Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old November 8th 03, 01:24 AM
Peter Grey
 
Posts: n/a
Default What are the size limitations of mini mills?

Hi all,

In researching mills, I'm stuck between the possible need for a larger mill
and the convenience/size of a mini mill. I realize that I'll have to stay
within the limitations of a mini mill, but despite my searching the NG, I
can't find any post that quantifies the limitations. IOW, is it possible to
say that for a certain mini mill that one will only be able to work on a
piece so big or take cuts so deep? Or are the capabilities entirely
dependant on what you're trying to do to the specific piece and type of
metal?

Obviously, I'm new to this and have a bunch of books coming. I'm just
trying to decide if I can get by with a mini mill or if I need to buy an
RF-30 machine. I have a very small garage into which this stuff will have
to fit, along with the car du jour.

I'd like to make pieces for automotive and motorcycle projects (brackets,
pillow blocks, component mounts,etc..) mostly out of aluminum but some out
of steel. Most of these pieces would FIT on a mini mill table but I'm
getting the feeling that the mill might be out matched. Are there any
general rules of thumb that suggest the maximum size (% of table, % of X,Y,X
travel, HP x phase of the moon?) or capabilities of a mill?

Thanks,

Peter




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Old November 8th 03, 01:47 AM
John D. Farr
 
Posts: n/a
Default What are the size limitations of mini mills?

I've been looking for a while too. One of the biggest boo-boos I've seen
with mini mills is that they usually have a round column. That coupled with
the short quill stroke makes it difficult to go from a spotting drill to a
jobber length drill. Look for one with the table dove-tailed into the column
or a square column so that the table can be raised or lowered without
turning. gl, John

"Peter Grey" wrote in message
nk.net...
Hi all,

In researching mills, I'm stuck between the possible need for a larger

mill
and the convenience/size of a mini mill. I realize that I'll have to stay
within the limitations of a mini mill, but despite my searching the NG, I
can't find any post that quantifies the limitations. IOW, is it possible

to
say that for a certain mini mill that one will only be able to work on a
piece so big or take cuts so deep? Or are the capabilities entirely
dependant on what you're trying to do to the specific piece and type of
metal?

Obviously, I'm new to this and have a bunch of books coming. I'm just
trying to decide if I can get by with a mini mill or if I need to buy an
RF-30 machine. I have a very small garage into which this stuff will have
to fit, along with the car du jour.

I'd like to make pieces for automotive and motorcycle projects (brackets,
pillow blocks, component mounts,etc..) mostly out of aluminum but some out
of steel. Most of these pieces would FIT on a mini mill table but I'm
getting the feeling that the mill might be out matched. Are there any
general rules of thumb that suggest the maximum size (% of table, % of

X,Y,X
travel, HP x phase of the moon?) or capabilities of a mill?

Thanks,

Peter





  #3   Report Post  
Old November 8th 03, 05:49 AM
Jon Elson
 
Posts: n/a
Default What are the size limitations of mini mills?



Peter Grey wrote:
Hi all,

In researching mills, I'm stuck between the possible need for a larger mill
and the convenience/size of a mini mill.


I've got a mini-mill, the one that sells for $499 or so. I use it
mostly for CNC demos. It has a 4" Y-axis travel. That is most
likely the biggest limitation. Other than that, it has plastic
gears in the head, and is awfully flexible for a machine tool.
Mechanical flex, I mean, and that is not good!

Jon

  #4   Report Post  
Old November 8th 03, 02:26 PM
Steve Smith
 
Posts: n/a
Default What are the size limitations of mini mills?

I'm in the same boat, made worse by just having sold my Van Norman #12
before moving. I don't have room for a full sized mill.

I've had a mill-drill and wouldn't do it again. The round column
(inability to change height without losing your position) and the lack
of rigidity are real problems. I'm also suspicious that the screws don't
wear well (mine was used and worn). I'm looking at a Clausing 8520 or a
Millrite (used).

You might try digging around in the Yahoo groups and see what they talk
about. Here's the one for Clausing:
http://groups.yahoo.com/group/clausi...1?viscount=100
There is probably one for Millrite, I don't know about Rong Fu. Another
useful site:
http://www.lathes.co.uk/
has decent descriptions of many machines.

