Jay, Why no W-D 40 on rolling mill? My poor rolling mill had some
rust when I acquired it used many years ago and unfortunately was
corroded more by nasty smoke in a studio fire years back, so the
rollers, tho now rust free are not a shiny milled surface. It leaves
an orange peel like surface on a polished plate surface. I mostly use
my rolling mill to print textures so often this is not an issue, but
it would be nice to have a smooth plate finish when I want one. I
have heard about someone who had their rollers refinished. I am
wondering if it is very expensive, and how I would find some one
competent. Another concern is getting it back together and rollers
even. Its a REAL drag when rollers are off even a tiny. My mill has
no name imprinted on it and has a flat side and square wire grooved
side for a total of about 6".
I have used W-D 40 on this mill & bench blocks and wasn’t thrilled
with a “smudging” that seemed to last even tho it was wiped well
repeatedly. Whats the story here?
April Bower, in AZ where it is 113 in desert and 82 here in the
mountains. We have it all,… except an ocean.
Jay will doubtless reply as well, so take this as an amplification
of what he’s about to come back with.
No WD-40: it’s not a very good rust inhibitor. It’s actually a water
displacer (thus the “WD”) It’s got a lot of volatiles that boil off
in the first few days, leaving…not much. Thus a heavier oil like
3- in-1 is better for short-med term. An actual rust inhibitor like
LPS-3 is needed for longer term protection. (Weeks/months/years.)
LPS-3 is great, but it’s a little more fun to get off than 3-in-1.
Not for everyday use, normally.
Oil also attracts and holds dust & crud, which both forms the
nucleus of rust spots, and can get rolled into your metal. Thus the
covering of the mill.
As far as getting rolls refinished, I’ve done that a couple of
times, on various mills. You want to find a machine shop that can
“grind between centers”. (That’s the phrase they’ll be listening
for.) If they can do that, they’ve got a precision grinder that can
refinish your rolls in a few minutes. I had the flat rolls for two
different rolls done for about $50/4 about 10 years ago. It may be as
much as $100 these days. Call around. The only things you care about
are surface finish, concentricity, and parallelism. When you talk to
the machine shop guys, tell them that the actual OD of the part
doesn’t matter much, just grind as little as possible. The important
parts are that the rolling surface be (A) parallel and concentric to
the journals, and that both rolls be the exact same OD, whatever it
is. Tolerance of about.0005". You’re looking for a 5-10 micron
finish. (Smaller is better) Most rolls are case hardened, so you really want to grind off as little as possible. Make sure they know
this. (There’s a thin skin of hard metal on the outside of the rolls.
Grind through that, and you’ve got scrap iron.) I’d guess most rolls
have at least.020" of case depth to them, and the grinder shouldn’t
take more than.005" or so, unless the rolls are really trashed.
I’ve got a tutorial on my website about getting rolling mills
straightened out after the rolls get misaligned, or taken out. It’s
heRe:
I can’t say that I’m any kind of an expert on tool and machine
lubrication.
However, during the 24 years I taught classes at UCSD, I developed a
good working relationship with the Bonner Hall Biology Research
Machine Shop. There are a friendly if quirky but hugely talented
machinists and specialty welders who work there. Some of their
machinists took classes from me over the years, so we do favors for
each other.
One of the machinists did most of my machined prototypes and also
regrinds and polishes my rolling mill rollers. One day he told me NOT
to use WD 40 on machine parts, long term. He claimed that WD 40 had a
somewhat corrosive effect on steel parts over time, was what he told
me. Anyway, I’ve stayed away from WD 40 ever since, using a high tech
spray lube instead.
I saw this wacky orange can of spray lube I am trying now, I think
called “Jiga-Lu” or something close to that. It was cheap, and seems
to work great. I love the orange can.
You might want to contact the Durstons about your "orange peel"
rollers. Mathew Durston’s father runs a Durston repair and service
center near Phoenix. They will be able to help you with your mill. Or,
check out machinists around you. See if they can regrind your
rollers reasonably. If they’ll do it, let them know you want an
extremely smooth surface polish. I think I’ve paid from $150 to $200
to have a mill resurfaced.
If possible, let the people regrinding the rollers disassemble and
reassemble ( and adjust) your mill. Many machinists prefer it that
way. Way easier for you!
I’d also REALLY suggest you cover your mill when it’s not in use.
Can you guess what kinds of stuff are blowing through your studio,
sticking to your nice oiled rollers??? A pillowcase is a perfect size
and works great. Mine are black so they don’t show oil stains.
I had some rollers refinished years ago by a machine shop here in
Portland Or. I can’t remember the name of the shop. It wasn’t very
expensive. Maybe 30 or 50 bucks?
They put it on a lathe. It came out beautifully. Any good machine
shop can do this for you. Have fun and make lots of jewelry.
I'd also REALLY suggest you cover your mill when it's not in use.
Can you guess what kinds of stuff are blowing through your studio,
sticking to your nice oiled rollers??? A pillowcase is a perfect
size and works great. Mine are black so they don't show oil stains.
Jay is right on about keeping you mill covered when not in use.
It’s best to use a cloth cover, not a plastic cover.
The cloth covers let the air & humidity in the air circulate between
the room & the tool being covered.
Depending on the humidity & the air temp, if a plastic cover is used
& the humidity is higher during the day than at night, the moisture
in the air that’s trapped by a plastic cover can form water droplets
on the cold steel at night.
I am reluctant to put oil on the rolls because it will end up on my
workpiece.
At some point, I was instructed that if the rolls needed help, I
should wrap some sandpaper around a dowel, set the gap smaller than
the dowel, and roll for a few minutes-- the dowel keeps the sandpaper
from going through but keeps it in good contact with the rolls. Then
polish the rolls with Simichrome and cover.
