Hi all. I just got a new lathe for Christmas and I have been trying it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's Handbook,
the Army metal working PDF, and some engineering reference books I have, but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?

Kelly Jones wrote:

Hi all. I just got a new lathe for Christmas and I have been trying it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's Handbook,
the Army metal working PDF, and some engineering reference books I have, but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?


You are either using a really pointy tool or a dull tool or both.

A good finishing tool is rounded when you look at it from the top, and
_sharp_ when you look at it from the side. If it's sharp when you look
at it from the top and dull when you look at it from the side then
somebody got things mixed up.

Is it the tool that came with the lathe? If so, it's probably too dull.
I had to sharpen up the tools that came with my Smithy before they'd
make decent cuts.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Kelly Jones" wrote in message
....
Hi all. I just got a new lathe for Christmas and I have been trying
it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD
to
about 0.38 OD. I have tried various speeds and feeds but still keep
getting
a very rough finish. The finish is so bad that it looks as is the
metal is
being torn rather than cut. The surface is full of small slivers that
would
cut your hand i a heartbeat. I am having similar problems with an
unkown
carbon steel, although not as bad. I have checked the Machinery's
Handbook,
the Army metal working PDF, and some engineering reference books I
have, but no help. I thought that I might even be using the tools
wrong
(cutting on the wrong face) but I can't seem to find the source of the
problem. The lathe is a Grizzly 12 X 36. Any ideas?

Hi Kelly;
The speeds, feeds and the amount being cut will all have an effect on
the surface but those are probably not the problem.

Do you have a bench grinder for your tool bits?

Two points:
1) line up the tool bit (where it is cutting) with the exact center of
the piece being turned. You can see this by taking a "face cut" - if you
are low you will see a little round "stub" when your tool bit passes the
center and under it. Shim the tool bit up repeatedly until the cutting
point passes thru (or almost) dead center. (better to be a few thousands
low than high - if high the "relief" or under side will be "rubbing"
rather than cutting)

2) Find a reference on the angles you should grind on the tool bit. In
general the softer the material, the sharper the angles. Also check the
rasdius at the cutting point - anywhere from a "hand stoned" very slight
radius to large "form tool" for a radiused shoulder on the work.

What you ask is not really "simple" and you will still be learning these
operations next year. You can learn about your "speeds and feeds" (for
each material) from the colors (steel) on the continuous "chip curl" -
or the small separate chips that fall to the bed... Aluminum will curl
and spiral or be in ling straight "strings."

I suggest you find a machinist, toolmaker or modelmaker in your area
that will let you watch and ask questions as he demonstrates - You will
learn more it two hours that way than with all the instructions - then
read the tables and instructions and play... You're going to love
this...
JHbs

Phants wrote:
"Kelly Jones" wrote in message
...
Hi all. I just got a new lathe for Christmas and I have been trying
it out. I have been trying to turn a piece of unknown CRES from
about 0.75 OD to about 0.38 OD. I have tried various speeds and
feeds but still keep getting a very rough finish. The finish is so
bad that it looks as is the metal is being torn rather than cut.
The surface is full of small slivers that would cut your hand i a
heartbeat. I am having similar problems with an unkown carbon
steel, although not as bad. I have checked the Machinery's
Handbook, the Army metal working PDF, and some engineering reference
books I have, but no help. I thought that I might even be using the
tools wrong (cutting on the wrong face) but I can't seem to find the
source of the problem. The lathe is a Grizzly 12 X 36. Any ideas?

Hi Kelly;
The speeds, feeds and the amount being cut will all have an effect on
the surface but those are probably not the problem.

Do you have a bench grinder for your tool bits?

Two points:
1) line up the tool bit (where it is cutting) with the exact center of
the piece being turned. You can see this by taking a "face cut" - if
you are low you will see a little round "stub" when your tool bit
passes the center and under it. Shim the tool bit up repeatedly until
the cutting point passes thru (or almost) dead center. (better to be
a few thousands low than high - if high the "relief" or under side
will be "rubbing" rather than cutting)

2) Find a reference on the angles you should grind on the tool bit. In
general the softer the material, the sharper the angles. Also check
the rasdius at the cutting point - anywhere from a "hand stoned" very
slight radius to large "form tool" for a radiused shoulder on the
work.

