--- In email@example.com
, Alberto Magnani <al@a...> wrote:
>> I figure before I get an actual machine, I'll want to try out all
the software ahead of time like EMC on linux, Mach2, turbo cnc,
etc... I've seen some expensive packages, but those are out of the
question, and these seem to do a nice job at low or no cost...)<<
Sort of pointless to test controller software without a machine
attached. Sure you can see what you like in the user interface, but
you will have no clue how it runs a machine. Just to give you an
example, I finally took EMC off of my Bridgeport and replaced it
with Mach2. I did not expect to have any performance difference. But
I was pleasantly surprised to find that I can run much higher
acceleration and the moves are smoother. Not that EMC was bad. It
made me a lot of money on that machine and that was a big part of
why I left it on so long. It was producing cash so I saw no reason
to change. Point is without a machine attached you will not see the
difference in the actual performance of various programs. I have
used DanCAD, DeskCNC DOS, DeskWinCNC (the older version that did not
have a special card), CNCPro, TurboCNC, EMC, Mach1, Mach2, DeskCNC
with a controller, and I forget what else. Nicest to use and best
performance is Mach2. DeskCNC with the controller is smoother in the
pulse stream, but I like the Mach2 interface better.
>> Taig vs Sherline<<
I own, use, and sell both. My opinion is that the Taig is a much
better mill and the Sherline is a much better lathe. Most people
giving an opinion do not have hands on experience with both so the
value of their insight is limited. Seeing as you are asking about a
mill here is my take:
1/2" screws = less wear and lash adjustments stay put as well as no
whip at high travel rates.
Much greater bearing area on the gibs so the machine wears better
and they are lapped in at the factory.
Wider spacing on the Y axis slide for better support and less
Serious heavy duty Z axis slide.
Covers on the bed.
Double the weight.
12+" of X travel.
Wider table with 3 slots.
Spindle takes a 3/8" end mill.
Motor is variable speed.
So in my mind and to my customers that look at both side by side the
mill to get is a Taig. You can easily put a Sherline spindle and
motor on it or put other DC motors with variable speed. The lower
rigidity and lighter construction of the Sherline are not easy to
>>I didn't really think about getting a metal lathe<<
Yup, you need one of each. If you want desktop size get the Sherline
Lathe and then you can "borrow" the complete spindle and motor unit
to put on your Taig mill plus have a great lathe. I will not get
into why I feel the Sherline is a better lathe, but when you put
them side by side it is obvious. Hard to believe the Taig mill and
lathe come from the same company.
>> 2. What do you think about using a cnc mill (like the taig) to
I have cut plenty of wood and it works just fine.
>> 3. I know machinists use fly-cutters with special elliptical
shapes for gear tooth shapes, but what do you think of just using a
small endmill and some good g-code?<<
Sure if it will give you the proper tooth shape.
>> 4. The escapement wheels can get kind of big (7 to 10 inches or
so in diameter...) too big for the y travel of the machine, but I
was thinking, a rotary table could be used to rotate the wheel in,
cut a tooth or two, and rotate it, cut, etc... Is this a feasible
kind of thing to do if you want to cut a 10 inch wheel on a machine
with a 12" x 6" table travel limit?<<
I take it you mean to lay the table down so the rotation is parallel
to the rotation of the spindle. That is a C axis. Works fine that
>> 5. There's an appeal to just getting the Sherline CNC setup all
pulled together already<<
I don't recommend either the Taig or the Sherline complete units.
They cost you about $300 - $500 more than doing yourself. The
Sherline drive does not work well with Mach2 in my experience and
EMC while a ground breaking program is not without it's issues. I
may be wrong, but I thing the Taig package is a half step driver so
you can get resonance, need big motors to compensate, and generally
don't have the performance you get with microstepping. I did not
believe the difference until I tried microstep and half step drives
back to back on the same machine.
>> 6. I know you can control the motors from the computer without
the hand cranks in-line, (the the taig cnc mill doesn't seem to have
handwheels built into the motors they supply on their cnc setup) but
am I being silly thinking that I'll even want to turn any wheels by
hand to begin with? <<
Many of my customers want cranks so they use dual shaft motors and
can crank by hand when the spirit moves them.
>> 7. These machines don't seem to have ball screws... don't I
really want ball screws if I want to be accurate?<<
Sure and you really want a 10,000lbs VMC instead of a little mill.
You don't need a Ferrari to get to work and you don't need
ballscrews on a table top machine. Had an interesting discussion
about this with a company that makes $15,000.00 table top machines.
His answer is that there is no advantages to ball screws on a little
machine, but people want them so he sells them that way. His
preference is for precision modified acme screws with BSA super
nuts. The stock screws will get you under .002" backlash. Most
likely your setups and cutter flex will move around more than that.
>> 8. The Minitechs and the MaxNC's look sturdier still, but they
seem a step up in expense too... <<
My 5000 lbs Bridgeport is more sturdy too. But it is hard to park
the car in the garage with it there. You have to pick a size that
suits your needs and accept that it is not a bigger machine.
>>But it seems like a Taig or Sherline sure is a nice way to start
in this hobby, and it might still be useful in years to come even if
I do get something larger later...<<
You have to start somewhere. The bigger machine also has more
expensive tooling. If you have the room, can afford it, and have a
need for it get a nice big mill. If not get a Taig and start making
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