The ideal weight or force to push a drill

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SUMMARY

The ideal weight or force for pushing a drill bit when drilling stainless steel, particularly A286 stainless, is determined by maintaining a constant feed rate rather than focusing solely on force. A feed rate that is too high can break the drill bit, while a rate that is too low can lead to work hardening and bit destruction. The slowest speed on a drill press should ideally be below 490 RPM for high-speed steel drill bits. Using cobalt HSS drill bits, specifically M35 or M42, along with proper coolant application, enhances drilling efficiency and prolongs bit life.

PREREQUISITES
  • Understanding of feed rates in drilling operations
  • Knowledge of drill bit geometry and types, specifically split pointed bits
  • Familiarity with high-speed steel (HSS) and cobalt HSS drill bits
  • Experience with coolant and lubrication techniques in metalworking
NEXT STEPS
  • Research the grinding techniques for drill bits to optimize for specific materials
  • Learn about the effects of relief angles on feed rates in drilling
  • Study the properties and machining characteristics of A286 stainless steel
  • Explore advanced drilling techniques for stainless steel, including optimal RPM settings
USEFUL FOR

This discussion is beneficial for machinists, metalworkers, and engineers involved in drilling operations, particularly those working with stainless steel and seeking to improve drilling efficiency and tool longevity.

abdulbadii
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TL;DR
The ideal weight or force to push (bit ibeing n) a driller down when drilling (stainless) steel
What is and how is the estimation of the ideal weight or force to push (bit being in) a driller down when drilling (stainless) steel to bore 3-9 mm hole?
 
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It's not a matter of force. Drilling metals, especially metals with large work hardening tendencies such as stainless steel, is best done with a constant feed rate. Too large a feed per revolution will break the drill bit. Too low a feed per revolution will cause the work hardened stainless to destroy the drill bit. And this is a photo of a 1/2" drill bit that I destroyed a few days ago doing exactly that. It was A286 stainless, which is harder to machine than the more common 300 series stainless steels.
Damaged drill.jpg

Part of the problem is that the slowest speed on my drill press is 490 RPM, which is over twice too fast for drilling this alloy with a high speed steel drill bit.

The force is also dependent on the drill bit geometry. For example, split pointed bits need less force.
 
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abdulbadii said:
What is and how is the estimation of the ideal weight or force to push (bit being in) a driller down when drilling (stainless) steel to bore 3-9 mm hole?
If you cannot set the feed rate, the bit-force should be held steady, so the drill keeps cutting.
Flood the hole with coolant / lubricant.

With practice, you should be able to produce two continuous helical coils of cut material, that pass freely up and along the flutes of the drill.

The relief angle on the drill will decide the maximum feed rate. Learn to grind drill bits to suit the material you are cutting.

https://en.wikipedia.org/wiki/High-speed_steel#Types
For stainless steel, use a cobalt HSS drill bit, M35 or M42.
https://en.wikipedia.org/wiki/High-speed_steel#Cobalt_High_Speed_Steels_(HSS)
 
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