What you ask is not really "simple" and you will still be learning
these operations next year. You can learn about your "speeds and
feeds" (for each material) from the colors (steel) on the continuous
"chip curl" - or the small separate chips that fall to the bed...
Aluminum will curl and spiral or be in ling straight "strings."

I suggest you find a machinist, toolmaker or modelmaker in your area
that will let you watch and ask questions as he demonstrates - You
will learn more it two hours that way than with all the instructions -
then read the tables and instructions and play... You're going to love
this...
JHbs
Sounds to me like your 'tool' is too sharp (read no radius).
--
http://www.rupert.net/~solar
Return address supplied by 'spammotel'
http://www.spammotel.com

You got a lathe for christmas?? shucks.. I'm so jealous all I got was $20
LOL

-Mike

--
A happy kid behind the wheel of a 98 Mustang GT
Cold air intake
FRPP 3.73 gears
Steeda Tri-Ax Shifter
Flowmaster 40 Series mufflers (self-installed woohoo)
Hi-speed fan switch
255/60R-15 rear tires
Subframe connectors
Aluminum adjustable clutch quadrant


"Kelly Jones" wrote in message
...
Hi all. I just got a new lathe for Christmas and I have been trying it
out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep
getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that
would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's
Handbook,
the Army metal working PDF, and some engineering reference books I have,
but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?

On Tue, 28 Dec 2004 16:52:42 -0800, "Kelly Jones"
wrote:

Hi all. I just got a new lathe for Christmas and I have been trying it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's Handbook,
the Army metal working PDF, and some engineering reference books I have, but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?

Fill in the blanks

1. What kind of tool are you using?
2. What is your feed rate in inches/rev?
3. What is your rpm?
4. How much material do you have hanging out of your chuck?
5. Have you tried a piece of aluminum?

Gunner

"Gunner, you are the same ridiculous liberal f--k you ever where."
Scipio

"Tim Williams" wrote in message
....
"Ken Davey" wrote in message
....
Sounds to me like your 'tool' is too sharp (read no radius).

Wouldn't that be comparable to cutting a flat with a threading tool?

Tim

Yes - cutting a flat with a threading tool produces a "bad surface" but
only if you are in a hurry and want to take a cut or two without
changing the bit. If the tool bit is set correctly this will produce
that bad surface, most likely with a spiral-like cut (a very fine and
uneven thread), when the feed is too fast. A flat can be cut with a
threading tool "point" by feeding really slowly and filing or stoning
the surface afterward. Do this only on a non-essential surface - a shaft
to provide sloppy clearance through a hole... (Called "mulyak
machining")

BTW - I almost always take a very small radius on a threading tool... a
pass or two with a fine stone or even a whitestone - absolute sharp
makes for a possible fracture point under shear...

And, yes, too sharp with no radius could be a part of the problem but
will not totally account for the problem being described as: "metal is
being torn rather than cut"

That description is usually caused by metal being "pushed off" or "torn
off" rather than cut off. The tool being too low (work attempting to
"ride up" onto the top of the too bit) or too high (rubbing under the
cutting surface) produces this. I have also seen this happen with a
"negative rake" on the top of a fairly flat cutting surface.

Remember this for the time you want a (small o.d.) surface to grip with
your fingers to turn and do not have a knurling tool... Tear it out
(it's sharp) then file off the tops of the points ... Not for clients or
others but quick and dirty in your own shop - and cheap...!

JHbs

"Gunner" wrote in message
...
On Tue, 28 Dec 2004 16:52:42 -0800, "Kelly Jones"
wrote:

Fill in the blanks

1. What kind of tool are you using?
2. What is your feed rate in inches/rev?
3. What is your rpm?
4. How much material do you have hanging out of your chuck?
5. Have you tried a piece of aluminum?

