Having trouble with machine cutting

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Rosemary
Posts: 8
Joined: Tue May 08, 2012 2:57 pm

Having trouble with machine cutting

Post by Rosemary »

Lately my machine is cutting the wrong depth. I have checked the bit and it is tight. I can run one .tap file and when the bit goes back to 0,0 it is way off. It says it's Z is 1.0 when it actually is .5 or less. Needless to say it was cutting deep gouges before I figured it out. I reset 0,0 and load another file. Now when it runs a .tap file half of it is the correct depth and then it cuts deeper on another part of the same .tap file. The bit is tight and not moving & the board is uniform thickness.

What is wrong?

Rosemary

jeb2cav
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Re: Having trouble with machine cutting

Post by jeb2cav »

Hi Rosemary,

Because you say 'lately', I'm assuming that the performance and outcome prior to this was fine and you've successfully carved some projects. You've checked the bit, are you sure the router isn't 'sinking down' during the job?

The first thing I'd check is the lead screw coupler - connects the motor axis to the lead (spiral) screw that moves the gantry up and down. There is a flat spot on both the motor axis and the lead screw where the 2 setscrews on the coupler should be in contact with. The screws need to be tight and you can use a dab of wood glue to minimize the opportunity for them to back out. It is more than possible that one of these is a 'little' loose, and that is why some of the project depth is fine and other parts are not.

Several folks have replaced the set screw with a short cap screw. You can certainly apply more torque when tightening a cap screw.

There are other possibilities - but it would be good to check this first. I'm sure other members may have some ideas as well. What model Shark are you using?

Rosemary
Posts: 8
Joined: Tue May 08, 2012 2:57 pm

Re: Having trouble with machine cutting

Post by Rosemary »

I'm using the CNC Shark. (smallest unit). No loose screws. Everything is tight. I talked to someone else and they said to reload the software. It's not the machine itself but a software problem. The only axis problem I'm having is the Z axis. It is off by more than 1/2" at times.

I just don't want to mess the entire thing up if it's software and I reload and something doesn't load.

Just wondering if anyone else ran into this and discovered what it was before I try all this hit and miss repair technique.

Rosemary

jeb2cav
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Re: Having trouble with machine cutting

Post by jeb2cav »

Ok - so another thing that I have seen result in this is that the SD card is not well seated in the control box. You may want to pull it out and then put it 'back in' - ensuring it is seated. We'll see if other Shark owners have some ideas.

If you've had your machine for a while, you may also want to check the electrical connections, particularly along the z axis. There may be a loose connection that is causing this intermittent failure.

I'm not sure that loading the Control Panel software will change any of this.

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Bob
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Joined: Sun Aug 08, 2010 3:35 pm

Re: Having trouble with machine cutting

Post by Bob »

Rosemary,
What is the thickness of the material you're trying to cut?
Is it thicker than what you have been doing?
What is the safe Z setting?
I have seen a similar problem when trying to cut a 2" thick board while the safe Z was set to 2" to clear clamps. The carriage would hit the top of the gantry during machining, causing a change in the Z setting. This would make changes in the depth of cut.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

Rosemary
Posts: 8
Joined: Tue May 08, 2012 2:57 pm

Re: Having trouble with machine cutting

Post by Rosemary »

Where would I find the safe Z setting? As you can see, I'm still learning the machine.

Rosemary

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Bob
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Re: Having trouble with machine cutting

Post by Bob »

Material setup is in the toolpaths menu (on the right side of the VCarve screen). In my older version of VCarve, It's in the upper left selection of tool path icons called material setup.Check to see what the clearance (Z1) setting is. Also, you should check to see what the home position is. If the combination of home,clearance, and your material thickness seems kind of high, you could be bumping up into the gantry and losing z settings.
Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

Rosemary
Posts: 8
Joined: Tue May 08, 2012 2:57 pm

Re: Having trouble with machine cutting

Post by Rosemary »

My material thickness is usually 1" or less than that. I haven't had a problem with this before. I am not using thicker wood than normal. I will check the settings.

When I started to have issues was when I set the 0,0. I joged the bit to where I wanted it and I accidentaly hit SET and not the XYZ0. Does this make any difference? I've always used the XYZ0 button before this. My program has [Set] [XYZ0] [X0] [Y0] [Z0]

Thanks
Rosemary

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Bob
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Re: Having trouble with machine cutting

Post by Bob »

Rosemary,
I've played a little with the "set" command, but not enough to feel comfortable with giving advice about it. The "set" command may be connected to your problem, I just can't answer.

I am curious, however, to see what the safe z and home settings are. So far it sounds like material thickness is not a problem.
Also, another thought...Are you using the same bit as before when you were not having trouble? Or, are you using a longer bit now? A longer bit would also cause the carriage to lift higher and possibly hit the gantry.


I always look for simple mechanical problems first, then the more "technical" problems later.

Bob
"Focus"
Antonie Van Leeuwenhoek (Developer of the microscope.)

Eagle55
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Re: Having trouble with machine cutting

Post by Eagle55 »

I'm not sure I have anything productive to contribute to your solution just yet, but check and make sure that when you press "set" that all the values are zero then say ok. I am pretty sure that's NOT your problem but it could give you fits understanding what its doing if you have something other than zero values in the Set screen. My guess is that they are still zero as they were. The Set feature has some good use and I am beginning to understand it but not worth diverting the attention away from the problem at hand. Just make sure they are zero for now.

Roger

PS Does V-Carve show the project cutting appropriately in the 3d preview of your tool paths? That kind of narrows it down to the machine and seems like I have seen something like this related to the seating of the SD card as has been mentioned. If or when you pull out the SD card, take a pencil erasure and rub it on the contacts of the card. Sometimes in dusty and harsh environments (as this could be considered) there can be some very light corrosion or dust inhibiting the connection to the contact points. Usually removing and re-inserting would wipe the contact clean but its good to have the whole area clean at some point, not just under the wiping contact.
CNC Shark HD ~ Control Panel 2.0 ~ Windows 7 & XP
Located in West Tennessee near the Tennessee River
http://www.eaglecarver4.com

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