Any Homemade line boring equipment?

"RogerN" fired this volley in news:jc2dndb_-avxUhDWnZ2dnUVZ snipped-for-privacy@earthlink.com:

I made a simple jig that mounts the work on the cross-slide, and holds the boring tool between centers. It allows me much longer bores than a single-ended boring bar mounted in the tool holder would.

It's really nothing more than a plate to which I clamp or screw the work. The boring bar is a piece of 5/8" stock with a hole for the tool bit and a hole for a setscrew, plus center pockets on both ends. Drive it with a dog.

About the only drawback is that the bore size is limited to the amount of tool overhang you can afford; with my little 1/4" bit, that's about

1.25"(or a bore of 2.5" max) before chatter kills the job. And, of course, you have to adjust the tool on every cut, rather than moving the cross-slide.

But it works.

LLoyd

Depends on the job. Years ago, on Hopto excavators, my dad would mount an engine cylinder boring machine to the side of the boom to bore out the pivot pin area, to install a replaceble pin in made.

This is essentially how the original boring machines worked. Lots of early automobile engine blocks were actually bored on lathes.

Some of the old English MAP books show miniature versions of those old boring setups on lathes. Brit lathes, which traditionally have T-slotted cross slides (or saddles; I forget which) are ideal for that work.

I seem to recall a rig by Wayne Cook. Maybe he'll chime in.

Pete Keillor

Haven't got there yet, but I'm with you. I need one and they seem to be priced too high for what they are. At some point when I asked about it getting an old bridgeport head (from folks rebuilding and upgrading the head) was suggested as a power-unit & feed option. I've also seen mention of getting one from army surplus, but have never seen such myself.

A lot of that type of thing is specific to the job at hand, locomotive steam cylinders, VW engine cases, compressor shells, car engines, etc. One of Guy Lautard's Bedside Readers had a description of such a rig and some of Colvin and Stanley's works described what they built up in locomotive shops to redo cylinders in situ. The Model Engineer magazine had a lot of such setups on the old Brit lathes, they had T- slots on the carriages so were easy to rig up. The cutter bar spun between centers and the work was fastened on the carriage and traversed with same. What you need to build is pretty much determined by what you need to machine. A lot of what they used to do with such rigs on a lathe is now done with boring heads on a mill. Basically all you need is a tool holder, a way to guide it through the rough bore, a method of spinning it and another one to periodically move it down the line. You'll also need some way of fastening the works so it doesn't move relative to the workpiece. The last could be easy or could be hard, depending on what you want to work on. A star wheel advance for the cutter is pretty easy to rig.

Stan

Or maybe not ~ but anyway, in DropBox/_2002_retired_files, see:

(Per 2002 section of )

Here's an example

They have a motor on a linear slide with a hand crank screw to feed. A bar with holes drilled and broached for tool bits, and holes drilled and tapped for the set screw. There's also pieces to mount a bearing and center the bar. The pictures of line boring bar in the dropbox looked like it would be much more difficult to construct and handier to use. I guess to me it just looks like one of those items that would be cheaper to make than buy, the eBay version that is, maybe not the dropbox version.

I would guess someone could run with the idea and make portable machine tools that you could bolt or weld on large equipment to do machine work. Seems like it would be interesting for HSM'ers with big ideas, limited space, and small budgets.

RogerN