Yes they are commonly found metric threads. I made an aftermarket edge guide for mine. I purchased allen set screws, with a bronze tip insert from McMaster Carr.
I can't get to my base at the moment. It is in storage due to me moving. I was not able to locate thumb screws. I was more concerned with marring the "drill rod"
guide rods, also bought from McMaster Carr. They are sold in pacs of 5. I remember taking mine to a hardware store to find the pitch of the threads, as mentioned by Theo above.
Im sorry that I can't remember the size to give you.
Ellery Becnel