Andy.
I believe they used to use lignum vitae wood as guides on bandsaws.
Very hard & self lubricating.
Here is a source :-http://www.turners-retreat.co.uk/timber/pen-blanks/5-8-blanks/lignum-vitae-5-8-x-5-8-x-5
Or crown green bowls are a good source as well, but you will need a bandsaw to cut it 
Ian
Edited By ian j on 22/02/2016 15:26:24