Plunging too deep on second cutout

[CDRLLC (Kyle Koetsier)]

Have had his problem for the past few recent uses. I have two different designs made, thus different g-code, and it’s happening on both sets of corbels I’m trying to make. I programmed it to make a set of two without having to change stock and save time.

The simulation shows the tabs on the second cut-out so it isn’t a depth setting in the toolpath

I am setting all zeros before cutting, using a bit setter, not changing the bit between.

First cut out works perfect, leaves tabs perfect, really happy. Then the router retracts and moves for the second cutout and plunges 1/2 inch into the material (programmed to start at .125 inch and step down .125 each pass.

The bit (201 1/4 inch endmill) handles it fine in the pine, but the problem is the CNC losing the z-zero in the middle of the cutting, then cutting through the bottom of the material by 1/2 inch. I have to stand there, and force stop the cut through the program once I see it go through.

Any thoughts on why?

[CDRLLC (Kyle Koetsier)]

[CDRLLC (Kyle Koetsier)]

[mhotchin (Michael Hotchin)]

Post your C2D file. Screenshots and pictures just don’t provide enough info to be useful.

[mhotchin (Michael Hotchin)]

That said, what is your retract setting? Could your Z be going too high and losing steps at the top of travel?

[WillAdams (William Adams (Carbide 3D))]

Where possible avoid slotting and add geometry and cut as a pocket

Making vacuum hose adapters

While cutting up vacuum extension wands for this is expedient, it’s a bit problematic given that Shop Vac recently filed for bankruptcy, was bought at the last minute, and production hasn’t caught up. I need a receptacle for the Sweepy 2.0 dust fitting — one option would be to purchase one from Woodcraft, but Carbide 3D sells blocks of HDPE: which looks to be just barely big enough for things to fit. Measuring the hose fitting I get a diameter of ~63.5mm — offsetting that twice we arrive at…

and/or

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…

and consider leaving a roughing clearance and taking a finishing pass.

Best Bit for full cut through

One which has a cutting flute length equal to or greater than the thickness of the stock — pretty much any tool should work. Big thing is the toolpaths — if cutting out, rather than just cutting a slot: [image] Offset to the outside by endmill diameter plus 10% or so: [image] [image] [image] Then cut as a pocket: [image] down to tab height or the penultimate pass: [image] then move the contour down to below the pocket and start cutting at the bottom of the pocket: [image] and…

[CDRLLC (Kyle Koetsier)]

Bingo, I haven’t cut another one yet, but I bet this is the problem! had it set to retract 1.5 over top of 1.5 material. I bet it was too much, have addressed this in the code and will confirm later.

Thank you I couldn’t figure that out, and wasn’t even thinking about that.

Kyle

[CDRLLC (Kyle Koetsier)]

That was indeed the problem, cutting like a dream now. Many thanks for the support.

Kyle