Steve Smith

Peter Grey wrote:

Hi all,

In researching mills, I'm stuck between the possible need for a larger mill
and the convenience/size of a mini mill. I realize that I'll have to stay
within the limitations of a mini mill, but despite my searching the NG, I
can't find any post that quantifies the limitations. IOW, is it possible to
say that for a certain mini mill that one will only be able to work on a
piece so big or take cuts so deep? Or are the capabilities entirely
dependant on what you're trying to do to the specific piece and type of
metal?

Obviously, I'm new to this and have a bunch of books coming. I'm just
trying to decide if I can get by with a mini mill or if I need to buy an
RF-30 machine. I have a very small garage into which this stuff will have
to fit, along with the car du jour.

I'd like to make pieces for automotive and motorcycle projects (brackets,
pillow blocks, component mounts,etc..) mostly out of aluminum but some out
of steel. Most of these pieces would FIT on a mini mill table but I'm
getting the feeling that the mill might be out matched. Are there any
general rules of thumb that suggest the maximum size (% of table, % of X,Y,X
travel, HP x phase of the moon?) or capabilities of a mill?

Thanks,

Peter






  #5   Report Post  
Old November 8th 03, 07:51 PM
Harold & Susan Vordos
 
Posts: n/a
Default What are the size limitations of mini mills?


"Peter Grey" wrote in message
nk.net...
snip----
I'd like to make pieces for automotive and motorcycle projects (brackets,
pillow blocks, component mounts,etc..) mostly out of aluminum but some out
of steel. Most of these pieces would FIT on a mini mill table but I'm
getting the feeling that the mill might be out matched. Are there any
general rules of thumb that suggest the maximum size (% of table, % of

X,Y,X
travel, HP x phase of the moon?) or capabilities of a mill?

Thanks,

Peter

My personal opinion is to stay away from miniature machines for projects the
likes of yours. I'd also avoid, like the plague, mill drills, unless you
budget simply can't stand the cost of something better. It's RARE to find
someone that is satisfied with a mill drill if they're using it as a milling
machine, not a drill press.

There are small knee type mills available, which would be a far better
choice, based on your suggested usage. Gorton, for one, made some that
are small enough that you sit to run them, and Gorton is an outstanding
builder of drop spindle type mills. I'd recommend one of their machines
highly. There are others, too, of varying sizes, so I'd suggest you keep
your eyes open for a "deal"and buy something that is much better suited to
your needs. If space allows, though, I think a Bridgeport or Bridgeport
clone might be a fine choice due to the flexibility of the machine. For
the most part, no other type vertical mill offers all the features that they
do in one machine.
That's why Bridgeport was such a grand success, along with the cost, which
used to be very reasonable.

A friend of mind has a mini-mill, CNC controlled. He's very happy with it,
but he's machining wax to make patterns for investment casting. The
rigidity of his machine would fall short, VERY short, of enough for
satisfactory machining of most any metal. In machines tools, rigidity is
everything. That's why they weigh so much.

Harold




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Old November 8th 03, 10:19 PM
Bruce Simpson
 
Posts: n/a
Default What are the size limitations of mini mills?

On Sat, 8 Nov 2003 11:51:49 -0800, "Harold & Susan Vordos"
wrote:

My personal opinion is to stay away from miniature machines for projects the
likes of yours. I'd also avoid, like the plague, mill drills, unless you
budget simply can't stand the cost of something better. It's RARE to find
someone that is satisfied with a mill drill if they're using it as a milling
machine, not a drill press.


(puts hand up -- me me ! :-)

I've had an RF30 for about four years now and it's served me well.

True, it's got limitations compared to a knee mill but I've done an
awful lot of work on it and it has done everything I have asked of it
(bearing in mind that I am aware of its limitations).

For me the choice was to buy an RF30 and have enough money left over
to get some decent tooling, (rotary table, vice, clamping set,
collets, flycutter, boring head, inserts, milling cutters, etc, etc)
-- or to buy a knee mill and just spend my days looking at it and
wishing I had all the accessories needed to use it.

