[Bonetools] bone details with screw thread

[Heidi Luik]

Dear all,

My colleague from Tartu asked me about some small bone details with 
screw thread. These probably come from the 18th-20th century context. 
I have some similar pieces from Tallinn also. In Tallinn they are 
from mixed layer, but 18th-19th century looks most likely here too. 
My colleague would like to know if such objects could have earlier 
date also, and when screw thread cutter was introduced. I hope maybe 
some of you has more experience with such things or maybe you can 
suggest some publications about the topic.
(I have found some similar objects in the book: Vilsteren, V. T. van 
1987. Het Benen Tijdperk. Gebruiksvoorwerpen van been, gewei, hoorn 
en ivoor 10.000 jaar geleden tot heden. Drents Museum, Assen.)
In the attachment are some photos of such objects.

Thank you in advance,
Heidi
  
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