question about tool holder alignment and boring

[hdgis1]

Ok. Total newbie question but I'm gonna ask it anyway. I think I understand that when boring using a boring cutter the perpendicularity of the tool holder to the spindle is not so relevant. Largely because the cutter geometry of the tool dictates that the point will do the cutting. Thus as long as the carriage travel is true and cutter deflection has been accounted for you should come out with a round object that has the same wall thickness.

Example picture below (i realize that isnt a boring bar or holder but was just giving you an idea of what I am talking about.

You know, I had this question about alignment and 4 flute endmills (instead of boring bar) and I think I have talked my self out of asking. Either that or I realized that end mills aren't meant for boring. Hell - I don't even know what it is I should be asking!!!!!! :shrug: Is there any other way to bore or are you only other options drilling?

Chris

 

[chucketn]

Actually, you can bore with an end mill... You just line up one flute as the cutting edge. I have made boring bars out of an allen wrench for small holes. But, that aside, you have the right idea. For boring say a cylinder for an engine, you drill the hole as big as you can and use a boring bar to make the hole bigger. Last few passes are made with no change to the cross slide to allow for 'spring' of the bar.

Chuck in E. TN

 

[hdgis1]

Actually, you can bore with an end mill... You just line up one flute as the cutting edge. I have made boring bars out of an allen wrench for small holes. But, that aside, you have the right idea. For boring say a cylinder for an engine, you drill the hole as big as you can and use a boring bar to make the hole bigger. Last few passes are made with no change to the cross slide to allow for 'spring' of the bar.

Chuck in E. TN

Chuck -

When you say dont change cross slide are you meaning make multiple passes in and out without changing depth of cut?

Chris <-------Lives in Knoxville

So if I am drilling a 5/16 hole with a 5/16 drill bit (final size) what alignments other then up/down and left/right do I need to check to ensure the hole is the same size as the bit going in?

 

[dalem9]

Hi All drills make a hole bigger then the stated size ,You drill a smaller hole then ream it or bore it to size. .Hope this helps Dale

 

[dalem9]

Hi Also make sure your lathe is level,This is from side to side ,very inportant. If there is a twist in the bed if will show up in your hole. Dale

 

[hdgis1]

Hi All drills make a hole bigger then the stated size ,You drill a smaller hole then ream it or bore it to size. .Hope this helps Dale

Makes perfect sense!

Thanks
Chris

 

[rkepler]

Hi All drills make a hole bigger then the stated size ,You drill a smaller hole then ream it or bore it to size. .Hope this helps Dale

And drills never end up exactly on center, and reamers follow the hole. So if you need holes on size and on position you drill a rough hole, bore for the position and ream to size (if you're not completely sure of your boring skills).

I had to make a series of holes for dowel pins in a fixture, 2 pieces with 32 holes spaced 3/4" apart and 1/2" vertically with something of .0002" tolerance on position and .0001" on size. Had to crank the resolution on the DRO to the max. It all came out, in the end you could put dowel pins randomly on one piece and insert it into the other piece. I never did all 32, figured it'd take too much to pull apart.

 

[chucketn]

Chuck -

When you say dont change cross slide are you meaning make multiple passes in and out without changing depth of cut?

Chris <-------Lives in Knoxville

Yes, that's exactly what I mean.

Chuck in E. TN

 

[hdgis1]

Thanks guys!

 

[raggle]

Just an aside here. Everything in the pic is Taig, but I don't recognise the headstock. Can you enlighten me anyone?

Ray

 

[Tin Falcon]

I suggest you get and read a copy of Army TC 9-524
chapter seven is on lathes and lathe operation http://metalwebnews.org/machinist/ch7.html
I think others have pretty well answered your question.
Tin

 

[rkepler]

Yes, that's exactly what I mean.

Just an observation: if you find yourself making a lot of spring passes it's usually the result of either using a smaller than needed boring bar or a tool that's either rubbing on the work (not enough clearance) or has a grind that's pushing it away from the wall. Sometimes it's unavoidable - really small deep holes or really hard work, but frequently you can find the cause of the problem and eliminate the additional passes (unless you want that final half-thousandth taken out).

Further - the 'spring' in a tool will also change with the cut taken. If you take a pass at .050 diameter you might have a lot more spring than a pass taking .025 diameter. If you see the depth of cut decreasing with the number of cuts it's usually the tool getting dull.

One thing I do is to rough cut the work then for the last 2 cuts try and split the remaining distance. If you have .025" to take out try a .012 cut and see where it goes, if it's .014 then you know that a .008 cut will take you close to the final diameter where another .012 cut would likely take you over.

It's all just another example of the "Everything's made of rubber" theory. Some rubber is pretty hard like carbide or diamond, but other rubber is pretty weak like aluminum, but it's all malleable to someone/something, somewhere.

 

[hdgis1]

That friends is a large bore headstock. Particularly useful for large stock!

Chris

Just an aside here. Everything in the pic is Taig, but I don't recognise the headstock. Can you enlighten me anyone?

Ray

 

[peatoluser]

As a taig user and fan, I'd love to know more about that headstock. enlighten us more please Chris
yours in anticipation
peter

 

[Mosey]

IMHP this thread contains tons of very expert knowledge about boring, materials, etc. I for one, appreciate getting all this learning for free. Thanks, guys.

 

[mklotz]

IMHP this thread contains tons of very expert knowledge about boring, materials, etc. I for one, appreciate getting all this learning for free. Thanks, guys.

Ah, what you don't realize is that we only send out bills annually.

 

[raggle]

Thank you. I had not seen these headstocks before so I Googled "taig large bore headstock".

Seems they come from the pool cue world, Peter, and can pass about 1-3/8" and have indexing built in, along with a dedicated chuck.

 

[Mosey]

Ah, what you don't realize is that we only send out bills annually.

Well, I only send the checks out every................................ :big: :big: :big: :big:

 

[djc]

As a Taig user and fan, I'd love to know more about that headstock.

Search for

large bore headstock Taig lathe cue lathe

http://www.ebay.ca/itm/180691906823
http://www.ebay.com/itm/TAIG-POOL-CUE-LATHE-/120764863570

Another alternative is to read http://www.cartertools.com/Cue Lathe FAQ.html and follow up leads therein.

 

[hdgis1]

Looks like you all beat me to the punch on the headstock thing! Yes they are primarily used in the pool cue world. In fact, this is where my interest lies. There is a huge overlap between metal machining and how most pool cues are made. With an extensive background in furniture making, four years working in a pool hall in college, and a desire to learn the appropriate machining techniques, I will have a lot of questions! Can any one provide me with a discount rate? ;D

Chris