With my new Shapeoko 5, several times now my bit has moved while cutting aluminum. Mostly up, but once actually down. The VFD/Spindle is not new, same one I have been using for about a year.
I feel like I am wrenching it rather tight. But I don’t know if there are some collet “rules” or best practices.
I did clean it with some alcohol, and some grime came off of the collet & nut, maybe that was it?
Lastly, I tend to choke up longer bits when cutting aluminum, some of the gold Zrn coating is up in the collet, that made me think if that is by nature more slippery since it is made to be less sticky with aluminum.
Just looking for general advice here. Sucks when it happens.
The ER collets or the trim routers have to have a clean and lubricant free surfaces. I use brake cleaner to clean out the collets and then spray the brake cleaner on a q tip and clean out the spndle/router internal shaft.
The collets on both the ER and router have a similar pattern. They are cut from the top almost all the way to the bottom and then cut from the bottom to the top in a pattern. This produces a W or M pattern and as you tighten up the collet nut the collet is forced up an inclined plane inside the spindle/router shaft. This forces the slices together in the collet holding your bits in place. So if there is dust or other debris inside the collet it can feel tight but not be fully tight all the way around.
The collets can become scratched if the bit becomes loose and again give you a false feel that the bit is tight when maybe only one segment of the collet is really tight. It would always be a good idea to have a spare collet around. They do wear out but not very fast. However if you are having a problem and you clean it and it still slips it is time to replace it.
I did notice a small metal “shard” between one of the teeth of the collet. I also deeply cleaned it and it is back to a shine, so far no slippage.
Question tho, is there any downside to having some of that Zrn gold coating be inside the collet? I find that there is less vibration when cutting metal to choke up the bit as much as possible, I just didn’t know if there was any “gripage” issues with that coating.
As long as your bit is tight I doubt the coating will rub off. The coating is made to be pretty tough so as long as the bit is not slipping I think you are ok. However if the bit spins the friction could rub the coating off. It is like sanding the bit with it sanding inside the collet.