Gunner

Thanks for the comments guys.

Answers to Gunner's questions:

1. Unknown tool. (I know this sounds crazy.) They are the tools that came
with the machine. They are indexable inserts, but I don't know if they are
carbide or simply HSS (although I suspect the latter).

2. I have tried a variety of feed rates, including the smallest available.
Usually I have it set mid-range (I don't recall the precise setting at this
time, but changes in feed rate seem to make no difference.)

3. I have tried all the speeds from 200 to 1000 RPM. I have been hesitiant
to go faster.

4. About 4 inches.

5. I have not tried aluminum yet.

I know that I have damaged some of the tools (inserts) in my experimentation
(chipped, dulled) but I still have this problem after rotating the insert to
a fresh surface. Phants' comment about the tool height may have some
bearing. I set the tool "high" to achieve the 5 degree offset described in
chapter 7 of the Army training manual. Could it be that this only applies
to square tools (not inserts)?

I ran into this by accident a few weeks ago. I was making a handwheel for an
Atlas milling attachment from an aluminum blank. The OD of the wheel turned
out with that 'torn' finish. But it was uniform, looked OK, and offered a
superior grip that let me set the gibs a little tighter than usual. So I
left it that way.

"Phants" wrote
That description is usually caused by metal being "pushed off" or "torn
off" rather than cut off. The tool being too low (work attempting to
"ride up" onto the top of the too bit) or too high (rubbing under the
cutting surface) produces this. I have also seen this happen with a
"negative rake" on the top of a fairly flat cutting surface.

Remember this for the time you want a (small o.d.) surface to grip with
your fingers to turn and do not have a knurling tool... Tear it out
(it's sharp) then file off the tops of the points ... Not for clients or
others but quick and dirty in your own shop - and cheap...!

JHbs

"Kelly Jones" wrote in message
...

1. Unknown tool. (I know this sounds crazy.) They are the tools that
came
with the machine. They are indexable inserts, but I don't know if they
are
carbide or simply HSS (although I suspect the latter).

If they are inserts they are probably carbide.


2. I have tried a variety of feed rates, including the smallest
available.
Usually I have it set mid-range (I don't recall the precise setting at
this
time, but changes in feed rate seem to make no difference.)

3. I have tried all the speeds from 200 to 1000 RPM. I have been
hesitiant
to go faster.


Speed is a function of diameter. Smaller stuff runs faster than larger
stuff.



Phants' comment about the tool height may have some
bearing. I set the tool "high" to achieve the 5 degree offset described
in
chapter 7 of the Army training manual. Could it be that this only applies
to square tools (not inserts)?

When turning, you want the cutting edge to be right on the centerline. What
I do is (with the machine off) pinch a small scale (ruler) in between the
bit and the work piece until it just stays without falling. If the top of
the scale tips toward you your cutter is low. If it tips away your bit is
too high.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.

When turning, you want the cutting edge to be right on the centerline. What
I do is (with the machine off) pinch a small scale (ruler) in between the
bit and the work piece until it just stays without falling. If the top of
the scale tips toward you your cutter is low. If it tips away your bit is
too high.


you would want it very slightly high, so that under load it is near
centerline, but never low, or so I was taught

"yourname" wrote in message
....

When turning, you want the cutting edge to be right on the
centerline.
What I do is (with the machine off) pinch a small scale (ruler)
in between the bit and the work piece until it just stays without
falling.
If the top of the scale tips toward you your cutter is low. If it
tips away
your bit is too high.

you would want it very slightly high, so that under load it is near
centerline, but never low, or so I was taught

You are absolutely right, and were taught correctly. The phrase you use
however (very slightly high) is also known as an RCH. Some think that
this is the smallest measurement that can be made. ;-}

This is also "book correct" and, like so many things, is not really
practical to achieve 100% of the time. This actually attempts to address
the fact that under the force the cutting, the work will "raise itself"
while being worked. The obvious part of this becomes "more correct" with
smaller, more flexible material and cuts further out from the spindle.
Diameters of the stock and heavy cuts come into play - the heavier the
cut the more force attempting to "raise the work."

