My very first pen
- Thread starter hesperaux
- Start date
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Paul in OKC
Member
Heck of a way to start! Nice!
egnald
Member
Very Cool and of course Congratulations. First's are always special. Thanks for sharing. - Dave
Jim15
Member
Great work.
Great first pen!
Go easy on the speed when buffing, remember that the lathe speed is at the spindle, so a 6" or 8" buffing wheel has a significantly higher relative speed to the material you are buffing! Delrin is soft so it will melt even faster than other synthetics like Alumilite. Just FYI, I use 8" buffing wheels and run the lathe at 1100 to 1200 rpm.
Go easy on the speed when buffing, remember that the lathe speed is at the spindle, so a 6" or 8" buffing wheel has a significantly higher relative speed to the material you are buffing! Delrin is soft so it will melt even faster than other synthetics like Alumilite. Just FYI, I use 8" buffing wheels and run the lathe at 1100 to 1200 rpm.
egnald
Member
David Bondi (d_bondi) is spot on regarding buffing speeds. The rule of thumb that I've always followed for buffing plastics has been to use between 1,200 SFPM (Surface Feet per Minute) and 4,000 SFPM. The calculation for converting RPM and wheel diameter in inches I use is SFPM = Diameter inches x RPM x 0.262 (there is some rounding error).
The PSI Acrylic Pen Buffing System uses two, 4" inch wheels and recommends running the lathe at 1,200 RPM to 1,700 RPM. Applying the formula it yields 1,258 SFPM (Surface Feet per Minute) to 1,782 SFPM.
The PSI 3 Step Lathe Buffing System uses three, 8" inch wheels and specifies about 3,000 RPM. The calculation yields 6,288 SFPM. This is too fast for my liking as it could lead to excessive heat, and it is outside of my rule of thumb for buffing plastics.
The PSI Probuff Buffing and Polishing System uses 4" inch buffing wheels and has a variable speed controller that operates between 2,000 RPM and 7,000 RPM. The SFPM calculation comes out at 2,096 SFPM to 7,336 SFPM. Although it can run up to 7,000 RPM, I would recommend running it on the slower side to keep the SFPM within my rule of thumb for buffing plastics.
I personally use a Rikon Model 81-608 8" Low Speed Buffer, but I use it with 6" inch wheels. It runs at a fixed 1,750 RPM so with my 6" inch wheels it runs at 2,751 SFPM. (The standard 8" inch wheels that came with the buffer push it up to 3,668 SFPM). This puts the 2,751 SFPM that I use very close to what Dave Bondi should be getting with his setup. However, even running at this speed I have still had rare occasions where I've started to melt my blank.
Best Regards,
Dave
The PSI Acrylic Pen Buffing System uses two, 4" inch wheels and recommends running the lathe at 1,200 RPM to 1,700 RPM. Applying the formula it yields 1,258 SFPM (Surface Feet per Minute) to 1,782 SFPM.
The PSI 3 Step Lathe Buffing System uses three, 8" inch wheels and specifies about 3,000 RPM. The calculation yields 6,288 SFPM. This is too fast for my liking as it could lead to excessive heat, and it is outside of my rule of thumb for buffing plastics.
The PSI Probuff Buffing and Polishing System uses 4" inch buffing wheels and has a variable speed controller that operates between 2,000 RPM and 7,000 RPM. The SFPM calculation comes out at 2,096 SFPM to 7,336 SFPM. Although it can run up to 7,000 RPM, I would recommend running it on the slower side to keep the SFPM within my rule of thumb for buffing plastics.
I personally use a Rikon Model 81-608 8" Low Speed Buffer, but I use it with 6" inch wheels. It runs at a fixed 1,750 RPM so with my 6" inch wheels it runs at 2,751 SFPM. (The standard 8" inch wheels that came with the buffer push it up to 3,668 SFPM). This puts the 2,751 SFPM that I use very close to what Dave Bondi should be getting with his setup. However, even running at this speed I have still had rare occasions where I've started to melt my blank.
Best Regards,
Dave
Another comment on buffing. Use LIGHT pressure, we aren't grinding here, just buffing. It truly only takes a little pressure to get the results you need.
Also... Less pressure = Less friction = Less heat, which also means less likelihood of shooting a pen component across the shop into a hard surface.
Also... Less pressure = Less friction = Less heat, which also means less likelihood of shooting a pen component across the shop into a hard surface.
