How do you home an A axis?

[FandZ]

After I build my next Z axis, I'd really like to build a Z axis mounted 4th axis. I'm thinking in this situation it's called an A axis. Anyways, I'm sketching out some ideas but I'm stumped on how you would home it. Since it'll rotate left and right, I wouldn't be able to use the cheapo homeing lever switch I use now for my x, y, and z since as it would run over it. I've thought about a detachable hard stop but I'm sure something much better has been done.

I've read through some 4th axis builds but I havn't seen anything about homeing it. Can someone enlighten me?

Also I notice a lot of 4th axis's use servos and not steppers. Any particular reasons?

[dertsap]

the magic of servos is the use of encoders

what about using a proximity switch , this guy sells them pretty cheap http://cgi.ebay.com/CNC-Proximity-Li...4.c0.m14.l1262
he's great to deal with , i've bought a fair bit of his stuff

[jalessi]

FandZ,

I use these on all my axis including the rotary, they work really well.

http://www.hamlin.com/specsheets/591...;20IssueAc.pdf

http://tinyurl.com/nn8bsq

59140-040-ND

Jeff...

[ger21]

A push button switch with a two sided ramp to activate it. The ramp can go past the switch without damaging it.

[amishx64]

Originally Posted by FandZ After I build my next Z axis, I'd really like to build a Z axis mounted 4th axis. I'm thinking in this situation it's called an A axis. Anyways, I'm sketching out some ideas but I'm stumped on how you would home it. Since it'll rotate left and right, I wouldn't be able to use the cheapo homeing lever switch I use now for my x, y, and z since as it would run over it. I've thought about a detachable hard stop but I'm sure something much better has been done.

Oh geez FandZ. What are you getting into now?

Just kidding. Can't wait to see what you are up to.

[FandZ]

Thanks for the links and replies fellas. It was just one of those nagging questions that had to be asked. I guess what I'll do is keep designing it and use what ever fits the design best. Glad to know it doesn't have to be too much of an exotic solution.

[FandZ]

Originally Posted by amishx64 Oh geez FandZ. What are you getting into now? Just kidding. Can't wait to see what you are up to.

I think it's the natural progression of building a cnc. But you know me, always looking for new ways to use up this stock pile of skate bearings I have left over.