G0704 Belt Drive
G0704 Belt Drive RPMs
G0704 V-Belt Belt Drive
G0704 Quill V-Belt Drive
G0704 Quill V-Belt Drive with MAD Drawbar
G0704 Belt Drive Prints
The 15 Meg .zip contains 200+ files in .dxf, .stl, .pdf and .jpg formats for both the timing pulley and V-belt versions.
Now with the Quill Version that allows full use of the Quill!
Also includes the Drawbar wrench,Tach Pickup Mount,
MAD Drawbar, and a Spindle Spanner Wrench.
Now has Prints for the motor used on the PM20/25MV from Precision Mathews, the 1100 Watt BF30 Spindle Motor and the Nordic Track Treadmill Motor. 3D models too!. Also a  simpler Single Pulley design from premade timing pulleys.

Downloadable file only.
A link and password will be emailed to you within 24 hours.
 

Full Quill operation with the Belt Drive!
 
Visit our parent site Hossmachine.info!
  G0704 Quill Belt Drive Complete
G0704 Belt Drive Prints
Downloadable file only.
A link and password will be
emailed to you within 24 hours.
   G0704 Spindle Bearing Replacement
High Speed Spindle Grease

Use Kluber Isoflex NBU-15
50 gram tube - $22.45

Search the Kluber Shop Online
for the Isoflex NBU-15, you need
to create an account to see the pricing and order. Note: The bearings need very little grease,
.5cc for the upper and 1cc for the lower bearing. A small syringe does well for applying the grease.

Notice:
These plans are intended for the DIYer. Access to a lathe and mill are required. Novices with very limited experience should get the DVD-ROM version.
Attention:
These plans were designed for the G0704.
Attempting to use on any other BF20/25 type mill is "Use At Your Own Risk"
There are small differ-
ences between the models which would require slight
modifications to the parts.
Compare the prints to your machine before you start.

 
Note:
I suggest trying to use the stock bearings first especially if they have been broken in for several weeks. The manufacturers use different suppliers and the quality can differ between mills. Yours may work fine at speed whereas mine overheated
My stock bearings in my X2 are still in use at
6000 rpm where others have burnt up at only 4500. It's a crapshoot. 
Bearing Upgrade

Replace the upper and lower stock tapered roller bearings with Angular Contact bearings. The stock bearings are only rated for about 4000 rpm.
Note: You'll need to make a 50x62x4mm spacer for the lower bearing,
and 25x36x3 for the upper, aluminum would be fine. The stock bearings
are thicker than the A/C's and the spacers are needed to fill the voids to have enough threads on the spindle to apply preload.
You can buy shims from mcmaster.com that should work instead.
part# 98089A404 25x36x1mm $7.39 for a pack of 10
part# 98055A435 50x62x1mm $4.22 for a pack of 5

Update: I thought of a better way to shim the lower bearing so that the retainer would screw back into the quill close to it's stock depth, (it sticks out a little when tightened against the lower bearing as I did it)
Use a 35x45x4mm shim that would go on the spindle first below the lower bearing instead of the 50x62x4mm on top of the bearing as described above. You can buy shims from McMaster.com that would work instead.
part# 98055A346  35x45x1mm $7.66 for a pack of 10
Check out Michael's thread starting on post# 234 for more details.

VXB.com
7007B Bearing 35x62x14 Angular Contact - lower bearing - $12.95
9500 rpm limit with grease, 3934 lb. dynamic load, .0004 runout - ABEC1
7005B Bearing 25x47x12 Angular Contact - upper bearing - $9.95
13,000 rpm limit with grease, 2540 lb. dynamic load, .0004 runout - ABEC1

Bearings Direct
7007C Precision Ball Bearing 35x62x14 - lower bearing - $25.45
16,000 rpm limit with grease, 3870 lb. dynamic load - ABEC1
7005C Precision Ball Bearing 25x47x12 - upper bearing - $18.59
22,000 rpm limit with grease, 2370 lb. dynamic load - ABEC1

High End ABEC-7 Bearings
BNH007TU Nachi Angular Contact 35x62x14 - lower bearing - $140.19
25,000 rpm limit with grease, 2607 lb. dynamic load, .0002 runout - ABEC7
7005CYP4 Nachi Angular Contact 25x47x12 - upper bearing - $110.35
22,000 rpm limit with grease, 2900 lb. dynamic load, .0002 runout - ABEC7

Also consider Deep Groove bearings
VXB.com
6007-2NSE Nachi Bearing 35x62x14 - 6800 rpm - lower bearing - $11.03

6005-2NSE Nachi Bearing 25x47x12 - 9500 rpm - upper bearing - $7.57

A Double Row lower bearing for extra strength, retainer may not fit using this bearing. Try at your own risk.

35BG06G-2DS A/C Compressor Ball Bearing 35x62x21
- $28.89
Read the Belt Drive Info Page.
All Sales Final!
Do yourself a favor
and get the
DVDROM version, there are many more detailed pics and installation videos to help you for not much more money.
Notice: It may be beneficial to upgrade the stock radial bearings on the gear assembly, parts 205 and 207 in the parts list. http://cdn0.grizzly.com/partslists/g0704_pl.pdf especially if you want to exceed
6500 rpm with the belt drive. You can replace them with some good Nachi bearings from vxb.com. The parts list incorrectly lists the lower bearing 207 as a 7007 bearing which is an Angular Contact bearing, it actually uses deep groove bearings so a 6007 bearing.

Upper bearing (205) 6209ZZ
vxb.com 6209ZZE, kit9569, 45x85x19, 7800rpm deep groove - $23.77

Lower bearing (207) 6007
vxb.com 6007ZZE, kit9537, 35x62x14, 12,000 rpm deep groove - $15.49