Hi David, my first visit to your channel as the "boring head" caught my attention. Up front, I'm not a trained machinist, just a self taught tinkerer of many years. Your description of the boring tool with the comparitor left me scratching the grey matter. Looking at the results of both cuts you did with the boring head and chosen tool they seemed to produce a bored hole but we're never told if it was the correct dimension. Finish could also be better. That I put down to the grind of the cutter and possibly its positioning. I went and dug out a nine piece set I bought when I purchased my boring head recently, niether of which have been used as yet. Both are of Chinese origin. The one cutter I selected to look at appears to have approximately 5°-7° clearances in all three directions as would normally be required. However the cutting edges have not been reground since the brazing took place so the faces could do with a touch with a suitable stone before use. The support pillar or shank of the tool is offset from the 1/2" shank centre line by about 1.5mm. the tip of the cutting insert is about 1mm beyond the 1/2" shank so if rotated about the 1/2" centre line this cutter would cut about a 14.7mm hole. Looking at your results I think sharpness, or lack of, is the first problem. The second, the spiral cut mark, suggests that the tool was deflecting on the way down and on the way back up, at an accelerated feed rate, ten or twenty times the down feed rate, it flexed back and cut the spiral. If you had repeated the cut as a spring pass I'm almost willing to bet that the spiral would be gone and the finish might have even been a little better. To avoid the spiral mark stop the tool at the bottom and withdraw it without rotation. You'll still get a line, unless you move either Y or X to get the tool away from the surface. One question just came to mind. After setting the tool to the diameter required did you lock the boring head gib screws? Don't know if any of this will help you but if it gives something to compare then you're welcome. Merry Christmas and a Happy New Year from Canada's banana belt. 🤞🇨🇦🍌🥋🇺🇦🕊️🇬🇧☃️🌲😁👍
Hi @ronwilken5219 Its been awhile since I made this video so memory is a bit sketchy. I think the main problem was the tool tip geometry is in front of the spindle centre line. On a lathe it would be the same as having the tool set above centre height. It can rub very easily as the clearance angle is reduced . Yep a spring cut would have been best, I do find my mill is not too sturdy and deflects hence the spiral as the tool gets removed. The tool was sharp I think that did not help either I do prefer to have a small radius on the tip. It smooths out the cut and helps stop the finish looking like a fine spiral. I did buy a couple of tungsten mini boring bars that are absolutely superb. I have thought about getting a couple more that fit the boring head. I think that would get me some really nice results. I have not managed to make many videos in recent times as I am building a new workshop. I hope to get this done and back to engineering by spring. Have a great Christmas and new year, thanks for the comment always appreciated. Hope the Banana harvest went well not easy to grow in Canada!!! Cheers David
Loving your channel still Iv a question unrelated to your mill , do you have a 32 tooth gear for your lathe and if so would you share the dimensions as I don’t have one but need to cut metric threads many thanks and keep up the great work
Hi MCP Auto Parts, I do have a 32 tooth gear its 42.4 dia x 10 thick with a dia 28 boss on one side 10 thick. There is a 5x2 approx. key right through. Not sure about the module of it its either 1.5 or 2 you will need to check with your machine as the manual is not accurate. Cheers
When you are explaining your gear choice (6:00) you mention the 127T wheel- but on the diagram you are pointing to, the 127 plays no part. The diagram shows 40/120/40- in other words a ratio of 1:1. If the 127 did take part, it would turn 1.058 times faster- which is the error you are getting. Are you sure you are not using the 127 by mistake?
Hi Mike, I have just popped out to check I think you are right the bottom pinion is the wrong way round and is engaged with the 127T. Well spotted I had a nagging feeling that something was not right, the lathe has worked perfectly for years cutting many threads without issue. I will have to be more careful next time. Cheers
@@CazualHaze Easy mistake to make- especially when you are videoing. I find the extra attention to camera positioning etc does distract... Keep up the good work!
