I am sure there are some engineers on this forum who might have the answer. When drilling with larger drill bits I use the slowest speed my pillar drill can provide. 180rpm. However, having drilled a pilot hole, then larger and larger bits but when I try to use the bigger ones they drill through the hole and when they have almost reached the end of the hole they jam. My local blacksmith explained that I was "hitting the flutes". This I understand but how to avoid the bits jamming. It's irritating and time-consuming.
Does anyone have any suggestions please?
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Drilling steel.
Re: Drilling steel.
I think the drill bit is turning too slowly so it gets caught.
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- Classic Wise Man
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Re: Drilling steel.
Chris is correct and 180rpm is far too slow to overcome the resistance of the larger drill flute edges - there is insufficient torque at that low speed to ensure a clean and progressive cut.
Once the pilot hole has been completed and provided the item to be drilled has not been disturbed, then the logical step is to increase the drill speed when using larger drill bits. TBH, you can use a fast speed even when drilling pilot holes.
The other issue of too low a speed, is that if the drill bit is not progressing with its cutting action it will generate unnecessary excessive heat which in turn causes the drill flutes to become less effective; in essence it becomes blunt - which can be witnessed by discoloration of the bit.
Regards.
Richard.
Once the pilot hole has been completed and provided the item to be drilled has not been disturbed, then the logical step is to increase the drill speed when using larger drill bits. TBH, you can use a fast speed even when drilling pilot holes.
The other issue of too low a speed, is that if the drill bit is not progressing with its cutting action it will generate unnecessary excessive heat which in turn causes the drill flutes to become less effective; in essence it becomes blunt - which can be witnessed by discoloration of the bit.
Regards.
Richard.
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- Wise Man
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Re: Drilling steel.
Having drilled a small pilot hole, (and I assume your work-piece is clamped in a machine vice) then use the correct size larger drill in one go, and keep a steady pressure onthe drill. Err to the side of a low speed as you are doing
Ignore the advice to increase the hole in stages with progressively larger drills as a large drill cutting only the perphery of a hole will snag - which is your problem.
Ignore the advice to increase the hole in stages with progressively larger drills as a large drill cutting only the perphery of a hole will snag - which is your problem.
Re: Drilling steel.
Or use a step drill.
Re: Drilling steel.
Stan, I agree. that’s exactly what I was taught.
Steve
Steve
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Re: Drilling steel.
Thank you Gentlemen for all your comments. Usually I use the step-by-step approach but now will adopt the pilot hole to finish hole technique. However, there are times when I have a component which needs to be bolted to something. The hole in the component is just over 16mm while that in the other item is 12mm. Thus I have to drill out a 12mm hole, which is where the problem arises.
I will try using a faster speed.
I will try using a faster speed.