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Posted by Robert Swinney on May 28, 2008, 4:45 pm
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Good post, Jim. I would bet your equipment consist mirrors about 90% of most
RCMers.
Bob Swinney
> I have to cut 2 perfectly matching slots in a 5 mm thick flat semicircular
> piece of steel, each 15 mm by 5mm.....
>
> Michael Koblic,
> Campbell River, BC
"perfectly matching slots" cut by hand???
Try a dish wheel in your angle grinder to gouge out most of the slot,
otherwise this is a job for cold chisels. Use a "cape" chisel to cut
narrow slots on the sides and a regular cold chisel to remove the
center. You still need good eye protection but this is a lot safer
than watching the line closely in a shower of sparks.
Grind the teeth off one edge of a file to make it cut sharp inside
corners and only work one surface at a time. Coarse files are better
for long cuts because the teeth don't fill with chips halfway through
the stroke.
The real answer is to pull yourself out of the 18th century and get
adequate machine tools. The skill to do good work by hand takes a long
apprenticeship to acquire but has almost no commercial value any more,
unless you are an artist. What's your time worth?
I picked auctions and second-hand dealers as my best time-vs-money
tradeoff. Even very old machines can cut metal more quickly and
accurately than I ever could by hand. My time is spent fixing/
restoring them and sharpening cutters. Almost everything I own was
broken when bought and still has problems but they work well enough
most of the time. When I'm stopped by one of their problems I fix it.
I think the minimum satisfactory home or experimental shop equipment
is a mill-drill or small vertical knee mill and a 9" - 12" lathe.
Smaller machines are OK to make models but not for equipment that does
useful work.
I have a Clausing vertical mill, a 10" South Bend lathe, a 4X6 bandsaw
and don't see the need for anything larger, and I built a log
splitter, a sawmill, and bucket loader for my garden tractor with
them. I could put up with a mill-drill for most projects.
A small horizontal mill could substitute if you get a good deal but
then you need a better drill press, and new cutters are much more
expensive than end mills.
Jim Wilkins
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Posted by Jim Wilkins on May 28, 2008, 5:43 pm
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> Good post, Jim. =A0I would bet your equipment consist mirrors about 90% of=
most RCMers.
> Bob Swinney>
I think it's typical of what we settle on after struggling to work
metal by hand, then buy undersized, inadequate machines because the
good ones look so shockingly expensive. I bought a 6" Sears lathe
first, and tried milling on it and a drill press. An adequate lathe or
mill doesn't really cost more than a motorboat, ATV, snowmobile or
HDTV and they hold their value much better. At least that's my excuse,
they are "investments".
Michael, that's where you may be headed.
Jim Wilkins
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Posted by Michael Koblic on May 28, 2008, 6:27 pm
Please log in for more thread options I see I managed to filter off Jim's post inadvertently, so I guess I have to
respond "second-hand".
> Good post, Jim. I would bet your equipment consist mirrors about 90% of
> most RCMers.
>
> Bob Swinney
> "perfectly matching slots" cut by hand???
***Perfection in this case being in the eye of the beholder...
>
> Try a dish wheel in your angle grinder to gouge out most of the slot,
> otherwise this is a job for cold chisels. Use a "cape" chisel to cut
> narrow slots on the sides and a regular cold chisel to remove the
> center. You still need good eye protection but this is a lot safer
> than watching the line closely in a shower of sparks.
***Never thought of chisels. Will they work on 5mm thick plate?
>
> Grind the teeth off one edge of a file to make it cut sharp inside
> corners and only work one surface at a time. Coarse files are better
> for long cuts because the teeth don't fill with chips halfway through
> the stroke.
***See, this is the sort of thing I would not have thought of and that makes
perfect sense
>
> The real answer is to pull yourself out of the 18th century and get
> adequate machine tools. The skill to do good work by hand takes a long
> apprenticeship to acquire but has almost no commercial value any more,
> unless you are an artist. What's your time worth?
***I am hoping to join the 18th century sometimes next year. The time
value - at present little. That may change.
