Cutting depth problems

[REG]

I really do appreciate all the responses and welcome any other thoughts about what could be causing this problem.
Larry

If it is software you would see the difference in the G-code. Make several toolpaths in various areas of your project area. Save it and load the G-code and see if there are any inconsistancies.
I can understand your frustration and sorry I haven't been much help. As I stated, I'm learning too.

Bobby

[jeb2cav]

Thanks Loren for those great tips.

Larry - for what it's worth, I've only found ~1/32 to 1/8 of an inch variance in z on the t-track table on my setup "out of the box". From your last post, specifically that the same project file will result in a different outcome between runs/jobs, I'd lean toward something loose or out of adjustment mechanically. I've recently seen some posts from other ProPlus users that seem to indicate several possible defects.

You're clearly setting z zero before you start the job, yet your first cut is .25" off. If you set z zero, jog the machine some, and then move to 0,0,0, is the z where you set it? Consistently? If not, I'd say mechanical, call Rockler, and let us know what they told you on how to fix it. I haven't experienced this one myself, so no good ideas. But it doesn't sound like a software issue. Certainly from comments here and ewhere, the Mach 3D would give finer resolution. Possibly there's a bug in the controller box, but I'd look to mechanical.

Sorry I missed the nature of the defect - ie significant z difference in a short run.

[Dwayne125]

Happy Hollidays

Larry

Im new to CNC and the Shark, but just a thought. Have you checked for a loose pin on the Z axis connectors, or perhaps a different USB cable? Also does this only happen when pocket cutting? What happens if you did a 0.01 depth plaining of a small board?. Does It change with the thickness of a board? I wonder if it would change if the top surface was 3in off the table, compared to being only 1/4th in off the table. Please let us all know what you come up with, and good luck.

Dwayne

[cvguitars]

Joe,
To clarify, I'm not necessarily finding a different depth across the cut (the cutting distance is much too small to measure accurately). It is the overall depth of cut that is wrong, i.e., specify .2 and get .273.
I suppose I would lean towards something mechanical as well. The machine does "moan and groan" sometimes as it's cutting and moving. This may be normal. This is my first experience with CNC (I've had my machine for around 2 months), but I would say I've heard this moaning and groaning at times from the start. Also, something new has started to happen on the Z axis that would appear to be a serious problem. Let me try to explain. I discovered (duh) that I can set the FRO to 25%, then jog for slower movement and better accuracy setting Z zero. However, something that started happening (not all the time, but very often at a specific location) that when I am lowering the the cutter, I press Page Down, I hear the motor turn, but there is no movement. Do the same thing again, hear the motor but no movement. Then, on the third press of Page Down, it "snaps" down, which appears to be the distance it would have traveled on the three presses of Page Down. What the heck is THAT all about and where do I look to fix it?

[REG]

Joe,
However, something that started happening (not all the time, but very often at a specific location) that when I am lowering the the cutter, I press Page Down, I hear the motor turn, but there is no movement. Do the same thing again, hear the motor but no movement. Then, on the third press of Page Down, it "snaps" down, which appears to be the distance it would have traveled on the three presses of Page Down. What the heck is THAT all about and where do I look to fix it?

I never used page down or the directional arrow buttons on the keyboard in Basic Control Panel. I almost always use mouse and pointer. I am using a Dell laptop (Inspiron) and the touchpad and mouse operations work fairly well but I do sometimes use a USB mouse especially when I am working in V-Carve. Reason I bring up the computer, I know that there are a number of different mouse/touchpad devices on other brands that can certainly cause unexpected operations (I think HP and Levono are one of them). As for what actions or shortcuts might occur for keyboard operation - I would think Tim Owens would have to respond to that. As far as I know there are no keyboard shortcuts to Shark Basic Control Panel.

Bobby

[jeb2cav]

Good morning,

On the FRO at 25% - I've been told by NextWave that using an FRO (feed rate override) value of less than 30% with the current controller software is bad. There apparently is a bug in the software for values 30% or less. I'm on the road right now, so can't duplicate what you describe at 25%, but I believe it.

I'm sure similar bugs exist when running a file when the FRO is set to 30 or less.

1. Does this condition occur (bad depth) when the FRO is set to 100?

2. You said you were seeing this with a pocket 1/2 inch away from your 0,0,0. Can you run a test with some small pockets at 2-4 inches away from 0,0,0?

3. Can you then repeat the cut with another scrap and do you at least get the same depths for the cuts (even if they don't match the depth you set in the toolpath in VCarve)?

You have installed the latest Basic Control software from Next Wave's website (11/26/10)?

In the toolpath the start depth is set to 0?

In the job setup -
a. The material thickness is correct?
b. The Z Zero is set to top of material?
c. The Data scaling boxes are cleared.
d. The units are set to inches.

