Plunge Rate... Breaking bits?

Good Day all,

I’m a beginner when it pertains to the CNC world. I’ve grasped the concept of creating more or less basic projects, some snags along the way but I’m doing my thing. My question to the masses is I’ve broken 2 bits when carving. I have broken these bits only when transitioning from 1 plunge to another. it seems as if the bit does not fully come up out of the cut before the X and Y axis begins to move and ultimately snaps the bit because it clips the uncut portion of the material . My table is pretty level, I have surface planed it and its good and level. I also notice that my bit is super close to the material as if its going to drag across the piece. If i increase the plunge rate will the bit pull up out of the cut faster to ensure that the bit is clear before the X and Y moves? Oh yeah, I use Vcarve Pro.

Thanks Jamaine

Sounds like maybe Z step loss when moving up. Check your ACME rod pulley and make sure the set screws are tight and loctite is recommended to ensure they don’t back out.

On older Xcarve, do the same for the Z motor.

Thank you, I’ll be sure to check that.

Set screws are good and tight, when I assembled the machine I made certain to loctite the pulley set screws. I’m not sure why the Z axis stays so close to the material and I use the Z-probe to set the material surface.

Regardless of plunge rate Z will retract to its safety height before any X&Y changes are done.
So changing the plunge rate will have no effect.

What is your safety height set to in Vcarve Pro? (the height Z retracts to between repositioning X&Y)

I don’t know VCarve, but most CAM software have a setting for safe hight. This will tell how high above the surface it needs to retract Z before moving X or Y.

I’m not sure didn’t even know about about that setting. I will look at that shortly. Thank you for your input. Much appreciated !

My safe Z was set on .02 !! Wow, super close! I think that will solve the problem. I set it on .5 and will make a cut and see if the clearance is better. Thank you all for your input. Really, really helpful forum. I’m sure glad I’m a part of it.

Indeed, I did a few test carves and the Z safe function on VCarve was definitely the issue. And yes @BobJewell .5 was overkill so I tweaked it a bit to increase my carve times and found suitable heights for the various material thicknesses. You guys are awesome! Thanks for such quick responses as well. Now I need to make a simple but effective dust boot… ha ha ha.

Ditto… Worth every penny…

I researched the Suckit and it looks like a winner… 2-3 week back order though. I hope its worth the wait.