One should always remember that unless you're planning to use your
mill for production work or your income depends on it -- *any* mill is
better than no mill :-)

You can always sell a mill-drill later and upgrade to a *real* mill if
you want/need/can-afford to -- and then all that tooling and other
bits you bought can still be used.

--
you can contact me via http://aardvark.co.nz/contact/
  #7   Report Post  
Old November 9th 03, 12:29 AM
Peter Grey
 
Posts: n/a
Default What are the size limitations of mini mills?

I agree. I could spend a year looking for the "right" mill and not be able
to do anything in the meantime. If I buy an RF30 or mini mill or whatever,
I'll have the opportunity to make some stuff, experiment, and then buy
something better if I determine it's what I need. In the meantime I will
have learned a lot about machining and about what I prefer and want.

I understand that drill/mills aren't perfect, but there seem to be too many
people on the web that are using the RF30 and its ilk successfully (while
keeping in mind its limitations) to buy into the "mill/drills are useless"
argument.

Thanks,

Peter
"Bruce Simpson" wrote in message
...
On Sat, 8 Nov 2003 11:51:49 -0800, "Harold & Susan Vordos"
wrote:

My personal opinion is to stay away from miniature machines for projects

the
likes of yours. I'd also avoid, like the plague, mill drills, unless

you
budget simply can't stand the cost of something better. It's RARE to

find
someone that is satisfied with a mill drill if they're using it as a

milling
machine, not a drill press.


(puts hand up -- me me ! :-)

I've had an RF30 for about four years now and it's served me well.

True, it's got limitations compared to a knee mill but I've done an
awful lot of work on it and it has done everything I have asked of it
(bearing in mind that I am aware of its limitations).

For me the choice was to buy an RF30 and have enough money left over
to get some decent tooling, (rotary table, vice, clamping set,
collets, flycutter, boring head, inserts, milling cutters, etc, etc)
-- or to buy a knee mill and just spend my days looking at it and
wishing I had all the accessories needed to use it.

One should always remember that unless you're planning to use your
mill for production work or your income depends on it -- *any* mill is
better than no mill :-)

You can always sell a mill-drill later and upgrade to a *real* mill if
you want/need/can-afford to -- and then all that tooling and other
bits you bought can still be used.

--
you can contact me via http://aardvark.co.nz/contact/



  #8   Report Post  
Old November 9th 03, 12:55 AM
Harold & Susan Vordos
 
Posts: n/a
Default What are the size limitations of mini mills?


"Peter Grey" wrote in message
ink.net...
I agree. I could spend a year looking for the "right" mill and not be

able
to do anything in the meantime. If I buy an RF30 or mini mill or

whatever,
I'll have the opportunity to make some stuff, experiment, and then buy
something better if I determine it's what I need. In the meantime I will
have learned a lot about machining and about what I prefer and want.

I understand that drill/mills aren't perfect, but there seem to be too

many
people on the web that are using the RF30 and its ilk successfully (while
keeping in mind its limitations) to buy into the "mill/drills are useless"
argument.

Thanks,

Peter
"Bruce Simpson" wrote in message
...
On Sat, 8 Nov 2003 11:51:49 -0800, "Harold & Susan Vordos"
wrote:

My personal opinion is to stay away from miniature machines for

projects
the
likes of yours. I'd also avoid, like the plague, mill drills, unless

you
budget simply can't stand the cost of something better. It's RARE to

find
someone that is satisfied with a mill drill if they're using it as a

milling
machine, not a drill press.


(puts hand up -- me me ! :-)

I've had an RF30 for about four years now and it's served me well.

True, it's got limitations compared to a knee mill but I've done an
awful lot of work on it and it has done everything I have asked of it
(bearing in mind that I am aware of its limitations).

For me the choice was to buy an RF30 and have enough money left over
to get some decent tooling, (rotary table, vice, clamping set,
collets, flycutter, boring head, inserts, milling cutters, etc, etc)
-- or to buy a knee mill and just spend my days looking at it and
wishing I had all the accessories needed to use it.