Is this a bad regimen? Is oil really the way to go?
Over time, WD-40 can leave a sticky residue that’s hard to remove. I
stored some machinery for a couple of years in an unheated space. To
protect from rust, I sprayed WD-40 onto unpainted steel surfaces.
When the machines were put into service, it required lots of stinky
paint thinner and much scrubbing to get the dried WD-40 off the
metal. But it did protect the surfaces! I recommend Waxilit, a
silicone-free paste wax much used in the wood-working industry to
minimize friction on table saw and jointer table surfaces. It really
works, and it stops rust better than anything else I’ve tried. I use
it on polished forming stakes, mandrels, etc. It’s readily available
in the US and Europe - just do a Google search on Waxilit.
Rolls in good rolling mills are heat-treated after machining to leave
the surface layer very hard, and the core much softer. This provides
a surface that is not easily damaged, but prevents the roll from
being brittle and prone to cracking from the forces involved in
rolling. The thickness of the hardened surface layer is not
something one can determined by inspection, but it probably is
extends inward no more than 0.050" from the surface. If the surface
pitting is very shallow so that only a few thousands of an inch of
metal needs to be removed, the hardened surface layer of the roll
will remain intact after grinding. Any competent machine shop with an
engine lathe, tool post grinder, and flood coolant can resurface the
rolls. The work should be much cheaper than the price of a new
rolling mill. But if the pits are deep, a lot of metal must be
removed to achieve a smooth surface. Once you’re down below the
hardened layer, the rolls must be re-hardened. Surface hardening is
not within the skill set of many machinists or blacksmiths, as it
usually done with specialized heating equipment. It may be difficult
to find a shop that really has the smarts and tools to do that kind
of heat treating, and even if you do, expect to pay a lot.
We have some large oil soaked sponges that we jam into the top and
bottom of our mill. As we use it it constantly oils and cleans them.
We also keep a dehumidifier in our shop.
They put it on a lathe. It came out beautifully. Any good machine
shop can do this for you.
And possibly ruin your rolls.
It is not difficult or expensive to have them ground but they must
be ground not turned on a lathe. They also must be ground between
centers. Those little cone shaped depressions on the ends of the
rolls are called centers. The rolls are mounted on tapered points
that go into those centers and then ground. This makes the outside
diameter of the roll concentric with the center of the roll and the
bearing journals. If you neglect to refinish the rolls this way your
sheet will vary in thickness because the rolls are not concentric
with the centers.
Rather than a machine shop what you want to look for is a grinding
shop who can grind between centers. The last time I had this done
was at Pacific Reamer and Cutter in Oakland CA (510) 654-1844. It was
about 60 bucks, however that was over ten years ago.
Is this a bad regimen? Is oil really the way to go?
In past 20 years I have not oiled my rolls. In fact I clean them
with alcohol to get oils and dirt off of them. In my opinion oil just
acts to cause dirt to stick to the roll surface and then into your
work. If you don’t live right next to the ocean or have a studio in a
damp basement or some other situation where steel will rust in the
air there is no need to oil your rolls. Keep the rolls, work and your
hands clean when using the rolling mill and there is no reason to
oil the rolls.
Surface hardening is not within the skill set of many machinists or
blacksmiths, as it usually done with specialized heating equipment.
It may be difficult to find a shop that really has the smarts and
tools to do that kind of heat treating, and even if you do, expect
to pay a lot.
Many folks have mentioned that resurfacing can be competently done
by a machine shop with center grinders. If the rolls become annealed
or the damage is deeper than the case hardened surface, Mark is
correct that it will need to be properly heat treated. Even a well
equiped machine shop will out-source this operation. In our town, we
use Dayton Heat Treat. This link shows the capabilities that a
company will have.
Yeah, you can do it on a lathe if you’re good. But if you’re good
enough for that job, odds are good you actually have a center
grinder. A lathe with a grinder is (A) bad for the lathe, and (B) a
half measure to expand a shop’s capacity for occasional jobs. If
they’re good enough to be worth talking to about rolling mill rolls,
they have the real thing.
Can't that be done on a lathe? Use centers and substitute the
appropriate abrasive for the cutting tool.
There are tool post grinders that fit on the lathe and would allow
you to grind on the lathe but it is less than an optimal method. It
is a tool that allows you to do occasional grinding but it will be
harder to get a professional result. It also can really mess up your
lathe if you are not very very careful the grinding dust can get in
the ways and degrade the accuracy of the lathe. So yes you can do it
on a lathe but a professional grinding shop will most likely do a
better job on a dedicated tool.
Can't that be done on a lathe? Use centers and substitute the
appropriate abrasive for the cutting tool.
It can be done on a lathe using what is called a tool post grinder.
However, few machinists use them anymore because grinding wheel
silica (whatever) on the ways of the lathe can cause uneven wear -
negatively impacting the machine’s precision.
Yeah, you can do it on a lathe if you're good. But if you're good
enough for that job, odds are good you actually have a center
grinder
Still, reason enough to believe Jo haemer's account.
I did not say that I did not believe her, I said that the lathe is
not the right tool to use. It is like driving a nail with a crescent
wrench. Yes you can do it but it is not the right tool and it is
easy to ruin a roll if you try to hard turn it rather than grind it.
If you take it to a machine shop that does not understand how
important the cylindrical and parallel tolerances are and that is
going to be difficult if not impossible to with hard turning. If you
ask a machine shop to turn it on the lathe they may just try, and you
will likely be dissatisfied with the results. My point was that if
you want the job done right you need to ask for it to be ground on
centers not turned on a lathe.