looking for a machine capable of cutting solid polycarbonate sheets 1-5mm

[DiTBho]

I don't know how feasible it is with a laser cutting machine, nor what laser power is needed.
nor how toxic it is to cut polycarbonate with laser (CO2-laser? laser-diode?)

I usually work with polycarbonate by hand, with a drill, hacksaw, file and fretsaw

is a CNC better?

I have a budget of 2K euros 

[wraper]

You should not cut PC with laser. Not because of toxic fumes but because the result will be awful. For laser cutting you should use either acrylic or polystyrene sheets.

[ebastler]

Others will be better positioned to comment on mechanical machining, waterjet cutting or whatever. But to put your 2 k€ budget into perspective, you probably should mention the required size of work pieces, and ideally also your throughput and precision requirements.

[DiTBho]

400x400mm should be enough!

[DiTBho]

the gray parts were made by hand, working thickness=5mm solid polycarbonate sheets.
It took me about 30 hours total 

the other parts are templates, made of paper and cardboard, preliminary feasibility study

ergo, I will also need a 3D scanner, and I am going to buy one.

[geggi1]

You coud get a little mill CNC to cut the PC there are kits on Ebay and other places on the internet for resonable price.
A little bandsaw would also do the job but will most likely give you some more filing and grinding.
Then there is also the option of a water jet cutting table if you are able to find something in your price range and size.

[fourfathom]

I've used my Shapeoko CNC mill to cut HDPE, aluminum and wood, and it works well.  I assume polycarbonate is more brittle, but that probably won't be an issue.  The Shapeoko mills cost a bit over $2000 US.

[ebastler]

It seems that a CNC mill is the only plausible option. Laser cutting is not great for polycarbonate (giving discoloured edges, and even large machines are limited to a few mm it seems). Water jet would probably work great, but I am not aware of any solution which is even in the ballpark budget-wise.

An affordable CNC mill should do. If you don't intend to machine metal with it, you don't need very high rigidity. So some hobbyist unit from the product class known as "Käse-Fräse" in German should work -- that's "cheese mill" in English, but does not rhyme as nicely.  

[jonpaul]

Your local TAP Plastic can do any cuting and shape with their very large NC machines.

Also supply the material.

If outdoor use is contemplated avoid polycarbonate instead use acrylic (Lucite)

Jon

[abeyer]

the product class known as "Käse-Fräse" in German should work -- that's "cheese mill" in English, but does not rhyme as nicely.

rofl, I love that 

[rstofer]

Part number '1', among others, has a very square transition in the corner.  Unless you remount the part vertically, you can't cut that with a mill.  Can you stand a 1/16th inch radius of a 1/8" cutter diameter?

A simple mill is 2-1/2 D (as opposed to 3D, debatable) in that it locates x and y and cuts down to a depth.  A 2D CAD program is adequate with a post processor like CamBam to handle the depth.  CAD -> CamBam -> Mach3 (machine control).

[fourfathom]

Part number '1', among others, has a very square transition in the corner.  Unless you remount the part vertically, you can't cut that with a mill.  Can you stand a 1/16th inch radius of a 1/8" cutter diameter?

No reason not to use a 1/16" dia bit (or similar  metric size). They are of course more fragile.

[thm_w]

You might consider getting the 3D scanner and a 3D printer first, then use that to print a prototype part.
After you are sure it works, send it out for someone else to make.

The cost for someone else to make these parts for you will not be that high, here is a US example, I'm sure there are many in the UK: https://sendcutsend.com/

[DiTBho]

Part number '1', among others, has a very square transition in the corner.  Unless you remount the part vertically, you can't cut that with a mill.  Can you stand a 1/16th inch radius of a 1/8" cutter diameter?

