Belt drive X3 conversion. New motor too?

[Thorpydo]

Hey,

I'm planning a belt conversion for my X3. The gearbox will be bypassed and I plan to have the max spindle be at least 5000 rpm. I run flood coolant and will be running it through a heatsink mounted on the head.

My question is, should I buy a more powerful motor and VFD while I'm at it?

I'm in the dark when it comes to VFDs. Does a VFD act like a gear ratio in a sense; when VFD slows the motor down, the motor gains torque. That's a big gain for me. I'd like to not have to change belts.

Could the X3 even use more power or will rigidity become a problem?

Thanks
Adam

[Matt McColley]

everything you want to know and more....
http://en.wikipedia.org/wiki/Variable-frequency_drive

in short, digital switching turns the imput power into a variable frequency (most often constant voltage) three phase signal.

this is used to supply a synchronos three phase (brushless) motor that turns at the same speed as the frequency of the supplied power.

advantage of brushless..... quiet

advantage of 3 phase...... low starting torque, smoother operation

advantages of variable frequency..... variable speed with constant torque

[HimyKabibble]

Originally Posted by Thorpydo Hey, I'm planning a belt conversion for my X3. The gearbox will be bypassed and I plan to have the max spindle be at least 5000 rpm. I run flood coolant and will be running it through a heatsink mounted on the head. My question is, should I buy a more powerful motor and VFD while I'm at it? I'm in the dark when it comes to VFDs. Does a VFD act like a gear ratio in a sense; when VFD slows the motor down, the motor gains torque. That's a big gain for me. I'd like to not have to change belts. Could the X3 even use more power or will rigidity become a problem? Thanks Adam

No, you don't get torque multiplication - ever. A good (i.e. - expennsive) "sensorless vector" VFD will maintain constant torque down to lower speeds. The more common, and cheaper, VFDs lose torque at lower speeds. With a VFD, you still end up needing at least two blet/gear ratios to cover the entire operation range from very large tools (flycutters, etc. to very small (1/16" endmills).

I suspect the stock motor has about as much torque as the machine can support. If you already have a variable speed DC drive, there's little to be gained by going to a VFD.

Regards,
Ray L.

[pzzamakr1980]

What I did was purchase a much better DC Drive and paired it with a big 2.5hp motor. I run belt drive with only one ratio and go from 500rpm to 6900 without any issues. The motor is a good quality dayton, not some cheap chinese junk. On aluminum nothing will slow the motor down except drills bigger than 1/2in or using a 2in face mill full diameter and big DOC. On harder materials I have to be more conservative but not much.

[cadmonkey]

Originally Posted by pzzamakr1980 What I did was purchase a much better DC Drive and paired it with a big 2.5hp motor. I run belt drive with only one ratio and go from 500rpm to 6900 without any issues. The motor is a good quality dayton, not some cheap chinese junk.

Any details on model #'s ? I looked through the Grainger catalog and didn't find anything that seemed like it would fit the bill (a while back) and to the best of my recollection they carry pretty much all the Dayton motors. Where did you get the speed control? Is it a servo motor or a treadmill motor? Sorry for all the questions but I'm very interested in putting a bit more HP on my X3 and getting a higher top speed, without loosing too much of the bottom end. (Eliminating the gear train is also VERY attractive)

Thanks for any info you can share.

[pzzamakr1980]

No problem about the questions. I used a few different dc drivers, I finally settled on one that runs pumps at precise flow levels or motors at precise rpms. Its called the m-drive made by fenner-contrex. Look on ebay under m-drive and a few will pop up. It's precise, reliable, and digital which is cool looking and easy to use. There is an analog input that allows 0-10vdc metering so mach3 can control it. I will have to check on the exact motor, its a brushed 2hp motor, and was a great ebay find. At the time the seller had 5 more available so I will find the exact model and get it up here tomorrow.

What also worked well is the dc drive through surpluscity? or whatever surplus outlet everyone goes to online. The drive has been linked to a number of times on threads throughout this site. Its the 180vdc drive without enclosure that uses basic voltage and amperage feedback to control the motor. That one is cheap and seems to be very popular. 70 dollars I think, and you can set it up to be controlled by the computer with a separate board.

Cad, or anyone else, if you would like I have another m-drive available that I would part with to a cnczoner cheapish. It works perfect and has just become extra since I now use a gearhead lathe instead of a belt drive. Let me know via pm. I even have an extra sensor for rpm feedback.