This is my first post, hopefully I haven't done anything horrible.

I am a highschooler (junior) at the Harker School (San Jose, Bay area,
California), part of the robotics team there. We participate in FIRST
robotics (www.usfirst.org), every year we build a 120 lb robot out of
raw materials and compete against teams nationwide.
Up until now, we've relied upon generous machine time donations from
machinists in our area, but we would like to do machining in house (for
both learning and time purposes, we only have 6 weeks to make our
robot, and the lead-times for machinists are long).
we've had everything from 6x4 plates with less than a mil of tolerance
to 36 inch long tubing with about 10 mils of tolerance.

I'm here to ask you what you all think is a good mill for us to aquire.
Space is not a problem, but we only have one-phase power wired to 15
amps. Although perhaps we can get the breaker changed, its unlikely we
can get three-phase. Would we have to invest in a VFD?
Also, I'd highly appreciate it if anyone could help us with how to find
auctions .etc in the area.

Lastly, would a CNC retrofit be as accurate (if not more) than a simple
DRO?

Tatsunori Hashimoto, Harker Robotics.

wrote in message
ups.com...
This is my first post, hopefully I haven't done anything horrible.

Nope.


Not easy questions to answer, as there are many possibilities. Used
Bridgeport, but they're usually 3 phase, and converter, either solid state
or rotary would be required. New, lower cost, KBC tools # VM-22-R8,
(kbctools.com) would be a good choice, BUT 220V single phase. Motor could
be changed out to 110V, possibly 1 HP without any great loss. Mill drills
can do nice work, but depend more on the experience of the one using it
than anything else.

Lastly, would a CNC retrofit be as accurate (if not more) than a simple
DRO?

Quick answer, the repeatability of a machine, to make identical parts within
tolerances is dependent somewhat on the machine. How accurately a machine
can work is dependent on the man running it. I've done some incredibly
tight work on a mill drill, but that doesn't mean I want to do it again,
only that it can be done. A good CNC retrofit for a mill will include ball
screws to replace the lead screws, eliminating backlash. A DRO reads the
actual positions of the table, both will reduce the errors caused by not
considering backlash. (But so would a handful of simple dial indicators
with mag backs on them, it just depends on how much fiddling you want to do
before you start cutting.)

A machine that is poorly set up will do only poor work, and who made it,
it's condition, will mean nothing. Again, right back to the man that's in
front of it. Not having enough time to do it right the first time only
means you'll find time to do it over. Cutting corners to save time will
only mean doubling the time it takes. Cnc requires that you know the
diameter of the cutter as closely as possible, Dro means cut and measure,
then take the finish cut. In the end, the results are liable to be
identical with one or the other. Cnc can produce complex curved shapes more
easily, but that's something that's been done with other methods for over
100 years too. Cnc imposes it's own set of requirements, different from
other methods, Other methods have their own set, mostly measure, measure,
measure. Getting in a hurry is the mother and father of all screwups.

Rich

wrote:
This is my first post, hopefully I haven't done anything horrible.

I am a highschooler (junior) at the Harker School (San Jose, Bay area,
California), part of the robotics team there. We participate in FIRST
robotics (www.usfirst.org), every year we build a 120 lb robot out of
raw materials and compete against teams nationwide.
Up until now, we've relied upon generous machine time donations from
machinists in our area,

Did you do the work or did the machinists do it for you? When I think
back to some of the stuff I managed to do as a kid, nothing would
surprise me, but I didn't know what a mill was at that time.

The reason I ask is that machine tools can be extremely(!!!!) dangerous.
All readers of your post will want you to go through life with fully
functional limbs. You need supervision, and from people who really know
their way around machines. Further, I would greatly prefer that the
supervisor(s) have experience teaching people to run machines.


but we would like to do machining in house (for
both learning and time purposes, we only have 6 weeks to make our
robot,

A deadline can be a good source of motivation, but it can also lead
people to take risks. Be CAREFUL.


and the lead-times for machinists are long).
we've had everything from 6x4 plates with less than a mil of tolerance
to 36 inch long tubing with about 10 mils of tolerance.

On a 6x4 inch plate, I would try to hold 0.001 in tolerances regardless
of the requirements, if only for practice, and because keeping things on
size avoids a spiral of corrections for errors in corrections for other
errors. A part that is 36 in +/- 0.010 is going to pose an interesting
measurement problem - by interesting, I mean it will require some
relatively expensive measuring tools. I think I would make the parts
adjustable, and then either tweak until it fits/works, or calibrate the
machine after assembly.


I'm here to ask you what you all think is a good mill for us to aquire.
Space is not a problem, but we only have one-phase power wired to 15
amps. Although perhaps we can get the breaker changed, its unlikely we
can get three-phase. Would we have to invest in a VFD?
Also, I'd highly appreciate it if anyone could help us with how to find
auctions .etc in the area.

Lastly, would a CNC retrofit be as accurate (if not more) than a simple
DRO?

CNC adds another level and type of skill: beyond knowing how to run the
mill, you will need to know how to program the mill to run itself.
Mistakes can lead to dangerous forces on tooling and the work, and the
fact that the machine is running itself, it is all the more difficult to
detect. Note that I have never used a CNC mill, but I have this from
good sources, and it makes sense.

A DRO simplifies some tasks. I have never actually used one. I started
on an old Bridgeport mill, disappeared for a while, and am now doing
quite a bit of machining in my garage on a mill-drill (a rebranded Rong
Fu 31). It has a power feed, but no DRO. The more I work, the less I
care to bother with a DRO. I will admit there are times when it would
help, but it is no substitute for skill and understanding of machining.

I certainly do not want to discourage you, but if you have the money to
get even a mill-drill and tooling, or the money required to get and ship
even a used knee mill, then you are obligated to spend it well. I had
to deal with lost mail, retailers recovering from two hurricanes, and a
less than interested salesman, but it took a few months to select and
receive a mill.

IMHO, it is not realisic for you to find, obtain, and learn to use a
mill with six weeks to delivery of your product. Once you have a mill,
keep in mind that the mill is useless without tooling. Some tooling
is very expensive and "permanent" (unless damaged by collision with a
cutting tool), other tooling is comsumable. You need an ongoing budget
for tooling and maintenance, but you also need to know how to care for
the machine.

