CNC Shark Forum

Why are my cuts looking like this? All bits are 1/4" shank. Wood is redwood
Pic 1....Outline cut using a 90 deg V carve bit. The oval is not meeting at the exact point from start to finish. Causing to go back and hand sand that area.
Pic 2.....Bottom clearing cut is not uniform leaving various ridges throughout the project. Bit is a 1/4" compression end mill from IDC. I get the same results when using down cut or up cut end mill from Amana.
Pic 3....Surfacing issue. Leaving a ridge with each pass. Bit is an Amana 1 1/8", 3 flute bit. Using a 60% stepover.

Depth of cut on Pic 1 & 2 are .2. Depth on surfacing cut is .05

Projects are SECURELY fastened (CA with tape) and flattened with a planer before cutting project. I'm running a HD520 with a 3hp spindle.
Its been suggested that something might be loose on the machine??

Any thoughts?
Thanks !!

Be sure to check all couplers between the motors and the drive screws. The setscrews can become loose. Plus, if the setscrew is not tightened against the flats of the motors and the drive screws there can be intermittent slipping. So, even if a setscrew appears to be tight, it may only be tightened against the cylindrical part of the shaft. This would allow the shaft to slip while being exposed to cutting pressures.
Bob

Everything seems to be tight. I'm thinking that I need to tram and shim the spindle.

Also, are all drive screws cleaned and properly lubricated? If not, it could cause the mismatched outline cut.
Tramming could cure the uneven bottom, and clean up the surfacing cut.
I'm still a little suspicious of those couplers...
Also what feedrates are you using.
Could you post your crv. file?
How high is your gantry mounted. There could be flexing if too high.

How high is your gantry mounted. There could be flexing if too high.

Rather than messing around with the Gantry if it is found to be a flex height concern is to adjust what is at the table closer to the pivotal axis point of the machine by raising/adding material under the Project Board thereby, moving closer to the pivotal axis point. This also maintains your Z-Axis Travel. I add material under my Project Board all the time with no problem issues. It sure beats the heck out of fiddling with moving the Gantry to another position thereby, losing Z-Axis Travel!!

Sharkcutup

What's a "pivotal axis point"?
It sounds nice and technical. And, kind of cool. I just want to know in case the term comes up again.
Thanks.

I have lubricated and checked everything for tightness. Nothing seemed off. The machine is almost brand new having run about 15 projects and about 7 hrs run time on it.

Not quite sure how to post the crv file....

Feed rates for the compression tool are...80 ipm @16,000rpm at a .2 depth in redwood
For the V tool......40 ipm, @16k, @.2 depth

Have you contacted Next Wave yet: https://nextwavecnc.com/support/
They have always proven very helpful.
Tramming sounds like the best idea to clean up the surfaces.
I'm stuck with the uneven ends. It would be a good idea to check with Next Wave.
Bob

rlussi45 wrote: ↑

Wed Feb 14, 2024 6:23 pm

I have lubricated and checked everything for tightness. Nothing seemed off. The machine is almost brand new having run about 15 projects and about 7 hrs run time on it.

Not quite sure how to post the crv file....

Feed rates for the compression tool are...80 ipm @16,000rpm at a .2 depth in redwood
For the V tool......40 ipm, @16k, @.2 depth

Another question: Did you make any changes at all, or notice anything different between the first 15 projects and when the problems started? Cables in the way? anything under the table or on the table? etc.

I did contact Next Wave and they sent me some files for tramming X & Y. After being gone for a while, I did those today. I had previously lubed the gantry and "y" bars underneath.I also dropped the spindle down about a 1/4" as I felt it was too high. After running the tramming per their instructions (on MDF on top of the NW unsurfaced spoilboard), everything looked REALLY good....NO ridges in either X or Y. So no need to shim!!
SO.....not really sure what exactly the problem was but all the steps seems to have taken care of it. I will surface the spoilboard tomorrow.

Thanks everyone for the help. I'm still a newbie at this after 3 months. As I tell my friends, I'm still in "kindergarten".