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Step Drill Bit: Spiral vs Straight Flute
- Thread starter SKAh
- Start date
larry4406
Well-known member
I like the step drills. Not sure what type the cheapies I have from HF are.
fsae0607
Well-known member
I like the step drills. Not sure what type the cheapies I have from HF are.
They're straight flute.
I see no difference in use between the two.
I like the step drills. Not sure what type the cheapies I have from HF are.
I just tried the HF one the first time yesterday to drill some holes on a 16ga ( maybe it was a 10ga... not 100% remember what I bought) , of 2"x2" tubes. I was surprised how well it cuts, but I do have to use cutting oil, like tap magic. The one I used was the 1/4 to 7/8 smaller ones and I did have a 1/4 hole pre-drilled....
yyc_ranger_4x4
Well-known member
Give me a straight flute.....I can run a diamond hone down it and make it last longer. Never had much luck with spiral flutes....
Hi.
Today was the first time I tested a stepped drill (Spiral flute). I used it to drill 2mm PVC plastic sheet with a regular drill, not a bench drill. I didn't like it because I felt that the drill advances and penetrates the piece automatically, it is pulled like a screw.
Does anyone know whether a straight flute would allow better control over the advancement of the drill in the piece? I imagine that, because it doesn't have a spiral flute, it would only advance as force is applied. Is this true? Thanks.
Today was the first time I tested a stepped drill (Spiral flute). I used it to drill 2mm PVC plastic sheet with a regular drill, not a bench drill. I didn't like it because I felt that the drill advances and penetrates the piece automatically, it is pulled like a screw.
Does anyone know whether a straight flute would allow better control over the advancement of the drill in the piece? I imagine that, because it doesn't have a spiral flute, it would only advance as force is applied. Is this true? Thanks.
Last edited:
rd65
Well-known member
your post says you used a straight flute. I have never used a spiral fluted one. They sure make a clean hole in plastics, use is metal is so-so for me.Hi.
Today was the first time I tested a stepped drill (Straight flute). I used it to drill 2mm PVC plastic sheet with a regular drill, not a bench drill. I didn't like it because I felt that the drill advances and penetrates the piece automatically, it is pulled like a screw.
Does anyone know whether a straight flute would allow better control over the advancement of the drill in the piece? I imagine that, because it doesn't have a spiral flute, it would only advance as force is applied. Is this true? Thanks.
rd65
Well-known member
Can these be sharpened? They get dull very fast in metal.Give me a straight flute.....I can run a diamond hone down it and make it last longer. Never had much luck with spiral flutes....
Step drills are designed/best used for thin materials like sheet metal. They won't grab as you break through & self feed. They'll produce a cleaner/rounder hole than using a standard twist drill in thin materials.
In machining, straight flute taps are generally stronger than spiral flute taps. Spiral flute reamers can be used in holes with an interrupted cut like a hole with a keyway where as straight flute reamers are only recommended for non-interupted cut. Sprial flutes cost more to manufacture, for that reason I only own straight flue reamers. I do own some spiral fltue taps but not many (great for blind holes).
Maybe spiral flute step bits might have an advantage over straight but none that I can think of, for my uses anyway. Perhaps a spiral flute step bit might have a tendency to stay centered better than a straight flute. Better chip evacuation is not a concern for me cause I only use step drills for thin materials as recommmended, not a whole lof chip load anyway.
At my work & for what I do/work on, I use step drills much more often than twist drills. I use straight flutes though.
In machining, straight flute taps are generally stronger than spiral flute taps. Spiral flute reamers can be used in holes with an interrupted cut like a hole with a keyway where as straight flute reamers are only recommended for non-interupted cut. Sprial flutes cost more to manufacture, for that reason I only own straight flue reamers. I do own some spiral fltue taps but not many (great for blind holes).
Maybe spiral flute step bits might have an advantage over straight but none that I can think of, for my uses anyway. Perhaps a spiral flute step bit might have a tendency to stay centered better than a straight flute. Better chip evacuation is not a concern for me cause I only use step drills for thin materials as recommmended, not a whole lof chip load anyway.
At my work & for what I do/work on, I use step drills much more often than twist drills. I use straight flutes though.
Sorry, my mistake, it was actually spiral. Edited and corrected.your post says you used a straight flute. I have never used a spiral fluted one. They sure make a clean hole in plastics, use is metal is so-so for me.
I found this video bellow and I believe it answered my question very well. At least when used on plastics, which is my case, the spiral bit is pulled and there isn't much control over the stopping point.
As in one of the video comments, I also think that the spiral bit would only serve me well when I needed to open the hole to its maximum size, penetrating the entire drill bit without worrying about stopping it at a specific step.
I will certainly buy and test a straight flute step drill.
As in one of the video comments, I also think that the spiral bit would only serve me well when I needed to open the hole to its maximum size, penetrating the entire drill bit without worrying about stopping it at a specific step.
I will certainly buy and test a straight flute step drill.
yyc_ranger_4x4
Well-known member
I've been able to keep an edge on most of my uni-bits with work by running a small flat diamond hone on the back side of the flute. I try not to do too much to the outside edge....this seems to keep them sharp enough to cut most of what I need. However....I'm usually doing sheet metal and electrical enclosures. I do use the milwaukee step bits for general hand made holes and use/abuse....sometimes they see cutting oil if I'm doing anything thicker than sheet metal.Can these be sharpened? They get dull very fast in metal.