Boring problem

Since this is a non-critical part I built up the bore with JB Weld today and will give it another try in a couple of days.
Mikey thanks for all of the suggestions. I will take the boring bar out of it's holder and see if it can be held by my tool post. If the tool post will hold the boring bar I will post a picture of my setup to see what you guys think.
Thanks
Chuck
 
Success! I did my do over today and I have a nice tight but not too tight fit. I want to thank everyone for their suggestions and advice. I particularly want to thank Mikey for the time he spent responding to my emails. His advice was invaluable. Thanks Mikey.
 
I just can't do anything with a hand wheel dial. I keep forgetting the numbers and back lash sometimes gets me. I stuck a DTI on the back of my Xslide and a sliding stop on a 1/2" bar that I threaded into the carriage. This has been a Godsend for me in the accuracy department. You can also watch it during the cut to see if the slide moves at all.
It's also a good idea to let the bracket protrude enough to prevent damage to the DTI if you forget to slide the stop bracket to the side and ram your Xslide into it.

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mickri said:
Thanks. Boy do I feel stupid.
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A friend of mine who's been a toolmaker for 40+ years told me one day when I was having this problem, "The hardest thing in machining is a hole. To make a hole that's round, on size, and where you want it is the hardest thing." I don't beat myself up too much when I screw up a hole. Turning, sure, but holemaking? That's always dark magic.
 
SmokeWalker, I agree and it gets even worse with smaller holes. At .750 the bar is rigid compared with a .250 hole, which I won't try without a reamer.

Jim
 
LATHES we had you couldn't depend on dials, so every cut was done with an indicator set up. To this day I only use indicators for cuts.
 
Hello Mickri,
As has been stated tool deflection,(spring), is something to take into account. Also as has been said you want as little protrusion as possible on any tool.
Here's a couple of pics of a boring job I'm doing for a friend. These are idler wheels off his Kubota 1 3/4 ton digger. the face seal got dirt in it, the oil leaked out and subsequently the whole caboodle failed. Then the track fell off :(.
I am doing a repair by boring, shrink fitting sleeves and fitting shielded annular double row ball bearings and new pins,(axles).
When I got within cooee of the finish size I ran the bar twice through the wheel for each cut. It always amazes me how much swarf comes off even after you think you have just touched the mark.
So my thoughts are you did nothing wrong other than not consider tool spring, you got off lightly.
I've just taken a few more pictures for my mate so I can post here if you are interested.
P.S. The only reason I am using a mill rather than a lathe is because the wheel rims had already been built up and centering/leveling on a mill table was easier and I'm lazy but the same factors of tool spring hold true.
The last pic is using a cut-off tool to skim the last 1/2 thou off a sleeve. They work great for fine finishing cuts and the thin blade allows working close to chucks and centers.

- Barry.

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