Doug W
Hot Rolled
- Joined
- Sep 22, 2003
- Location
- Pacific NW
I picked up a Van Norman #12 milling machine about two years ago and have been slooowly refurbishing it. The spindle had the odd ball 5V taper. I received no tooling with the mill so I was considering options for changing the taper to something more common.
I got a very lucky bit of inspiration when I was at the local flea market and found a guy selling an quick change Erickson R8 (external) to 30 NMTB adapter, the wrench, nine collet holders and about 25 various size collets for $100. He had dragged them to the flea market several times and never had a nibble. What luck!
I tore down the spindle assembly and discovered the factory spindle was a little chewed up where the seals rode and someone replaced the class 3 tapered bearings with class one. The bearings were rusty any pitted anyhow. In fact I replaced all the bearings in the machine and knew that the spindle bearing would probally need replacing anyhow.
I researched what material to use for the spindle on this and other boards. I took the original spindle down to the heat treat shop to get their opinion. They hardness tested it and we were both suprised at the results. Basically the hardened skin on the factory spindle was so very thin that the diamond simply broke through and never would give a reading over 25C. Eventually I decided to use 4140 annealed and then harden it to 54C to 56C. $50 so far.
So I planned on using the 30 NMTB taper and the threaded quick change lock ring feature off the Erickson adapter. This would allow me to have quick change or use the drawbar. I also found 30 NMTB arbors were reasonably priced. The Van Norman is a horizontal and vertical mill.
I sweated out machining the shaft. I do mean sweated! I am no machinist, just a weekend warrior. It took me about 40 hours. My usual mistake of cutting undersize was avoided by measuring everything with a mike and dial calipers before taking another cut. I turned the bearing diameters 0.030 oversize for finish grinding.
Off to the heat treat shop. A day and $50 I had it back and was off searching for a guy to grind the internal taper and the bearing seats. I read Forrest's opinions about home grinding or turning a spindle and other than a few seconds of delusion about trying the grinding with a toolpost grinder it never crossed my mind. Honest Forrest
Finding someone to grind the internal and external in Phoenix was a little difficult. As I mentioned I am not in the machine shop business. Any way 3 months later and $400 I have got it back and it looks great. Couldn't tell you about how accurately it is ground because I don't have mikes that measure to tenths in that size or probally couldn't repeatably and accurately measure it if I did.
Total cost $500 minus selling off seven of the collet holders for about $75 each.
Now if I could only figure out how to post a picture
I got a very lucky bit of inspiration when I was at the local flea market and found a guy selling an quick change Erickson R8 (external) to 30 NMTB adapter, the wrench, nine collet holders and about 25 various size collets for $100. He had dragged them to the flea market several times and never had a nibble. What luck!
I tore down the spindle assembly and discovered the factory spindle was a little chewed up where the seals rode and someone replaced the class 3 tapered bearings with class one. The bearings were rusty any pitted anyhow. In fact I replaced all the bearings in the machine and knew that the spindle bearing would probally need replacing anyhow.
I researched what material to use for the spindle on this and other boards. I took the original spindle down to the heat treat shop to get their opinion. They hardness tested it and we were both suprised at the results. Basically the hardened skin on the factory spindle was so very thin that the diamond simply broke through and never would give a reading over 25C. Eventually I decided to use 4140 annealed and then harden it to 54C to 56C. $50 so far.
So I planned on using the 30 NMTB taper and the threaded quick change lock ring feature off the Erickson adapter. This would allow me to have quick change or use the drawbar. I also found 30 NMTB arbors were reasonably priced. The Van Norman is a horizontal and vertical mill.
I sweated out machining the shaft. I do mean sweated! I am no machinist, just a weekend warrior. It took me about 40 hours. My usual mistake of cutting undersize was avoided by measuring everything with a mike and dial calipers before taking another cut. I turned the bearing diameters 0.030 oversize for finish grinding.
Off to the heat treat shop. A day and $50 I had it back and was off searching for a guy to grind the internal taper and the bearing seats. I read Forrest's opinions about home grinding or turning a spindle and other than a few seconds of delusion about trying the grinding with a toolpost grinder it never crossed my mind. Honest Forrest
Finding someone to grind the internal and external in Phoenix was a little difficult. As I mentioned I am not in the machine shop business. Any way 3 months later and $400 I have got it back and it looks great. Couldn't tell you about how accurately it is ground because I don't have mikes that measure to tenths in that size or probally couldn't repeatably and accurately measure it if I did.
Total cost $500 minus selling off seven of the collet holders for about $75 each.
Now if I could only figure out how to post a picture