My recent experience with the Gyros #78 drill bits I bought through Amazon was not good. They broke on the second hole I drilled with each bit. Earlier purchases of Gyros drill bits were ok as they would last 15-20 uses. Even buying a recommended Starrett pin vise did not help. It works much better with some older #78 Gyros I had on hand.
I used to buy from Otto Frei (ouch that rhymes) before the Pandemic as they are local in Oakland and I could order and they drop by for pickup avoiding shipping costs. The drill bits were fairly long lasting.
The thicker shaft on the GMAUVAIS bits at MSC looks like a possible solution to constant breakage. I will put together an order in the near future for 10 packs of 77/78/79 bits and see if shipping is not prohibitive. -- Ken Adams Omicron BA2.2 may come and go but I still live mostly in splendid Shelter In Place solitude Location: About half way up Walnut Creek Owner PlasticFreightCarBuilders@groups.io