>
> I picked auctions and second-hand dealers as my best time-vs-money
> tradeoff. Even very old machines can cut metal more quickly and
> accurately than I ever could by hand. My time is spent fixing/
> restoring them and sharpening cutters. Almost everything I own was
> broken when bought and still has problems but they work well enough
> most of the time. When I'm stopped by one of their problems I fix it.
>
> I think the minimum satisfactory home or experimental shop equipment
> is a mill-drill or small vertical knee mill and a 9" - 12" lathe.
> Smaller machines are OK to make models but not for equipment that does
> useful work.
>
> I have a Clausing vertical mill, a 10" South Bend lathe, a 4X6 bandsaw
> and don't see the need for anything larger, and I built a log
> splitter, a sawmill, and bucket loader for my garden tractor with
> them. I could put up with a mill-drill for most projects.
>
> A small horizontal mill could substitute if you get a good deal but
> then you need a better drill press, and new cutters are much more
> expensive than end mills.
I am sure you are right. I am in fact looking. The 9-12" in the lathe
department would be the swing-over-bed? There is a slew of small lathes on
the EBay, 7"x 8-12", all under $600. The bigger machines are out of my
league. The other issue is space.
--
Michael Koblic,
Campbell River, BC
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Posted by Jim Wilkins on May 28, 2008, 8:10 pm
Please log in for more thread options > I see I managed to filter off Jim's post inadvertently, so I guess I have =
to
> respond "second-hand".
>
>
> > Bob Swinney
> > ... cold chisels...
>
> ***Never thought of chisels. Will they work on 5mm thick plate?
Mild steel plate? Sure, as long as you clamp it solidly to something
heavy. You can practice on wood across the grain to get the feel to
cut a constant depth. Chisels are "Armstrong Milling Machines". The
last steel I chiseled was rivet heads on a truck frame, the last wood
was a new transom I fitted onto a neighbor's boat last week. In
neither case did machine tools help. It's a useful skill.
>
> > Grind the teeth off one edge of a file to make it cut sharp inside
> > corners and only work one surface at a time. Coarse files are better
> > for long cuts because the teeth don't fill with chips halfway through
> > the stroke.
>
> ***See, this is the sort of thing I would not have thought of and that mak=
es
> perfect sense
You can buy files with a safe edge for finishing inside corners. The
common types are "hand" and "pillar".
I use them a lot for custom cutouts in electronic control panels.
> ***I am hoping to join the 18th century sometimes next year. The time
> value - at present little. That may change.
This crazy guy is a good source of technical books from the early 20th
century, which is about the state of the art for many of our home
shops today. He has had a better selection in the past but Elements of
Machine Work and Advanced Machine Work are good.
http://www.lindsaybks.com/
> I am sure you are right. I am in fact looking. The 9-12" in the lathe
> department would be the swing-over-bed? There is a slew of small lathes on=
> the EBay, 7"x 8-12", all under $600. The bigger machines are out of my
> league. The other issue is space.
> Michael Koblic,
> Campbell River, BC
US practice is to specify a lathe by maximum work diameter over the
ways and length of bed. My 10" x 42" lathe can hold a 10" pulley blank
on a face plate but it's limited to stock a bit less than 6" diameter
over the carriage and about 20" long.
If I had the space I'd own a Bridgeport. I passed up a Monarch 10EE
for $2000 because I had no room for it.
Jim Wilkins
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Posted by Wes on May 27, 2008, 6:35 pm
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>I have to cut 2 perfectly matching slots in a 5 mm thick flat semicircular
>piece of steel, each 15 mm by 5mm.
>As per suggestion on another thread I doubled up on the hacksaw blades. This
>gave me only just over 2 mm. Cutting this length with a file is not a
>prospect I relish. I tried with a 3/32 cut-off wheel in a 4-1/2" grinder.
>This works but holding the grinder in exactly right plane is tricky.
Know anyone with a surface grinder? Dress the wheel to 5mm far enough to do
the slot. Carbide em in a bridgeport. I'm assuming this is something
fairly hard.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
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> piece of steel, each 15 mm by 5mm.....
>
> Michael Koblic,
> Campbell River, BC