A simple mill is 2-1/2 D (as opposed to 3D, debatable) in that it locates x and y and cuts down to a depth.  A 2D CAD program is adequate with a post processor like CamBam to handle the depth.  CAD -> CamBam -> Mach3 (machine control).

they are still raw parts, I have to make a third piece, assemble them on an axis, then chamfer and round further
I don't have an exact impression of the quarry, only a fuzzy idea, and I'm going by trial that "somehow" fit, with two or three templates, taken in three different points

in turn, I have to insert a very thin tip inside the hollow (the black piece in the pic), to try to make the excavation as uniform as possible.
90% is already ok, just not perfect.

it's all hacking work on parts made for a bicycle

[DiTBho]

This is instead a piece that I built for a particular computer (not a PC)
It has a thickness of 5mm, I drilled it and opened a rectangle to be able to mount a 2x16 character LCD
Opening that rectangle was a bloody hell, all done with a small iron file, it took me nine hours!!!

[DiTBho]

my pellet stove had pieces of ceramic in the upper part, which broke because they were too fragile and positioned too close to the door where the pellets are inserted

I redid them both in polycarbonate, using the ceramic pieces as a template (their fragmented pieces temporarily glued together), then I softened the curves with sandpaper

it took 18 hours to make them

[jpanhalt]

Why use polycarbonate?  That is my least favorite plastic to work with.  For the pellet stove, why not aluminum?  It's easily machined, filed, etc. and colored or coated.

[DiTBho]

Why use polycarbonate?  That is my least favorite plastic to work with.  For the pellet stove, why not aluminum?  It's easily machined, filed, etc. and colored or coated.

The primary reason is that I don't pay a penny(1) for polycarbonate sheets 

I have a friend who sends me free polycarbonate sheets classified as "industrial waste" that has been discarded because  of defects, but which I can still fully recover.

Usually if a whole sheet of polycarbonate is 1000x600mm, with thicknesses ranging from 1mm to 5mm. When a solid sheet is discarded, I manage to recover 70% of its area, in the worst case I obtain many small pieces which can still be used to machine small parts.

Many parts of the bicycle are made of aluminium. The brakes, the derailleurs, the wheel rims(3) ... every now and then I file, cut, fix, polish those thing

I find it much more difficult to work with aluminium, both because I would have to wear a closed mask(2), and because I have to anodize, de-anodize (in soda caustic), rather than polishing with a brush using the natural aluminum oxide.

Furthermore, both the drill bits and the files are different. For polycarbonate I use wood tools, which are not suitable for working with aluminium.

(1) in return, I gave my friend about two dozen wheelbarrows of wood, already cut to size for his fireplace
(2) aluminium dust is toxic for the nervous system, but is also harmful to the pulmonary alveoli
(3) lately I've been using (experimenting?) wooden and resin rims, same concept, but better than the one used in the 1940s

[DiTBho]

this is the aesthetics of the pellet stove with polycarbonate parts.

I would say...not too bad.

I showed these stove pieces to basically show some of the things I would like to do with a CNC machine

the goal is to take less time and make 100% reproducible parts

[jpanhalt]

@ Post #18

We disagree on the relative risk of debris from machining aluminum.  Its particle is usually quite a bit larger than anything that can enter your alveoli.  If concerned, mask wearing is sufficient.  On the other hand, what about fumes from resins?

Anyway, 'free" costs less than per pound surplus aluminum sheet/plate.

[DiTBho]

what about fumes from resins?

less exposure time!

less than 40 minutes to impregnate the wood of the wooden rims
~ ~ ~ vs ~ ~ ~
several hours for the processing of the aluminum parts

[5U4GB]

the other parts are templates, made of paper and cardboard, preliminary feasibility study

If you've got templates, what about running around them with a trim router to cut the polycarbonate?  The bit type you want is a flush trim bit which is designed for exactly this use.

[DiTBho]

For laser cutting you should use either acrylic or polystyrene sheets.

Never used, but ... very interesting, even though I don't really like that they are transparent, I could always cover them with paint 

[DiTBho]

If you've got templates, what about running around them with a trim router to cut the polycarbonate?
The bit type you want is a flush trim bit which is designed for exactly this use.

excellent idea!
I've never owned one, I've always wanted one
is there any "micro" trim router?

[DiTBho]

I have a column drill, on which I mount abrasive brushes of various diameters and grits, as well as various drill bits

These are the tools I use for most jobs