The TDI usually fits on the other side of the carriage. Lots of room there... Please do not use phrases like 'perfect' or 'spot on'; only woodworkers and newbies do this. Nothing is perfect, everything has tolerances. You are aiming to be to specification by being within tolerance. BTW, can I have your throwouts? I will re-grind them...
Hi Mike M, unusually the TDI is fitted on my machine on the wrong side I have thought about changing it as if you leave it mounted it jams up with swarf. Another thing for the never ending list. If it works for me its spot on or perfect!! The 'bucket of broken dreams' is not always a one way trip, I still have the cutters' cant bear to throw anything away that might be useful. Cheers
As you say, you're not the first to discover the problems with the brazed carbide boring bars. The video shows one way to modify them: ruclips.net/video/IGuOwSGCPaQ/видео.html
It doesn't have to thin the cutting part of the brazed tip. You grind the insert part at an angle and rotate the bar in the holder. It will leave full width at the cutting edge but you will have to put a bit of clearance to stop it rubbing.
What you did with the optical comparator is complete bullshit. The only thing that matters is the cutting tip which is at 90 deg to the direction you are showing. Cutting bits do not have a "cutting face" as you imply, but a cutting point. I have used the exact same boring head with a triangular carbide insert with chip breaker and achieved excellent results. And no, I rarely ever resort to brazed carbide inserts unless I need a special grind. I think you need to learn more about machining before you make a pretense of doing tool reviews.
Hi Paul, I dont do tool reviews it may not have been clear but the point of the video is how to adapt it to my power drawbar if that's unclear; apologies. The boring head looks like a well made tool and if you dont use the cutters supplied then how can you comment on them being OK? When I was trained ( many years ago now) getting cutters on centre height was the only way to get the rake and clearances' correct. You will also know the cosine error you will encounter if the cutter is not perfectly aligned with the boring head centre line. Cheers.
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Hi David, my first visit to your channel as the "boring head" caught my attention. Up front, I'm not a trained machinist, just a self taught tinkerer of many years.
Your description of the boring tool with the comparitor left me scratching the grey matter.
Looking at the results of both cuts you did with the boring head and chosen tool they seemed to produce a bored hole but we're never told if it was the correct dimension. Finish could also be better. That I put down to the grind of the cutter and possibly its positioning.
I went and dug out a nine piece set I bought when I purchased my boring head recently, niether of which have been used as yet. Both are of Chinese origin. The one cutter I selected to look at appears to have approximately 5°-7° clearances in all three directions as would normally be required. However the cutting edges have not been reground since the brazing took place so the faces could do with a touch with a suitable stone before use.
The support pillar or shank of the tool is offset from the 1/2" shank centre line by about 1.5mm. the tip of the cutting insert is about 1mm beyond the 1/2" shank so if rotated about the 1/2" centre line this cutter would cut about a 14.7mm hole.
Looking at your results I think sharpness, or lack of, is the first problem.
The second, the spiral cut mark, suggests that the tool was deflecting on the way down and on the way back up, at an accelerated feed rate, ten or twenty times the down feed rate, it flexed back and cut the spiral.
If you had repeated the cut as a spring pass I'm almost willing to bet that the spiral would be gone and the finish might have even been a little better.
To avoid the spiral mark stop the tool at the bottom and withdraw it without rotation. You'll still get a line, unless you move either Y or X to get the tool away from the surface.
One question just came to mind. After setting the tool to the diameter required did you lock the boring head gib screws?
Don't know if any of this will help you but if it gives something to compare then you're welcome.
Merry Christmas and a Happy New Year from Canada's banana belt.
🤞🇨🇦🍌🥋🇺🇦🕊️🇬🇧☃️🌲😁👍
Hi @ronwilken5219
Its been awhile since I made this video so memory is a bit sketchy. I think the main problem was the tool tip geometry is in front of the spindle centre line. On a lathe it would be the same as having the tool set above centre height. It can rub very easily as the clearance angle is reduced . Yep a spring cut would have been best, I do find my mill is not too sturdy and deflects hence the spiral as the tool gets removed. The tool was sharp I think that did not help either I do prefer to have a small radius on the tip. It smooths out the cut and helps stop the finish looking like a fine spiral. I did buy a couple of tungsten mini boring bars that are absolutely superb. I have thought about getting a couple more that fit the boring head. I think that would get me some really nice results.
