Interesting thread. Perhaps I could shed a little light here because I was the guy who created the Sierra conversion.
When the sierra pen was introduced in the latter part of 2005 or the early part of 2006 (my memory is a little hasy on the exact time) I thought it would be the perfect kit for a pen & pencil set because 1 blank could make both so the chances of a good match would be increased. It also seemed to be a good fit in either a man or woman's hand so I thought that my chances of selling to men & women would be increased. I also wanted to see if I could make the conversion so that the pen was not "damaged" and could be converted back to a pen if you so desired and I believe that I succeeded in that aspect. In addition, I wanted to create a design that was simple enough that a person who could follow basic directions could make the conversion with a minimum of tools so that I could give back to the community that taught me so much. I believe that I also succeeded there.
My target buyers were the Doctors, Lawyers, Dentists & Engineers who I normally sell to. We all know that Engineers never make mistakes so an eraser is not necessary for them

. You usually cannot read a Doctors or Dentists handwriting anyway so you would never know that they made a mistake and an eraser is not necessary. A lawyer would not be able to erase a mistake because that would be altering a document and we all know how honest they are

so an eraser is not necessary. So, for my targeted buyers an eraser was not a necessity and it was left out. :wink:
My biggest selling point with the set was that If you wanted a pen & pencil set you had one in the size of the sierra, which at the time was the smallest pen with the exception of the atlas & the original wall street pencil which I believe was only sold by woodcraft and had a cross mechanism which I did not care for. Oops, I got off the subject. My selling point was that you could have a pen & pencil set or you could remove the pencil mechanism and could put the ink refill back in and have two pens (read as His & hers set). That worked very well when the wife was standing right there. Truth be told, I did find a way to attach an eraser to the sierra kit but It was far beyond what the average pen turner had available to them as far as equipment was concerned so I never published it. I did have a guy who took my conversion and began competing directly with me when I was selling at shows so when people came to me asking why his pens were $10- $15 less than mine I pointed out that his did not have an eraser and mine did. However I found that the pencil with an eraser did not sell that well for me because of the added costs in converting to the eraser and the fact that it was no longer a "convertible pen" I abandoned that design rather quickly.
You also have to remember that this all happened back in 2006 and since the pen turning world has progressed by leaps and bounds since then I think this is probably outdated information. As Don pointed out you can now get a sierra pencil (I think it comes with an eraser) from many suppliers so my conversion is no longer necessary to create a sierra pencil.
I hope that I might have inspired someone out there to experiment and see what they could produce.
Kevin,
I like your conversion and if you would ever like to discuss anything about the conversion please feel free to drop me a line and I would be happy to discuss.