Milland
Diamond
- Joined
- Jul 6, 2006
- Location
- Hillsboro, New Hampshire
Hi all,
My (mostly) trusty VF-5 has started to show a random slipping in Z that seems to be around .023" max. Today was the first time I saw this excess motion, and it's showing up as deep or shallow cuts on a series of parts that are fixtured pretty consistently in Z, so I don't think it's a parts location issue. Tooling is just three different smaller endmills, all secured in good toolholders with clean pockets and tapers. Cutting forces are low, this movement occurs even when rapids are turned down to 25%. When movement occurs it seems to be consistent per part, but I've only done a few pieces to avoid too much scrap.
I have searched for info on similar problems, not come across a definite failure mode, but could this be pointing to a slipping coupling between the Z servo motor and the ballscrew? My understanding is there's no key or other "fixing" element in the coupling, but if you know better please say so. With the encoder on the servo, coupling slipping will ruin your Z positioning, anything else it could be? I'm pretty sure the thrust bearings are OK, I don't hear anything on axis reversal or constant feed.
Gotta love these weekend failures...
Thanks for any help!
My (mostly) trusty VF-5 has started to show a random slipping in Z that seems to be around .023" max. Today was the first time I saw this excess motion, and it's showing up as deep or shallow cuts on a series of parts that are fixtured pretty consistently in Z, so I don't think it's a parts location issue. Tooling is just three different smaller endmills, all secured in good toolholders with clean pockets and tapers. Cutting forces are low, this movement occurs even when rapids are turned down to 25%. When movement occurs it seems to be consistent per part, but I've only done a few pieces to avoid too much scrap.
I have searched for info on similar problems, not come across a definite failure mode, but could this be pointing to a slipping coupling between the Z servo motor and the ballscrew? My understanding is there's no key or other "fixing" element in the coupling, but if you know better please say so. With the encoder on the servo, coupling slipping will ruin your Z positioning, anything else it could be? I'm pretty sure the thrust bearings are OK, I don't hear anything on axis reversal or constant feed.
Gotta love these weekend failures...
Thanks for any help!