[springer-]

I am looking to fit a Jet JMD-18 mill/drill with a CNC system. I would also like to replace the original 2 HP motor with something I can control the speed on with the CNC system.

I have been looking at kits on eBay and I have no idea what I should look for. I understand the difference in a stepper vs servo and I'm thinking the servo would be a better system (??). Can I use a servo with a direct drive or will I have to use some sort of reduction system?

Any suggestions would be greatly appreciated.

Here is a link to the Jet JMD-18 manual if additional info is required .... http://content.wmhtoolgroup.com/manuals/m_350017.pdf

[springer-]

Seems the question was too hard. Maybe this would be an easier question ... can someone recommend a good forum to ask questions on?

[Bubba]

To answer your last question first, a better forum might be the:
Benchtop Machines
As it says in the header "Discuss all mini mills sherline, taig, square column, round column and CNC mill conversions here!"

As for replacing the motor, I would suggest a 2 HP 3 phase with a VFD as the controller. I put one on mine several years ago and it works great. Mine is also a round column like yours (only an RF) and what I did was to mount the motor slighly lower such that the top pulley was lined up with the second one down on the jack shaft. Now, the top pulley on the jackshaft is belted "permanently" to the top of the spindle and I use the top and third down on the motor to have overlapping speed ranges of 115/1120 and 410/3900 with just the one belt change.
It is nice to have to worry about just one belt change and the easy one at that!

As to cncing this machine, I don't think you will find any "kits". When I did mine, I took things apart to measure them and then assembled it to make the necessary parts. While your machine looks the same as mine, I don't know for sure that it is. I would assume your going to replace the lead screws with ball screws?? When I first did mine, I used the original ones and within weeks had to replace them as the slop in the nut got so bad that backlash was on the order of .25"! Personally, I also prefer servos and generally, you will find them used with a reduction system. This way, you multiply the available torque and servos can run much faster than most steppers. Also to my way of thinking, it makes mounting easier as a belt drive is more tolerable to miss alignment than a solid coupler.

If I can help further, please let me know.