Excellent!
It sounded pretty good, except the soft swishing cut I am used to is verging on a squeal with your boring tool. Of course, the sales are good for people who make these adjustable boring tool holders, but I rarely use mine. The tool is 10mm diameter on mine. Compared to the stiffness of my "proper boring bar" - a piece of 3/4inch ground steel round with holes for a tool insert and locking screw - held in a collet into the quill of the milling machine. Need a micrometer and calculation to adjust each cut. But doesn't make the "squeal" you have. Because you are at your lowest speed, and using that type of tool - you suggested it is ground for cutting Aluminium? - you have done the job "successfully" - but not the same as I would have done it. Boring in the vertical machine, or lathe, where the tool rotates and translates through the bore is the best way to ensure a round and parallel bore. I hope you agree it was the best set-up? Holding the workpiece in the lathe chuck and approaching a rotating part (of unknown alignment) past a fixed tool is not good enough for cylinders, IMHO. (I have made cylinders that way and they felt tapered when I inserted the piston! Ok at one end but tight at the other.). So I always keep the work stationary and rotate the tool.
I was taught (in the 1960s - Memory still good!) to listen to the work being cut. I.E. Cast materials at the correct speed make a lovely smooth "Swish" noise. - No squeal. and because of sound reflections the "whow-whow-whow" sound is a result of the cut being from the far side (so you hear sound waves directly, with some echoes from the bore, then near-side, where you hear sound waves that have to come up the bore and reflect before they come to the ear. Those slight variations of sound line from cutting point to ear give the "whow-whow-whow" effect. Compare that to when you are on the lathe, the workpiece is rotating, and the tool passing along a length of cut, so the passage of sound from point of cut to ear does not change as the part rotates. The rate of "whow-whow-whow" relates to the rotational speed, and not an indication of an uneven cut. But the "Squeal " relates to a vibrating point of contact - like a violin bow stops and starts as it is dragged across the string to excite the string note, or not. So any squeal and you should slow the cutting speed - if you can - or stiffen the tool/mounting/whatever - if you can. But the best cuts need the correct cutting angle and relief at the tool, so only the leading edge of the actual cutting point contacts metal, without any flat behind dragging over the surface. Then you get just the "Swish" noise. So as you cannot improve speed, mounting etc, next time do not use a tool ground for aluminium, but a sharp tool ground for cast iron, with relief to clear the bore internal radius. I suspect that if you examine your tool, you will see some polishing below the sharp cutting point, where the cast iron had ground/polished the surface of the tool at the cutting point so the relief is rubbing on the bore as the cut progresses. An indication of rubbing, not cutting, as the speed is too fast and the tool is being ground by the cast iron, not being cut properly.
Use a strong light and magnifying glass to examine the tool.
Enjoy! You are obviously newly experiencing this and learning a lot. - Good presentation too.
I look forward to you linishing of the bore. Make particular attention to the linishing bar/tool to make sure it only erodes the peaks of the cut lines, and not increases the diameter more than 0.001" !! (or the depth of machined lines). You Must also ensure you do not make bell ends, where the ends open wider than the main bore, and aim for a 30 degree criss-cross on lines from the linishing. You should stop linishing when the machining grooves are still JUST visible, so you don't go too far. I linish at a slow speed - like your speed for boring. - lubricate with light oil - or paraffin is better (I use paraffin with a drop of lube oil), to keep washing the junk out while linishing. Although using proprietary Hones on cast iron bores of engine blocks we did not use anything, when I was a lad. Like this:
I.E. Open so the dirt can fall out easily through the open array of stones, and to the floor. The exhaust blow from the driving motor also blew a good draught through the bore.
But for con-rod ends to fit gudgeon pins on a Delapina honing machine we always used paraffin with a drop of oil, for the finest finish, as the bar filled the hole and needed something to wash the residue out from the stones. (a paint brush a jar of paraffin!). Like this:
This is like my honing of small model cylinders, on a bar on the lathe. The long square stone is set into a groove, with 2 small springs beneath. - on mine.. On a Delapina machine and bar the stones sit on a slightly tapered bar, that is drawn through the middle of the honing bar to get incremental advance of the stone in tenths of a thou.
