Messages

31

General Mach Discussion / Re: Strange X axis distance travel at higher Feedrate % ; (

« on: December 16, 2014, 08:01:10 AM »

Problem solved!
Thanks Ger, I increased the acceleration values, from 200 to 600, in Motor Tuning, and it now runs fast as hell ; - )
Above 9000mm/minute, design faults manisfest themselves: a not very rigid Z axis, flexes with such brusque movements of the Y axis, causing sloppy milling detail. But that will be another chapter in this build.
Many thanks for being there,
Regards,
Frank.
Attached a photo of a Buddha head milled using MACH3 in conjuntion with DESKPROTO for gcodes.

32

General Mach Discussion / Re: Strange X axis distance travel at higher Feedrate % ; (

« on: December 15, 2014, 12:29:51 PM »

Hi Ger,

when you say Turn off all CV options, on the Settings Page, what CV options are there? Please see pdf "Settings Page"  attached.

As far as a possible drivers or mechanical problem, that was November 22, I´ve since tweaked them , and to test to see if they´re ok, I´ve loaded a short routine (see attached "Test File") at 12000mm/min feedrate, it does it perfectly, and Homes back on Material Zero perfectly (No steps lost, right?) . If I change the G61 to G64 (Exact Stop off, Constant Velocity On, yeah?) it cuts the pocket way short of the 600mm indicated, about 580mm.

I am about to try your suggestion of all CV settings off in General Config, with CV mode on. Will not exceed 100%, that value I am not changing since you advised.
Thanks,
Frank

33

General Mach Discussion / Re: Strange X axis distance travel at higher Feedrate % ; (

« on: December 15, 2014, 11:04:53 AM »

Hi Ger,
Tried that, (turned off Tool Display in Diagnostics) but no noticeable improvement.
It seems I´m up against using either Constant Velocity mode for  fast but very inaccurate 3D milling at 9000mm, a speed which polystyrene foam allows, or Exact Stop mode for fast straight-line milling (very little of this in  in 3D milling), followed by painfully slow reliefs.
Having built a machine capable of these speeds, its now extremely frustrating to think I wont be able to use it at these speeds with MACH..; (
Are there other Mach configs..…..kernel speed, “CV Dist tolerance”, “Stop CV on angles”, “G100 adaptative NurbsCV”.... or even pc processor speed or RAM,  that influence such speeds?
My pc is Windows XP, 2.8GHz processor, with 2.0GB RAM.
Would MACH 4 be a solution?
Thanks again,
Frank.

34

General Mach Discussion / Re: Strange X axis distance travel at higher Feedrate % ; (

« on: December 15, 2014, 08:27:48 AM »

Dear Ger,
I tried various approaches; not changing feed rate in percentage FRO window, or only lowering it below 100%, , and to no avail. I´ve since tweaked the Drivers, and it mills fine at 9000mm (and probably quicker) but only in straight lines.
When I load an stl file of, for example,  a human face, then it suddenly slows as if the calcs for a "3D" object were too complex to do quickly. Mysterious....
I´m currently doing tests, and hope to publish another post with additional data to see if anyone can throw some more light on the subject.
Many thanks for your input!

Frank.

35

General Mach Discussion / Re: Strange X axis distance travel at higher Feedrate % ; (

« on: November 22, 2014, 09:36:37 AM »

Many thanks Gerry, I will try that straight away!
Frank.

36

General Mach Discussion / Strange X axis distance travel at higher Feedrate % ; (

« on: November 22, 2014, 06:03:26 AM »

Hi!
I´ve come onto a problem that  as a relative beginner has me baffled ; (.
I´m milling polistrirene foam, quite quickly, on a home built machine thats X axis is 13 feet long,  Y axis 2 feet 4 inches and  Z 35 inches. (4000mm x 2000mm x 900mm aprox).
I´m using Easy Steppers, by Leadshine, NEMA 34, ES_MH33480, which give 8Nm,with encoders,  driven by ES DH 2306 Hybrid Servo Drivers.An economical alternative to servos.
I tend to give feed rates of 12000mm per minute in DESKPROTO, the software that generates the g codes. I then vary the feed rate in the MACH3 screen, depending on the area being milled, often way above 100%.
I´ve discovered that if  I speed up above a certain rate, much lower than the machine is capable of delivering, the distance travelled in both X and Y axis is not accurate ; (. But the machine does not loose steps nor position (due to the encoders) as I can G0 X0 Y0 Z0 and it goes back perfectly to the work piece zero point.
If I then decrease % speed, again on the MACH screen, it reverts to correct travel, and milles the piece with the desired form.
 I´ve yet to try changing to another computer, it has XP installed.
If I manually instruct for example, G0 x 2000mm, it goes perfectly there, even though the speed percentage is quite high. G 0 X 0 and it come back perfectly.
Anyone any ideas?
I made a short video, I´ll try and post it.
Thanks in advance,
Frank.
www.franknorton.com
PS This is a second attenpt to upload this Post, hope I´m not repeating it; )