I have not managed to make many videos in recent times as I am building a new workshop. I hope to get this done and back to engineering by spring.
Have a great Christmas and new year, thanks for the comment always appreciated.
Hope the Banana harvest went well not easy to grow in Canada!!!
Cheers David
Loving your channel still Iv a question unrelated to your mill , do you have a 32 tooth gear for your lathe and if so would you share the dimensions as I don’t have one but need to cut metric threads many thanks and keep up the great work
Hi MCP Auto Parts,
I do have a 32 tooth gear its 42.4 dia x 10 thick with a dia 28 boss on one side 10 thick. There is a 5x2 approx. key right through.
Not sure about the module of it its either 1.5 or 2 you will need to check with your machine as the manual is not accurate.
Cheers
When you are explaining your gear choice (6:00) you mention the 127T wheel- but on the diagram you are pointing to, the 127 plays no part. The diagram shows 40/120/40- in other words a ratio of 1:1. If the 127 did take part, it would turn 1.058 times faster- which is the error you are getting. Are you sure you are not using the 127 by mistake?
Hi Mike,
I have just popped out to check I think you are right the bottom pinion is the wrong way round and is engaged with the 127T.
Well spotted I had a nagging feeling that something was not right, the lathe has worked perfectly for years cutting many threads without issue.
I will have to be more careful next time.
Cheers
@@CazualHaze Easy mistake to make- especially when you are videoing. I find the extra attention to camera positioning etc does distract...
Keep up the good work!
The TDI usually fits on the other side of the carriage. Lots of room there...
Please do not use phrases like 'perfect' or 'spot on'; only woodworkers and newbies do this. Nothing is perfect, everything has tolerances. You are aiming to be to specification by being within tolerance.
BTW, can I have your throwouts? I will re-grind them...
Hi Mike M, unusually the TDI is fitted on my machine on the wrong side I have thought about changing it as if you leave it mounted it jams up with swarf. Another thing for the never ending list. If it works for me its spot on or perfect!! The 'bucket of broken dreams' is not always a one way trip, I still have the cutters' cant bear to throw anything away that might be useful.
Cheers
As you say, you're not the first to discover the problems with the brazed carbide boring bars. The video shows one way to modify them: ruclips.net/video/IGuOwSGCPaQ/видео.html
Thanks Eric,
I still have them, too tight to throw them out! I will regrind but it will make them pretty thin.
Cheers
It doesn't have to thin the cutting part of the brazed tip. You grind the insert part at an angle and rotate the bar in the holder. It will leave full width at the cutting edge but you will have to put a bit of clearance to stop it rubbing.
If you had any sense, you could re grind the boring tool
Fair point but it would be damn thin to get the geometry right.
Cheers
What you did with the optical comparator is complete bullshit. The only thing that matters is the cutting tip which is at 90 deg to the direction you are showing. Cutting bits do not have a "cutting face" as you imply, but a cutting point. I have used the exact same boring head with a triangular carbide insert with chip breaker and achieved excellent results. And no, I rarely ever resort to brazed carbide inserts unless I need a special grind. I think you need to learn more about machining before you make a pretense of doing tool reviews.
Hi Paul,
I dont do tool reviews it may not have been clear but the point of the video is how to adapt it to my power drawbar if that's unclear; apologies. The boring head looks like a well made tool and if you dont use the cutters supplied then how can you comment on them being OK? When I was trained ( many years ago now) getting cutters on centre height was the only way to get the rake and clearances' correct. You will also know the cosine error you will encounter if the cutter is not perfectly aligned with the boring head centre line.
Cheers.