Most important, you must have skilled supervision. It sounds as though
you have engineers working with you. That's good, but many engineers
are not machinists. My experience is that most engineers would be
helpless in a machine shop. I know some glowing exceptions, and learned
a lot from them. BTW, I am an engineer, so I can speak.

Good luck,

Bill

wrote:

Up until now, we've relied upon generous machine time donations from
machinists in our area, but we would like to do machining in house (for
both learning and time purposes, we only have 6 weeks to make our
robot, and the lead-times for machinists are long).

What Bill said, and more.

The real value in the donated time you were getting was not the machine
but the machinist. The 'lead time' for learning machining is measured in
years. Presuming, of course, that you have a qualified instructor to
help you keep all your fingers, etc. while you are learning.

That said, it still might be worthwhile to buy or even borrow a benchtop
mill/drill for minor quick modifications. You will need a considerable
assortment of cutting, fixturing, and measurement tools that will cost
more than the mill/drill - the "borrow" option might provide all of
those if you are lucky. And you will still need the qualified instructor.

If any machinists local to Tatsunori are listening: you should consider
offering your time and equipment to help. I've done this and working
with bright, motivated high schoolers is an absolute boatload of fun.

The kids these days are awesome, incredibly more aware and sophisticated
than we were at their age. 'Public opinion' tends to be stilted by the
press' choice to publicize only the dysfunctional kids. (Imagine that!!
The press doing a bad job .... snort)
--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
Drop TROU to email.

Silly question but there is likely a High School in your area that still
has a machine shop and a Machine shop teacher with the tools and
experience to help and get you guys started.

REGARDLESS of whether there are competing high schools in your school
board cross school assistance when it comes to equipment is done and is
reality because the school board owns the capital equipment. (Meaning
all the inter school competition really doesnt matter when another
school or team needs a hand)

Approaching the teacher to see if you could get some time or assistance
from a highschool with a full machine shop would likely get you good
results. or the VIce procipal or shop coordinators

Had i heard about FIRST earlier i'd have volunteered some of my time and
machines for the idea where i am from.



wrote:
This is my first post, hopefully I haven't done anything horrible.

I am a highschooler (junior) at the Harker School (San Jose, Bay area,
California), part of the robotics team there. We participate in FIRST
robotics (www.usfirst.org), every year we build a 120 lb robot out of
raw materials and compete against teams nationwide.
Up until now, we've relied upon generous machine time donations from
machinists in our area, but we would like to do machining in house (for
both learning and time purposes, we only have 6 weeks to make our
robot, and the lead-times for machinists are long).
we've had everything from 6x4 plates with less than a mil of tolerance
to 36 inch long tubing with about 10 mils of tolerance.

I'm here to ask you what you all think is a good mill for us to aquire.
Space is not a problem, but we only have one-phase power wired to 15
amps. Although perhaps we can get the breaker changed, its unlikely we
can get three-phase. Would we have to invest in a VFD?
Also, I'd highly appreciate it if anyone could help us with how to find
auctions .etc in the area.

Lastly, would a CNC retrofit be as accurate (if not more) than a simple
DRO?

Tatsunori Hashimoto, Harker Robotics.

I just realized that I've never mentioned what material we work with..
We use 6061 aluminum for everything. The only steel on our robot is the
gears and shafts. So the only real machining of steel we'll do is
keyways.
Does that change any of your advice? (esp concerning accuracy.. im
guessing alu is easier to machine..)

Tatsunori Hashimoto. Harker Robotics

wrote:
I just realized that I've never mentioned what material we work with..
We use 6061 aluminum for everything. The only steel on our robot is the
gears and shafts. So the only real machining of steel we'll do is
keyways.
Does that change any of your advice? (esp concerning accuracy.. im
guessing alu is easier to machine..)

Tatsunori Hashimoto. Harker Robotics

Hi Tatsunori,

Be sure the school has sufficient personal injury liability insurance,
that it has or can obtain competent instructors, that the parents all
sign permissions slips, and that your entire class and the instructor
follow all the other advice from all these other gentlemen responding
to you.

That being said:

I'm window shopping for my own machine, and inexpensive but idiot
proof (BUT NOT CHILD SAFE !!!!) choices seem to be offered by MAX NC
(http://www.maxnc.com/). If you have a couple thousand to spend, I
would recommend that the school buy the MAXNC 10 CL-B.

Essentially, the CNC has already been done for you in a hassle-free
manner, and the owner evidently stands by his product. The only
problem might be shipping expense, this place is in Chandler, AZ (about
5 miles drive from where I live).

I can afford to talk like a naive idiot (at least in the eyes of some
of the people in this group and a lot of others) because not only do I
have no pride left, I'm also not afraid to speak up and ask lots of
questions just to learn... I've also found a friend who was a CNC
mechanic but was laid off, he is willing to be my tutor until he judges
me competent. Could be a while (he he).

Good luck,

The Eternal Squire

wrote:

Fred R-

I'd imagine that it takes many many years to be skilled at milling (our
machinist says he's worked for 50 years..)


I think, judging by comments some of the skilled machinists here, that
there is no end to learning the finer points. Even learning to make
acceptable parts and fix mistakes takes a long time. The fact that you
*have* a 50-year machinist to talk to is a gift you should not take for
granted.

As for tooling, a graduating member is willing to donate to us R8
collets , vises, indicators and end mills. Of course we'd still have to
buy alot of tooling, but I think we can get buy most jobs with end
mills and a boring head (of course I could be terribly mistaken..
please correct me if I underestimate this)..


That is Wonderful! It certainly means whatever you get must use R8
tooling. As for how much you need, it seems to me that I am forever
buying yet another kind of cutter for milling jobs. One of the reasons I
got a shaper was so I could do small strange jobs using hand-ground tool
bits. 15 minutes grinding a tool blank from the bin-full on hand and
another 30 minutes setting up and cutting. Way better than spending $60
and waiting a day or more.

In short, More = Better. Roughing and finishing, shorter and longer,
various diameters. It does really help that you have somewhat
standardized on 6061 Al since it is tractable to machine and you can
focus on getting the cutter geometries appropriate for it. Delrin is
another material you might want to have on hand; it cuts well with the
same tools as aluminum and is great for sliding or rotating bearings
against either Al or steel.

