- Joined
- Dec 18, 2019
- Messages
- 7,430
Thought I'd make a couple of bushings to hold some "undersized" boring bars in my AXA-4D boring bar holder. I have a 6mm and a, 3/8" carbide shank boring bars and would like to use them. Previously, I made a bushing or sleeve for my 1/2" carbide shank bar. Thought I would basically do the same thing, mount a 3/4" diameter 12L14 rod in my AXA-4D and use a drill mounted in the chuck to drill through the rod. Then ream the hole to size.
Except this time, things didn't go so well. For the 3/8" bar, I drilled through the rod using an 11/32" drill, followed by a 23/64" drill. Then reamed the hole to 3/8". One problem, my boring bar won't pass through the hole. My boring bar mics at 0.3746", the reamer is 0.3750". I was able to pass a short dowel (1.25") through the hole without any problem. The dowel mics at 0.3752". But the carbide bar hangs up around 3/4 of the way through. This is independent of which way I start the carbide bar. What is odd, is that I made a bushing for this same boring bar for my mini-lathe and used the same reamer last year. The boring bar just nicely slipped into the bushing. The difference is that the bushing was narrower wall, and it was shorter, since the OXA-4 is smaller.
The hole doesn't come out the same place in the rod on the back, but that could be that the boring bar holder has a tilt, or the drill wandered. Having learned my lesson last time, I have not yet slitted the bushing.
I could use an oversized reamer 0.376, or ? If the hole is crooked, will the reamer follow the hole? Is there a way to fix this? If not, what could I do next time to get better results?
I'm just thinking about doing this for a 6mm bar and shaking my head. How can I drill a 3" long straight hole with an even smaller drill?
Looking for some ideas, or helpful suggestions.
Except this time, things didn't go so well. For the 3/8" bar, I drilled through the rod using an 11/32" drill, followed by a 23/64" drill. Then reamed the hole to 3/8". One problem, my boring bar won't pass through the hole. My boring bar mics at 0.3746", the reamer is 0.3750". I was able to pass a short dowel (1.25") through the hole without any problem. The dowel mics at 0.3752". But the carbide bar hangs up around 3/4 of the way through. This is independent of which way I start the carbide bar. What is odd, is that I made a bushing for this same boring bar for my mini-lathe and used the same reamer last year. The boring bar just nicely slipped into the bushing. The difference is that the bushing was narrower wall, and it was shorter, since the OXA-4 is smaller.
The hole doesn't come out the same place in the rod on the back, but that could be that the boring bar holder has a tilt, or the drill wandered. Having learned my lesson last time, I have not yet slitted the bushing.
I could use an oversized reamer 0.376, or ? If the hole is crooked, will the reamer follow the hole? Is there a way to fix this? If not, what could I do next time to get better results?
I'm just thinking about doing this for a 6mm bar and shaking my head. How can I drill a 3" long straight hole with an even smaller drill?
Looking for some ideas, or helpful suggestions.
These are bushings , these bushings do not have to be made within .00001 tolerance because it makes no difference . Run an oversized reamer thru the hole and use the bushing after slotting it . It's fun trying to make everything perfect , I get it ........................but when perfection is not needed , take the easy way home .