Simple Dome for the Domeless Person

[Kiwi]

Bill
I have V20.7 and this is how I have done the dome.
I'm open to better/faster ways to get the part drawn with BCC.
Draw three lines
X-1.6 Y0 to X1.6 Y0
X-1.6 Y0 to X-1.6 Y0.125
X1.6 Y0 to X1.6 Y0.125
Point, End of each line (upper end)
Arc through 3 Entities (the three points)
Change,Trim (all lines left of the centre line)
All Change Rotate (3D) X90
Pick 3 profile lines (not centre line - arrows must follow)
Solids/Surface/Revolve/360deg Pick Linea/OK/Pick Centre Line

[krymis]

bill could you post your g-code for just the dome. I am doing some of the same parts right now. I have the design and the file is all stepped but now i need to dome it like you were showing. Any advice on a walk through of how to do this would be great. I am using the updated ver21 of bobcad

[bill south]

Hey Krimis;
I generated this code but have not tried it yet. I looks OK on the screen but you know how that is. Maybe someone with experience can look at it and give us some pointers. Anyway, enjoy and have a good day.
Bill

[Kiwi]

Bill S
Ran your code with BCC simulator with ball nose cutters 0.25" and 0.5" and this is the result. Not sure what dia. cutter you had planned to use but this will alter the outside diameter.
I also see some blank lines N7284 and N7292. My controller would stop at these points.

[bill south]

Thanks Kiwi;
Again, I had not tried the code and this is most definately not the smooth surface I'm looking for. Guess I'd better start adding motors to my lathe!!!!
Thanks again.
Bill

[turmite]

Bill did you actually carve one of the domes? Many times the resolution on the simulators are not as good as the part itself. What kind of stepover did you use for the toolpath? What bit did you use? Now I don't think you will ever get a part like this as smooth on a mill as you can on a lathe, but you can get it better than the simulator photo shows.

Mike

[Kiwi]

Bill S
I see the tool does all the passes at the same step-over.
Suggest you do a finishing pass at a smaller step-over.

[erase42]

it would seem to me that you could get a better finish on this shaped part with a radial toolpath? doesnt the domed shape lend itself to that.

[Kiwi]

erase42
With a radial toolpath the cusp height will get greater towards the edge along the radial line.
With a spiral toolpath the cusp will be more consistant with a variation from the near flat in the centre to higher as the side gets steeper.
I think the spiral with a small stepover will give the better finish.

[tjones]

I typically do solids with sepperate paths for roughing and finishing.

Rough the entire form with a larger stepover and leave stock in solids by cheating a little.

I transform my part up in Z (.01"-.02") before posting the roughing cuts so it will not finish the depth. Also lie about the tool diameter to leave stock on the walls when generating.

Translate the part back to the finished Z position then generate the finish cut.


BTW: Did you know you can limit the inside by using double boundries?