Another reason to reserve a budget for tooling: remember that cutting
tools are consumables. Slowly when used correctly, very quickly if you
make mistakes.


Also, what mill-drill would you reccomend? if its a RF-31, I've always
wondered why one wouldn't get the sieg x3 (Grizzly carries it as g046)
it has dovetail ways which means you dont loose your position..


Speaking of ways, square ways do just as good a job as dovetails, they
just need two adjustments instead of one.

I really think your best value would be to find a carefully used
mill-drill. It will have the manufacturing leftovers (like the notorious
sand in the headstock) already corrected and may come with more tooling.
Try craigslist.org It is very active in your area.
http://www.craigslist.org/pen/tls/136952564.html
shows a Smithy combination machine that was listed Saturday and is sold
already.

http://www.craigslist.org/sby/tls/137077555.html
shows a small lathe that would be handy for you as well.


Also, what other good ways of learning (for highschoolers..) do you
know of?


Talking to and watching machinists is the best. Second-best is watching
videotapes and then CAREFULLY trying it yourself. After that you try to
stop the bleeding and figure out what went wrong. Then try it again.
Repeat until crispy and golden.

Have a great time!

--
Fred R
"It doesn't really take all kinds; there just *are* all kinds".
Drop TROU to email.

"The Eternal Squire" wrote in message
oups.com...


I'm window shopping for my own machine, and inexpensive but idiot
proof (BUT NOT CHILD SAFE !!!!) choices seem to be offered by MAX NC
(http://www.maxnc.com/). If you have a couple thousand to spend, I
would recommend that the school buy the MAXNC 10 CL-B.

With respect, the worst advice I have yet read in this thread.

MaxNC machines are too small and flimbsy to put up with ameteur machinists.
CNC is *not* required or recommended(!). A good manual machinist is required
to make a good CNC machinist, period.

I would recommend a Bridgeport or knockoff. You'll spend the least amount of
time messing around with the machine, they are the most tolerant of
mistakes, and they are the most rigid of the mentioned machines (desktop,
benchtop, floor).

Personally I like a heavier machine with a more powerful motor and faster
spindle for manual aluminum work, but the BPT will be a good match for the
type of work being described.

Regards,

Robin

wrote in message
oups.com...
Thank you very much for your insightful opinions, I appreciate it.

greybeard -

so would you say it would be easier to do work on a bridgeport rather
than a cheap RF-31 milldrill because of the rigidity?

It is always benificial to have the largest, most powerful machine that will
fit in your space, is within your budget, and will hold the part you're
machining.

A bridgeport is ideal for your work. A mill/drill is a compromise (less
rigidity and smaller capability in exchange for less money and smaller
footprint).


And is a DRO absolutely accurate? (ie reading on DRO always corresponds
to table distance..)

As far as the work you're doing is concerened, yes.


Also, how would you cut complex shapes without CNC? with a rotary
table?

What kind of "complex" shapes are you producing? Can you specify examples?


We've used bandsaw, lathe at RC's shop but not a mill. How much more
dangerous would a mill be? (fly cutters do look dangerous..).

It's not a matter of degree. A bandsaw will cut your finger off while a mill
may pull your finger off. Neither are ever acceptable. Both machines require
respect and proper training.


6x4 1 mil of tolerance is easily doable? or is it a fairly difficult
task? I'm trying to gauge the relative difficulty of the work we do.

Truly +/-.001" on a bridgeport is pretty tight, but certainly attainable.
What kind of work are you doing that requires such a tolerance?


And our build season is already over this year (we shipped our robot on
tuesday). I intend to learn how to use a mill (regardless of whether or
not we acquire one) over the next year. (any suggestions? I've been
thinking about volunteering at a machine shop..)

Here's a rule of thumb: 1st and 2nd year apprentices are considered losses
(pay and overhead versus output). 3rd year apprentices might break even. 4th
year apprentices should make the company money.

If you happen to find someone willing to let you work in their shop (costing
them money! even if they never give you a dime), ask as many questions as
they'll allow, do your best always, and always be respectful of that
person's sacrifice as well as their experience and capability compared to
yours.

As for tooling, a graduating member is willing to donate to us R8
collets , vises, indicators and end mills. Of course we'd still have to
buy alot of tooling, but I think we can get buy most jobs with end
mills and a boring head (of course I could be terribly mistaken..
please correct me if I underestimate this)..

*Important advice below*

Make a point of designing parts around the tooling you have. Cutters get
expensive *very* quickly and you will inevitably run out of time. If you
want to keep the price and complexity of your parts low, Keep It Sweet and
Simple (KISS).


Also, what other good ways of learning (for highschoolers..) do you
know of?

You're in a rough position.

In high school, I entered two Canada-Wide Science Fairs with projects I had
built in machine shops. I was lucky because of the people and facilities to
which I had access. I'm sure you've seen that there are many skills that you
have to master to be successful in large projects like a robotics
competition. Time management is huge. Conceptualization, design, fabrication
and assembly of the project. Perhaps a write up. Computer programming. The
list is endless. Adding machining is a big jump, but if you can pull it off
you'll be far ahead.

Good luck with everything. Enjoy this time, as you are working towards your
own goals. Once you start making parts for other people, it'll never be the
same.

(Go for the Bridgeport, if you can)

Regards,

Robin

Robin S. wrote:

With respect, the worst advice I have yet read in this thread.

With respect, the subtext of the original request is not fully
understood by my distinguished colleage somewhere else out there on the
Internet.

No matter how well motivated or cautious or intelligent or bright a
high school student is, legally and morally that student is still a
minor. Special considerations apply.

MaxNC machines are too small and flimbsy to put up with ameteur machinists.

The intended operators are not amateurs, they are children.
Bridgeports and related machines will almost certainly exercise lethal
forces in the event of an accident. While smaller mills can generate
lethal forces, due to physics the amount of total momentum applied
against any part of a child's anatomy will certainly be less. That
increases the chances that the ER team can save the child in time.

CNC is *not* required or recommended(!). A good manual machinist is required
to make a good CNC machinist, period.

These children do *not* have the time, let alone the attention span, to
become good machinists. They best they can do is a 13 week semester
(never mind the 6 week deadline) is to develop an appreciation of the
basics. A good manual machinst,
however, should be required as an instructor, simply for safety
reasons.

