3D carving comes out jagged, not smooth

[jshinn]

I have a Techno Isel with stepper motors. Use bobcad for coding.
When cutting a carved top for a guitar it comes out jagged. I have seen other machine move in "continuos" motion. Between x/z or y/z movements
there are puases and jerks a little.
Any thoughts?
I am assuming it is in the coding/toolpath generation. I was thinking that the post for my machine could be also the problem...?

I usually have to do a lot of sanding.

I could try put a small video perhaps on u tube if anyine has any thoughts.

[Cartierusm]

I kind of have the same problem. I've only started doing 3d stuff and noticed the machine is kind of jerky when doing the carving. I figured it's the programming because the surface does not show signs of hesitation marks...hmmm hesitation marks, I think I watch too much CSI...anywho...and comes out fairly smooth, I say fairly because i know I could program much cleaner cuts but don't want to. I noticed today when cutting an angled neck pocket that it was jerky but also realized that my z axis was tuned to 40 ipm and the Y was 60, so I figure it's a timing issue. It looks jerky because one axis is stalling waiting for the other axis to catch up. But I'm no expert so I could be totally wrong.

[ger21]

Does your machine have a Constant Velocity mode?

[cuemaker1]

I also use Techno Isel and have Servos. Several things affect the jerking. I don't know if steppers are the same tho. I have a constant mode that I can use to cut. Depends on what interface you use. I'm using an old dos and Gcode with .ncd.... good luck.

I am looking for a servo amp card for techno if anyone has one. They want $450 at techno. I want to put my 4th axis in....

[Khalid]

Check following:
1-Use ballnose mill for finishing pass...
2- Reduce the step over of finish pass to 10%
3-Check your original model resoulution. The higher the resoulotion of model the great detail you will get
4-If using Mach3, then always try to do on CV mode on...

[Cartierusm]

I'm sure we all want to know and I'll try to look it up but in case I can't find any info -- What is Constant Velocity mode, how do you turn it on, how does it affect the system from normal? Thanks.

[Khalid]

In Mach3 go to CONFIG--> STATE--> here u will find Constant Velocity Mode & exact stop mode. Click Constant Velocity mode.

[Cartierusm]

Thanks, I read a small section in Mach 3 manual and it doesn't tell what it does. I know, I know, it makes the machine run smoother, constant...but why would someone choose exact stop over constant, are there physical machine parameters that I should take into account? Should I keep CV on all the time?

I know a lot of questions..but one more, are there any other "special" settings in Mach3 that use noobs to CNC should know about? Thanks again.

[jshinn]

As far as I know I don't have constant velocity...I am using Techno's "G-code interface"
along with Bobcad to make my drawings and toolpath. The "interface" can read different machine codes...fanuc ect.
If I increase the reolution it just cuts the arcs into smaller segments...thus increasing the pauses and jerks when actully cutting the piece.

Is this just something inherent with stepper motors or is it with the controller?
If I change the controller would it run smooth/continuos motion?
If so any recomendations for a controller?

If I can get a smoother motion from steppers I will keek them.
When I talked to Techno they said to upgrade to servo...$4000.00. Right now don't have that kind of $ to upgrade. Besides, the code will be the same and who knows if it will hesitate/jerk between moves...only faster and of couse more accuratley.

[Khalid]

if ur controller can run G02 and G03 commands then u will also get smooth cut

[Cartierusm]

I already had CV turned on but some of my router's movements are jerky when doing 3D but still seems like the cuts come out smooth. The CV settings have some numbers:

Plasma Mode is Unchecked
CV Dist Tolerance 180 Units
G100 Adaptive NurbsCV is Checked
Stop CV on angles is Unchecked

Should I be doing something else or do I already have is set correctly. Thanks.

[Khalid]

see the screen and uncheck all CV mode features here ..
Put the G64 at the top of your Gcode file...