Hi Moly M7 vs m42 cobalt # drill set for model engine cast iron machining, big difference in price.

[Ridetoeat]

Considering the Norseman M7 #drill set for my model engine machine shop, would be my first # drills and don't want to buy twice !! I have M42 regals in my older fractionals and they have been life changing when I use them, Will I regret not spending triple down the road and getting M42 cobalt ??

Thanks..

 

[Ulma Doctor]

if you are predominately drilling cast iron, you can use just about any drill you wish.
cast iron is not usually a challenge to drill, unless there is lots of hard spots in the cast iron
if there are hard spots, even M42 could be less than stellar in performance

i use both 8% cobalt (M42 HSSE) and HSS drills, dependent on material to be drilled

you'll not go wrong by buying higher quality drills, if the end result is important

 

[pontiac428]

I'd say it mainly comes down to heat. Cobalt can take a lot more of it than HSS and still retain its hardness. That's about the long and short of it. I find HSS adequate for 90% of the work.

 

[Ridetoeat]

Ok, I done some testing by drilling a 1/8" hole through a 1" forged steel torsion bar key with the mill this morning. I was surprised that I could do that with a cheap lowes / dewalt drill bit I found new in the pack in my loose drawer of bits. That went so well I checked the needed drills for this first model casting kit I am starting on and only 1 of the needed drills on the list I made was off more that .002" so I ordered 2 cheap drill and tap combo kit's from amazon for like $15 and problem solved for now. I am just building model gas engines from casting kits and I don't think any of this is going to be difficult materials for now. I will just supplement my existing m42 fractional drill set as needed from the local fastenal, the same way I do when I need replacements, they stock the m42 cobalt. Being I was trying to spend money and failed, I ordered a set of 5c collets, square and hex blocks with closers as well, problem solved.

I appreciate the weigh in on bits, I had found m42 to be preferred as well for everything prior and was just struggling to spend $160 on a set I have never needed in 57 years prior and only thought I needed 4 of the 60 currently. Worked out and put the money to better use.

Thanks Again, Doug...