Probably for legal and liability reasons, the students should not even
touch the machine.
(Sorry!). A hands off approach would then mandate the use of CNC.
The students can develop an understanding of the parts of the milling
machine, draft CAD diagrams, download, and run in the presence of the
instructor.


I would recommend a Bridgeport or knockoff. You'll spend the least amount of
time messing around with the machine, they are the most tolerant of
mistakes, and they are the most rigid of the mentioned machines (desktop,
benchtop, floor).

Can you image how high the school board would go ballistic when they
hear that you want to reintroduce the machine shop? Selling the idea
as a computer controlled demonstration that could fit on a desktop,
with live demo at the board meeting, would go a LOT easier with them.


Personally I like a heavier machine with a more powerful motor and faster
spindle for manual aluminum work, but the BPT will be a good match for the
type of work being described.

Save that for college or vocational school.


Regards,

Robin

Robin S. wrote:
"The Eternal Squire" wrote in message
oups.com...


I'm window shopping for my own machine, and inexpensive but idiot
proof (BUT NOT CHILD SAFE !!!!) choices seem to be offered by MAX NC
(http://www.maxnc.com/). If you have a couple thousand to spend, I
would recommend that the school buy the MAXNC 10 CL-B.


With respect, the worst advice I have yet read in this thread.

MaxNC machines are too small and flimbsy to put up with ameteur machinists.
CNC is *not* required or recommended(!). A good manual machinist is required
to make a good CNC machinist, period.

I would recommend a Bridgeport or knockoff. You'll spend the least amount of
time messing around with the machine, they are the most tolerant of
mistakes, and they are the most rigid of the mentioned machines (desktop,
benchtop, floor).

Personally I like a heavier machine with a more powerful motor and faster
spindle for manual aluminum work, but the BPT will be a good match for the
type of work being described.

I agree.

I bought a MAXNC-10 for my electronics business
thinking it would be useful for making test fixtures.
The small working area, tiny spindle and steppers
and slow speed have caused it to be nearly useless
to me. I've had a couple chumps wanting to buy it,
but I'd feel guilty if I sold it.

A bridgeport or equivilent would be good. Next on
the list would be the cheapest knee mill you could
find with an R-8 spindle.

In article ,
Jim Stewart wrote:

to me. I've had a couple chumps wanting to buy it,
but I'd feel guilty if I sold it.

Explain your reservations to the chumps before the sale, if that be the
case - but they may have different needs/expectations, and if they go in
with eyes wide open, you have no need for guilt, some money, and less
space being taken up by nearly useless objects.

--
Cats, coffee, chocolate...vices to live by

"The Eternal Squire" wrote in message
oups.com...


No matter how well motivated or cautious or intelligent or bright a
high school student is, legally and morally that student is still a
minor. Special considerations apply.

Perhaps "special considerations apply" but the size or power of the machine
has nothing to do with it.


MaxNC machines are too small and flimbsy to put up with ameteur
machinists.

The intended operators are not amateurs, they are children.

Uh, they are amateurs. Call them children to their faces.

Bridgeports and related machines will almost certainly exercise lethal
forces in the event of an accident. While smaller mills can generate
lethal forces, due to physics the amount of total momentum applied
against any part of a child's anatomy will certainly be less. That
increases the chances that the ER team can save the child in time.

Absolutley wrong. *This* is what's wrong with the internet.

I've run a Taig milling machine (essentially a MaxNC without CNC),
Bridgeports, 3 ton horizontals and 30hp CNC machines. My Taig will cut your
finger off just as fast as the 50hp CNC machines at work will.

Tell me your experience with milling machines. I'm guessing you haven't run
a mill for more than a dozen hours. I've got 5,000 hrs of my tool and die
apprenticeship done. I've about 1,000 hrs on bridgeport machines and about
150 hrs manually programming and using CAM software to program CNC mills.


CNC is *not* required or recommended(!). A good manual machinist is
required
to make a good CNC machinist, period.

These children do *not* have the time, let alone the attention span, to
become good machinists.

Then they *certainly* don't have time to become decent CNC machinists. As I
said, you have to be good on a manual machinist to perform on a CNC machine,
period. Ask me how I know.

They best they can do is a 13 week semester
(never mind the 6 week deadline) is to develop an appreciation of the
basics. A good manual machinst,
however, should be required as an instructor, simply for safety
reasons.

Probably for legal and liability reasons, the students should not even
touch the machine.

They shouldn't be allowed to walk on the sidewalk or ride in a car either.
Very dangerous activities (bridgeport is 1hp, smallest common care engine is
about 100hp).

(Sorry!). A hands off approach would then mandate the use of CNC.

Bull****. Will the teacher saw off the stock for them? Put it in the vice
and set up the mill? Perhaps program the machine because there's not time to
teach the *children* how to do it? I guess we'll just let the students press
the green button.

Great learning experience. Indeed you've entirely missed the point of
school.

The students can develop an understanding of the parts of the milling
machine, draft CAD diagrams, download, and run in the presence of the
instructor.

They can setup their manual mill and crank the handles as well. It's not
rocket science and it isn't dangerous when the student has proper training.
Many Europeans start their apprenticeships well below 18 years old.


Can you image how high the school board would go ballistic when they
hear that you want to reintroduce the machine shop? Selling the idea
as a computer controlled demonstration that could fit on a desktop,
with live demo at the board meeting, would go a LOT easier with them.

Great. Buy a machine that DOESN'T have the capacity the students need,
requires programming and setup skills they DON'T have and probably costs
more than a used knockoff bpt.

Great idea. We need more great ideas like that in industry too.



Personally I like a heavier machine with a more powerful motor and faster
spindle for manual aluminum work, but the BPT will be a good match for
the
type of work being described.

Save that for college or vocational school.

There are those who say, and then there are those who go and do (as the
sayers watch). The student asked what kind of mill was required for the type
of work he is doing. A MaxNC WILL NOT DO THE WORK REQUIRED. That's the
bottom line.

Regards,

Robin

"Ecnerwal" wrote in message
...

with eyes wide open

You should try that for yourself...

