Rough cut on rounding gadget

Topics related to wrapped rotary machining in Aspire or VCarve Pro
Post Reply
hmatyas
Vectric Apprentice
Posts: 96
Joined: Sun Sep 06, 2015 2:49 am
Model of CNC Machine: Shark HD3

Rough cut on rounding gadget

Post by hmatyas »

I used a 1/4 inch End Mill (got a rough cut), then a 1/4 inch ball nose while using the rounding gadget. With the 1/4 inch end mill with a 40% stepover I expected a rough cut. With the 1/4 inch ball nose I used a 25% stepover. (I expected a smoother cut).
So is the stepover the problem or could it be something else?

(I also created a straight line, but I posted that in the gadget's section, that is why there is a pencil mark on the wood).

Thanks in advance.
Harvey
DSCN2871.JPG

User avatar
adze_cnc
Vectric Wizard
Posts: 4303
Joined: Sat Jul 27, 2013 10:08 pm
Model of CNC Machine: AXYZ 4008
Location: Vancouver, BC, Canada

Re: Rough cut on rounding gadget

Post by adze_cnc »

1/4 inch ball-end cutter with a 1/16 inch inch stepover:
 
stepover.png
 
Looks a fair match to the wood piece.

hmatyas
Vectric Apprentice
Posts: 96
Joined: Sun Sep 06, 2015 2:49 am
Model of CNC Machine: Shark HD3

Re: Rough cut on rounding gadget

Post by hmatyas »

Thank you, I'll give it a try tomorrow.

hmatyas
Vectric Apprentice
Posts: 96
Joined: Sun Sep 06, 2015 2:49 am
Model of CNC Machine: Shark HD3

Re: Rough cut on rounding gadget

Post by hmatyas »

That is what I had 1/16 inch or .0625 or 25%. I'll reduce it to .05 or 20% tomorrow.

User avatar
SteveNelson46
Vectric Wizard
Posts: 2275
Joined: Wed Jan 04, 2012 2:43 pm
Model of CNC Machine: Camaster Stinger 1
Location: Tucson, Az.

Re: Rough cut on rounding gadget

Post by SteveNelson46 »

I very seldom use the rounding gadgets. This was done with the spiral wrap gadget. It will round a 18" long 4.25" square to 3" diameter round with a 1/4" end mill, 30% stepover (.075") and .125" pass depth leaving 2" on each end.
Attachments
Round 4.25 to 3.png
Round 4.25 square to 3 in.crv
(172.5 KiB) Downloaded 47 times
Spiral rounding setup.png
Steve

User avatar
jimandi5000
Vectric Wizard
Posts: 1046
Joined: Wed Mar 11, 2015 6:50 pm
Model of CNC Machine: Home Made 60 x 120
Location: North Houston Tx.
Contact:

Re: Rough cut on rounding gadget

Post by jimandi5000 »

Hi Harvey,

After looking at your pictures and further contemplation, and assuming you're using a flat end mill. I believe it is your stepper count for your A axis.

Try this. Place a square or round stock of material (as large as you can accommodate in the fourth axis) in your fourth axis. Place mark on material and a pointer that is mounted to your table (something that will move). Enter this Gcode in your controller G01 A3600 F100 . This will result in the stock turning 10 times around which will multiply any error you have by 10 times now check your pointer to the mark you made and determine how accurate your a axis is operating. If you see a significant difference you need to adjust the number of steps for your A axis.

I hope this helps.
Thanks,
Jim

hmatyas
Vectric Apprentice
Posts: 96
Joined: Sun Sep 06, 2015 2:49 am
Model of CNC Machine: Shark HD3

Re: Rough cut on rounding gadget

Post by hmatyas »

Steve

I downloaded your file. I you look at the simulation and rotate the piece of wood, there will be a straight line
going down your project. It's not a big deal as it can be sanded out. I was just wondering if there is a way to avoid it if possible.

hmatyas
Vectric Apprentice
Posts: 96
Joined: Sun Sep 06, 2015 2:49 am
Model of CNC Machine: Shark HD3

Re: Rough cut on rounding gadget

Post by hmatyas »

Attached is a screen shot of the line.
Attachments
Line.jpg

User avatar
SteveNelson46
Vectric Wizard
Posts: 2275
Joined: Wed Jan 04, 2012 2:43 pm
Model of CNC Machine: Camaster Stinger 1
Location: Tucson, Az.

Re: Rough cut on rounding gadget

Post by SteveNelson46 »

It isn't possible to have a vertical "seam line" with a continuous spiral cut. I'm not sure why it shows up in the preview. Notice the line shows up even on the uncut sections. If you zoom in close the line disappears.
Steve

User avatar
adze_cnc
Vectric Wizard
Posts: 4303
Joined: Sat Jul 27, 2013 10:08 pm
Model of CNC Machine: AXYZ 4008
Location: Vancouver, BC, Canada

Re: Rough cut on rounding gadget

Post by adze_cnc »

I think what you are seeing is an artefact of the software trying to wrap a flat representation into a cylindrical one. The "line" is the seam where the material texture wraps around. It's readily apparent if you change the material to a horizontal grained one such as this bamboo:
 
seam.jpg
 
The real proof is to turn on the toolpath preview and see if there is any dip in the toolpath:
toolpath.jpg
 
In this case there is none.

Post Reply