Z access doesnt seem to move during cut

[gogogad]

Good afternoon,  This is my first time posting here so I apologize if i missed a rule.

I purchased my Carve King back in October of last year, managed to get it set up and working fairly well.  Since then I have managed to cut out a handful of things pretty successfully.  I will admit that there has been a decent learning curve and I may have miscalculated more then once and ran the machine up against the ends in one direction or another a few times.  Luckily that doesnt seem to have done any serious damage and have always been able to figure out my mistake and keep making things.

I recently noticed though that I have about .05" of travel in the z access from the front of the to the back of the machine.  IE i can measure 2" inches from bottom of router bit at the rear and 2.05" at the front (worth nothing those aren't accurate measurements, just used for reference purpose).  Not a big deal but i decided to create a new waste board to compensate for that.  I cut a peice of 3/4" MDF to slightly smaller then the overall cutting area for the machine, created a facing program that cut .1" deep and ran that.  That seemed to resolve my .05" difference from front to back.  Part of my goal with creating the new waterboard was to have a slightly different style of hold downs I can use.  My idea was to have holes drilled in it evenly distributed across the entire surface, then fill those holes with threaded inserts.  The inserts would be roughly .25" below the top of the board, so if I do miscalculate and cut a little too deep i would have that extra material before the bit hit the inserts.

Sadly thats where my problem begins.  I created my hole pattern using fusion360 (which is what I use for all my projects, including the face cut on the same wasteboard), used the 2d bore setup to create my cuttings.  I was going to use the drill setup, but I dont have a bit thats the right size and fits into the router.  So instead I am using .25" 2 flute that comes with the machine when you first get it (which thanks for that by the way!).  I then simulate it, everything looks basiclly right. I post process it and then have my Gcode.

My process for cutting goes:  Boot laptop, power cnc machine, connect the USB, launch Universal G code sender, load my gcode.  Then use the connect button in the Gcode Sender.  I then home the machine,  from there I set my zero to be the same spot as I designed into the Fusion 360 model.  Once thats done I hit run.  (most of the times i cross my fingers and hold the power cord for the cnc machine incase i did something dumb again)

This particular program starts out good,  machine raises the router to the highest point of z travel, moves over to the first cutting spot,  slowly lowers the machine back to the z zero i initialy set, then starts its spiraling decent to create the first hole.  It gets to what I think should be the bottom of the hole nicely.  But, instead of picking the router back up in the z access it proceeds to move in the x and y directions towards the 2nd hole, cutting nasty fat channel thru my waste board. 

I have attached the gcode for my holes that arent working and another one from a project I successfully cut.  I have recreate the gcode at least 3 times thinking something maybe went wrong in the post processing process.  I have also tried comparing the hole cutting gcode to a successful project and I cant figure out what I did wrong.  At least I hope its something I did wrong and not be finally breaking the machine.  I have also included my Fusion360 model (i think, i exported it).

I greatly appreciate any help anyone thinks they can provide.  If I left anything out to help me try and diagnose my mistake I will happily try to add it or explain it. 

james

Successful 1-8th knife cutout.nc (30.93 KB)Unsuccesful hole drilling.nc (294.18 KB)

Attachments:

facing waste board v5.f3d (477.12 KB)

[rowiac]

Is the endmill moving up at all between holes, just not enough? If so, you may not have your 1/4" endmill's z-height zeroed properly.

After your facing cut, how do you set the zero height for the 1/4" endmill? Your WCS origin is set at the top of the stock, so you would need to zero the endmill to that, but after you have faced off the surface, the surface to zero to is now gone. You should make sure that when the endmill is just touching the faced off surface, that UGS reads z as -0.1".

I only recently started learning the CAM part of Fusion 360, but I see that your toolpath does lift between holes, so that seems OK. An incorrect z-zero position for the second operation endmill is the only thing I can think of.

[gogogad]

The facing cut was a different cut. I create a separate gcode for each cut. Probably not the most efficient, but i barely know what I am doing, and that seems to keep me from screwing up too badly.

The z doesn't move at all between holes. Its basically moving in the x,y directions at the bottom of the hole, after it finishs getting to the bottom of the first hole.  When I get home I will take a picture of my waste board.  Maybe that will help explain what its doing.

[rowiac]

A separate gcode file for each cut is fine--that's pretty much what you have to do with UGS anyway, unless you aren't changing tools between cuts. I still think the problem might be your z-height for the endmill cut. Anyway, a picture will probably help.

[gogogad]

Picture as promised.  Ignore the holes with the screws in it.  Thats just the lazy way i mounted the waste board to the existing machine.

Attachment Deleted

[gogogad]

I guess i could understand it being a problem with setting the z wrong.  But if i was just off a bit, then i would expect it to dig a path by a little bit.  It digs the path from the very bottom of the cut. 

But I am sure its just something simple I am over looking.  I will take another stab at it.  I just don't like re-trying at this point,  it puts a nasty twist into the router mount every time it cuts at that depth.  I worry at some point it will put a permanent bend into the gantry or the router mount.

