Karl for the most part the only difference in the bits is size. I do not know how available #70 to #59 drill bit sizes are for the Irwin branding at the Ace Hardware you shop at. The bits carried by the scroll saw retailers such as Wooden Teddy Bear are sized to fit the blades we use however like any drill bit that is small like those are forcing ti to cut faster than it can handle, bending it while drilling, etc will break them no matter who the manufacturer is. Personally I use Mikesworkshop.com. the following are available - Size Millimeters Inches #42 2.3749 .0935 1/16" 1.5875 .0625 #55 1.321 .052 #56 1.181 .0465 #57 1.092 .043 #59 1.041 .041 #60 1.016 .040 #63 .94 .037 #64 .9144 .036 #65 .889 .035 #68 .787 .031 #70 .7112 .028 #71 .66 .026 1/2 dozen $5.00 1 dozen $8.50 Basically all bits are the same at this size. So if you can get them cheaper, go for it DW