Ok. So I have been battling terrible vibration problems for some time with my spindle and pulley drive setup and a while back I had drawn up plans to change from the timing pulley setup to a multi rib poly v type pulley as they seem to work really well with higher RPM and run very smooth and have long life spans. My spindle finally got bad enough to require another set of bearings so I figured it's now or never.
So I went ahead and started the project this week. And have finished the pulleys as seen below. I used my G0704 setup like a Lathe to make the pulleys and used a SVVCN neutral Lathe tool holder with a 35deg diamond Point to cut the grooves which are a 40deg angle. It is tight in there and a cringed a bit on the G0704 when it made its final pass bit it worked out great in the end. I was able to keep run out to .001" which I think is significantly better then the previous timing pulleys used. I designed the spindle pulley to drive the quill barrel to keep the load on the spindle as close as possible to the larger body and keep any twist from occurring from driving it at the top.
While working on this project I started using Instagram.. I know I know.. I'm a late comer bit better late then never and conveniently enough happened to be the perfect time. I found a G0704 owner who may be on here as well?? his call sign on Instagram is @bens.Benz if you are on here I can't thank you enough for your ingenuity and to others reading, I recommend following him as he is quite the inspiration with this platform!
He used a phone app called "vibration monitoring" which uses the phones accelerometer to show imbalance from vibrations and a balancing ring added to the spindle just under the retainer on the bottom of the spindle to dial in the balance of the spindle while fully installed and under its own power. Very clever indeed. He used a jewelers scale with .01g divisions and an excel spread sheet available for download by searching "Conrad Hoffman Balance" on Google, showed up as the top result for me.
He ran the test with the ring rotated at 0, 120, 240 degrees (120degree increments) and exported recorded data from the vibration monitoring app into the spreadsheet and with some trial and error and removing discretionary weight as defined by the spreadsheet from the balancing ring (measured on the jewelers scale for accuracy) was able to balance his spindle so that it was silky smooth and quiet even at 13,000rpm!!!!
Maybe he will come in here and explain any items I missed, I will let him know I started this thread.
Linked below is his Instagram post.
https://www.instagram.com/p/9myfKxRz0U/
https://www.instagram.com/p/9myfKxRz0U/
Hopefully it works, never tried linking to Instagram before. I plan on documenting my efforts to replicate his work once my Belts and bearings arrive and will update e this thread with my progress!
Below are the pulleys I made as well as a short video of the last bit of groove cutting performed on the G0704 in transformer Lathe mode...lol. Sorry the video is so short but I didn't think to film it until it was almost done cutting. I used the J series groove profile since it was a little lighter weight then the automotive K series and was able to get a 6 groove in no problem and shouldn't have as much problem with the belt weight adding to vibrations. In retrospect and in future designs I think I will grind a custom tool from HSS and make a dual ratio setup, bit with the 12x12mm SVVCN tool it would have added ~.25" height from being able to get the tool on the smaller diameter step of the pulley. So once I finish converting my new 3 in 1 17x31 Lathe mill combo I may have a go at making a dual ratio drive. For now I just want to eliminate vibrations and noise and finally be done with bearing failures.
So here you go!
https://youtu.be/QucGaWH7fQI
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