Last Tool path has unexpected "turn"

[Pwim (Paul)]

Hello Im hoping someone can take a look at this project. Yesterday I ran this project and it was a few percent from being done. It was finishing the last contour path and all of a sudden made a direct turn back into the main piece, I dint have a specific picture but it almost seemed like it wanted to return to the path where it started from. It rendered the piece useless and locked everything up because it was a full depth cut. This happened one other time on a smaller project and I was unable to determine why it happened. Im not sure if its an error on my part or some sort of glith. Failry new to all this so any insight would be appreciated. Ive added a highlighted drawing to show the path the bit took at end as i described
lh board final pocket do heart handle.c2d (196 KB)

[Jeffish (Jeff de Ruiter)]

This can happen if the endmill came loose in the collet.

[Pwim (Paul)]

Thanks for responding,
It would cause it to make a turn like that? The whole spindle went with it

[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…

[Jeffish (Jeff de Ruiter)]

Yes and it will pull down into the project as well. @WillAdams gives good advice above

[Redlander (Tim Jones)]

@Pwim

To add to what Will and Jeff posted, when I cut the contour outline of a project I will offset the initial cut (by 0.02”) all the way down to the tabs with a rough cut bit that handles contour cuts a bit better in my experience. Then I will swap to a standard downcut bit for the finishing pass to get a nice clean cut.

[Pwim (Paul)]

Hi Tim, thanks for your feedback, what I dont get though is why the turn if there is nothing in the toolpath designating that?

[Redlander (Tim Jones)]

@Pwim

Lots of torque on the bits that can be affected by wood grain and or loose bits. I’m not the authority on these issues but have seen posts about them on the forum. I have a S5 Pro with the 65mm spindle and have not experienced this yet. I have have had issues due to my setups for toolpaths with som retract heights and cutting across a project, or two….

I do know from extensive use of hand routers that “slotting” can go wrong quickly especially with a climb cut and grain direction.

I didn’t see you mention which machine you were using when this happened?

[Pwim (Paul)]

Hi Tim i think you may be right with the slotting, the bit was deep at the time when it grabbed and pulled and I was definitely near the max cut depth. for that bit. I know what your talking about w hand routing so now it may make sense.
Im using a Shapeoko pRo 4 w same 65mm spindle

[Redlander (Tim Jones)]

@Pwim

Yep, max depth on the bit is a lot of bit surface area to grab onto material.