Projects

Gear Mod RPM Increase

03/06/10 The first project I tackled was trying to boost the rpms of the stock mill from
it's max of 2250. The easiest way seemed to be just swapping the motor and intermediate gear. Unfortunately the shafts are different sizes, 10mm for the motor and 15mm for the intermediate shaft. I looked for some commercially available gears with the correct bores and the same no. of teeth but no luck. The motor gear is 20T and the Inter gear is 37T.
A direct swap would have given an output of about 7700 rpm which would be WAY too fast
for the bearings to handle anyway.
I went with (2) 36 tooth gears from qtcgears.com part # KSS1-36. One fit the motor already with it's 10mm bore but the Inter had to be opened up to 15mm. The motor gear had to have .125 faced off the flange and the Inter gear to a .200 thick flange. Setscrew holes added to both, keyways would be best if you could manage.
Max rpm was 4700 with this gear mod. The stock bearings are only good for about 4000 though so an upgrade to A/C bearings would be wise.

The problems don't seem to be related to any mills delivered before July 2010, mine has worked flawlessly. There have been a couple similar problems with the PM25MV mill from Precision Mathews early on even though it uses a different motor and controller.
Chalk it up to growing pains. I'm sure they will get it staightened out and all will be well.
In the event your're unlucky enough to have the same woes and don't want to wait on replacements or maybe you're just like me and looking for an upgrade, I'll list several alternatives here that will give the same or better performance from the mill. Most will require some modding to get them attached and running. After folks start doing the upgrades, I'll provide links and pics to completed motor/controller swaps. For right now they are mostly ideas of what could be done.

Motors

1. Buy a replacement from Grizzly if your warranty expires.
    Motor (#221) http://www.grizzly.com/products/G0704/parts/2 $71.25

2. Adapt an X3 motor, should be pretty similar in size and power to the original.
    Grizzly (#224) http://www.grizzly.com/products/G0463/parts/1 $215.50
    LMS (#3381) http://www.littlemachineshop.com $252.81

3. Swap in a treadmill motor, a popular choice for X2's and others. They can be found all
    over Ebay for less that $70, give great RPM and power. They usually need a bit of
    work to adapt to a mill including adding a fan for extra cooling. Search Ebay.
    Ebay Barkers Bargins $50
    Treadmill Doctor - New and Rebuilt Motors
    My treadmill motor test with the stock controller - http://www.youtube.com

4. Replace both with a VFD and 3 Phase Motor. Another popular choice for many mill
    owners. You get lots of power and complete variable speed control that can easily be
    interfaced with Mach 3 for CNC spindle control. Available in 115 and 220 Volt versions
    that don't cost that much especially if you can find a deal on a motor on Ebay or a
    Surplus Outlet. RPM isn't as high as other motors though.
    Automation Direct GS2-11P0, 1 HP 115 VAC $185.00
    Automation Direct GS1-21P0, 1 HP 220 VAC $133.00
    Automation Direct MTR-001-3BD36, 1 HP 3-Phase, 3600 RPM. $100
    Note : This is a huge motor as you can see on Teybers X3, we'll keep looking for a
    smaller one.

    Update: Paulsv found this one at Surplus Center, It's only 3/4 HP but much smaller.

5. Replace both with a BLDC package from Keling. They had a couple bugs with the
    circuit boards but those are apparently corrected. 2 sizes available 1.5 and 3 HP.
    The 1.5 HP should be well suited for the G0704, the 3 HP is huge and heavy and is
     more suited for a mill like an RF45.
     KL-1160_BLM Brushless Motor 1100W (1.5HP) / 6000RPM $219.95
     KL-1160_BLM Brushless Motor Driver kit $209.95
     KL-2260_BLM Brushless Motor 2200W (3HP) /6000RPM   $239.95
     KL-2260_BLM Brushless Motor Driver kit $229.95

6. Replace both with an RC Brushless Motor and Driver. There have been some people
    do this swap on Sherlines and Taigs but haven't seen one on a mill the size of the
    G0704 yet. They seem to have plenty of power and RPM for such a small motor,
    could at least be considered a good option for a High Speed attachment. This thread
    on Cnczone has some good links to suppliers and reviews of them. Cost seems to
    be around $100 - $200 for both for a large high amp motor and controller.
    Hobbypartz - one of the many RC stores with motors and controllers

7. Replace both with a large servo motor and driver, cost can be pretty low if you find a
    deal on Ebay or Surplus. You can also spend a lot for new but with an encoder, you
    could have feedback for spindle orientation with an ATC like the big boys.

8. Use a simple 1-Phase AC motor and a belt drive for basic on/off spindle speeds
    like on a Taig or drill press, not great but will get you going to make chips.
    You'd get 2 speeds using the Hi/Low selector.

   3400 RPM 1 HP 120 VDC PM MOTOR from Surplus Center, can be used as AC too.

   2 HP SPL. 120 VAC 3450 RPM COMPRESSOR MOTOR




Controllers

1. Buy a replacement from Grizzly if your warranty expires.
    Controller (#78) http://www.grizzly.com/products/G0704/parts/1 $63.25

2. Replace the controller with a KBIC 125 board which the original seems to be copied.
    KBIC-125 http://www.galco.com Add a HP resistor and a heatsink. $100.91
    Read the manual.

3. Replace the controller with a treadmill speed control. I've used one on my X2 for years
    now without trouble. You can still find some on Ebay.
    Treadmill Doctor