unfortunately you need a super awesome air compressor to support it which can be pretty expensive. On the up side though there is no real mess, just cold air and chips. I think that the fogger would be a good alternative though. Let us know how that works out. Maybe I'll get one and cut aluminum more if it works out well. My current setup would have to change a bit to handle the mess though.
Eric

The one I found online ( http://tinyurl.com/m8tavr ) doesn't seem to be too demanding - 80-100 psi. I have a DeWalt compressor that can easily supply that (it's currently used as a 140psi source for the pick-and-place surface-mount component placing tool). Apparently this is the cool-air gun they use too (according to the sales rep).

When I suggested the fogger, he pointed out that the maintenance is much higher because there are parts (presumably the screw-rod and fittings though he didn't say) that can rust - they don't use stainless parts.

Simon.

[ger21]

Find out the CFM requirements first. They may be quite high.

[SpacedCowboy]

Find out the CFM requirements first. They may be quite high.

Point taken. 15 SCFM is well out of the range of my existing compressor, and in fact might make it out of my range completely. I'll have to see if I can find a low-cost compressor anywhere...

Simon

[MA$TER_E]

I work for a company that does huge aluminum wax injection molds for investment castings so I'm familiar with wax injection tool design and construction.

What kind of injection process will you be running and at what kind of volumes; a couple, a couple dozen or hundreds of cycles? reason I ask, is it necessary to run aluminum tools or could you use a plastic/acrylic tool? I suspect that would be a bit cheaper than aluminum and easier to machine with better results with no coolant system and I think mold release would be easier as well.

If you're planning on some kind of low cycles and low pressure wax injection I think an acrylic would be a good alternative to aluminum but if its some kind of high cycle or high pressure plastic injection; aluminum...

[SpacedCowboy]

I'm thinking several hundred cycles... The goal is to make an LED-holder in transparent polystyrene resin that snap-connects to other identical parts. I have the electronics worked out for the LED-drivers and snap-interconnect etc. I just need to get the holder-parts made.

The idea is to make it easy to use LED lighting above my fish-tank, and then (once I've worked out the kinks) commercialise it thereafter. A single 6' fish-tank will need ~140 LEDs...

The holder is actually fairly simple (read: angular, not smooth curved surfaces), and fairly small (2"x1"x0.5") so I wouldn't have thought the mould would be a huge strain on the machine - I just want guarantees of accuracy so the air-escape channels (0.05" wide by 0.002" deep radiating outwards from the part) in the mould actually work (for example). The absolute accuracy of the part itself ought to be laughably-easy for any machine... +/- 0.1" would be fine...

I thought about using epoxy moulds with an off-the-shelf master-mould shell, but I think I'd be spending a lot of my time re-making the mould rather than actually using it... I'm open to ideas though

Simon

[MA$TER_E]

Hmmm... It may be worth a phone call to my buddies at Tap Plastics. Tap is where I go for all my mold making and plastic supplies. I'm not up-to-speed on the different types of plastics/compositions and how they react with each other. But if I remember correctly the polystyrene resin is a two part mixture with a cure time. I don't know for sure thus the phone call to Tap but I think you can make molds using polycarbonate and pour/inject the polystyrene. I'd check to be sure and maybe do a quick test but the savings could be pretty significant from the machine/setup to cost of materials if you could go that route.

Aluminum should be doable though and I'm not trying to detour you from that option. Its just going to be expensive. My setup has been pretty close to 2x what I thought it would cost and I still don't have it dialed in the way I would like it just for cutting plastic/wood and the occasional aluminum panel.

Looking back now it would almost be worth it to spend that extra money up front and buy a large syil or novakon mill or second hand bridgeport with a large envelope made for these kinds of projects.

[SpacedCowboy]

Hmmm... It may be worth a phone call to my buddies at Tap Plastics. Tap is where I go for all my mold making and plastic supplies. I'm not up-to-speed on the different types of plastics/compositions and how they react with each other. But if I remember correctly the polystyrene resin is a two part mixture with a cure time. I don't know for sure thus the phone call to Tap but I think you can make molds using polycarbonate and pour/inject the polystyrene. I'd check to be sure and maybe do a quick test but the savings could be pretty significant from the machine/setup to cost of materials if you could go that route.

Well, the injection moulder (http://injectionmolder.net/ to start off with :-) just melts the polystyrene pellets and forces the resulting fluid into the mould. I don't think it's two-stage.

Given the low accuracy requirements I have (± 0.1"), it's possible I could use a different (higher melting-point temperature) plastic to form the mould (eg: Polycarbonate melts at 475, compared to polystyrene's 185), but the problem then becomes heat conduction. In order to cool, the part needs to lose heat, and a non-metal mould loses heat slowly...

It may be an option if I can make enough moulds to not care how long it takes to cool, I suppose, and if the moulds hold together for enough repeat runs, and if the part and the mould don't bond

Aluminum should be doable though and I'm not trying to detour you from that option. Its just going to be expensive. My setup has been pretty close to 2x what I thought it would cost and I still don't have it dialed in the way I would like it just for cutting plastic/wood and the occasional aluminum panel.

I did look into getting the KG model, but it's (as you say) about twice the price. I'm not sure I can get that past the wife

Simon.

[kjmdes]

Judging by my KT, the Z-axis is far too unstable to cut alum. I'm even having problems with platics and composites. Ok in the X, but rocky in the Y.

They said it would be fine. It is not.