I don't really see any problems with it. It's just as safe as a regular
lathe as long as the spindle can securely hold the material. Now I would
imagine it would be a bit of a pain to program.
We've done it before to change a tool holder a bit. eg. turn the
diameter down a bit for clearance.
But for production, I don't see any advantage.
On 10/2/2009 5:23 AM, Lon Jetivati wrote:
Forces in turning are a lot higher than with milling. So it will be limeted
to small parts and light cuts.
Why not just buy a CNC lathe? You can pick up a five year old 2-axis
Japanese lathe for well under 10 grand at auction nowadays. And there's no
shortage of auctions.
Limited on length. No possibility of using a tailstock. A cut that would be
nothing on a lathe will easily rip the tool holder out of a mill. No single
point threading ability, No tool nose radius compensation. No diametrical
programming, Strigy chips will just lay on the tools, hell every chip will.
Can't run parts from a bar. Can't use a collet chuck.
Should I go on?
How much does this rig cost?
The chuck and the tool holder block sell for $1148.
The block alone is $799.
No single point threading would be a drawback, that's a mainstay in
the lathe department.
But tapping can be done with the mill's tapping cycle.
One design flaw...the cutting pressure on the tools is toward the
"mitee-bites" clamping them instead of the solid part of the holder.
CNC lathes usually have some thick safety glass in front and often
some steel bars...where most mills have an 1/8 inch of acrylic.
Something to consider when this setup spins to 10k rpm.
While I'd like to say I would never use a mill as a lathe, I already
have done it in a pinch.
I still don't like the idea of turning parts using this method as a
matter of course. If you have enough turning work to keep a mill bust
doing lathe work you probably ought to buy a lathe,
OTOH, if it's a once in a while thing and everyone uses their head and
works safely, then it's OK. The pricing seems reasonable.
I looked at the site again and I see that they do in fact single point a
thread using the rigid tap function. I'm not sure every control could do
that or even if the threads would come out accurate enough, but it's
Heh. Kind of a different thing. But I've never had a real high opinion
About a dozen years ago I was at JIMTOF standing in the Mazak booth. No
lie, they had a darkened room in there, with a glittering disco ball,
and a light show, all to showcase the lathe inside, which was merely a
two-axis gang tool that was alleged to be very accurate. But by its
construction I knew it could never be.
Then I walked out of the Disco room and was standing in front of this
HMC that was blisteringly fast. Super high RPM spindle just going balls
out on a big block of aluminum and chattering like a school girl. I
suddenly noticed that the great big windows were shaking. They were
about 1/32" thick acrylic. They would barely stop a flying chip, never
mind a face mill launched at 20,000 rpm.
I backed away and looked around. It was all so cheesy. Then it hit me.
This was Japan's equivelent of Haas. A decade and a half ahead of Haas
maybe, but the same damn thing. Cheap and cheesy.
I've done this in B'-ports 25yrs ago, in a pinch. It works great for
"certain" types of jobs. Light cuts, with custom bored spindle collet
ie(R8 soft blank) /holder/chuck jaws- to hold work pc, ect.
Whats really neat on a CNC, A precision arbor for 7-8" surface grinder
wheels. Mount a clear-view dresser in the vise for wheel shape. I did
this for CNC grinding graphite trodes for automotive (Cadillac
interior) lens bezels molds(v-groove on large rad. X-Y steping up
another rad. in Z- kinda bowling ballish. Don't try this a home!<g> If
ya do, cover your machine with ? so grinding grit do'nt get were it
aint sposto.- same as when toolpost grinding on the lathe. I gathered
up used shop aprons for cover/protection.
Moldmaker story: certain types/brands of surface grinding wheels
perform very well in graphite. They dont load-usually a major freekin
squelling problem in graphite,retain their shape fine detail not
always achivable with an endmill due to 0 cutting surface speed at the
bottom of V grooves for examlple.
The harder 150g+ "open pore" wheels soft bond G are the ticket for
trode work.IIRC we used a 200g "por0sway". Tip: these wheels need to
be rough dressed 1st with "standard" marble diamond, then finish dress
with a SHARP phono point.
If ya can't say it here where the hell can ya?<g>
That reminds me of something I had never heard of being done before,
but thought I'd give it a try.
This was back around '79 or '80 and on a Bridgeport
Boss I CNC. I tried grinding (with a surface grinding wheel in a
special holder I made to fit the CNC) some mold ejector pins at an
angle to the axis of the pin. The grinding wheel would come and
contact the pin and circle around & around the pin until the pin was to
size and go home. The ejector pins ended up with boss on the end that
was at an angle. Actually it worked pretty good. That is, until one
time something happened in the program (I don't remember now just what
- maybe a mid-program start that lost some parameters) and the grinding
wheel tried to go sideways right THROUGH the pin and cracked the
grinding wheel which then broke and tried to throw a chunk of grinding
wheel, the size of about 1/3 of the grinding wheel, right
through my chest at 3600 rpm! No sheet metal enclosure on this mill.
I stood there just stunned holding may hand to my chest on top of the
chunk of grinding wheel. Man, my chest was black and blue for weeks.
To use your phrase, now that's REALLY something you don't want to try
at home. :)
Yup been there done that, mine was on a B-port, damn moldbase plate(2
cav Norelco Dial-A-Brew strainer basket-floating B plate that slides
rode on - actuated by cam rollers outside in tracks- very cool design-
no angle pins! , decided to contunie rotating - after the bolt
sticking thru the LP hole fell out - directly into my chest.:-( the
other downhill snow skiing. Black & then every color under the sun as
We had a Gorton MicroMaster? mill we did grinding on- with a cross-
slide turntable. It had a precision 6K spindle- Light touchup only-
Lots O 1/4" Plexiglass sheilds- couldnt see thru'm from burnt chips,
but will save your life!
Have an average Day!
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