The less obvious part of this is that a cut that starts several inches
from the spindle or Collette will allow much more "lift" in the material
which will be less and less as the cut approaches where the material is
being gripped in the spindle. As this happens your cutting tool will get
"higher" until, if you started high it will become high on the work once
again.

Start "dead on center" if you can - or a thousandth or two low... Being
Highwill cut an RCH from where it should, but it cuts. Being Low cuts
only at the start and then does not cut - it rubs...

JHbs

You might want to get yourself some free machining steel like 12L14. There
is a lot of steel that does not machine very nicely unless you have
everything just right.

In article ,
Kelly Jones wrote:

"Gunner" wrote in message
.. .
On Tue, 28 Dec 2004 16:52:42 -0800, "Kelly Jones"
wrote:

Fill in the blanks

1. What kind of tool are you using?
2. What is your feed rate in inches/rev?
3. What is your rpm?
4. How much material do you have hanging out of your chuck?
5. Have you tried a piece of aluminum?

Gunner

Thanks for the comments guys.

Answers to Gunner's questions:

1. Unknown tool. (I know this sounds crazy.) They are the tools that came
with the machine. They are indexable inserts, but I don't know if they are
carbide or simply HSS (although I suspect the latter).

Carbide -- almost certainly.

2. I have tried a variety of feed rates, including the smallest available.
Usually I have it set mid-range (I don't recall the precise setting at this
time, but changes in feed rate seem to make no difference.)

I forget whether you mentioned what machine you were using, but
if your lathe has both power feeds and threading (threading controlled
by the half-nuts lever, power feed by another), you want to use the
power feed (which is slower) for turning, and keep the half nuts for
threading only, to minimize wear on the leadscrew. If it has power
feed, it probably also has power cross-feed, perhaps selected by the
same control in a different position, or perhaps selected by a separate
control. (Lathes which have three controls -- half-nuts, cross-feed,
and longitudinal feed -- can often have both cross and longitudinal
engaged at the same time to produce a taper. However it should not be
possible to engage one of the power feeds and the half-nuts at the same
time.

3. I have tried all the speeds from 200 to 1000 RPM. I have been hesitiant
to go faster.

With carbide, and with a 0.750" diameter workpiece, I would
consider 300 RPM minimum, and probably 1000 RPM to be a reasonable
choice in mild steel. (Without bothering to look up the proper SFM for
that -- just going by feel.) As you reach smaller diameters, the speed
can be increased.

4. About 4 inches.

4 inches -- with only a 0.750" OD? That is likely to be a
significant source of your problem. Before attempting to cut it, use a
center drill ("drill and countersink") to make a center hole in the end
of the workpiece, and then bring a "live" center (ball bearings) (if you
have one for the machine) into the hole. If you don't have a live
center, you'll have to use a hardened "dead" center and be careful to
lubricate the hole with a good thick lube. What used to be used before
all the hysteria about lead was white lead paste. Now, perhaps
something like a molybdenum disulfide grease.

This offers support to the free end of the workpiece, so it will
not flex as much. With really long extensions, you will need more
support than that -- with a follower rest if you are turning the whole
exposed length, or a steady rest if you are only working on the end.

5. I have not tried aluminum yet.

Aluminum can be very nice to turn, or also be ugly, depending on
the alloy. Pure aluminum is too soft to turn nicely. However, an alloy
like 6061T6 can be very nicely turned.

I know that I have damaged some of the tools (inserts) in my experimentation
(chipped, dulled) but I still have this problem after rotating the insert to
a fresh surface. Phants' comment about the tool height may have some
bearing.

It could, indeed.

I set the tool "high" to achieve the 5 degree offset described in
chapter 7 of the Army training manual. Could it be that this only applies
to square tools (not inserts)?

