[GreatNorthGnome]

Hey guys, havent been around here for a while. Main motor died on my mill a couple years ago, so I came up with big plans of building a high speed spindle and custom head for it. I welded up a frame, got some bearings ordered, had a plan for an r8 spindle. Machined a few parts... then I lost all motivation and its sat in pieces collecting dust looking sad.

Been really missing the little guy! Can use the HAAS mills when ever I please, but I want my mill back.

Out of the blue I got struck by a massive wave of inspiration. Over a year ago I bought a 1.5 hp 4900rpm treadmill motor and KBMM driver, figured if I wanted to get this back up and running I need to dumb things down a bit and make it more realistic for my busy schedule. So I scraped the custom head idea and decided to use my existing head, smart! Things have come together beautifully.

Learned some interesting things about this BusyBee model craftex CT129 once I took it apart. General consensus on the G0704 and BF20 mills is you're limited to 4000rpms due to the lower taper bearings in the quill. The CT129 has an mt2 spindle taper, the lower bearings are a 32005 taper roller bearing, and after a long time searching for this particular bearing it seems they sit around 8000rpms with grease lubrication. The CT129N mill has an mt3 spindle taper so it might be different.
I didn't look into the two larger ball bearings in the gear assembly since I removed that all together.

So for the sake of doing so I got some new nachi 32005's in the quill and began reassembling the head. Idea was to lock the quill in place, and add a support bearing to the top of the spindle for belt drive. Origionally I wanted to be lazy and use a couple set screws on the side of the head locking the keyway in the side of the quill. But I discovered anything more then light pressure on that keyway causes the bearings to bind slightly.
I drilled and tapped the face to lock it in place, used a couple nordlock washers. Solid
The driven pulley on the spindle also acts as a bearing fit for the upper support bearing which is a nachi 6005. Used opposing set screws to hold it in place between spindle splines, nice little aluminum bearing carrier in the top of the head. And to my surprise the stock machine work on this head is fairly good since everything lined up pretty good.
Goal is 6-7000rpm max speeds since I only machine aluminum and brass.

The motor mounting is kind of a temporary situation since I'm not 100% confident in this motor. Plus It did not occur to me until after it was mounted, that it was spinning my tool in the wrong direction :tired: Ahh the important little things... Reversed to polarity, not sure how long the brushes will last. But its running, and I at least have a good spindle set up for a better motor alternative.
Attachment 251042
Attachment 251044
Attachment 251046

Couple new additions to the mill, I have ball screws on all three axis. Added some oil retaining grooves on some dovetails, and a few misc other little things. Can't wait to wire it back up and get it running

Anyway, theres my little spindle project. Thought I would share.

[GreatNorthGnome]

Really happy with the results. On the stock motor geared for 4000rpm I didn't have much power. Was basically limited to 10-15ipm for any hogging in aluminum.
Been taking some .060 deep cuts at 35-40ipm with no issues.
I think a big help is how rigid the spindle is now compared to before also. Not sure what rpms I'm running since I don't have a tach set up yet, but she's got some good speed
Still going to find another motor with perpindicular brushes to keep on hand as a back up though.