You would have to re-reference all three axis each time. Is this easy/safe to do within a running program.
To be able to hold the tool holder during a "very" heavy cut you need the drawbar to be as tight as is safe for the drawbar. Which I believe is a lot higher than 20 ft-lbs. Wasn't it up at about 65 ft.-lbs or something like 6,000 to 9,000 lbs tension.
A simple cam operated large/small hydraulic piston might also be a way to achieve force multiplication.
Phil
Originally Posted by justgary  Phil -
The open loop part can easily be solved by re-referencing at every tool change (or referencing to the change position, making it closed-loop). A few more seconds, yes, but much more likely to hit the target every time. I'll allow a few more seconds if I know it will work every time. Especially if I can be at the pub!
The more I think about a geared motor, the more I like it. At 5:1 reduction to a drive motor, we're only talking 4 ft-lbs to tighten the drawbar to 20 ft-lbs. If that is the upper limit (which we still don't know for sure, but somebody had mentioned that number as coming from Tormach), then we're not talking about a very big motor, and indeed it could even be a stepper.
The good part about numbers is that you can at least get a notion for the upper and lower limits of that which you seek. Whatever the numbers, I don't want slipping tooling.
Regards,
- Just Gary |