Hi everyone,
My name is Cleo, I am originally from France but I have been living in Shanghai China for a couple years now. Yesterday I went and purchased a 2nd hand BF25 mill for just under 300 bucks. Its in pretty good condition but I am already wanting to upgrade it. The original DC motor setup is extremely loud. I would like to convert it to an AC motor with a belt drive. I know a lot of you guys have done the conversion so I was wondering what motor and gear ratio you guys would recommend. Other than the original motor being loud, the quill has some slop when it goes up and down. I would like to remove it since I will be converting the mill to a CNC very soon.
Thanks in advance
Cleo
Removing the quill components is easy. You just need the tools and the patience to do it.
The motor noise is almost certainly a combination of things. The gear drive tends to be noisy, as the gears themselves make noise running against each other. On top of the that, the gear that fits over the spindle has an internal spline that drives the spindle spline. This tends to be a loose fit, so it makes noise too. The best course of action is to get rid of the gear drive and run a belt drive. While your at it, it's a good opportunity to do the motor too.
It's a reasonably difficult project to take on. Good luck!
Thanks for the reply,
Any recommendations on motor rpm, gear ratio and power? I've been looking at some 1.5kw AC motors but I'm not sure if they are the best option.
I run 1:1 ratio with a 2.2kw BLDC motor. 6,000 RPM.
It has been working very well for me. I don't think you need 2.2kw, 1.5kw would be fine. I ended up with a 2.2kw because I figured overkill would be better than running out of power. It's not stalled or over heated yet, so I guess it worked out.
I was looking on youtube and I found a lot of guys using AC servo motors. I found one near me, it's a 1.3kw servo rated at 3000rpm. I am planning to do a 2:1 gear ratio to end up with 6000rpm at the spindle. Keeping in mind that I will mainly machine aluminum and brass, do you think 1.3kw is enough?
Thanks
Cleo
It depends solely on how aggressive you want to run your machine. My thinking is that if you halve the torque you will be taking fairly light cuts in aluminum. Maybe .2" deep with a .375" end mill. You'd have to run some calculations on that cutting force and horsepower draw. That said, if you aren't running production or some reasonable number of volume parts, then it might not matter. The machine runs longer, no big deal. I often have parts waiting to be machined while parts are machining, so speed is somewhat of a concern for me.
Chinese BF25 Mill Upgrades
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