Why is this happening...again?

[scotttarnor]

Leo, the Pirahna did come with software called “ready to control basic” that allowed the machine to be ran off of a.computer rather than a thumb drive. So the OP could try your suggestion if he has a computer available.

I keep going back and looking at the 2 extra cuts, it looks like a ramped BN rather than an EM to me.

[Leo]

Scott, If the Z axis lost steps it would bore down deeper than expected, just like the OP said it did. Then on retract it would not clear the top of the material and then move in Y- and Z+ on an angle - like the cut from the hole at 12:00. Then from the center of the board it may move to the outer perimeter in X- and Z- just like the cut ay 9:00

A square end mill cut on an angle like that would look like a ball nose cut.

This is what I see in the pictures.

[scotttarnor]

Okay now I see, like I said earlier only 2 years into this fun still a lot to learn.
That said I know my Pirahna would not do well plunging an EM in at 30ipm to hardwood with no ramp or spiral, its made out of some type of plastic it’s not very rigid.

[Leo]

Okay now I see, like I said earlier only 2 years into this fun still a lot to learn.
That said I know my Pirahna would not do well plunging an EM in at 30ipm to hardwood with no ramp or spiral, its made out of some type of plastic it’s not very rigid.

I don't know the machine, but I have heard this before.

[scottp55]

I'm ass-um-ing that the hole pocket was done first and the 12 cut was made from the bit returning
from the +.5" Z1 to the Home Z of +.8".

Then the cutout was made without Z-Zeroing(why should you), and then we're seeing almost the same ramp into that cut.
(Neither toolpath has a ramp)

Thoughts are;
Bit slipped down(metric shank in imperial collet/not tightened enough, or just worn collet caused slippage?)
Router(spindle(?)) slipped down in the mount.
Machine lost Z-zero on the Hole cut.

Caliper the bit shank/replace collet nut(possibly bit also(?)/tighten securely/Ramp the cut!
Check router/spindle mount and tighten/scribe a line on router body at the mount for change(?)/Ramp the cut.
Ramp the cut and accurately measure the Z-zero home to make sure it's +.8"

my 2cents:)

[martin54]

Not quite how I saw it Leo based on how I thought my machine moves but I could be wrong about that, can't even check it because the machine is not usable just now.
I was thinking that the z axis was to low from the start & both those cuts were done as the machine was moving towards the start point for the cut, I know with my machine as it starts to move in X & Y it also starts to ramp down towards the safe z height but after a cut I thought it moved all the way back to the X Y zero at the safe z height & the z axis didn't move up again until the end, so if that were the case the 2 cuts wouldn't be ramped & would run all the way to the centre

[AboveCreations]

I do not know the machine that well, but if I ran my 1/4" EM at 100 i/m feed rate, it could be a disaster and I am pretty sure my machine is built just as sturdy as the Piranha. I am surprised someone didn't notice that. The 30 plunge is a bit too much too imho. But as noted, it returns properly to the XYZ after cutting wrong is strange. If it was static, then it most likely would lose the XYZ on return. So I would probably start with slowing feed rate and plunge down and like someone suggested, do trial cuts on cheap pine. I sure wish I had some extra maple boards handy to make a few of those boards for Christmas. I really like your design, but I would worry about the 1" neck. Dropping that board accidently could possibly break at the neck. Again, just my opinion. I hope you get it worked out.

[pd417]

Thank you all for all the suggestions, much appreciated
I gave them all a try hoping to find out why this weirdness keeps happening, but unfortunately, I couldn't
come up with any clear answers.

This is what I did:
1. Ran only the machine with no dust collection to prevent power fluctuations and static electricity
2. Made minor changes to my settings
- Slowed plunge rate to 20 in/min
- Slowed feed rate to 100 in/min
- Increased Clearance (Z1) by 0.2
- Increase Plunge (Z2) by 0.2
3. Cleaned and lubricated rails and threaded drive rods

So, I crossed my fingers, said a small prayer and ran the job on my one extra piece of teak. Ran with no problems. I still don't have confidence that it will work without any errors on my next project, A new CNC is definitely on my list, but for now I'll just have to deal with my psychotic little machine.

Attached is a photo of the completed piece finished with Odie's oil.

[scotttarnor]

I do not know the machine that well, but if I ran my 1/4" EM at 100 i/m feed rate, it could be a disaster and I am pretty sure my machine is built just as sturdy as the Piranha. I am surprised someone didn't notice that. The 30 plunge is a bit too much too imho. But as noted, it returns properly to the XYZ after cutting wrong is strange. If it was static, then it most likely would lose the XYZ on return. So I would probably start with slowing feed rate and plunge down and like someone suggested, do trial cuts on cheap pine.

I run any where from 75-150 IPM on my Piranha depending on the wood type, but I use a slow plunge 5-10 ipm and ramp the bit in.

pd417 I forgot to ask what EM you are using and what your pass depth was on your EM ?

[pd417]

Scott...

I'm using a Whiteside 0.25" upcut EM and have the pass depth set at 0.125"

[AboveCreations]

I do not know the machine that well, but if I ran my 1/4" EM at 100 i/m feed rate, it could be a disaster and I am pretty sure my machine is built just as sturdy as the Piranha. I am surprised someone didn't notice that. The 30 plunge is a bit too much too imho. But as noted, it returns properly to the XYZ after cutting wrong is strange. If it was static, then it most likely would lose the XYZ on return. So I would probably start with slowing feed rate and plunge down and like someone suggested, do trial cuts on cheap pine.

I run any where from 75-150 IPM on my Piranha depending on the wood type, but I use a slow plunge 5-10 ipm and ramp the bit in.

pd417 I forgot to ask what EM you are using and what your pass depth was on your EM ?

Well, I wasn't clear on my comment and I was mainly referring to the cutout tool and settings in his file. 1/4" end mil at 100ipm with a .125" pass depth would be too much for my comfort.

[Leo]

I am happy that you were able to make it work,

However, the machine is not junk. It is quite capable.

As with any and with all machines there will be quirks. I have been working with CNC machines of all sorts professionally for 40 years and to date I have never found one that does not have quirks. Some of machines are in the $500,000 range.

Testing on something like cheap pine, firewood (bandsaw cut into boards), scrapwood, FREE wood, is the best practice. Construction sites discard TONS of FREE scrapwood. Walk into the woods and pick up FREE wood that has fallen on the ground. There is no limit on the availability of FREE wood. I use a lot of trim wood that was torn off my house. Don't test on teak.

A lot of suggestions were made here and something mentioned here will fix the issue, or at least give you the understanding of the quirks in your machine. It may not be anything I said, but "something" is causing the issue. Test ONE thing at a time over and over until you can make the issue happen. Once you know what the machine does and how the quirks work you can begin to trust the machine.

If you get rid of that nice machine you have you will fast discover that your next "better" machine is really no better, as it will also have quirks. That I can guarantee!!

The machine you have is a very nice machine and is very capable of some really awesome stuff. It's all about learning how to work with it.

Please do not give up - you CAN do it.