One should always remember that unless you're planning to use your
mill for production work or your income depends on it -- *any* mill is
better than no mill :-)

You can always sell a mill-drill later and upgrade to a *real* mill if
you want/need/can-afford to -- and then all that tooling and other
bits you bought can still be used.

--
you can contact me via http://aardvark.co.nz/contact/


I agree in principle with each of you, but practical experience is a great
teacher. One of the hard lessons learned in life is buying something that
is ill suited to a job, then trying to liquidate it in order to replace it
with a tool that is better suited. The better investment would have been
the proper tool to do the job at the outset. Often times the money is gone
and the tool simply can't do the job at hand, and has poor resale value, if
it can be sold at all.

My point is that if a person buys a mini-mill, it is woefully underpowered
and, in general, not really equipped to make parts, regardless of the fact
that they can be placed on the machine table. For example, how about
drilling a " or larger hole in steel? Seems like that would be one of the
things Peter would encounter in his quest to build his projects.

When it comes to a mill drill, I recognize that they are better than
nothing, but they are, at best, a poor compromise for a reasonable milling
machine. The problems with mill drills have been well addressed, and
addressing them yet again in this thread serves little to no purpose.
Resale value isn't great, but then buying new is not all that expensive,
either. I accept that fact that for those that are limited economically,
and perhaps have no prospects of anything better in the future, they are
better than nothing.

Regards the argument about being satisfied with one, one of my friends, a
retired tool and die maker, owns one, and built his 1" scale model steam
locomotive with it, along with countless other projects. He's a patient
person, willing to make the necessary sacrifices in order to achieve the end
result. I respect him for that, but my time is far too valuable to spend
it spinning my wheels endlessly, and achieving a less than acceptable end
result because the machine simply doesn't have the necessary quality built
into it. I guess it all depends on the nature of the work you intend to
do, and the quality level that you find acceptable.

I used my Bridgeport for gain, mostly building tooling for the aero-space
industry. I consider it the absolute minimum machine one could own and get
reasonable results. I do not look at the Bridgeport as a great machine,
but, like in your case, it was the minimum I found acceptable in order to
accomplish my mission. No way in hell could I have done my work with a
mill drill. Maybe now that I'm no longer working for gain I might see it
differently, but I still have the Bridgeport and wouldn't give the idea a
second thought as long as I do. I still do not recommend mill drills, and
for many reasons.

Harold


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Old November 9th 03, 02:03 AM
Peter Grey
 
Posts: n/a
Default What are the size limitations of mini mills?


"Harold & Susan Vordos" wrote in message
...

I agree in principle with each of you, but practical experience is a great
teacher. One of the hard lessons learned in life is buying something

that
is ill suited to a job, then trying to liquidate it in order to replace it
with a tool that is better suited. The better investment would have been
the proper tool to do the job at the outset. Often times the money is

gone
and the tool simply can't do the job at hand, and has poor resale value,

if
it can be sold at all.


A better financial investment perhaps, but I'm not concerned enough to have
this be the only consideration. If I have to sell the mill/drill if I find
something better, I will. I don't mind spending the time required in order
to educate myself about which small used higher-quality machine will work,
is in my price range, is truly small enough and is being sold by a source
that I trust or is close enough so that I can look at the machine. While
I'm doing that, I can be making things (or trying to) and learning on an
RF30, which is a known entity.

My point is that if a person buys a mini-mill, it is woefully underpowered
and, in general, not really equipped to make parts, regardless of the fact
that they can be placed on the machine table. For example, how about
drilling a " or larger hole in steel? Seems like that would be one of

the
things Peter would encounter in his quest to build his projects.


I've come to the same conclusion.

When it comes to a mill drill, I recognize that they are better than
nothing, but they are, at best, a poor compromise for a reasonable milling
machine. The problems with mill drills have been well addressed, and
addressing them yet again in this thread serves little to no purpose.
Resale value isn't great, but then buying new is not all that expensive,
either. I accept that fact that for those that are limited economically,
and perhaps have no prospects of anything better in the future, they are
better than nothing.


