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Fixing rollers gap in Pepe rolling mill


#1

I have a Pepe rolling mill.

Having loaned out my workshop I now find that the rollers, although
parallel, do not meet together and have a gap of about .5mm between
them.

I can’t figure out how to raise and lower them independently of the
turn screw at the top so that I can eliminate this gap.

Anyone have an answer?

Tony Konrath


#2

Tony,

It depends on the manufacture of the roller. All I have to do on mine
is pull the handle straight up and turn each cog to adjust the
distances, then replace the adjustment handle. My very first
experience with my roller was dropping it. I picked it up by the top
adjustment handle. It came off and my new roller fell to the floor.
The thing you have to do is remove the center handle that you use to
make the thickness adjutsments (it has cogs on it that turn the cogs
on both sides at the same time) and adjust the roller by hand then
replace the center adjusting handle. Good luck


#3
remove the center handle that you use to make the thickness
adjutsments (it has cogs on it that turn the cogs on both sides at
the same time) and adjust the roller by hand.. 

I’ve done that and managed to reduce the gap to.5mm but the rollers
still don’t meet. Thanks for your input.

Tony Konrath


#4

Tony, Pull off the bracket that hold down the t-bar at the top of
the mill, then pull the t-bar straight up and out from between the 2
gears. Wind the two gears down until the rollers meet and are level,
then replace the t-bar and the bracket. Feel free to give me a call
if you have any additional questions

Best regards,
Mike Stromberg
Director of Sales and Marketing
pepetools.com


#5

Tony:

If I remember correctly you said you loaned the mill to someone? Did
they change the rollers? Did you give them all the rollers?

I am the newbie here so don’t know the protocol about answering, but
maybe I can help. The suggestion folks gave about removing the
center gear and dropping the rollers was good as we all were
assuming you had not done that.

Given you must have the adjustment gears all the way down, the only
other reason the rollers are not meeting is someone has messed with
the rollers themselves. In another life I was an auto mechanic, so
have a little experience with things mechanical. I don’t wish to
offend anyone but if you are not particularly mechanically inclined…
find a mechanical person and ask them to help you look at it. Do you
have a manual? Are you comfortable going through the procedure of
changing rollers? It sounds to me like someone has changed rollers
and not gotten them in right, or got them back in but not adjusted it
right. I am looking at my cheapo rolling mill right now… and the
rolls slip into the cast iron housing of the body riding in square
brackets. The bottom roller is fixed, and the top moves up and down.
On mine, the rollers hit before the brackets… so they HAVE to hit.

I am sure yours is different.

I am equally sure… that the first thing that popped in everyone’s
mind was removing the center gear and dropping each side
independently to true it… but that does not appear to be the
problem on yours. If you have a consistent half a mm gap… with the
center gear out and both side gears down… someone has removed the
rollers and not gotten them back in right. Just my humble opinion.

Brent


#6
Tony, Pull off the bracket that hold down the t-bar at the top of
the mill, then pull the t-bar straight up and out from between the
2 gears. Wind the two gears down until the rollers meet and are
level, then replace the t-bar and the bracket. Feel free to give me
a call if you have any additional questions 

Few days ago, I have received private email from one of the forum
participant, asking me, why I am “so angry” and why I am fighting all
the time? Everybody is entitled to their opinion so I did not
respond, but I said to myself maybe there is some truth to that, may
be I should tone it down.

But as Al Pacino in “God Father” said “just when I thought I was
out, they pull me back in”

I am quite sure that recommended procedure would not work. It is
neither possible to adjust rollers by eyeballing them, nor should it
ever be tried. One can close rollers completely without them been
perfectly parallel. It is possible because like in any mechanically
linked assembly, there are small gaps. By driving rollers against
each other, the side that touches first, will simpye transmit the
force to these gaps closing them and creating impression that rollers
are parallel, while they are not.

What is even worse, is that by using this method, slight
mis-alignment becomes a major problem in a short time, causing you to
purchase new rolling mill. I am sure that it is just a coincidence
that advise came for Sales and Marketing, but that does not make it
less ironic.

The correct procedure is to purchase or borrow a thickness gage. If
you have the spark plug gage which has many blades, and each blade
has marked thickness on it, it may work as well, but for best
results is to obtain thickness gage used by tool makers.

Select the most commonly used gap for your rollers, let’s say 1mm.
Select 1mm gage and wipe it clean. Open rollers wide and wipe it
clean. You can follow the procedure given above with the exception
that instead of closing rollers on one another, adjust rollers until
the selected gage fits snag on each side.

It is not trivial to get it just right. DO NOT CLOSE THE ROLLERS
UNTIL YOU CANNOT PULL THE GAGE OUT. It would be the same mistake.
Instead, close the rollers and try if gage is fit in, and adjust,
adjust, and adjust until it fits right.

