Hello My CNC design could do with some help and advice

[caterry10]

Hello my name is Chris, I am new to all this and would like to build my own CNC machine. I have a design for my CNC machine that I have made in Autodesk maya and was wondering if it is a good design and if need be how could I improve my design any advice would be really apprciated.

PS: It is 800mm Wide x 1400mm long

Well here's my design











Thanks for looking ,
Chris

[mefiu]

How is the table supported?

[caterry10]

^_^ ah YE . . . . . . little design floor thanks for spotting that out will redraw now :P

[mefiu]

Next ones:
What is the steppers power?
What is the construction material?
What is this machine design to?

We all need more data to estimate your design...

[caterry10]

Here it is ^_^ it will be place on the outside (front and back) box but its only supported at 2 points and not too sure if it is sufficient :S

[mefiu]

not too sure if it is sufficient

Yes, it's sufficient.
As long as the table is made of a kavlar or titanium...
Need more data.

[caterry10]

What is the steppers power?

1150 OzIn 8-Wire Stepper Motor
Click to enlarge1150 Oz In. Hybrid
1.8° /200 Steps Per Rev.
8 Amps Current Per Phase (Bi-polar)
8-wire Uni-polar or Bi-polar
NEMA 34 Frame
Single Shaft

What is the construction material?
outer body: laminaded MDF

Working mechanisms: metal

What is this machine design to?
PC modding, flight sim pannels, engraving ect

thanks

[mefiu]

outer body: laminaded MDF
Working mechanisms: metal

These are generally the same design assumptions I made for my mill (300x250mm).
I used 22mm MDF, hardened metal rails (20mm, unsupported) and aluminium bearings boxes.
Be warned that MDF could (and probably would) not handle the forces a mill can generate while working.
See these pictures:
http://www.cnc.info.pl/pics/52a836ded37f.jpg
http://www.cnc.info.pl/pics/62c2eea48c45.jpg
Yellow and red arrows point the spots that will split if too much force is put to the MDF.
Green arrows - places that will work OK.
I also believe that a back plate of your frame is too small, giving not enough stability to the frame.
Generally, all 90-degree frame connections should be as stiff as it is achievable.

The table of this length should be supported.

The down of the bit mounted in the spindle in its lower position should be approximately max. 10-15 mm above the table.
Estimating your design proportions, the end of the bit is way too high above the table.

flight sim pannels

Now that's what I do!
See my first B737 cut & engraved COMM radio panel at the end of this thread.

[caterry10]

wow your radio is very impressive I undestand all the points you have made and will do a re-design and post it up, how big is your CNC machine ? and is it possable so see some pics?

many thanx
Chris

[hemsworthlad]

What is the steppers power?

1150 OzIn 8-Wire Stepper Motor
Click to enlarge1150 Oz In. Hybrid
1.8° /200 Steps Per Rev.
8 Amps Current Per Phase (Bi-polar)
8-wire Uni-polar or Bi-polar
NEMA 34 Frame
Single Shaft

What is the construction material?
outer body: laminaded MDF

Working mechanisms: metal

What is this machine design to?
PC modding, flight sim pannels, engraving ect

thanks

Hi Chris,

You dont state how you intend to drive the axis IE: Ballcsrews etc but unless your gantry is very heavy (which it doesn't look) then you dont need those big motors and infact they will be more an indurence than a bennifit. Large motors spin some what slower than smaller nema sizes like 23's plus they require larger power supplies and more expensive larger Amp drives.
3Nm nema 23's will more than be enough for this size machine even if you use a poor drive mechanism and will be lots cheaper.

It's not easy to tell from these renders but the rails look unsupported which is not a good idea.
The gantry has some weak area's that will cause problems if not beefed up. First the uprights need some kind of bracing with the bottom cross brace, maybe some kind of triangle brackets to help keep it square.
The top cross brace looks a little flimsy and could bend. I would consider bracing these with thinner strips bolted to them., this will make them much stronger but without adding very much weight with the added bennifit that you can also tie them into the gantry uprights increasing resistance to twist affects and generally making the gantry much stiffer.

Give some more info on what you intend to use component wise IE: rail type, drive type(ballscrew etc) frame materials.