auto feed 4th axis?

[Teyber]

hey all!

Around January, i got a grizzly x3 mill. i am in love! It is absolutely a gem. Most of the work i do is lathe work, but had a very bad experience with a lathe so adopted the mill do to 4 axis work. Basically, i spend about 5 hours milling a week. usually after school and i often play hooky through my 3rd and 4th period to play with my mill (yeah i love it that much). 90% of my work i do on my rotary table. i originally purchased a 3" indexing rotary table (POS), sold it and got a 4" rotary table. too small so the great people at littlemachineshop let me swap it for the 6" rotary table and a 5" 3 jaw Self centering chuck.

So i am really getting tired of spinning the tiny hand wheel for hours on end. I don't want to CNC my mill, as im only 16 and am currently saving 1000$ for a nicer lathe. So what would the easiest way to have an auto-feed on my rotary table be? basically just want to have it set to spin, so i can slowly mill out sections.

criteria:
1) Must have forwards/reverse
2) variable speed not necessary, no need for a VFD
3) Machining a mount so i can have a handle would help.

if it would help to post some pictures of what i usually mill, please LMK(let me know). Any suggestions? preferably pretty cheap, $100< would be best. Would servos be best way to tackle this? printer perhaps?

Thanks so much for your suggestions!

regards

[Crevice Reamer]

Hi Teyber. Welcome to the Zone!

What you want to do is basically "cnc" the rotary table, without benefit of computer & electronics. A Servo motor with a simple on/off switch MIGHT work. It would want to run much faster than your RT can though.

Maybe a gearmoter would be better. Anyway, whatever motor you choose, would have to be mounted just like a stepper. Here's an example:

CNC rotary table:

http://www.embeddedtronics.com/rotary.html

Sample gearmotor:

http://surpluscenter.com/item.asp?It...08060406132637

Good luck!

CR.

[Crevice Reamer]

I calculate that your maximum rpm would be about 200 by hand, so maybe this motor would be better:

http://surpluscenter.com/item.asp?UI...-1266&catname=

CR.

[Crevice Reamer]

On further reflection, those motors are only rated for intermittant duty and you need continious duty. This motor is larger, but workable, and it is rated continuous duty:

http://surpluscenter.com/item.asp?UI...-1112&catname=

CR.

[Teyber]

thanks so very much!

yes that last one you linked is perfect for me! almost never see those things in the 110vac-120vac range either it seems...

Making a mounting isn't really a biggy it would seem for me. Would you use a belt, or directly mount it to the rotary table?

also is reversing it an option? will it hurt the motor to stop/start it often?
http://www.xtremesystems.org/forums/...7&postcount=30
those are what i make, but also:
http://www.xtremesystems.org/forums/...&postcount=323

The reason why i would like an option to start stop/ manual is the maze looking ones... the reason i would like to be able to have a motor is for the ones that have steps...

So thanks so much for your help! ill do a little more research and prolly buy that. I havn't done any mods to my mill yet, so i might need some simple help along the way.

regards

[Crevice Reamer]

That last motor is fully reversible and continuous duty. It is quite powerful and it shouldn't hurt it to stop and start. Better not wait too long--They only have 14 left.

That's some nice work you do!

CR.

[Teyber]

word!

thank you so much for your help... really means a lot!

ill order that tonight. Also, any thoughts about being able to switch to manual? maybe just un-screw it from the rotary table and turn the inner dial(closer to rotary table) by hand.

also, would mounting it directly be easiest? ill draw up some mounting ideas once i get the motor.

regards

[Teyber]

ordered it! thanks so much mate.

ill have quite a few questions once it comes.

regards

[Crevice Reamer]

Manual control will be tricky because you must keep the graduated manual wheel. I would mount the RT to an aluminum plate that extended to the left with enough room to also mount the motor. You could pivot the motor and use a spring tightener on the belt.

You could then run a 1:1 belt drive (Or the pulley ratio could be used to slow it down.) to the manual control--either somehow attaching a pulley, or using the wheel itself as a pulley. This last would be best as just slipping off the belt would return manual control.

The plate could be dowel pinned in place on the X3 table for repeatability, with mounting holes drilled and tapped.

CR.

[Crevice Reamer]

I would mount the plate to the extreme right, so that the motor part was extended off the table to the right of the actual work envelope. This way you would still have plenty of table left for other options. The X3 table can hold up to 150 pounds of accessories. The right side is more supported than the left side.

CR.

[Stepper Monkey]

In my teen years before CNC was commonly available, I did something very similar to this, and it worked quite well. I think you are on the right track.

My odd creation was an old power supply rigged run an old cordless drywall screwgun chucked to the crank to rotate it, and I put a couple of reversing switches at the limits of travel on the machine to change motor rotation. It was designed to affect a repetitive linear motion on a blade-grinding machine, as hollow grinding all four sides of a long sword blank manually was similarly monotonous. The basic idea should work just as well for a rotary motion.

Just don't worry about getting too fancy. Since you aren't looking for reaching any calculated positions, just absolute positions, you can actually get away with a pretty rudimentary system. This is because accuracy is never a factor with an absolute positioning system, only repeatability, and surprisingly crude systems can achieve some insanely good repeatability.

[Teyber]

thanks mate! i don't want it to look ghetto, but for the most part accuracy doesn't matter here. just needs to spin. the rotary table is for the accuracy.

Well it came tonight! its lookin good. i got out of school TODAY! yay sophomore year over. later this weekend i will start drawing up some ideas. i think i want to make a short term mount out of LDPE which i have here, then once i get it right ill make it out of aluminum (perhaps delrin? idk i like machining plastic)

how do you reverse the direction? only things i have played around with that reverse are DC and you just switch the leads (as manufacturers specs), but how would you do that on AC? preferably somethign on a switch...

also how would you guys attach the spindle on the motor to the rotary table?

sorry dinner is served, g2g

regards