[ttabbal]

I checked your Fusion file and the gcode file in a simulator. It looks ok to me.

Where are you setting the machine (UGS) zero to? It looks like Fusion is set to the back right corner on the TOP of the stock.

How are you setting the Z zero?

Try setting zero, then put this command in the console..

G0 Z0.4

Does it go to 0.4 inches above the Z zero point you just set? That command is from your gcode file after each hole drills.

Try it while pressing down a little on the Z plate to test under load.

You can raise the Z after zeroing and remove the bit. That way, anything going wrong won't hurt anything. Leave the router off for testing.


You can simulate gcode files a bunch of ways, I used this website... ncviewer.com/

[gogogad]

I might be doing it wrong,  but when i set the zero, i typically move the router tip to the same spot as I designed into the fusion drawing.  So in this case, i move the machine to the back right corner, and then jog the router down until the tip of the cutting bit just touches the MDF.  Then in the Universal Gcode sender I hit the reset zero button.

When I get home tonight I will try your suggestion. I have been assuming there was nothing wrong with the machine, but only because after i set my zero spot, then hit the go button, the machine moves up until it gets to max upward z, then moves over to the first cutting spot. 

I have been wondering if I should just redo my holes using the 2d contour setup in fusion360.  Up till now that's what I have used for everything.  Its probably inefficient, but its also as far as my learning curve has gotten.

I will add, everything that I have taught myself up to this point in my life,  CNC routing has got to be the most challenging. But it may also feel the most rewarding,  once everything comes together and i see my finished product there is a pleasant pride in knowing i created that mess.   I will post some pictures of my "successful" things in the other areas.

[ttabbal]

To be clear, I don't know that there is a hardware problem. I'm just trying to eliminate possible issues. Your zero setting sounds alright. I'm confused by the mention of the machine going to max Z on start. It should move to the clearance Z, which is 0.6" above the zero for your file. Is that what you see?

I noticed there is a bit change. Are you resetting the Z zero after installing the new tool into the router? You don't need to reset X/Y, but Z is important.

[gogogad]

The bit change shouldnt be there.  My lack of knowledge has me only having 1 bit per gcode file.  I havent figured out how to do it any other way yet.

Max z means,  moves all the way to the top of the z access.  Not sure why it does it ( havent mastered reading gcode yet).  But I am pretty sure it does it on all of my projects.

[rowiac]

Mar 19, 2019 16:38:55 GMT gogogad said:

The bit change shouldnt be there.  My lack of knowledge has me only having 1 bit per gcode file.  I havent figured out how to do it any other way yet.

Max z means,  moves all the way to the top of the z access.  Not sure why it does it ( havent mastered reading gcode yet).  But I am pretty sure it does it on all of my projects.

You should only have one cutter type per gcode file.  That is all that GRBL supports.  If you had a fancy CNC with an automatic tool changer, that would be a different story.

If you have two different toolpaths that are using the same cutter, you can combine those into one gcode file, since no tool change is needed.

[ttabbal]

I didn't mean that there is a tool change command in the file, just that you need to change the tool at some point as the first operation is using a surfacing bit. When you change the bit, you need to reset the Z zero. Since you are surfacing it, I would use the area your surfaced as the zero point. It likely doesn't matter in this case, but for things like V-carves, it does.

For the jump up, I suspect it's that the "Unsuccesful hole drilling.nc" file has a G28 command in it. You can delete that in a text editor or just disable it in Fusion when post processing the file. There's an option on that screen to display advanced settings or something like that. Click that and it opens up some extra options. Uncheck the G28 one. The line I'm referring to is toward the top, "G28 G91 Z0". You can open it in Notepad or whatever text editor you happen to have on your machine.

[gogogad]

I got it sorted.  I am not 100 percent on why it failed the way it did, but I do know why it failed.  I want to thank ttabbal. I hadn't thought of running it with out a bit and with the router off.  With out that tip, i wouldn't have figured it out.

I set my zero to low.  I had the router sitting really high up in the holder because the last thing I built was super thick, and I only wanted some off the top.  Because of that, once it got about half way thru the depth it hit the bottom of the router mount.  For whatever reason once it hit it got stuck and wouldnt move upwards or downwards.  Once I saw it hit the mount i stopped the program, but couldnt get it to jog up.  I could jog x and y, so knew that wasnt it.  I reposition the router way lower,  ran my test run, and everything worked perfectly.   Well except for the human, who got so excited he put the bit in, set the zero (about half in to the left of where it should have  been) and started the program.

But I can work with what i made.  When i cut holes in this one and destroy it, the next one will come out perfect.

Thanks again for the help,  greatly appreciate it.

[ttabbal]

Glad to hear you got it figured out! The whole point of the spoilboard is to cut little bits of it, so it's all good. Looking forward to seeing what you make with it!

[rowiac]

Glad you figured it out. That was a real mystery. I did "air cuts" myself when I first started out.