Regards,

Robin

On Mon, 27 Feb 2006 08:32:44 -0800, Jim Stewart
wrote:

Robin S. wrote:
"The Eternal Squire" wrote in message
oups.com...


I'm window shopping for my own machine, and inexpensive but idiot
proof (BUT NOT CHILD SAFE !!!!) choices seem to be offered by MAX NC
(http://www.maxnc.com/). If you have a couple thousand to spend, I
would recommend that the school buy the MAXNC 10 CL-B.


With respect, the worst advice I have yet read in this thread.

MaxNC machines are too small and flimbsy to put up with ameteur machinists.
CNC is *not* required or recommended(!). A good manual machinist is required
to make a good CNC machinist, period.

I would recommend a Bridgeport or knockoff. You'll spend the least amount of
time messing around with the machine, they are the most tolerant of
mistakes, and they are the most rigid of the mentioned machines (desktop,
benchtop, floor).

of the floor models..they rank pretty low on the rigid scale.

Personally I like a heavier machine with a more powerful motor and faster
spindle for manual aluminum work, but the BPT will be a good match for the
type of work being described.

I agree.

I bought a MAXNC-10 for my electronics business
thinking it would be useful for making test fixtures.
The small working area, tiny spindle and steppers
and slow speed have caused it to be nearly useless
to me. I've had a couple chumps wanting to buy it,
but I'd feel guilty if I sold it.

A bridgeport or equivilent would be good. Next on
the list would be the cheapest knee mill you could
find with an R-8 spindle.

If he were in California..I could probably get a company to donate a
Shizuka CNC knee mill with a Dynapath 10 control. Runs pretty well,
but the spindle bearings are likely to need replacement. Located in
Monrovia California

Cross posted into alt.machines.cnc. Mostly pros there..may have some
input

Gunner




"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

As this was Tatsu's first, this is also my first post. Who knows, I
might get this right.

Anyway, I am student mentor for Tatsu's team at the Harker School. I
have had a good bit of machine tool use, and could say I am decently
proficient with manual and cnc mills. The robotics team is looking to
get about a bridgeport sized mill, but not a full knee mill. The one
that Tatsu posted a link to, from industrial hobbies, is a chinese
import mill with a decently sized travel (12x30x 24 vertical) and R8
taper, with a 2 hp single phase motor. This mill basically fits into
all of our requirements, and is what we are seriously considering
getting.

Gunner, thank you for your offer. We will have to see with the school
if it is at all possible to house something like a full-size knee mill
(I am guessing it is the size of a normal bridgeport).

I agree with all of you who say that a student that doesnt know how to
manually mill doesnt know how to CNC. I learned the hard way first, on
a 1967 bridgeport with no DRO. I have gradually worked up from then...
but I do believe that a high school junior or senior could be taught to
mill decently in three months. The kids at Harker are bright, I have
seen several outstanding examples. Of course, not everyone would be
even allowed to touch a mill, as Tatsu said.

We plan on having a mill, 3 axis DRO, milling vice, clamp set with
t-nuts and studs, rotary table, boring head, indicators and
edgefinders, end mills, full tap die and drill sets, mill vice parallel
bars, a nice keyless chuck, center drills, calipers and mics, carbide
insert face cutter, some reamers, and I am probably forgetting
something. Anything else we might want to get?

Currently my main concern is getting a DRO without selling an arm and a
leg. Would anyone have suggestions on DROs and where to get them?

Thanks,
Veselin Kolev

On 27 Feb 2006 21:46:20 -0800, wrote:

Gunner, thank you for your offer. We will have to see with the school
if it is at all possible to house something like a full-size knee mill
(I am guessing it is the size of a normal bridgeport).


The foot print is about half again as large..is much much more rigid
and much heavier than a BP.

http://www.beamonoregon.com/img/shizuokadyn.jpg


http://www.precisesensors.com/

Ask for the shop manager..tell him you were refered by Gunner, the
OmniTurn service guy..the big ol ugly cowboy.

Be nice..they pay me on time G

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3

Wow... DOS based software included. That's a real space age
machine.

The Eternal Squire wrote:

Hi Tatsunori,

That being said:

I'm window shopping for my own machine, and inexpensive but idiot
proof (BUT NOT CHILD SAFE !!!!) choices seem to be offered by MAX NC
(http://www.maxnc.com/). If you have a couple thousand to spend, I
would recommend that the school buy the MAXNC 10 CL-B.

--Hiya; just caught this thread. FWIW head on over to mcmanis.com
and ping Chuck who runs the site. He's active in the Silicon Valley HBRC and
he's built a few battlebots as well.. Last time I talked to him he was
organizing his own shop with mill, lathe, etc.

--
"Steamboat Ed" Haas : Are you prepared to
Hacking the Trailing Edge! : obey the Noodly Master??
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

Gunner -

I sent you an email, but I'm cross-posting (right term?) in case you
havent seen it ...

First of all, What would be the travel on this mill.. (im assuming its
a 17x36 table)? Mainly because we'd love to have the capability to work
on some larger peices.
Second of all, This mill would be three-phase correct? then we'd need
to get a VFD? or something else?
Third of all, If we obtain a CNC mill, is there any way to operate it
manually?
Lastly, We're located in the Bay Area; how exorbitant would the
shipping be to our school? (we're located in san jose ca).

Tatsunori Hashimoto

wrote in message
oups.com...
Third of all, If we obtain a CNC mill, is there any way to operate it
manually?

Perhaps not what you meant, but virtually all controls allow for MDI (Manual
Data Input) programming. That is, you can just enter and execute one line of
code at a time instead of writing an entire program.

Given standard canned cycles for facing, pocketing, shoulder milling,
drilling, tapping, etc., I'd argue that one can MDI a part faster than one
can manually machine it. This is even more apparent when the machine has an
automatic tool changer.

The kicker, unfortunately, is that it takes the knowledge of a manual
machinist as well as that of a CNC machinist to efficiently operate a
machine this way. Looking at the picture Gunner linked to, the mill doesn't
include the option for fully manual operation (no handwheels, for example).
This makes the novice's life difficult because you're fighting with a
non-intuitive computer while simultaneously trying to learn how to cut
metal. Steep learning curve.

Regards,

Robin

In article . com,
says...

