Drilling With A Mini Lathe

Tool Chatter said:
That makes very good sense, to not risk damaging the tailstock, that hadn't occurred to me at all. As far as drilling a smaller initial hole through the aluminum, what would be a recommended percent of the finished size? Something like 80% to 90% of the finished 25.00mm?
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You need a hole bigger than the boring bar to follow, also room for the chips to get out. That restrains you at the small side. You also want to go no bigger than what the lathe will safely drill without drills or chucks slipping, tail stock trying to flip over, or other theatrics. A good rule of machining is that if it looks dicey, it probably is. Broken parts on your lathe ends your project until and if you can get it fixed. Save your macho for other sports...
 
turnitupper said:
Smaller,Mike, if he drills 1" and tries to bore it to 25mm it wont work. Perhaps he could use a boring bar that adds metal. I have had use for one many times but the machinery vendors always seem to be out of stock. Must be a very popular tool. :frown 2:
John.
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One inch is 25.4 mm, exactly. You are correct, John.
 
25mm=.98425 I would use a 7/8" drill bit and bore to clearance fit. Cut and face the spacer to size. Drill a pilot hole just larger then the web of the 7/8" drill.
 
kd4gij said:
25mm=.98425 I would use a 7/8" drill bit and bore to clearance fit. Cut and face the spacer to size. Drill a pilot hole just larger then the web of the 7/8" drill.
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Thanks, that sound like a decent size to open the material up to initially. So the real dumb questions will be coming now. Opening the 0.875" to a finished 25.00mm, boring the 6061 aluminum, about how much material should I limit to removing with each pass?

That was my thought, to basically make the shape of the spacer, and face both ends to the proper length first, then check the run out of the part in the chuck before boring. This also will be a stepped, or a flange on one end of the spacer. It'll look like this attached. I have to acquire a few more parts before I can determine all of the finished dimensions.

axle spacer.jpg
 
A poor man's boring bar could be placing an end mill in the tool post.



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turnitupper said:
Smaller,Mike, if he drills 1" and tries to bore it to 25mm it wont work. Perhaps he could use a boring bar that adds metal. I have had use for one many times but the machinery vendors always seem to be out of stock. Must be a very popular tool. :frown 2:
John.
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Right, 1" = 25.4mm. I don't think in metric.

Sure would be nice to have a reverse boring tool, though!
 
Tool Chatter said:
Thanks, that sound like a decent size to open the material up to initially. So the real dumb questions will be coming now. Opening the 0.875" to a finished 25.00mm, boring the 6061 aluminum, about how much material should I limit to removing with each pass?

That was my thought, to basically make the shape of the spacer, and face both ends to the proper length first, then check the run out of the part in the chuck before boring. This also will be a stepped, or a flange on one end of the spacer. It'll look like this attached. I have to acquire a few more parts before I can determine all of the finished dimensions.
Click to expand...

If you use your 3 jaw chuck, I suggest you turn to the OD of the flange, then turn the smaller OD to size, then drill and then bore to final ID. Part it off a bit long and face the flange of the larger OD to bring it to final length. This will give you the best chance to keep the bore concentric with the OD.

If this is the first piece you are boring then I suggest you spend some time practicing. Boring is not difficult but there is a bit more to it than you might think.
 
Welcome to the HM, if you have a drill chuck for the lathe and it’s ½” capacity. And you have a ½” drill bit. Then just use that. And bore it out, simple enough. Don’t buy a larger drill bit. Anyway, your lathe is on the small side for drilling the holes you are talking about. You could break something trying…Dave
 
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