37

General Mach Discussion / Re: Position and direction problems on all axis only with Slow Jog Percentage

« on: January 05, 2014, 01:50:54 PM »

Hi Tweakie, hi Ger,
I tried the Sherline 1/2 pulse mode, no improvement, but it was worth a try ; )

Ger, your telling me that alu could be milled at much higher speeds than I was trying ( probaby out of beginners fear of wrecking the tool...single flute, btw, as you suggested, and at 30.000 revs) prompted me to try faster.

So I´ve just done a cut perfectly at F= 150, in CAMBAM, 0.20mm/pass, spiral entry at .5º to help the tool do its job,  with no apparent chatter and all axis on spot. I will later try at double that speed, and increase to .3mm per pass, until I find the machines "limits", which I´m sure are not far off, lack of rigidity being one sure obstacle, plus small steppers (Chinese, only visible reference on the invoice from a local importer who gives a good garantee is "23HS8425") with probably very low torque for any serious milling in metal.
Drivers also Chinese.

Ger, when you say resonance, do you mean mechanical or electrical/electronic? Any ideas about resolving it if that were so?

On principal, I can easily get round the problem with adequate feed rates. Still, it would close the circle perfectly if anyone could point the finger in the right direction as to why this happens.  How the problem stiil effects things is in not being able to set the Z axis to zero on the surface of the material, as my method up to this has been the use of a multi-meter on resistance scale, connected to both tool and aluminum plate. I jog down the Z axis with Slow Jog Percentage at 1%, and for really fine tuning at .1%, until the meter reads contact.* But as things are, the Z axis only goes in one direction, down ,  at that percentage rate, no matter what direction key I touch. Baffling!

Many thanks to both of you for such prompt answer and useful feed back. This forum is wonderful...

Frank.

PS: Hope both of you get to read my reply, still not too clear on how to answer individually : (


*Still havent had time to configure auto tool zero in MACH...it´ll come! On that subject, Ger, I´ve seen references on other sites e.g. http://www.mycncuk.com/forums/project-showcase/4670-tool-height-setting-probe-mach3-solution.html to something (a screen??) you´ve done that eases the whole configuration / settup of  tool zeroing, I´ve save the link for when I eventually get round to it.

 

 

38

General Mach Discussion / Position and direction problems on all axis only with Slow Jog Percentage

« on: January 05, 2014, 07:36:34 AM »

Hi all! This is my first time on the Forum, hope to be able to concisely explain my problem and not waste people´s time. I´ve checked the Forum for similar problems but cant find anything.
I´ve been 3D milling polistirene for 2 months at “normal” feed-rate perfectly, (“normal” for my home-built cnc machine being 1875mm/minute) using g-codes from MESHCAM and recently DESKPROTO, and want now to use CAMBAM to mill aluminium NEMA plates  for a bigger, stronger router, and as my home built router is not very strong, So I´ll need to use quite slow feed rates, which is fine by me.
So, to the point:
If I set the Slow Jog Percentage DRO to 3% or lower, and manually jog  in a +X direction, all works well…the tool moves  at the same rate/distance as the DRO.
However, if I jog in a –X direction, the tool does not keep up with the DRO…if the DRO says 20mm of movement, the tool has only moved about a third of that.
In the Y axis, again at 3% or lower in Slow Jog Percentage, whatever direction I jog, the tool moves the in same direction, always – .
 If I jog in a –Y direction, the tool and DRO are equal. If I jog in a +Y direction, the tool as well as going in the wrong direction, only goes about half the distance the DRO reads.
In Z, similar to X…..in  – direction (down) the DRO and actual distance travelled is the same…in + direction (upward) it loses position.
Its as if the motors at these low speeds don’t have the torque necessary, to do the job, as well as having direction problems.
Attached is xml file.
I´ve tried changing kernel speed , and also step and direction pulse width in the motor setting, all to no avail.
My PC has XP sp3, 1.67Ghz and 2.25GB Ram., and a www.cnc-robotica.com USB interface.
My MACH is licensed,  and is Version R3.043.022.
Many thanks in advance,
Frank