Re: Handwheels
Posted by
Fred Smith
on 2000-11-07 06:00:14 UTC
Regarding the use of hand wheels, there is a very simple modification to any hand wheel that makes it perfectly safe & does not cost anything. Simply remove the handle. I have found this to be the most elegant solution in a Bridgeport sized machine. I don't mean remove the wheel, I mean remove the handle that sticks out & will pierce your tender parts a several hundred RPM. Most of the time you don't need the handle part for rapid kinds of moves, so use the jog buttons. This is an appropriate place for electric control. However when you are finishing the sides of a slot the you can control the final size by the feel of the cut, it is not necessary nor appropriate to use the CNC control for this. Anyone who does not have experience will of course pooh pooh this concept as they tend to let the machine be the machinist & since it is hard work to really learn the interaction and the "FEEL" of the cutting of the metal by the cutter. It also takes a lot of practice & hands-on usage to tell the difference between .002 and .003 depth of cut. The important place to have this kind of control is where the sound and vibration of the machine make the action of the cut impossible to sense by sight, smell or sound. Since the hand feel is actually more accurate and reliable than the others, it can be used in this kind of cutting condition.
On the benchtop machines, it may be that the control handles and screws are so coarse that you cannot feel the difference one way or the other. On a Bridgeport machine there is no question that you will want to leave the control handles on the machine if at all possible. It is also fairly easy to use them without the handles and many retrofits of this type of machine have included a round aluminum disk instead of a handwheel to reduce the effects of the inertia in the heavy cast handles, but still leave the option to do fine-precise work.
As far as the Accurite system is concerned, it is still an over priced 2 axis control, and limits you to only a conversational mode. This is very shortsighted and egotistical on their part, and were it not for their quality scales and dros, I would personally launch a campaign against their predatory marketing methods and misleading advertising. Remember Ron, you still have to pull the "Z" handle on your fantastic Accurite system! If you added a 3rd axis in place of the manual needed for the Accurite style, you could program in Vector and run the controller with the same computer. Maybe with Flashcut in Windows., or Linux-EMC with Win4Lin to Run Vector at the same time. 3 clicks and your making chips ;-) No sneakernet required.
Lastly about safety. NEVER NEVER NEVER climb mill on a manual machine period. The acme screws used in Mills will not make this kind of cut without causing harm to people, tooling, parts and the equipment itself. That being said to all first year apprentices, it is later pointed out that on a CNC machine ONLY WITH BALL SCREWS, it is possible and recommended to PROGRAM climb milling as it requires 1/3 the horsepower as conventional milling, improves tool life, surface finish and chip evacuation. My personal experience with climbmilling on my own and other people's machines is that there are a couple of places where if done very carefully, it is OK to use climb milling in manual machining. The most significant is light finishing cuts on aluminum contours(eliminates recutting of chip), but NEVER roughing cuts. I have also found that when using a power feed on a mill with ball screws, it can be used to climb mill too, in other words, no CNC program required, just the gear head power feed. I have never experienced the problem of climb milling causing inertial runaway conditions, because I never allowed my machine to operate without being in control of the cutting. Those that do should review what they are doing to leave the machine in a loose condition. If you are manually machining on a mill, one axis is almost always locked in position. Axis locks may be the difference in my experience and those of others that have problems with manually machining on a machine with Ballscrews. Personally I much prefer the ball screws over the acme, as there is no backlash to account for & there is reduced effort required to move the table and workpiece loads.
Gotta throw this out too - there are lots of rumors about new Windows based controllers coming soon.
Best Regards, Fred Smith- IMService
Listserve Special discounts and offers are at: http://209.69.202.197/cadcamedmdro.html
imserv@... Voice:248-486-3600 or 800-386-1670 Fax: 248-486-3698
On the benchtop machines, it may be that the control handles and screws are so coarse that you cannot feel the difference one way or the other. On a Bridgeport machine there is no question that you will want to leave the control handles on the machine if at all possible. It is also fairly easy to use them without the handles and many retrofits of this type of machine have included a round aluminum disk instead of a handwheel to reduce the effects of the inertia in the heavy cast handles, but still leave the option to do fine-precise work.
As far as the Accurite system is concerned, it is still an over priced 2 axis control, and limits you to only a conversational mode. This is very shortsighted and egotistical on their part, and were it not for their quality scales and dros, I would personally launch a campaign against their predatory marketing methods and misleading advertising. Remember Ron, you still have to pull the "Z" handle on your fantastic Accurite system! If you added a 3rd axis in place of the manual needed for the Accurite style, you could program in Vector and run the controller with the same computer. Maybe with Flashcut in Windows., or Linux-EMC with Win4Lin to Run Vector at the same time. 3 clicks and your making chips ;-) No sneakernet required.
Lastly about safety. NEVER NEVER NEVER climb mill on a manual machine period. The acme screws used in Mills will not make this kind of cut without causing harm to people, tooling, parts and the equipment itself. That being said to all first year apprentices, it is later pointed out that on a CNC machine ONLY WITH BALL SCREWS, it is possible and recommended to PROGRAM climb milling as it requires 1/3 the horsepower as conventional milling, improves tool life, surface finish and chip evacuation. My personal experience with climbmilling on my own and other people's machines is that there are a couple of places where if done very carefully, it is OK to use climb milling in manual machining. The most significant is light finishing cuts on aluminum contours(eliminates recutting of chip), but NEVER roughing cuts. I have also found that when using a power feed on a mill with ball screws, it can be used to climb mill too, in other words, no CNC program required, just the gear head power feed. I have never experienced the problem of climb milling causing inertial runaway conditions, because I never allowed my machine to operate without being in control of the cutting. Those that do should review what they are doing to leave the machine in a loose condition. If you are manually machining on a mill, one axis is almost always locked in position. Axis locks may be the difference in my experience and those of others that have problems with manually machining on a machine with Ballscrews. Personally I much prefer the ball screws over the acme, as there is no backlash to account for & there is reduced effort required to move the table and workpiece loads.
Gotta throw this out too - there are lots of rumors about new Windows based controllers coming soon.
Best Regards, Fred Smith- IMService
Listserve Special discounts and offers are at: http://209.69.202.197/cadcamedmdro.html
imserv@... Voice:248-486-3600 or 800-386-1670 Fax: 248-486-3698