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View Full Version : Considering DIY machine build - reality check



greenz123
22-09-2014, 05:17 PM
Hello all cnc gurus !

I'm considering building my own cnc machine. I'm hoping If someone can tell me whether the capabilities Im looking for in a machine are achievable.
I dont have a great deal of knowledge about CNC machines so I apologise in advance If what Im asking is ridiculous !

Id like a cutting area of 700mm x 2000mm.
Id be mainly cutting sheet plastics and wood.
If possible Id like the ability to cut aluminium and hard woods, but that would be a bonus.
Accuracy is very important to me. (+/- 0.1mm ?)
I have a budget of approx 2000.
I have built a 3D printer (Kit from Ultimaker). I have basic welding(mig) and mild steel fabrication skills/tools.
I have very good modelling/CAD skills. I have a pretty accurate FDM 3D printer (Ultimaker2) (max build volume 200mm3)

A little more on what I'm hoping to do with the machine:

Firstly I have some designs Id like to produce large scale stencils for which have some very fine details in. About 0.1mm details to be precise. These details would only need to be cut in a very thin plastic, although I wondered If stacking multiple sheets up and cutting a number at once would be possible.

Id like to be able to cut basics shapes from 18mm ply for furniture design prototypes.

Any advise on whether the above is feasible with this budget would be greatly appreciated.

Jamie

EddyCurrent
23-09-2014, 10:07 AM
It cost me double that amount; http://www.mycncuk.com/threads/6565-Ready-Steady-Eddy
but I wasn't building to a budget.

mekanik
23-09-2014, 10:42 AM
Hi Jamie
Welcome to the forum, take a look through the build logs these will give you an idea of what is required for a decent machine. The usual route is to draw it in sketchup and offer it up for critique, the guys will then highlight any problems with the design.
Good luck
Mike

JAZZCNC
23-09-2014, 04:02 PM
Hi Jamie,

Yes it's very do able with 2K provided you do your home work and all the work your self plus don't waste money on buying wrong kit. It won't be top end kit wise IE: Motion control cards etc and you'll have very little room for mistakes but 2K will get you a nice working machine.

0.1mm isn't high accurecy so again provided you use a good design and build to decent standard then won't be a problem achieving this. You'll almost certain need to work with steel to meet your budget and provided your comfortable with working it then makes for very strong accurate machine at sensible money. It just takes longer and few more tools/skills required.

See your in Leeds which side.?

greenz123
23-09-2014, 04:17 PM
Hi Jazz, thanks for the reply. Do you think I could build a machine capable of cutting very fine details around 0.1-0.2mm widths in 1mm plastic sheets ? Is cutting multiple sheets at once possible ?
I'm just North of the centre of Leeds but my workshops over in Bradford.

JAZZCNC
23-09-2014, 04:59 PM
Hi Jazz, thanks for the reply. Do you think I could build a machine capable of cutting very fine details around 0.1-0.2mm widths in 1mm plastic sheets ? Is cutting multiple sheets at once possible ?
I'm just North of the centre of Leeds but my workshops over in Bradford.

Yes to both but positional accurecy mostly comes down to 2 things.? Type of Linear components used and quality of build. If either one are wrong or bad then accurecy suffers. Ballscrews and Profiled linear rails are definate must for higher accurecy.

Cutting multiple sheets is easy enough just a matter of having enough real estate and setting up fixturing or coding to suit.
Setting up fixtures and coding for multiple sheets, known as offsets, is not difficult but it's slightly above entry level G-code so you will probably need some hand holding or do some head scratching for a while until penny drops but easily do-able within short period of time even for someone compleltely new to CNC.

To be honest yours and often most peoples biggest challenges are not working the machine or producing G-code but rather WORK HOLDING and fixing. This becomes even harder with very thin or narrow material and this will by far be your biggest challenge to get on top of with really thin material and engraving.

Fine Engraving needs more than just component accurecy it needs very good level of build quality and high attention to detail.
Also correct selection of materials it will be built from. The stiffness of the machine will need to be high and the bed surface to high precision for engraving fine detail so material selection is very important and areas like the bed and Z axis etc will need machine ground tooling plate not just standard aluminium or steel plates.

When you start upping the accurecy Spec then you really do start taking things to higher price level build wise so with a budget of 2K you can't expect really high accurecy but still 0.1 - 0.2mm isn't a problem.! 0.01 or better at this size machine then you better get your wallet fattened up. . .lol

JAZZCNC
23-09-2014, 05:06 PM
Hi Jazz, thanks for the reply. Do you think I could build a machine capable of cutting very fine details around 0.1-0.2mm widths in 1mm plastic sheets ?

Hold on just realised you said widths and not meaning resolution.? . . . . In what way do you mean widths.? Can you give an example of the type thing your trying to achieve.!

greenz123
23-09-2014, 05:37 PM
Yes by widths I mean Id like to be able to cut very small details, some as small as 0.1mm.
Im not even sure a 0.1mm bit would do anything other than drill 0.1mm holes though ? I imagine the bit wouldnt have the strength to travel through any material laterally ? The design I have in mind has thousands of holes ranging in size from 3mm to 0.1mm. Is this feasible ? Am I expecting too much ? As I said Id like to be able to drill/cut multiple sheets at a time too.

JAZZCNC
23-09-2014, 05:50 PM
Thats just tooling accurecy not positional accurecy. Cutting with 0.1mm tool is easily done with correct tooling and feeds etc.! . . . . . What resolution would you like to work to IE: Smallest movable amount.?

0.1mm is not considered high positional accurecy for CNC work so if your talking this is highest positional resolution you'd like to work with then yes can be achieved and not too much to ask for DIY.