Is There A Faster Way To Bore A Hole On A Lathe?

If I have a hole greater than 1.5 inches and not too deep, I usually start with a hole saw a bit smaller that the final diameter, then bore it out the rest of the way.

Randy
 
I like to drill a hole, then with a boring bar insert about 1/8" and feed out. Feed back in, go another 1/8", repeat.
 
I have a smithy granite 1324. It has its limitations on how much it can take on each pass. If I had a rotary table I would have tried it out, but I do not have one.

I am still new and have never heard of trepanning. Looks like it would do exactly what I need. However it looks like the tool bit is specific to this purpose. I know I do not have one of these, dont really think I can justify one for just one time use. Can I grind one from a tool blank? Or does it have to have that downward slope to it? I have something I think I might be able to make work.
 
If it were just one part I would just keep boring as you are doing, shouldn't take that long. If it is several parts I would look at ordering aluminum tube with 5.25 OD and 2.5 ID and finish off the inside with boring a little.
 
You might say more about your experience with the boring bar. You should be able to take pretty deep cuts if everything is set up right (speed, tool height, tool shape.) At .100 per pass that's only 5 passes per inch of diameter. Shouldn't take that long, which makes me wonder whether you're having fundamental problems boring in the first place. I use boring bars when I need precision in deeper holes.

I make a lot of .500" deep pockets, 1.85" diameter in 2 1/2" aluminum - I don't use a boring bar bar at all - I use a standard turning tool with triangular insert (CCMT if I recall). I make facing cuts. I actually run the lathe in reverse and cut from the center toward the rear as it is easier to see what I'm doing. I do it dry as lube isn't required. I can do about .075" passes on my PM1127. Chip clearance approaching the side of the pocket is an issue - plunging right at the side causes a lot of chatter. I have learned to plunge as I am approaching the side - then cut on the outside-to-insde pass.
 
I ended up getting it cut today. I had some unknown carbide tipped tool bits that I have no idea what they are actually for. I ended up doing a little custom grinding on them and was able to make it work. They are a little thicker than a parting blade, but about half as tall, bottom is almost kinda triangle shaped. I need to take some pictures and post them up to see what they actually are for. They kinda chattered pretty bad. I dont know if it was the shape/angles of it, or that I had to extend so far to go all the way through. But I kept it lubed and made it on through.
 
you do need to grind your own trepanning tool, although you can buy them they're fairly expensive. It's not hard - I did one out of a 1/4x3/8 HSS blank using pics off the net for reference and it worked pretty well. Any failings were due to woeful lack of rigidity and power in my lathe :) (that's a 3" chuck before anyone gets too excited!)
IMG_3548_zps899c8135.jpg

when I need it again, I'll grind more of a cutting edge on the right hand side, as both corners cut - like a cut off tool basically
 
Please with the pics. so we can figure out why you are having issues boring. Show your set up the tools. what type of boring bar are you using.
Mark
 
markknx said:
Please with the pics. so we can figure out why you are having issues boring. Show your set up the tools. what type of boring bar are you using.
Mark
Click to expand...

Hole has already been bored and the project is done. I didnt take any pics of it while I was doing it.
 
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