It's not a matter of being limited economically with no prospects of
anything better (Jeez, that sounds depressing). I'm trying to find a
reasonable entry point into this "hobby". I've been heavily involved with -
and taught - bicycle racing, music, car racing and other things that require
equipment. I didn't buy the "best" equipment when I got into them because I
didn't know if I needed it, and what my level of long term interest and
competancy was going to be. I believe that there is a point of diminishing
returns for most things. I'm not yet convinced that for my needs, the
Bridgeport is the point of diminishing return.

I'm a jazz musician and there a ton of players that believe that one needs a
$8,000 guitar in order to make good music. My 30 year old $1,500 guitar
feels and sounds like a $8,000 guitar, but I wouldn't have recognized this
guitar had I not owned and played a lot of other guitars. Those guitars
weren't what I wanted ultimately, but I learned a ton by playing them. I'm
sure that the equivilent of my guitar exists in the mill world. But I don't
yet know enough to recognize the used mill I need when I see it. Maybe
after hacking around on an RF30 for a year or so, I will. Or I may be
satisfied with what I have. BTW, I've got a bunch of guitars, all with
different purposes. You can never have too many - it's just like machine
tools.


I used my Bridgeport for gain, mostly building tooling for the aero-space
industry. I consider it the absolute minimum machine one could own and

get
reasonable results. I do not look at the Bridgeport as a great machine,
but, like in your case, it was the minimum I found acceptable in order to
accomplish my mission. No way in hell could I have done my work with a
mill drill. Maybe now that I'm no longer working for gain I might see it
differently, but I still have the Bridgeport and wouldn't give the idea a
second thought as long as I do. I still do not recommend mill drills,

and
for many reasons.


I'm not going to be making my living at this and I don't think I can fit a
Bridgeport in my garage. I live in San Francisco and my house was built 90
years ago. Garages just weren't a priority. There may very well be a small
Bridgeport or other high quality mill in my future. Using an RF 30 will
play an important role in learning enough to make an intelligent choice on
the "point of diminishing return" machine - assuming that for me the RF30
isn't it.

Regards,

Peter


  #10   Report Post  
Old November 9th 03, 04:07 AM
jim rozen
 
Posts: n/a
Default What are the size limitations of mini mills?

In article et, Peter Grey
says...

I'm a jazz musician and there a ton of players that believe that one needs a
$8,000 guitar in order to make good music. My 30 year old $1,500 guitar
feels and sounds like a $8,000 guitar, but I wouldn't have recognized this
guitar had I not owned and played a lot of other guitars. Those guitars
weren't what I wanted ultimately, but I learned a ton by playing them. I'm
sure that the equivilent of my guitar exists in the mill world.


What you want is a solid mill, inexpensive, that fits into a small
shop - with a small footprint and low overhead. Bounus points
for high quality and a 'name.'

I would suggest what I chose for a similar application:

http://www.metalworking.com/RCM-gallery/files/Rozen,Jim/Nshop2.jpg
http://www.metalworking.com/RCM-gallery/files/Rozen,Jim/Nshop3.jpg

This machine looks like hell but it just won't quit cutting metal.
Total cost from a used machinery dealer was $800 about ten years
ago. It had been pretty well abused and I had to replace the
handwheels, and make a new feed nut for the table. But after
cleaning it up it's been a strong worker in my shop and does not
require much attention at all.

The latest chip-fest involved making a specialized puller
for removing a timing gear from a vintage motorcycle crank.
The correct puller would cost about a bazillion dollars if
one could find one for sale, and they're not for sale. So
I had to take some chunks-O-steel and build two blocks that
would get under the gear, in the limited space. Then I had
to drill mating holes in a steel ring to hold them, and
allow a puller to grab. The thing worked first time, and
it was all hogged out, rough and ready, on the horizontal.
The limiting factor was how tightly the small vise would
hold the parts - early on in the project I realized that
a part rip-out was entirely possible.

You can find machines like this, in much better condition
than the one I bought (I have a soft spot for 'wing-down'
stuff) for a bit more money. Watch on ebay and you do
sometimes see them go by.

Jim

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



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