It could be. Any insert tooling should have whatever angle
needed built into it, so the shank can be level, as most quick-change
and turret toolposts tend to hold the shank level, and the angle can
only be easily set on one of the old "lantern" style toolposts, which is
what was mostly in use at the time the Army manual was written.

If you have an import 13x40 or similar lathe (Chinese or
Taiwanese), it most likely came with a turret toolpost (four slots for
tools on a rotatable device). These need stacks of shim stock under the
tools to bring the cutting edge up to on center.

If you have a quick-change toolpost, you have the ability to
adjust the height of each tool individually without shims. Ideally, you
should have a separate holder for each tool which you have.

Note that many inserts can be totally level, and have a groove
in them to make the effective angle correct.

Cheap insert tooling (commonly sold in sets of five) tends to
have inserts which are too thin, and are not properly supported. *Good*
insert tooling has a secondary carbide anvil between the insert and the
holder. And I tend to prefer insert tooling which fits a negative rake
holder, but has a groove to make it into a positive rake cutting edge.
I normally use these in an Aloris BXA-16N tool holder (the letter code
changes for the size of the toolpost, with AXA being the smallest of the
standard size, and BXA usually being a better fit for a 12" or 13"
lathe. The "-16N" mounts two negative rake inserts, one on the turning
end and one on the facing end, so a single holder handles most of the
common operations. There is a plain "-16" (or is it called a "-16P"?)
which uses positive rake inserts.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Thanks. Lots of good info. I spent the day playing with the machine. The
first thing I did was to reset the tool height like Phants suggested and got
an immediate improvement. Then I chucked up some 6160T6511 I got at the
local scrap yard. It turns beautify. I also experimented with some
internal turning / boring. Learned quickly that the thickness of the tool
was greater than the width (i.e. it started rubbing). Thought I really
screwed up, but I hit the emergency stop fast enough and everything still
looks OK.
I am surprised that the machine came with carbide inserts, but I am not
complaining. Is there a way to tell by looking?
I've got center drills and a cut off tool on order. Should be here within a
week. The machine came with a quick change tool post. Thanks again for the
info.

In article ,
Kelly Jones wrote:
Thanks. Lots of good info. I spent the day playing with the machine. The
first thing I did was to reset the tool height like Phants suggested and got
an immediate improvement. Then I chucked up some 6160T6511 I got at the
local scrap yard. It turns beautify. I also experimented with some
internal turning / boring. Learned quickly that the thickness of the tool
was greater than the width (i.e. it started rubbing).

Yep -- you need a special format to use for boring. My own
favorite is a 1/2" solid carbide bar with carbide inserts. (The benefit
of the solid carbide is that it has less give than any steel of the same
size, so it is harder for it to start chattering at a long extension.

For shallow bores, get some of the brazed carbide insert boring
bar sets for boring heads. Just make sure that the shank will fit into
your tool holders. The BXA quick-change tool holders will accept 5/8"
square shanks, and the one which you want has a 'V' bottom to the tool
holder slot, so a round piece won't try to roll out under cutting loads.

Thought I really
screwed up, but I hit the emergency stop fast enough and everything still
looks OK.

O.K. Good reflexes help a lot. :-)

I am surprised that the machine came with carbide inserts, but I am not
complaining. Is there a way to tell by looking?

It may be cheap insert tools (which tend to have more expensive
inserts. :-) A quick test for whether an insert is carbide or HSS is a
magnet. HSS should be attracted, while the carbide should pretty much
ignore it. (I think -- I would have to go downstairs to check it for
sure.)

Some of the inserts are TiN coated (Titanium Nitride, not the
metal "tin"). Those will look gold. Though HSS can be (and is) TiN
coated, too.

I've got center drills and a cut off tool on order. Should be here within a
week.