As visual help, after you think you got it right, smear some oil on
the gage and look at how oil film is disturbed after inserting it.
Try to get it to match on both sides. YOU MUST WIPE IT CLEAN AFTER
EACH TRY.

One last point. The variations may be tiny, and you may say to
yourself, I do not care for few microns difference. You should,
because any mis-alignment, is causing excessive wear and tear on
gears and linkages between gears and rollers. It may start as one
micron, but damages mill to an extend that no alignment is possible.

Leonid Surpin
www.studioarete.com


#7
You can follow the procedure given above with the exception that
instead of closing rollers on one another, adjust rollers until
the selected gage fits snag on each side. It is not trivial to get
it just right. DO NOT CLOSE THE ROLLERS UNTIL YOU CANNOT PULL THE
GAGE OUT. It would be the same mistake. Instead, close the rollers
and try if gage is fit in, and adjust, adjust, and adjust until it
fits right. As visual help, after you think you got it right, smear
some oil on the gage and look at how oil film is disturbed after
inserting it. Try to get it to match on both sides. YOU MUST WIPE
IT CLEAN AFTER EACH TRY. One last point. The variations may be
tiny, and you may say to yourself, I do not care for few microns
difference. You should, because any mis-alignment, is causing
excessive wear and tear on gears and linkages between gears and
rollers. It may start as one micron, but damages mill to an extend
that no alignment is possible. 

Will this take into account the backlash inherent in the system? It
seems to me that you would just be evening out the unloaded mill and
if the upper bearings weren’t identical, seated an identical amount
in the upper bearing journals with identical runout, and machined to
the identical height the loaded system might have a different
parallel than the unloaded system that has been trued up.

Jason


#8
The correct procedure is to purchase or borrow a thickness gage.
If you have the spark plug gage which has many blades, and each
blade has marked thickness on it, it may work as well, but for best
results is to obtain thickness gage used by tool makers. Select the
most commonly used gap for your rollers, let's say 1mm. Select 1mm
gage and wipe it clean. Open rollers wide and wipe it clean. You
can follow the procedure given above with the exception that
instead of closing rollers on one another, adjust rollers until the
selected gage fits snag on each side. 

From an engineering aspect, this is NOT the way. When a rolling mill
is used, the considerable pressure required to squeeze the metal is
transferred to the bearings at each end of the rollers. After a
period of use there will, inevitably, be some wear in the bearings,
making them slightly oval instead of round.

For the bottom roller this is not a real problem because it’s own
weight ensures that it settles with the gap above the roller axle.
The top roller is a different matter. When the gap between the
rollers is measured with a feeler gauge, or piece of shim moved
across them, it doesn’t lift the top roller to make the wear gap
below the axle, which is where it is when actually rolling something.
In other words, any adjustment made without pressure being applied by
the bearings will ignore any wear that has developed.

The correct way is to take a bit of copper sheet, about 3mm wide,
and roll 20-30mm of one end at the left-hand end of the rolls, then
reverse the direction to take it out and then roll the other end at
the right-hand end. You then carefully measure the thickness at each
end and adjust the rollers accordingly.

I usually take a longish strip of copper, bend it into a long "U"
shape so that the two ends are at either end of the rollers, and
roll both ends at the same time. I then measure with a micrometer and
adjust as required.

Regards, Gary Wooding


#9

Leonid, yes I know, and that’s how I’d adjust the rollers of a very
expensive and accurate mill.

But this is a cheap and cheerful Pepe mill and thats how they put
them together in the shop.

The rollers are not accurate to a thou and never will be.

It would like trying to adjust a spark plug with a hammer.

I’ll also defend Mike Stromberg at Pepe. His advice was valuable and
concurs with that of others.

Tony Konrath


#10

I was investigating getting a small mill and noticed that the roller
gap was between 4 and 6 mm. I’m confused. Is that correct? That’s the
thickest piece you can fit between the rollers? If you use 18 ga
brass as a sandwich (.0403 in or 1.2 mm), you have less than 2mm for
your metal and pattern material. What am I missing?


#11
I was investigating getting a small mill and noticed that the
roller gap was between 4 and 6 mm. I'm confused. Is that correct?
That's the thickest piece you can fit between the rollers? If you
use 18 ga brass as a sandwich (.0403 in or 1.2 mm), you have less
than 2mm for your metal and pattern material. What am I missing? 

The degree to which the rolls can be separated is determined by the
gears that drive them. Separate the rolls too much, and those gears
only barely contact each other, and instead of one roll (the one
driven by the crank) driving the other, they jam, or worse, if you
persist, break.

The main thing your missing is that rolling mills are designed as
their primary purpose, for making metal thinner. Their use in
producing roll printed pattern metal is very much secondary. Useful,
yes, but not their prime purpose.