In the tool database for the tool you're using - is the information correct and in inches for the tool you selected?

Did you install the latest CNC Shark Post Processor files from the Next Wave website?

When you save the toolpath, are you selecting CNCShark-USB Arcs (inch)(*.tap)?

I'm out of ideas at this point beyond a mechanical defect either in the Shark itself or the controller box.

[cvguitars]

Joe,
Thanks for the heads up on the FRO. I will keep it at >30%. I only use that for jogging, never while actually cutting.
I downloaded the new Basic Control software and ran my test cut again. Same result: .122 specified cut depth, .203 actual depth.
I then moved on to something else. I wanted to cut a pocketed hole in a piece of material .806" thick. Cut depth was set to .806", and, watching the Control software, lo and behold, it made the last pass at exactly 806 (this was the first time it occurred to me to watch the actual depth reported by the control software - duh). However, there was still a little material left, so I modified the toolpath to cut .807 (I have some clearance under the piece), got the warning about cutting beyond the depth of the material, saved the new toolpath, shut off the controller and exited the control software (I read somewhere it was a good idea to do that when reloading a .tap file of the same name). Started everything up again (XYZ zero already set) and started the cut. I watched it plunge on the last pass to .848", at which depth it did cut very slightly into my Pro Grip clamp underneath. It was only supposed to go to .807, but decided to go to .848. Upon completion of the cut it went to the home Z position of .750, which is where it's supposed to home to. So, it obviously didn't miss a step or it wouldn't have gone back to the specified .750 at home, correct? It would seem to me that either the Gcode is bad, or the controller is not doing what the Gcode is telling it to do.
To answer your other questions:
1) bad depth occurs at FRO 100
2) pockets were run at various distances from 0,0,0. I mentioned that I did a "test" one inch from 0,0,0 to verify it wasn't an uneven surface issue
3) several cuts were made with the same bad depth results.

New control software installed today; toolpath start depth at 0; material thickness correct; Z zero top of material; no data scaling; units in inches; correct tool information; always use/save correct Shark-Inch PP.

Larry

[jeb2cav]

Hi Larry,

At this point I'm down to three ideas:

1. Exit both the Control Panel and VCarve. Go to the VCarve installation location (in my case: C:\Program Files\VCarve Pro V5.5\PostP) and delete the 2 shark files (inches and mm). Download a clean copy from the website. Copy them back to this folder. Write out the project again.

2. I didn't ask this (and really a long shot), but have you tried creating a new project and seeing if it all "works". If not, you could try that. Sometime the air is dirty... and the new one works magically.

3. Call Rockler support, get them to read through this, and solve your problem. Then post what solved it back here so we have a good reference for the future. At face value, if the g-code said go to .807 (and you could see this after loading the file), and the machine went to .847 (and reported that while running), there is a defect either in the controller or the z motor. But both are beyond my direct knowledge or experience (and that's what those folks get paid for).

Regret that earlier suggestions/ideas from forum members didn't work for you thus far.

[Dwayne125]

Joe,
To clarify, I'm not necessarily finding a different depth across the cut (the cutting distance is much too small to measure accurately). It is the overall depth of cut that is wrong, i.e., specify .2 and get .273.
I suppose I would lean towards something mechanical as well. The machine does "moan and groan" sometimes as it's cutting and moving. This may be normal. This is my first experience with CNC (I've had my machine for around 2 months), but I would say I've heard this moaning and groaning at times from the start. Also, something new has started to happen on the Z axis that would appear to be a serious problem. Let me try to explain. I discovered (duh) that I can set the FRO to 25%, then jog for slower movement and better accuracy setting Z zero. However, something that started happening (not all the time, but very often at a specific location) that when I am lowering the the cutter, I press Page Down, I hear the motor turn, but there is no movement. Do the same thing again, hear the motor but no movement. Then, on the third press of Page Down, it "snaps" down, which appears to be the distance it would have traveled on the three presses of Page Down. What the heck is THAT all about and where do I look to fix it?

Larry

The moaning and groaning is the normal sounds of the stepper motors. As you stated you run you shark above 30% FRO,so no problems with the bug.However while lowering the z axis, it getting stuck is not normal. What I recomend is trying some spray silicon or teflon. I have used liquid wrench (no oil but has teflon) on my powertool slides, however not sure if this would harm the backlash nuts,or any of the plastic. If that doesnt help with the z axis I would recomend the following. Set a flat bit to the table and zero out (z). Next jog the (z) and when it sticks a few times record the (z) reading. Do this test in a few diff x and y locations. If you get a constant reading, its most likely mechanicall. Since the stepper seems to be working, I would look at the ballscrew setup, backlash nut or slider rods and berrings. Let us know if this helps

Happy Hollidays to all
Dwayne

[rapiddawg]

How about getting a new Z stepper motor.