We plan on having a mill, 3 axis DRO, milling vice, clamp set with
t-nuts and studs, rotary table, boring head, indicators and
edgefinders, end mills, full tap die and drill sets, mill vice parallel
bars, a nice keyless chuck, center drills, calipers and mics, carbide
insert face cutter, some reamers, and I am probably forgetting
something. Anything else we might want to get?

Has not been touched on yet, but do you have access to a lathe?

Currently my main concern is getting a DRO without selling an arm and a
leg. Would anyone have suggestions on DROs and where to get them?

If you are not interested in sub-tenths accuracy you could consider
a DRO from Shooting Star Technologies.

I think that Robin's given some pretty good comments here.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

wrote in message
oups.com...
Mr Robin - I guess my meaning was whether or not this cnc machine could
still use the handles, I guess the answer is no.
Although I feel very comfortable with CAD and programming, I'd still
think that learning to code for cnc and learning to mill at the same
time would be an unnecessary burden.

However, isn't there a way to use a handheld pendent type control to
move the mill "manually" as if one was operating a power-feed machine?

The pendant basically allows the user to "jog" the machine manually.
Essentially used only for setups. I have seen some seasoned machinists at
work use the jog functions (with the little thumbwheel) to machine parts.
The problem is that the wheel does not have precise control over the
machine. There are lags and jumps where your feed is either too small or too
large (50hp, 50000 lb machine rattles the floor in a 20ft radius) as the
machine control tries to keep up with the thumbwheel and also
accelerate/decelerate the machine to the correct position.

The bottom line is that you will be disappointed trying to run a machine
with the pendant. If you're going to buy a CNC mill (in my opinion a mistake
given the work and the environment to which it will be subject), you will
need to learn g-code to write programs, and you will have to learn how to
operate the control (setting up and running tools, programs, work pieces,
etc.)

I'm fairly certain a manual Bridgeport (or knockoff) will machine everything
you robots require, and you'll be able to make actual parts much faster with
less learning and less frustration.

Unfortunately the only way you'll understand my perspective is to actually
learn how to cut metal, and then learn how to use a CNC machine. I've done
both. I've done more than a thousand hours on a manual mill and over a
hundred hours doing setup, programming and machining on a CNC mill. Not a
lot compared to many here, but enough to know that a student without much
experience who is under a deadline doesn't want to fight with a CNC control
to make a robot.

YMMV.

Regards,

Robin

In article .com,
says...

... We have access to a lathe (ie our machinist has one) but we
dont own a lathe. We don't have the resources to buy both lathe, mill
and their tooling (I dont think..) so although I know some would
disagree, we're starting with a mill.

It's not a bad choice, given that you have access to one elsewhere.
You can perform lathe operations in a milling machine, which is
actually easier and more effective than the reverse.

Also, we've considered the shooting star DRO and it looks to be very
nice, however, we are currently considering a mill that has 20 inch of
Z travel (travels are 30 1/8 , 12, 23.15 ) the shooting star DRO wont
cover our Z travel... AND its also nontrivially expensive (at $749, we
could get a small lathe). How does the accuracy compare on the
Shumatech DRO with chinese scales attached? we're not likely flood
cooling so fluid resistance is not that big of a concern

The Shooting Star instrument uses a piece of precision threaded
rod as the spar, with a shaft encoder geared to run along the
length. You can pretty much get whatever length of threaded rod
you want. I suspect that setup is +/- 0.001 inch at best, so
you can learn what you need to compare the two by simply inspecting
the web pages for each to see the specs. If you want to cut costs,
do not buy a three axis DRO, only do the X and Y axis.

Do not buy a lathe that costs 750 dollars. That would really
be a mistake.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

jim rozen wrote:
In article .com,
says...


... We have access to a lathe (ie our machinist has one) but we
dont own a lathe. We don't have the resources to buy both lathe, mill
and their tooling (I dont think..) so although I know some would
disagree, we're starting with a mill.


It's not a bad choice, given that you have access to one elsewhere.
You can perform lathe operations in a milling machine, which is
actually easier and more effective than the reverse.

Also, we've considered the shooting star DRO and it looks to be very
nice, however, we are currently considering a mill that has 20 inch of
Z travel (travels are 30 1/8 , 12, 23.15 ) the shooting star DRO wont
cover our Z travel... AND its also nontrivially expensive (at $749, we
could get a small lathe). How does the accuracy compare on the
Shumatech DRO with chinese scales attached? we're not likely flood
cooling so fluid resistance is not that big of a concern


The Shooting Star instrument uses a piece of precision threaded
rod as the spar, with a shaft encoder geared to run along the
length. You can pretty much get whatever length of threaded rod
you want. I suspect that setup is +/- 0.001 inch at best, so
you can learn what you need to compare the two by simply inspecting
the web pages for each to see the specs. If you want to cut costs,
do not buy a three axis DRO, only do the X and Y axis.

Do not buy a lathe that costs 750 dollars. That would really
be a mistake.

Jim


Well do not buy a brand new lathe for $750.00 . For students you might
well find some kind business with an eye to the future willing to put
you into a used one for that price . There are a lot of business people
that are in a position and willing to help students out . Luck
Ken Cutt

Bill Schwab -

Apologies for the delay.


We've used bandsaw, lathe at RC's shop but not a mill. How much more
dangerous would a mill be? (fly cutters do look dangerous..). If we
have this at our school, we'll definately have machinist supervision
and instruction. I believe we have a few former machinists in faculty..

Any power tool can be dangerous. Because bandsaws pull the work down
onto the table, they are _relatively_ safe. In contrast, you must read
and understand "The Table Saw Book" or similar material before
attempting to use a table saw - they like to throw work at high speed.

Mills and lathes are very powerful cutting tools, and have an ability to
grab loose clothes, hair, jewlery etc., with potentially horrible
consequences.

Flycutters cover a larger area than the typical endmill one encounters,
putting the operator that much closer to harm's way than with an
endmill. The tool bit on a flycutter tends to be less visible than the
boundaries of a end or face mill, which you should keep firmly in mind
when using them. However, don't get any where near any moving tool.
Machining is not a forgiving activity.

With their cantilever bits, flycutters arguably add risk of breaking the
tool. That is true of any tool, but also particularly true of any small
endmill or drill bit. Wear safety glasses any time a machine is running.



