[j1979]

first of all if this is the wrong section im sorry! the forum has so many different sections i did not know where to post. i am new to CNC and infact milling in general. the wiring and computer stuff is not a problem and doesn't daunt me. but when it comes to choosing a machine am a little stuck. I am a complete noob so if i say something stupid sorry.

i want to mill aluminium to, possibly 10mm deep in some areas. Speed is not an issue as i will only use the machine infrequently.

ok after after looking at the sable 2015 the v90 and various others, i think im going to opt for the CNCDIY CNC2520

http://sites.google.com/site/cncdiymachines/cnc2520

it looks like it will fit my needs OK. Does anyone own one of these and can they give me any advice. or am i totally out of my depth, and i need a much more powerful machine for my intended use?

thanks in advance

[MrWild]

That machine looks fine for wood. It is not good for aluminum. Why is it not good? A serious lack of rigidity. Every rail is unsupported. These unsupported rails will allow vibration to ruin every cut in aluminum unless you take VERY light cuts. The spindle is a high speed spindle and is made for wood. Again, extremely light cuts at very fast cutting feeds might let you cut aluminum, but if you think you can take cuts 10m (3/8") deep, the answer is no, no way, not with this machine.

[j1979]

That machine looks fine for wood. It is not good for aluminum. Why is it not good? A serious lack of rigidity. Every rail is unsupported. These unsupported rails will allow vibration to ruin every cut in aluminum unless you take VERY light cuts. The spindle is a high speed spindle and is made for wood. Again, extremely light cuts at very fast cutting feeds might let you cut aluminum, but if you think you can take cuts 10m (3/8") deep, the answer is no, no way, not with this machine.

yes i didn't mean in one go, i mean to 10mm deep with several passes. surely there is software out there that can do that? I am making aluminium enclosures for custom motherboards.. the bottom part of the enclosure will need recesses for components.. like a 7 - 8mm deep hard drive.

would you say this style, is more rigid, as the table moves not the arm?
http://sites.google.com/site/cncdiymachines/cnc2518

[MrWild]

Again, the rails are unsupported. Vibration ruins cuts and cutters. Once a cutter starts degrading due to chipping from vibration, it gets worse fast. What kind of aluminum are you cutting? How big a cutting area do you need? Oy, I just looked at the motors. An even firmer NO WAY. Many machines clam CNC capable, but the axis motors and drives are only good for light duty. Notice the note by the motor stating (used). Usd motors of puny size with weak drives that ham string you into not being able to upgrade without major extra expenses make these machines poor choices. While aluminum is easier to cut than steel, it is a LOT harder to cut than wood and plastic. The pictures show it cuts plastic, wood, and .002 thick copper on PC boards.

I realize you are on a budget, but going cheap with something that appears like a good deal will ruin a business fast when it fails you.

[j1979]

Again, the rails are unsupported. Vibration ruins cuts and cutters. Once a cutter starts degrading due to chipping from vibration, it gets worse fast. What kind of aluminum are you cutting? How big a cutting area do you need? Oy, I just looked at the motors. An even firmer NO WAY. Many machines clam CNC capable, but the axis motors and drives are only good for light duty. Notice the note by the motor stating (used). Usd motors of puny size with weak drives that ham string you into not being able to upgrade without major extra expenses make these machines poor choices. While aluminum is easier to cut than steel, it is a LOT harder to cut than wood and plastic. The pictures show it cuts plastic, wood, and .002 thick copper on PC boards.

I realize you are on a budget, but going cheap with something that appears like a good deal will ruin a business fast when it fails you.

Thanks for the advice. the maximum size will be 170mm x 260mm x 10mm.
are there any machines you can recommend?

[Walky]

Remember you'll need some extra room for clamping the piece, and you must consider the tool's width, plus a safety margin (cutting into a clamp is no fun).

