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Author Topic: circular interpolation not showing on arc cutting surface  (Read 3078 times)

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circular interpolation not showing on arc cutting surface
« on: April 25, 2011, 05:36:26 AM »
hello any body can help me to get a fine cutting surface for a milling operation of an arc/ circle shape.now the round surface are showing some steps after milling. Does the speed ,acceleration are playing the role regarding this matter or any thing else? does the circular interpolation is missing in mach3 ?
« Last Edit: April 25, 2011, 05:51:52 AM by bjhmc »

Offline Tweakie.CNC

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Re: circular interpolation not showing on arc cutting surface
« Reply #1 on: April 25, 2011, 08:17:00 AM »
Not sure I fully understand but most CAD software draws circles as a number of straight lines, the lower the resolution the less the number of lines and worse the appearance. On the other hand, CAD/CAM that uses circular interpolation produces smooth contours without any of these visible straight lines.

Which CAD/CAM are you using to create your toolpaths and does it allow circular interpolation ?

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: circular interpolation not showing on arc cutting surface
« Reply #2 on: April 26, 2011, 03:44:14 AM »
for this particular case i used an autocad dxf file and generated toolpaths using lazycam,can i change resolution in lazy cam?or any other cam software will give fine result?are u sure that the mach3 can do nothing regarding this?

Offline Tweakie.CNC

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Re: circular interpolation not showing on arc cutting surface
« Reply #3 on: April 26, 2011, 04:23:13 AM »
As far as I am aware Mach will only produce the GCode it is given.
Autocad or other CAD/CAM is the place to improve your resolution as LazyCam has extremely limited capabilities.
If you draw your work and export as, for example, .jpg format then using other programs such as Vector Magic which are capable of generating extremely high quality .dxf files may be an option but there are many many alternatives to this and everyone has their own preferences.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: circular interpolation not showing on arc cutting surface
« Reply #4 on: April 28, 2011, 06:14:27 AM »
any way i forgot to say thanks for your reply, so thanks for the replies.
 let me to bring this matter to a small area. may i know that a simple G-code for a circle /Arc using g2 or g3  with a medium feed rate  will give a fine cutting surface.consider that all the other supporting g-codes are also  included. at this condition what may be the reason for a "stepped surface" after the arc/circle milling?
Re: circular interpolation not showing on arc cutting surface
« Reply #5 on: April 28, 2011, 06:43:28 AM »
Dear Mr.Tweakie , can u give that spindle motor's(black colour)full  specifications shown on your website in a CNC machine? from where shall  i get that?

Offline Tweakie.CNC

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Re: circular interpolation not showing on arc cutting surface
« Reply #6 on: April 28, 2011, 06:56:36 AM »
Sorry but I have never seen another one of these.

(It is 240 volt 3 phase, has internal shaft brushes to connect rotor to frame (perhaps ceramic bearings) used to have a magnetic shaft brake on the top where I have now fitted a cooling fan and had a high ratio planetary gearbox on the front. It is German made and came from a large format printer transport mechanism - it was perhaps used as a servo motor ?).

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline ger21

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Re: circular interpolation not showing on arc cutting surface
« Reply #7 on: April 28, 2011, 05:51:45 PM »
Quote
Not sure I fully understand but most CAD software draws circles as a number of straight lines, the lower the resolution the less the number of lines and worse the appearance.

I'd say exactly the opposite. Most CAD software draws circles as circles or arcs, and NOT straight lines. Autocad definitely does.

As for your stepped circles, lots of things could cause that. How is your machine driven?
Gerry

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Re: circular interpolation not showing on arc cutting surface
« Reply #8 on: April 28, 2011, 10:00:25 PM »
most of the cad programs make circles with as little as 14 segments per quadrent or maybe even per diameter as default. usually a right click on the entity and hit properties and in a "surface" or "solid" tab you can change this to as much as 90. 45 gives me good circles and less code, but only bigger then an inch,

Offline BR549

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Re: circular interpolation not showing on arc cutting surface
« Reply #9 on: April 28, 2011, 10:16:58 PM »
I am with Gerry Most cads make circles as arcs.  I have used most major players in the cad arena. Only the converted art drawing program seems to do the line method.

(;-) TP