6x4 1 mil of tolerance is easily doable? or is it a fairly difficult
task? I'm trying to gauge the relative difficulty of the work we do.

The answer is "yes" if you remove the word "easily". Does that mean it
is difficult? Not really, but there are many factors that can lead to
errors, and once one removes too much metal, it's over. Do not expect
to reliably hold +/- 0.001 inches at the beginning.


And as a user of RF-31, do you wish you got a larger mill or one with
dovetail ways on the z axis? (we're looking at some benchtop mills..
from RF-31, Sieg X2 clones, X3 clones, and the mill at
(www.industrialhobbies.com))

I have never used a dovetailed mill-drill, so I cannot comment on their
accuracy and robustness. Somehow, I find it difficult to believe that
moving the head on such a machine is equivalent to moving the knee on
knee mill. As I said, don't take my word for it. With ER collets and
reasonable care, I don't get into that much trouble. True, I do a few
more edge finds than would be strictly necessary on a knee mill or
perhaps a dovetailed mill-drill, but that seems to be the worst of it.

As for the bench top knee mills, I have yet to see one that matches the
travel on my machine. Hindsight is always 20-20, but I would be hard
pressed to find much fault with my mill.



And our build season is already over this year (we shipped our robot on
tuesday). I intend to learn how to use a mill (regardless of whether or
not we acquire one) over the next year. (any suggestions? I've been
thinking about volunteering at a machine shop..)

I am not the one to ask. I first learned to use a mill in college, went
back to it for some test fixtures in graduate school, and then more
recently got sufficiently frustrated one day to type "home milling
machine" into google.

Bill

wrote:
Thank you very much for your all's time.

As for MaxNC, that's out of the question for us since we'll end up
frequently manufacturing parts greater than the 12 inch travel.
For the safety question, we've gotten a ok for a manual mill as long as
there is a machinist watching over, and there is restricted access (to
ensure some of the more careless members dont play with it like a toy).
We've also been fairly careful with our handeling with machine tools
and even though it is a risk, we think its one worth taking (for the
things learnt).

"
Truly +/-.001" on a bridgeport is pretty tight, but certainly
attainable.
What kind of work are you doing that requires such a tolerance? "
We manufacture our own high-speed gearboxes whose mounting plates
require about 1/1000th tolerance. we've previously found that even
1/1000th off can cause the motor to bind and start flipping the
breakers, or cause unacceptable current draw.

This is where you need engineering input. You do not need to hold tight
tolerances to get good alignment; you need to have adjustable mountings
and have good alignment procedures, and/or use couplings that allow
misalignment. Keep in mind that what starts out aligned might not stay
that way under various loadings.

That said, I shoot for tight tolerances on everything I make. Failure
to do so leads to a downward spiral of corrections for errors in
corrections for other errors. I recently made a part with a channel
that snakes from one side of the part to the other, with through holes
connecting them. That required flipping the part and reading the
drawing from the other side; it worked, but would not have been so
"easy" had I been sloppy with the dimensions.

Good machinging is always desireable, but it is no substitute for good
design.



As for the mill, we are in fact located in California (bay area,
however.) , so we are highly interested in Gunner's offer of a Shizuka
CNC mill. If that is not possible, we can of course, go for a
bridgeport, or we've also been looking for something like
http://www.industrialhobbies.com/ the square column mill. The work
envelope is more than adequate, it seems to have a strong enough motor
for our work, and the spindle speed seems okay for aluminum work. the
Free shipping also makes it very attractive for us.

I have no CNC experience, but my instincts align with those saying that
manual experience is essential to CNC work. It would be very easy to
instruct a mill to take a dangerously deep cut. There is a lot to be
said for feeding manually before engaging a power feed, at least for
rough cuts, and especially when cleaning up uneven edges.

In general, I suspect you would be better off without a DRO. If you
want to learn, learn to navigate w/o one. A steel rule and a small
drill bit allows you to get within 0.1 inches, at which point the dial
readings become meaningful. A machine with uneven wear on its screws
weakens this argument.

Bill

Thank you very much for your input.

I agree with all of you that we should definately learn without a DRO
in order to understand the functions of the machine. That's something
we'll figgure out later (whether or not backlash is a main concern for
us.. I suspect it's not too bad compared to the other aspects)

Amongst the manual offerings, we're pretty much set on the chinese
import shown at www.industrialhobbies.com, because of the large work
space (30x12x23 travel) and free shipping. Of course if we could find a
9x42 bridgeport for around 2.5k, that'd be a different story.

Am I making a horrible mistake here? Are knee mills alot better than
dovetailed column mills? And does anyone have more suggestions as to
what machines are good?

Thanks!

Tatsu Hashimoto

" wrote:

Update -

On craigslist, we found a Bridgeport mill with a DRO and KURT vise for
4k. Its in very good condition, and the ways are not worn. We've gotten
arrangements for transportation (its only a 10 minute drive.. so it
should be nice and cheap.) But the seller insists we pay him in cash..
is that a bit weird? or is that normal for machine tools.. (I'm not
even sure HOW to get 4k in cash without setting off alarm bells).
We've seen the mill in storage, and we know it exists, so its not a
fraud or something. but still kinda strange.

Awaiting your opinion,

Tatsu Hashimoto

You are actually worried about what will happen if you grab $4000 out
of a bank account? Wow. Personally, I would not be worried about it. If
it has to do with the finance dept., then you are on your own...
accountants tend towards easy to follow money trails.

As to HOW, I would suggest a withdrawal slip at your bank. Have ID
available.

It sounds to me like the seller is quite certain that he will not be
scammed in the deal either. Cash pretty much always spends, whereas
checks and money orders sometimes have "issues". I cannot comment on the
price, though it seems within the realms of the reasonable. If you are
at all worried about being ripped off, agree to the cash payment, but
after the mill is on your transport, and before the mill leaves the
former owners yard. Find an arrangement that both of you are comfortable
with. Or find a different deal.

I have done deals for cash that were larger than that. And I have
driven out of total strangers yards leaving nothing for ID except the
info that was on my personal cheque. Niether I nor the guys I dealt with
was unhappy with the arrangment in any case. I figure that my
involvement in the sellers life ends when I make one of those deals, and
really, I don't care why cash was specified, if the deal looks clean.
It's not quite in the same league as being asked to bring cash into the
alley way to deal on a nice used Rolex, now, is it?


