need fricken LONG endmill

You are NOT..NOT going to be able to use a boring bar in a 24" deep hole thats 1" in diameter.

You might use a "Line Boring" setup...but not a boring bar. End program. Full Stop. EnditEnditEndit.

Gun drill yes. Line boring yes, no boring bars. There is simply nothing..nothing stiff enough to work. not even carbide.

Gunner

"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state. Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic problem of Socialism, until it becomes obvious that nothing has been changed but the name. The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy, and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

Ayup..even small cuts. One of the unavoidable facts of life that Achimedes discovered..."Give me a long enough lever and I can move the world"

"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state. Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic problem of Socialism, until it becomes obvious that nothing has been changed but the name. The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy, and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

I'm trying to bore a 1" hole 12" to 14" long in a 1.75" square rod PERFECTLY on center to my CHNC lathe...

Not an easy task. I wouldn't ask if it was easy. OK, a slight misalignment at the center won't bother, so now I only need to bore

My best idea to get it in perfect alignment is to mount an end mill just under one inch in the spindle and bore with the square rod mounted in position on the lathe. Then take the part out and bore to correct diameter in the mill.

I just searched my stash, found a 5" long by 7/8" EM. I'd sure like to find a longer one. Anybody have one? Quick search on fleabay, no joy.

FWIW, I'm trying to gundrill 24" long in a lathe with 12" travel. The drills mount in a one inch bore.

Karl

You just need a long holder; the endmill can be one of those cheapo 1/2in shank jobbies like Enco sells for hand mills although I would probably first go through with a slightly undersized silver and deming, retracting fully at very frequent intervals.

Might it be easier to get 12" and 24" gun drills and just change drills after you bottom out the shorter one? That way you don't have some sort of monstrosity hanging off the toolholder.

Thanks for the idea. I didn't know they made 1/2 shank by 7/8 endmills. Just the ticket.

Yes, i didn't mention, I'll ruff drill it first. Just use the endmill to true it up.

Karl

Karl, I think that most people would use a boring bar on the lathe in this situation. Especially since you have a CNC and can write a program to take off a small amount in each pass.

I would rough drill then use a push broach in a hydraulic press to achive the desired final size. This eliminates a lot of problems like tapered hole when trying to bore small sized diameters. Even drilling a long 24" hole say

Best Regards Tom.

EVen making very small cuts?

Alternate between a 7/8 in S&D drill and an endmill 1/16th or so smaller than the finish hole that's been cicular ground and has about 1/2 degree of backtaper , switching back to the drill after every inch or so in depth, then finally, run your finish tool, removing .03 or so per side, preferably in a single pass.

He *might* except he'd need a ~3/4 inch diameter solid carbide bar a tad over 48 ionches long...

..LOL..

=======================

Long response

If at all possible, rethink your material requirements and use something like sched 80/120 pipe or heavy DOM tubing.

To do this from solid stock is possible, but won't be cheap or easy. The project divides into two parts, both of which involve considerable construction of tools and tooling. First getting a nominal size hole the length of the stock, and then getting the hole to the required dimensions, finish and straightness.

Assuming a reasonably equipped HD home/hobby machine shop, this can be done, but the set-up, tool/fixture fabrication etc. will take *MANY* times as long as the machining, and the machining will likely be an all day job (or more, depending on materials/ tollerances(yours and the machine) ==>for each phase. which should remain in place until this phase of the job is completed for maximum accuracy.

Ignoramus11700 fired this volley in news:lbadndwhNN2jmtTPnZ2dnUVZ snipped-for-privacy@giganews.com:

Not even taking off mere swarf, Ig.

Lloyd

How about using three guide hole blocks instead of one challengingly long hole?

You could make a 1.75" box channel from flat stock with your 1" holes in the end plates, and if necessary add one or more blocks within. If sliding a drill rod through shows they aren't aligned, cut down the inner one and locate with setscrews.

A 1.75" box channel made of 0.375" ground flat stock might be good enough with just end plates, if you drill the dowel pin holes accurately enough. jsw

I just tried boring some water pipe scrap with a 9/16" diameter Armstrong boring bar extended 7.5" from the holder and set slightly above center to let it deflect out of the cut. The pipe was chucked close so all vibration came from the bar. It's slow at 0.002"/pass and the finish is poor but it does work well enough to remove the welding flash and recenter the hole to drill or ream it further.. Reducing speed removed the chatter pattern.