I am putting new fictures on my aluminum boom and the SS screws are fused with the aluminum so I am drilling them out to be replaced. I am using a Cobalt drill bit and have broken or dulled 4 of them so far. Is there a better drill bit to use for this. They do work but they only last for 1-2 screws.
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drilling screws
when drilling ss go slow and use alot of cutting oil to keep the bit as cool as possible.
when drilling ss go slow and use alot of cutting oil to keep the bit as cool as possible.
SS
Stainless steels work harden when machined. If the tool is allowed to rub instead of cut the steel immediately hardens to the point where it is harder than the drill, so the drill blunts instantly. This means any cutting tool MUST always be kept cutting. The previous advice re oil and slow speed is good - but you also need as much pressure on the tool as it will take. This is particularly so after the surface has hardened after a previous attempt. There are free machining grades of stainless but these are not hard enough for self tapping screws. Its a bitch really.
Stainless steels work harden when machined. If the tool is allowed to rub instead of cut the steel immediately hardens to the point where it is harder than the drill, so the drill blunts instantly. This means any cutting tool MUST always be kept cutting. The previous advice re oil and slow speed is good - but you also need as much pressure on the tool as it will take. This is particularly so after the surface has hardened after a previous attempt. There are free machining grades of stainless but these are not hard enough for self tapping screws. Its a bitch really.
Big screw driver
I had a number of ss screws I couldn't get out that were holding a spinnaker track. Same trouble drilling. Asked neighbor for help, very large man with machine work savy. He took a large screw driver and a hammer and with the blade perpendicular to the slot and at a 45 degree angle to the pland of the top of the screw and at the outer end of the slot the slot hammered away. He got them all out for me. Geoff
I had a number of ss screws I couldn't get out that were holding a spinnaker track. Same trouble drilling. Asked neighbor for help, very large man with machine work savy. He took a large screw driver and a hammer and with the blade perpendicular to the slot and at a 45 degree angle to the pland of the top of the screw and at the outer end of the slot the slot hammered away. He got them all out for me. Geoff
Drilling SS
Donalex is right. SS work hardens if you're not cutting with a sharp drill. Take your drills and sharpen them. Highly recommend Drill Doctor for sharpening. I just drilled a SS plate with mounting holes and it went very well. Key is sharp bits.
Donalex is right. SS work hardens if you're not cutting with a sharp drill. Take your drills and sharpen them. Highly recommend Drill Doctor for sharpening. I just drilled a SS plate with mounting holes and it went very well. Key is sharp bits.
Use a carbide drill
there are many different grades of stainless. some are martensitic (harden and temper grades) but those will rust in the marine environment. Most of the marine stainless is austinitic and as others note it will work harden. The material is very ductile also so getting chips to break off and out of the cutting zone is more difficult. There is a huge variety of tooling available, you are using the wrong kind of drill. Get a split point carbide and preferably titanium nitride coated and use a good coolant as previously noted. The split point allows for easier penetration of the drill. Think of it like this, at the exact center of rotation to relative speed of the drill point is zero. So try taking a very small diameter rod and forcing it through a piece of solid stainless, hard right? (also known as a punch). A split point drill or s-point removes the center of the bit so you start cutting further out on the diameter of the drill making the drill penetrate more easily. Carbide is much harder than high speed steel drills so it will last much longer (also more expensive but worth it). In short a garden variety drill from a hardware store is a poor choice for cutting stainless steel. Ok for aluminum and wood. Pay for the good tools and be happy. dave
there are many different grades of stainless. some are martensitic (harden and temper grades) but those will rust in the marine environment. Most of the marine stainless is austinitic and as others note it will work harden. The material is very ductile also so getting chips to break off and out of the cutting zone is more difficult. There is a huge variety of tooling available, you are using the wrong kind of drill. Get a split point carbide and preferably titanium nitride coated and use a good coolant as previously noted. The split point allows for easier penetration of the drill. Think of it like this, at the exact center of rotation to relative speed of the drill point is zero. So try taking a very small diameter rod and forcing it through a piece of solid stainless, hard right? (also known as a punch). A split point drill or s-point removes the center of the bit so you start cutting further out on the diameter of the drill making the drill penetrate more easily. Carbide is much harder than high speed steel drills so it will last much longer (also more expensive but worth it). In short a garden variety drill from a hardware store is a poor choice for cutting stainless steel. Ok for aluminum and wood. Pay for the good tools and be happy. dave
Screwdriver Shock Effect
As Geoff points out, hitting the screwdriver with a hammer may help by breaking the fused zone which resulted from corrosion. Combining that with penetrating oil for a few days may work or as I found once it may result in the screw breaking which lets you try the drill or look for an alternative attachment site. Dick
As Geoff points out, hitting the screwdriver with a hammer may help by breaking the fused zone which resulted from corrosion. Combining that with penetrating oil for a few days may work or as I found once it may result in the screw breaking which lets you try the drill or look for an alternative attachment site. Dick
Have you tried ...
... an impact screw driver? As you strike it with a hammer, the bit rotates slightly counter-clockwise. I used this tool a lot when I was working as a diesel mecahnic.
... an impact screw driver? As you strike it with a hammer, the bit rotates slightly counter-clockwise. I used this tool a lot when I was working as a diesel mecahnic.
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