Cheers
Trevor Jones

Update -

On craigslist, we found a Bridgeport mill with a DRO and KURT vise for
4k. Its in very good condition, and the ways are not worn. We've gotten
arrangements for transportation (its only a 10 minute drive.. so it
should be nice and cheap.) But the seller insists we pay him in cash..
is that a bit weird? or is that normal for machine tools.. (I'm not
even sure HOW to get 4k in cash without setting off alarm bells).
We've seen the mill in storage, and we know it exists, so its not a
fraud or something. but still kinda strange.

Awaiting your opinion,

Tatsu Hashimoto
If I were selling it, I'd want cash.
$4k is no problem at a bank. I seem to recall $10k is the alarm amount, although
I recently bought a Mack truck with $10k cash from the bank with no problems.


Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com
My hobby pages are he
http://www.plansandprojects.com/My%20Machines/

Severe stupidity is self correcting, but mild stupidity is rampant in the land.
-Ron Thompson

On 9 Mar 2006 23:30:59 -0800, "
wrote:

Update -

On craigslist, we found a Bridgeport mill with a DRO and KURT vise for
4k. Its in very good condition, and the ways are not worn. We've gotten
arrangements for transportation (its only a 10 minute drive.. so it
should be nice and cheap.) But the seller insists we pay him in cash..
is that a bit weird? or is that normal for machine tools.. (I'm not
even sure HOW to get 4k in cash without setting off alarm bells).
We've seen the mill in storage, and we know it exists, so its not a
fraud or something. but still kinda strange.

Awaiting your opinion,

Tatsu Hashimoto


Hey Tatsu,

I assume you want to pay with a cheque. Sounds like he just wants to
minimize his risk, which is understandable. But if it is because he
does not have a bank account to deposit a cheque, or ID to cash it
someplace, then there may be a bit more to his reason(s), and more
than a bit of caution on your part would be wise.

Ask if he will accept a "Certified Cheque" as payment, paid on
delivery to your shop floor, which should quiet your "alarm bells".
You can show him the cheque prior to his loading it for the "10 minute
drive", and give it to him when everyone is satisfied. Once written
and Certified by the trip to YOUR bank, it is as good as cash to him,
and if the deal falls through, you just take it back to your bank for
a re-deposit in your account. Keeps the bean-counters happy too, and
the cost is minimal to you.

Take care.

Brian Lawson,
Bothwell, Ontario.

wrote:
Update -

On craigslist, we found a Bridgeport mill with a DRO and KURT vise for
4k. Its in very good condition, and the ways are not worn. We've gotten
arrangements for transportation (its only a 10 minute drive.. so it
should be nice and cheap.) But the seller insists we pay him in cash..
is that a bit weird? or is that normal for machine tools.. (I'm not
even sure HOW to get 4k in cash without setting off alarm bells).
We've seen the mill in storage, and we know it exists, so its not a
fraud or something. but still kinda strange.

Re the transaction, get a certified check. IIRC, you want it made out
to the seller (by name of course) or you, so that you can easily
redeposit if you abort the deal.

$4k is a lot to carry around in cash. Not meaning to sound like a
survivalist nutcase, but look into the concept of forfeiture. Fire,
theft, etc., are also risks to cash.

Bill

In article .com,
" wrote:

Update -

On craigslist, we found a Bridgeport mill with a DRO and KURT vise for
4k. Its in very good condition, and the ways are not worn. We've gotten
arrangements for transportation (its only a 10 minute drive.. so it
should be nice and cheap.) But the seller insists we pay him in cash..
is that a bit weird? or is that normal for machine tools.. (I'm not
even sure HOW to get 4k in cash without setting off alarm bells).

Walk into the bank and withdraw it. To avoid alarm bells, have it in
your account to start with, and don't hand the teller any funny notes or
wear a mask...

Not a big deal, and perfectly normal when making transactions with
people you don't really know that well - especially if you might be
negotiating a bit based on condition, etc. If you think the seller is
going to club you over the head and take your money without giving you a
mill, well, shop elsewhere. Otherwise, bring cash if that is what the
seller wants.

Certainly SOP for private transaction used cars, for instance. Likewise
used lathes. Makes sense for used mills, too.

Cash - handy stuff, serves a purpose. Given the broad pervasion of fake
cashiers checks as can be seen if you look up "Nigerian scam", it's
hardly surprising that a person who does not know you from a hole in the
ground would be happier with cash money. They _might_ take a cashiers
check from a local bank - you could ask...

--
Cats, coffee, chocolate...vices to live by

Hey, I'm the student machinist on Los Altos High school Eagle Strke
#114 Los Altos, CA (we had that swivel drive last year at Silicon
Valley, Sacramento, and Galileo Division at nationals).
We have an Excello 602 knee mill we purchased last year and recently
acquired the three-phase power for it. We purchased it off Ebay from
connecticut, but there were some issues. Shipping is a large expense,
expect to pay about $1 per pound (3000 pounds). Second, you need
space (about 5 feet wide and tall) and the facilities to move and
accomodate a 3000 pound piece of equipment (ie it won't fit through a
standard 36 inch door). Finally, any piece of equipment you buy should
be examined by an experienced machinist before you buy. Ours came
sight-unseen and had several problems that took many days to solve.
Finally, on a more general note, you need to look at training and
experience. Several members of our team took machining classes at San
Jose City College. Milling machines are large, dangerous machines that
need training and experience to learn how to use. Another note, one of
the largest difficulties faced by our team is acquiring tooling such as
end mills. It is a substantial investment (1000's of dollars) and
unless you buy new, sharpening and grinding is a major issue. Also
consider things such as collets, a vise, and a clamping set. These are
hundreds of dollars of things that are basic necessities for machining.
Also think about liability and other issues related to the school.

CNC type equipment is another issue entirely. A DRO will significantly
increase your precision and accuracy but needs skill to operate. CNC
isn't useful without an excellent working knowledge of manual
machining.
Hope I answered your questions but think twice first.
Michael Fagan
Student Machinist
Los Altos High School #114
www.lahsrobotics.org
contact me off-list for more info
woodworker88 at gmail dot com