Noob 1st post, ? on low cost BP CNC retrofits

[cmjohnson]

Hi. This is my first post at cnczone.

It's such a big site, I'm sort of confused as to where to start so I'll ask for directions here.

I have a Sharp YC 1 1/2 BP clone with 2 HP 3 ph motor, and it's a recent
acquisition and the first machine tool I've acquired for my little hobby
machine shop. It's already equipped with ball screws and I've torn it down
for a thorough cleaning (it definitely needed it!) and it will soon be upgraded
to a 30 taper Erickson Quick Change spindle taken from a scrapped BP CNC
Series 1 (Boss) mill. Spindle rebuilding is in progress as part of the many tasks
I have been performing on this mill. (Cleaning and repainting, and repairing both the power feed and the lubricator pump) This mill is a bolt for bolt
clone of a BP Series 1 J head, with almost every part being fully
interchangeable with the genuine BP part.

I'm interested in a low cost CNC retrofit for this mill.

I know electronics pretty well (it's what I do in my day job plus it's been my
hobby for 34 years) so a homebrew CNC kit isn't out of the question.
Certainly a DIY kit is a better solution for me than to go out and spend
thousands more than I can afford to get a premium retrofit.

Give me some pointers on what's an affordable, quality CNC retrofit kit for
a Series 1 J head, and where to start.

I've decided that I'd prefer servo motors instead of steppers. Other than
that, I'm not too picky but it needs to be a good system, easy to build
and install, and reliable.

CJ

[Cartierusm]

Sorry I don't know that there is any cheap BP CNC retrofit. Most are $6000 or more, from what I've seen. The only way I see to do it cheaply is learn how to do the conversion by reading here and then draw up the parts in CAD and pay to have them machined. Just because something has ballsrews doesn't mean they are right for CNC conversion. First you have to check whether there is any backlash in the screw and nut. I'm by no means an expert but what I do it put a very accurate dial indicator on the table, with a stand of course, then move it over until it touches the spindle. Move over until you have an easy readable position then start to slowly move the table in the opposite direction...VERY SLOWLY. If the handle moves and the needle on the indicator doesn't you have backlash. Others here I hope will chim in as to the best way to accurately determine backlash, my idea will at least curb your curiousity as to whether is any until someone else can give you an idea. As far as if you have any it can be correcte without having to buy more than a few dollars worth of stuff. If you do have backlash just find out who made the ball nut and size balls in there and buy oversized balls. I've never done this so you'll need to read up on it here. Good luck.