Is my new boring bar defective?

D

DaveBarbier

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Hi everyone, first, I have very little experience (no experience?) with machining, so I'm prepared to get taken to school for asking this question.

I just bought a QCTP from LittleMachineShop.com for my little Atlas/Crafstman 618. Everything seems great except this one boring bar.

Here's a picture. It's the one in the middle which I'm questioning. I really hope the image isn't too large.

IMG_9345.JPG

Notice how on the left and right boring bar the cutting part is angled so the tip hits the work first? Well the middle one is angled in such a way that it almost hits the work square, even angled the opposite way a hair. Is this just for a different operation and not traditional boring?

Thanks
 
BigMo said:
Adjust toolpost to get optimum cutting angle and roll on
Click to expand...

I was thinking of that, but it didn't seem right. I installed it and I'd have to be a more of an angle than I thought would be right. Note to self: don't trust me.

Thanks for the help, BigMo. I've got a lot to learn obviously. I've been watch Tubalcain like crazy the past months. I'll watch more :)
 
OK can I just ask question on using a boring head. . And I am sure you will figure it out but I am a newbie to machining.
I am trying to make the bearing block for Hoss' CNC X2 upgrade.
Ok..
I work up the drill bits until I get to 15/32".
I assume then don't move any mill axis and chuck up the boring head...
I have several boring bars. Which size should I use..
I have been using one just a hair smaller than my drilled hole. But I have had issues with the boring bar being in the center of my hole. I have had to adjust the boring head using the adjustment to get it centered. .
Then I move the boring bar to just scratch the hole surface.
Then I proceed to boring hole .285 deep and .687 wide.
The I have to flip and do side 2.
How to I realign the boring bar to center sick I have moved the work. .
Tried 2 of these.. both the shaft does not come out straight..
Any help is appreciated

Sent from my SM-N910V using Tapatalk
 
When I used to use those I found that most of the inexpensive import ones needed to be touched up on a grinder to perform well or at least a good hone. They rarely performed well IMO straight off the shelf. Corner radii were also too small for my liking.
 
The import boring bars are not really ready to use tools, but rather "kits." Besides the carbide being brazed on crooked like we see here, there is often not enough clearance below the cutting edge for the lower portions of the brazed insert and supporting bar to clear the work. Watch for that rubbing if you are getting poor results. You can see the rubbed areas on the bar if you look carefully. You can grind away the interfering areas, or as a stopgap solution you can twist the cutting edge downward, which gives a negative rake to the cutting edge and gives more clearance for the lower portions. The tool height will need to be readjusted to the new cutting edge height. The first time I tried it I was amazed at the improvement of the cut, and also with how well the negative tool rake worked. It is still probably better to regrind the tool. Once the geometry of the tool is made into something that will work, and the cutting edges sharpened, those boring bars work just fine.
 
Yes, it’s not the same as the others. But if it was me, I won’t be worried one little bit. In fact, I would like that bar for making a square shoulder, yes I would. But, if you are not happy with it, then just dress it up a little. Those bars will need to be touched up as you use them anyway. They tend to wear quicker than you would like them to…Dave
 
Ok, cool thanks everyone. I'm not against regrinding this one (I actually found another one that's the same), especially since it's probably common practice to grind your own cutting tools into specific shapes or touch things up. I should probably get used to that.

And Bob, thanks for that. I'll definitely look out for that rubbing if I'm having issues. And also play with rake angle and such to see how it performs.
 
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