CNC conversion

[ballendo]

Mojo,

Thank you for your reply. Now that we've both had our say, others can decide for themselves whether to use handwheels or not...

I think the posts will speak for themselves.

Ballendo

[Bloy2004]

I've got a "ringside seat" on these posts.....

[HomeCNC]

Well the start of this post was about converting an Asian drill/mill to CNC. The concern was the Z axis.

All I know is on my drill/mill, the Z axis hand wheel is crap. The marks on the hand wheel don't work for what you really get for movement. Setting a zero is pain. The only way to get an accurate position with the existing Z axis hand wheel is to add a DRO to the Z axis, and why do this if you’re converting to CNC. You get a DRO automatically.

I was glad to get rid of the hand wheel and be able to use the DRO on the PC and tell the Z to move what I needed. Using the Ball screw on the Z instead the rack and pinion has made my positioning in both up and down +- .002

[cncmojo]

Jeff

To clarify, the factory Chinese Z axis setup on the mill you have on your site is truly not worthy for CNC use. That is the main problem that I have seen with the retrofits, but there are some enhancements that can be made to make the Z work well. The rest of the metal on the ways is nothing to brag about, but it is OK, with proper lubrication.

Like I said before Quote “Jeff’s Z drive is a very complex and interesting design that took lots of skill to conceive, and make; but it doesn’t have a wheel, and you can’t jog it when you are on the limit switch”.


What would happen if some clothing, jewelry, air hose or something else got tangled up in the spindle and pulled you into the machine while using the machine. Lets say you were able to hit an emergency stop button on the mill. What if you hit the limit or can’t reach the keyboard. Especially if you are injured, what if your rescuer has no idea how to operate the CNC controls? Now you are screwed, can you reach up and simply manually operate the axis to free yourself, only if you have manual controls, or hand wheels. If you are afraid of them make them a solid smooth disk with no knob, that makes them about as dangerous as milk, but remember you can drown in milk.

This is the stuff that law suits are made of, and by selling them you should be aware of just this. What are the chances of someone getting pulled into the machine, pretty slim. Will some careless nut, maybe one who has had a few beers do it some day? The answer is if there is any way to screw something up some day some one will somehow do it, that is just a fact of life.

Now I go in peace, Besides I just got in a big shipment of new ball screws and ball nuts it is time to play.

[anoel]

That's another good thing about a CNC only machine... You don't have to be right there at it while it's running... No danger of getting caught in the spindle if you are not within arms reach of it. No hand wheels = No temptation to use them... If you don't have them or never used them then you don't miss them... I've never had them... Would not know how to get a good part with them either... But I can run TurboCNC well enough to get the job done plus I can make a command in the console to go 1.532" and it will. No need to look for a scribed line on the part or keep an eye on a DRO.

Yes I know it's very tempting to hunch over and watch the endmill cutting. Who can resist... But that gets old after a while and you just simply want to get the part out of the clamping fixture and go about other business.

Not lookiing to spur this thread on. Just giving a perspective of someone that never used a manual mill... But I have had my knuckles busted by handwheels on other types of power fed machinery. OUCH!!! I'd rather not have them...