I have owned a new tumbler from the Jar Doctor for the last 10 years, but I still haven't used it (too many surgeries.) I am ordering the pulley belts and the manuel now.Tape the pontil over with ,usually duct tape works. I use 3/4 teaspoon on the inside and 11/2 on the outside. I bought my machine from Jar Doctor and its been running perfect for 5 years. He is without a doubt the best to deal with. The motor runs at one revolution per second so if you do the math you are 3600 per hour and 86400 per day. I usually tumble early squats so its around three days or 259200 revolutions per bottle. You can switch the tube from end to end for even polishing. I get excellent results with early bottles.Its a learning curve for sure,newer stuff like flint glass I have found is much harder to get good results. I dont collect crown tops so my experience is really with old green glass in the 1850-80 range. Hope this helps ,B
I usually go with the slower RPMS, even with my sodas. I once tumbled a pontiled A.P. Smith, it took 6 weeks. I taped the embossing with duct tape until the end when I did the final polishing tumble. Yeah, I had dug 8 Charles Clarks and one A.P. SMITH . One yellow /amber Charles Clark broke while tumbling (bummer!)
I am lazy, so I have a reverse on my motor.
Tumble mostly 1840 -70 bottles. I have tumbled flint glass and they were a little harder. Never tumbled anything past 1870-80.
I do using different cutting grits to hasten the process, but very carefully.
Your being able to do the math in regards to revolutions is smart and is dizzing (for me.)
I have about 15 mustards that I am going to start tumbling for practicing until I feel confident about doing it again.
Here is the picture of the 6 week tumbled light cobalt A.P. SMITH.
Thanks for the email, it was helpful.
opmustard