The spindle speed command -M03- cannot be trusted on benchtop mills. Incorrecly set RPMs can lead to poor surface finish, broken cutters etc. In order to measure spinde speed an RPM meter (tachometer) is highly recommended. The design turned out to be a bit too robust. If I did it again I would use a smaller sensor and thinner aluminum . As you see the electronics is still on a breadboard but the software is complete. The meter is quite accurate and it has been verified with a scope.
I decided to upgrade my original MaxNC spindle to the Taig ER16 spindle. The main reason was that the TIR (Total Indicated Runout) with the original spindle/collet combo was unacceptable. With a 1/8 cutter it was over .002 at nose.
Since TAIG supplies the MaxNCs spindle I didnt expect any incompatibility issues. Before ordering I had to let the TAIG guys know that the spindle was for the Max because the TAIG only has one threaded mounting hole the Max needs two. I had to bug TAIG for two months to send me a spindle with two mounting holes. I guess it doesnt worth for them to stock the modified spindle. It took about 7 working days to ship to Canada which is OK. I also ordered the (1040ER) ER 16 Collet Set 1/16, 1/8, 3/16, 1/4, 5/16, 3/8. I do not recommend buying the collet set from TAIG because one collet 1/8 the one I use the most was rusty. Each collet is individually sealed and packaged so this one must have been rusty prior to packaging.
As seen on the picture the spindle taper is bigger to accommodate the 3/8 collet. It looks definitely better than the original taper. It was quite a process to remove the pulley from the old spindle because the set screw which holds the pulley in place damaged the axis. The pulley sits very tight on top of the spindle and the tiny bits which came out from the axis when the set screw was originally screwed in made it very difficult to remove pulley. The new axis has a flat groove for the set screw. Once it came out I cleaned the inside of the pulleys hole with some very fine (grit 1500) sand paper. One thing to watch out for Max owners is that the new spindle has a threaded nut holding the top bearing in place. With the nut installed the motors pulley will not line up with the spindles pulley. So the nut had to come off. I didnt like this one.
TIR TEST
note: The test indicators accuracy is 0.0001 inch
I repeated all tests 3 times there was no significant difference between the 3 readings.
Old Spindle Taper
TIR is <.0005 Inch which is pretty good
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New Spindle Taper
TIR is <.0004 Inch not much difference to be fair its a bigger diameter taper
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Old spindle 1/8 cutter & old collet
TIR <.0025 Reason #1 why I wanted to get rid of this spindle/collet combo
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New spindle 1/8 cutter & new collet
TIR <.001 Inch I expected a bit better here. This collet was the rusty in the package when arrived. I am not sure that I've manager to clean it properly.
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Old spindle 1/4 cutter & old collet
TIR <.0005 very good!
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New spindle 1/4 cutter & new collet
TIR <.001 I never expected that my old spindles runout would be better than the new one!
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My conclusion is that the spindle upgrade itself didnt improve much on my situation with the exception of the 1/8 collet case. Maybe I was just unlucky with my original 1/8 colet being so crappy. It would be interesting to see the readings with more expensive collets.
Last Updated on Thursday, 08 July 2010 23:55
MaxNC Gibbs
Written by James Nagy
Friday, 25 May 2007 16:57
Gibbs are holding the moving tables tight. It takes a bit of practice to adjust the gibbs right. If the gibbs screws set too tight the motor will stuggle or stall. If they are too loose the table will wobble. Delrin gibbs slide better than the original aliminum pieces.