Hope this is of some use?
K2
It sounded pretty good, except the soft swishing cut I am used to is verging on a squeal with your boring tool. Of course, the sales are good for people who make these adjustable boring tool holders, but I rarely use mine. The tool is 10mm diameter on mine. Compared to the stiffness of my "proper boring bar" - a piece of 3/4inch ground steel round with holes for a tool insert and locking screw - held in a collet into the quill of the milling machine. Need a micrometer and calculation to adjust each cut. But doesn't make the "squeal" you have. Because you are at your lowest speed, and using that type of tool - you suggested it is ground for cutting Aluminium? - you have done the job "successfully" - but not the same as I would have done it. Boring in the vertical machine, or lathe, where the tool rotates and translates through the bore is the best way to ensure a round and parallel bore. I hope you agree it was the best set-up? Holding the workpiece in the lathe chuck and approaching a rotating part (of unknown alignment) past a fixed tool is not good enough for cylinders, IMHO. (I have made cylinders that way and they felt tapered when I inserted the piston! Ok at one end but tight at the other.). So I always keep the work stationary and rotate the tool.
I was taught (in the 1960s - Memory still good!) to listen to the work being cut. I.E. Cast materials at the correct speed make a lovely smooth "Swish" noise. - No squeal. and because of sound reflections the "whow-whow-whow" sound is a result of the cut being from the far side (so you hear sound waves directly, with some echoes from the bore, then near-side, where you hear sound waves that have to come up the bore and reflect before they come to the ear. Those slight variations of sound line from cutting point to ear give the "whow-whow-whow" effect. Compare that to when you are on the lathe, the workpiece is rotating, and the tool passing along a length of cut, so the passage of sound from point of cut to ear does not change as the part rotates. The rate of "whow-whow-whow" relates to the rotational speed, and not an indication of an uneven cut. But the "Squeal " relates to a vibrating point of contact - like a violin bow stops and starts as it is dragged across the string to excite the string note, or not. So any squeal and you should slow the cutting speed - if you can - or stiffen the tool/mounting/whatever - if you can. But the best cuts need the correct cutting angle and relief at the tool, so only the leading edge of the actual cutting point contacts metal, without any flat behind dragging over the surface. Then you get just the "Swish" noise. So as you cannot improve speed, mounting etc, next time do not use a tool ground for aluminium, but a sharp tool ground for cast iron, with relief to clear the bore internal radius. I suspect that if you examine your tool, you will see some polishing below the sharp cutting point, where the cast iron had ground/polished the surface of the tool at the cutting point so the relief is rubbing on the bore as the cut progresses. An indication of rubbing, not cutting, as the speed is too fast and the tool is being ground by the cast iron, not being cut properly.
Use a strong light and magnifying glass to examine the tool.
Enjoy! You are obviously newly experiencing this and learning a lot. - Good presentation too.
I look forward to you linishing of the bore. Make particular attention to the linishing bar/tool to make sure it only erodes the peaks of the cut lines, and not increases the diameter more than 0.001" !! (or the depth of machined lines). You Must also ensure you do not make bell ends, where the ends open wider than the main bore, and aim for a 30 degree criss-cross on lines from the linishing. You should stop linishing when the machining grooves are still JUST visible, so you don't go too far. I linish at a slow speed - like your speed for boring. - lubricate with light oil - or paraffin is better (I use paraffin with a drop of lube oil), to keep washing the junk out while linishing. Although using proprietary Hones on cast iron bores of engine blocks we did not use anything, when I was a lad. Like this:
I.E. Open so the dirt can fall out easily through the open array of stones, and to the floor. The exhaust blow from the driving motor also blew a good draught through the bore.
But for con-rod ends to fit gudgeon pins on a Delapina honing machine we always used paraffin with a drop of oil, for the finest finish, as the bar filled the hole and needed something to wash the residue out from the stones. (a paint brush a jar of paraffin!). Like this:
Hope this is of some use?
K2
Last edited:
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