My machine uses supported rails on all axis (sbr16, seem to be the same used in the Sable's X axis), anti backlash nuts and 280oz-in motors running at 41V, ~2.5A each (many, many times more powerful than the motors on the DIYCNC and Sable you are looking at), and I still try to cut no deeper than 0.15mm deep per pass, 35IPM when using a 3/32" endmill on aluminum. My machine's structure is made of MDF, though, but using torsion boxes and some threaded rod for reinforcement of the Y axis. If you are thinking on hollowing a 200mmx200mm aluminum block with the Sable or other similar entry level machine, I bet it could take days.

Sbr16 bearing blocks have two adjustment screws (on top and on it's side). I found it takes a lot of pressure in these to get a really tight fit into the shaft (these bearings, when tightened, become hard to move through the shafts even by hand); with strong motors it's OK, since these can have the extra force needed to move each axis, but with small ones I don't think it will be enough, since the bearing blocks would be too loose.

BTW, as MrWild said, PCB milling is nothing like metal milling; PCBs are actually quite soft and easy to work with.

I still think the Sable seems like a really, really nice machine for the price, I just think it's just not meant for aluminum cutting (engraving, at most).

[j1979]

thank you for everyone's help an input. And i have taken this onboard and changed my expectations of what these machines can do. So my next question is..

does anyone know of a kit that will perform cnc aluminium milling out of the box? like i said speed is not a major issue. is the Fireball v90 more suited or is this likley to suffer the same problems?

[Walky]

thank you for everyone's help an input. And i have taken this onboard and changed my expectations of what these machines can do. So my next question is..

does anyone know of a kit that will perform cnc aluminium milling out of the box? like i said speed is not a major issue. is the Fireball v90 more suited or is this likley to suffer the same problems?

The v90 would be more pòwerful than the Sable, but probably a lot less rigid so I don't think it would be a good idea (I could be wrong).

How much do you want to pay? I would go for a real mini mill if I wanted to make aluminum, but of course that takes the cost quite higher.

[j1979]

http://www.axminster.co.uk/proxxon-p...5/?src=froogle

something like this?

i don't want to spend more than £1000 ($1550), ideally £700 ($1000) but if going for a mini mill, the CNC stepper motors would not be needed at the start and i would retrofit, in the future if needed. the machine doe not need to be CNC it would just help in the long run.

what size motor would i need to mill aluminium? i presume a basic mill with a 200w motor would not be powerful enough?

any suggestions, around £700?

[awerby]

The site doesn't give the actual travel dimensions, but it's nowhere near the size you said you wanted. (As I recall, they're about 3 inches in X and 2 inches in Y). If you're making aluminum jewelry it might work for you, but otherwise, keep looking. You might be able to buy a used CNC mill and retrofit it with new controls, or build something yourself (if you're good at scrounging components) but I don't know of any CNC mills capable of reasonable cuts in aluminum pieces that size which sell new for the amount you want to spend, especially in the UK where everything seems to be more expensive than in the US.

You might be able to find a low-quality manual Chinese mini-mill within your budget, but they don't make the best candidates for retrofits. An older CNC mill with a blown controller might be a better bet - you can sometimes find them for the price of the scrap metal they contain.

Andrew Werby
www.computersculpture.com

[j1979]

http://www.bzt-cnc.com/product_info....ZT-PFL330.html

what about this? it looks a little better built.

when you say the rails are unsupported, i am not 1005 sure what you mean.

[Walky]

http://www.bzt-cnc.com/product_info....ZT-PFL330.html

what about this? it looks a little better built.

when you say the rails are unsupported, i am not 1005 sure what you mean.

Supported rails means the rails are fixed into solid supports that prevent flexing (and vibration) of the shaft under heavy loads; the supports are then fixed into the machine's gantry.

It's something like this: http://www.todomercado.com/tm/aviso/..._Alucarudo.jpg

Unsupported rails have a much higher tendency to flex, depending on their lenght and diameter.

The machine you mention seems nice, motors look to be Nema23 around 300 oz-in or something like that. Fixed gantry is nice for metal working. Still, I'm no expert (been a cnc hobbyst for less than 2 years) and have no first-hand experience with machines others than my own builds (I've only used supported rails so far), so I wouldn't dare to say if it would or would not work for your needs. It still seems much, much more adequate for aluminum milling than the Sable and V9, I'm just not sure if it's enough. I'd start by looking for info on the machine (by actual owners) and looking if thar website has a good reputation.

