Reply with QuoteI have seen on VMCs a spindle speed booster. Some are mechanical. Some are air driven. Used with very small tools for high RPM, with very small loads. Application was graphite electrodes for die sinking machines.
George
More RPM's from a V2XT
V2XT, 2hp motor. 4200 max spindle RPM. Is there a way to get more RPM (7500) or so? Can the spindle bearings handle it? Some kind of upgrade?
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I have seen on VMCs a spindle speed booster. Some are mechanical. Some are air driven. Used with very small tools for high RPM, with very small loads. Application was graphite electrodes for die sinking machines.
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Maybe. Many standard bearing types are now available in ceramic versions that will handle higher RPMs. Check the bearing numbers used on your spindle and see if you can get ceramic replacements for them. Check the RPM limits on both the original and replacement bearings to see if they really can take this higher RPM.
mcmaster.com lists some of the ceramic bearings as will any large bearing house.
To get this overspeed you could use a VFD on the motor. If the motor is currently running at 1750 you could probably go 2 times overspeed without failure but the HP will be reduced to about 1/3 of normal. If the motor is running at 3400 already I would'nt try to spin it any faster than that.
Be very careful and proceed slowly when you try this. The fact of the matter is that your spindle really wasn't designed to run this fast so you need to try this in small steps an very carefully.
Balance of the spindle, motor and tooling becomes a much larger issue at these higher rpms. Please don't sue me if something blows up and hits you in the face.
Paul T.
What is a VFD?Originally Posted by titchener
VFD stands for Variable Frequency Drive. It gives you continous speed control of 3 phase motors. For units at 3HP and less it will also generate true 3 phase output from a single phase power input, like a rotary phase converter but including the speed control.
On my mills I have the VFDs set to run from 12 hz. output up to 120 hz. output, giving me a 10 to 1 speed range control. At 120 hz. out the motor runs at double normal speed, but like I said earlier, with HP reduced to about 1/3. At lower speeds you lose HP also, but its still great for things like tapping, and the VFD gives you instant controlled reversing of the spindle (smoothly decellerates then reverses and accelerates).
I got my 2HP VFD from www.dealerselectric.com . I have 2 of their Westinghouse/Teco models and they work well. The manuals suck but there is an 800 number with a pretty helpful tech guy available. If you go for a VFD make sure to buy the optional braking resistor, about $25 extra. This allows you to automatically brake the spindle in about 1 second.
Don't stick one of these on your mill and go double speed without upgrading your bearings, they'll probably overheat and fail.
Paul T.
Hi did you get your board problem fixed if not I know someone that mite beable
to help I know he has a good supply of most Bridgeport parts, you can fax him your
phone # Fax 765 332 2788
Also about your spindle you can run it at 6,000 to 6,500 rpm with no problems
I run mine at 6,000 ( Boss 5 ) I did rebuild and removed most of the Bridgeport drive
components
mactec54
No, board not fixed, Ill include a pic of it. Really like to know how you got that kind of spindle speed. I dont use the mill to make a living but I cut a lot of wood and aluminum on it and just have to feed pretty slow.
Hi I have 2 photos of my Boss5 this has the 2hp Bridgeport motor with all the outer covers removed, This works better for the motor with the VFD drive the fan is also removed as has no air flow at low RPM It has a fan on top of the motor housing plus encoder on the spindle,It also has a 7" disc brake and is 1-1 drive The head also has
5.5" removed out of the top
mactec54
higher speeds
I think cooling might be your biggest problem with running the spindle faster. Most of the high power production cncs have actively cooled spindles. As long as they are well lubricated and don't overheat, most ball bearings should be capable of at least 6000 rpm (generally faster). If someone has the part numbers of the spindle bearings on hand, it is pretty trivial to look up the manufacturer's rated max rpm for them.
The next question of course is if the belt drive variable speed can handle the higher speed... anyone ever tried this?
james
I seem to have somthing messed up can't get the photo uploaded I will
try again mybe somebody can help me with this
Hi I think I have got it the photo mite be to small now
email me and I will send the full size
mactec54
Last edited by mactec54; 11-10-2005 at 03:27 PM.
Pretty sure new bearings could handle the rpm's but I too wondered if it would cook the belt drive. More rpms would sure make the finish alot nicer.
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