Within a *week*? You need to learn about MSC. Check out:

http://www.mscdirect.com/

and register for a catalog. (It is *big* -- over 4000 pages last time I
checked.) While there are places which will charge you less, MSC is
*very* quick. I don't know where you are located, but where I am, most
things called in by about 6:00 PM or so will be here about 3:00 PM the
next day. (The nearest warehouse is in Harrisburg PA, and I'm just a
bit south of Washington DC.) They've got enough warehouses around the
country so I would think that at worst you would only need one more day
on top of that for most things.

The machine came with a quick change tool post.

Great! Those are *so* much better than the turret toolposts.
Any idea what size? Aloris and several other makers use the
"AXA/BXA/..." markings, while Phase II and some others use
"Series 100/200/...". The tool holders are interchangeable between
them. I have the Phase-II Series 200 toolpost, and use a mix of
Phase-II and Aloris tool holders.

Thanks again for the
info.

You're welcome.

BTW. When commenting on the 4" stickout for 0.750" diameter situation
I forgot to mention that anything beyond 4X the diameter of
stickout needs support -- and if you're close -- use a center to
support it anyway.

Good Luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

How about getting some "known" material for starters? Do you know what
tool angles, speeds and feeds you need?
What are you using for tool bits? Are they sharp? Do you
understand how to set the tool to work?
I'd get a "how to run a lathe" book if the answer to more than one
of these questions is a "no". They can be had for about $10 on E-Bay.
I don't mean to sound harsh, but with so many variables, it's hard to
give any useful advice.
If you don't want to do that, I'd at least visit a high school or
vo-tech shop and ask the instructor for some help.

If you want to get some help over the phone, email me back off list. We
can plan a time when you can be at the lathe and have a phone in one
hand. Then we could start working through the issues.

Pete Stanaitis
--------------------------------------------

Kelly Jones wrote:

Hi all. I just got a new lathe for Christmas and I have been trying it out.
I have been trying to turn a piece of unknown CRES from about 0.75 OD to
about 0.38 OD. I have tried various speeds and feeds but still keep getting
a very rough finish. The finish is so bad that it looks as is the metal is
being torn rather than cut. The surface is full of small slivers that would
cut your hand i a heartbeat. I am having similar problems with an unkown
carbon steel, although not as bad. I have checked the Machinery's Handbook,
the Army metal working PDF, and some engineering reference books I have, but
no help. I thought that I might even be using the tools wrong (cutting on
the wrong face) but I can't seem to find the source of the problem. The
lathe is a Grizzly 12 X 36. Any ideas?

"Kelly Jones" wrote in message
....
Thanks. Lots of good info. I spent the day playing with the machine.
The
first thing I did was to reset the tool height like Phants suggested
and got
an immediate improvement. Then I chucked up some 6160T6511 I got at
the
local scrap yard. It turns beautify.

For a "quick test" - You can tell carbide by attempting to sharpen (or
to just grind) a spot on a "back surface" where it won't hurt the intent
of the tool. If the grinding wheel breaks down instead of the tool - it
is probably carbide.

You need a "green wheel," for sharpening carbide, a very soft wheel
(counter intuitive) or a diamond (very hard) wheel... You can also
sometimes tell by weight - if you have a comparative size in steel -
carbide is noticeably heavier...

And You are "off and running" - congratulations..! Machining Beautifully
is as exciting and gratifying as you can get in any hobby; the joy of
actually producing a piece or a part that looks good and/or functions
just the way you wanted it too only adds to the joy. That is why so many
people that do this for a living choose to come home and do it as a
hobby as well...

One caution in recognition of your status as a "newbie" - Be careful of
taking advice from us "old farts" at face value, and remember that
advice is restricted to only what you told us. There are sometimes valid
reasons that the material is chosen, and for reasons other than the fact
that it "machines better."

If this part you are making is a "pressure vessel" or must have certain
hardness or even electrical properties, be careful when substituting one
material for another. Probably not important in your first practice
pieces, but a good opportunity to remind you that you are ultimately the
only one responsible for the entire process; start to finish. Think it
through...

Good luck and happy tooling...
JHbs