Also, you’re missing that if your total thickness is limited, then
for heavens sake don’t sandwich your metal and pattern material with
such thick sheet. Go thinner.

also, you don’t really have to put the brass on both sides. Your
silver or metal to be patterned can serve as it’s own back side, if
it doesn’t have a pattern there already that you’re trying to
preserve. You only need to back the pattern side, and then only
really if you’re patterning your sheet with something that could
otherwise damage the rolls (like anything steel or similarly hard)

When I roll print, my favorite patterns are engine turned engraved
patterns (guiolloche engraving) which are engraved onto starret flat
ground tool steel stock. the back sides were finished to a finer
degree than the sheet as purchased, so their finish is equal to, or
better, than the finish on the rolls. And they are the full width of
the rolls. So I use nothing behind that. Their steel is at least a
little softer than the rolls, and pressure is evenly distrubuted
across the whole roll. In use, after a couple uses, the pattern sheet
curves too, so it’s a curvature about twice the radius of the roll
itself, which also makes patterning my metal easier. that metal, be
it silver or gold, does not need backing or sandwiching any more than
it would were I merely rolling it thinner, and the lack of a softer
metal back means pressure from the rolls is absorbed entirely by the
sheet being patterned, rather than also by the sandwich, so I get
good patterning without such extreme pressures anyway. When roll
printing other things for texture, whether I use a backing depends
on the material. with various papers, nothing seems needed. Sometimes
I’ll use another piece of silver or gold, so one on each side of the
paper or material, and get a pattern on both surfaces at the same
time (it’s a slightly different pattern, but still useful, if planned
for.)

bottom line, a rolling mill that opens to 6 mm, or even just 4mm,
should be quite enough to give you a lot of happy roll printing. But
remember. Larger diameter rolls also equal stiffer rolls, so more
pressure, enabling deeper better pattern developement or patterning
harder metal. So get the largest size rolling mill you can afford.
Also, the more expensive brands of mills, Durston, Cavalin, Dinkel,
are also more sturdy and better built. Last longer, work better.
Yes, they’re more money. But if you actually need a rolling mill at
all, buy the best you can manage. Higher quality tools are seldom a
poor choice, while less expensive ones sometimes turn out to be the
most expensive in the long run.

Peter Rowe


#12
From an engineering aspect, this is NOT the way. When a rolling
mill is used, the considerable pressure required to squeeze the
metal is transferred to the bearings at each end of the rollers.
After a period of use there will, inevitably, be some wear in the
bearings, making them slightly oval instead of round. 

Not to be repetitive, but when bearing become oval, it is time to
throw mill away. If you do not, then do not be surprised when metal
come out in waves instead of straight.

Leonid Surpin
www.studioarete.com


#13
Will this take into account the backlash inherent in the system?
It seems to me that you would just be evening out the unloaded mill
and if the upper bearings weren't identical, seated an identical
amount in the upper bearing journals with identical runout, and
machined to the identical height the loaded system might have a
different parallel than the unloaded system that has been trued up. 

Your observations are correct, but this problem should be addressed
by engineers while mill is designed. If you telling me that there are
mills which level only when loaded, I suppose some creative soul may
try to sell something like that, but it is a serious design flaw and
I would avoid such mill at any cost.

Leonid Surpin
www.studioarete.com


#14

OK I did It!

Underneath the two top gears is a screw that descends into the
frame. Under this screw is a “cup” of metal and the right hand side
one had slipped out and was sitting by the side of the screw, held
there by the thick grease. This screw and cup seems to drive the
depth of the rollers. putting it back fixed the problem.

Many thanks peeps.
Tony Konrath


#15

I just lower my rollers to almost touching and the check the light
coming though the gap. When you get to the tiniest of gaps it is
very easy to see which side needs adjusting. More than accurate
enough for making jewellery.

Cheers, Hans


#16
I just lower my rollers to almost touching and the check the light
coming though the gap. When you get to the tiniest of gaps it is
very easy to see which side needs adjusting. More than accurate
enough for making jewellery. 

Yes Hans. I agree. The simplest way is the best.

Also, If the rolls are touching in 2 places and there is still a gap
then you are never going to get them to close perfectly. The rolls
cannot be straight.

Matthew Durston
Durston Rolling Mills
www.durston.com


#17

I just saw that Leonid made basically the same suggestion only using
a thickness gauge.

The digital ones are $900 ++.

This site has manual gauges for a lot less.

http://www.easterngage.com/standard-feeler-gage-sets.asp

Cheers
Sandra in Snohomish


#18

I have been following this thread and wanted to add a comment. If
this has already been mentioned, forgive me. I don’t always read
every single word of every single post :slight_smile:

Anyway, I use an automobile feeler gauge to calibrate the rollers in
my rolling mill. It seems that even if you use a piece of metal for
calibration, who is to say that the metal is even from side to side?
It probably would be, but…

The nice thing about the feeler gauges is that you can check the
calibration at different thicknesses.

Sandra
…in Snohomish where there are never enough hours in the day