BTW, that machine doesnt seem to include a controller board, nor a spindle

[Walky]

This is the kind of machine I'd get if I was in your dilemma and had such an ammount of money. It's surely way too much for what you're willing to spend, but it can give you an idea of the mill that would be adequate for the job:

http://www.probotix.com/syil_cnc_mac...lling_machine/

What a beauty, eh?


I wouldn't start by milling metal if I had no experience with CNC, though, it's probably a recipe for disaster (I can't remember how many times I screwed up when cutting wood and crashed my machines into the material, I bet it's not fun when something like that happens with a metal block and a broken 1/4" bit comes flying towards your face, your dog or that new 42" lcd... and some bits are expensive, too!). I think I'd probably feel like a monkey with razor blades

I liked the idea about buying a used manual mill, it's safer (still wear protection at all times!) and cheaper that getting a brand new cnc mill. And you can retrofit it once you've gained some experience about metal-working (speed and depths of cut, kinds of endmills, etc). Proper g-code creation is still very important when it comes to safety (you don't want your endmill to approach the material thinking it's gonna find a block of butter).

Or... perhaps you can get a V90 or similar, get used to toolpath creation, make some prototipes in wood, acrylic or other materials, maybe make some money with the machine and then sell it (optionally keeping the controller and motors, if you'll need it) and get "the big one". Or maybe you can make negatives with the V90 and then cast your parts in aluminum if you like that approach and the final results.

[RomanLini]

Unsupported rails are probably OK on such a small machine (like that first CNCDIY 2520 machine you mentioned) as the rails are quite short and hence stiff.

Since you want to get up a running pretty quick on a tight budget I'd consider getting a CNCDIY 2520 and maybe adding 3 decent sized motors to it (motors cost maybe $100?) and throwing the little motors out.

The other problem would be the spindle, I would toss the little DC motor spindle and get any small frame router, 500W or 650W and put that on, so that's $50 to $100 or so, and some cutting bits specially for aluminium maybe another $50.

Then maybe a little touching up of the machine like adding a bracket here and there to stiffen it would be easy enough. All in all I think you could be cutting your small aluminium parts after a weekend or so.

Remember it's easy enough to *improve* a working machine to make it stiffer, better etc as you can use it to cut some of the brakets and stuff needed, and that includes the hold-down jigs and things you will need to cut anyway to set up for your production.

The moving table machine you mentioned in post #3 is probably more rigid out of the box and looks easier to strengthen with brackets and easier to align etc.

It's just my opinion but you might be best off to jump in and get a small cheap machine up and running and start production now, then IF you start to make more serious money you have many options including building better machine(s) using the one you already have to cut the parts, or just buying bigger and better later. In that case you can easily re-sell the small machine at very little loss, or keep the small machine as a dedicated engraver etc keeping your bigger machine for the cutting tasks.

[brazza]

hi i own a 3040 cnc which diycnc also sell (but not purchased from them)
the controller box it came with was crap , only ran the 2 amp motors at half an amp and wouldn't go higher, this controller box comes with many chinese cnc's on diycnc site , i tossed that after it eventualy commited suicide and brought a 4 axis more expensive no name controller , which ran my machine amazing. I regulaly produce aluminum parts with ease on my machine , i take .1 to .2 mm cuts at around 1000 mmpm to 2000mmpm with the small 200w dc motor that a lot of diycnc machines come with it , apart from the small tool marks or chatter marks when i try to take a .4 - .6mm cut in aluminum it performs well.
Not perfectly suited for aluminum but an amazing all round machine, perfect small scale wood machine great for plastics and amazing with pcb because of its .01-.02 accuracy (what ive measured , not the specs listed) , nice decent travel , and quite fast ( it will rapid at around 3000mmpm to 6000mmpm depending on microstepping setting ) here is a part i just recently machined on it made from 13mm thick 6061. Oh yer it's a paper weight i might add