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Using Split LapPolisher


#1

Hi There,

Well I broke down and bought a split lap polisher, now I need some
help on how to use it. I have a few questions i.e. can you use other
buffs than just the split laps? I assume that you should use Tripoli
or bobbing compound for the first round on a hard lap, would you
then go to rouge on a med lap? Any help you can give me would be
appreciated.

Thanks
Gerry


#2

Hi Gerry;

Well I broke down and bought a split lap polisher, now I need some
help on how to use it. 

The split lap is usually only used with a slotted hard lap. I prefer
hard, but some like the flint hard. I charge it with Gray Star, an
aggressive pre-polish compound. The lap is used to create smooth
surfaces after sanding, and will even take out file marks. It cuts
fast, so get some practice in with some brass scraps, as you can
easily remove too much material with it. After the split lap, I go
to a stitched muslin buff charge with white diamond tripoli, a light
pass to “read” it, looking for scratches the lap didn’t remove.
After that, a final buff with a soft stitched cotton buff charge with
red or green rouge. Once you get used to the split lap, you’ll really
appreciate what a useful finishing tool it is. You can get really
crisp finishes on your work, it doesn’t drag out seams or pits like
a regular felt lap can.

David L. Huffman


#3

Gerry,

Unless you have a death wish JUST use hard or rock hard split laps.
Grey Star is good, bobbing or tripoli will work. They are designed to
cut down to a really flat surface, buffing with rouge best done with
a regular buffing machice.

Split laps are great but a machine which deserves above average
respect. Sort of like carving wood with a chain saw.

Jeff

Demand Designs
Analog/Digital Modelling & Goldsmithing
http://www.gmavt.net/~jdemand


#4
I have a few questions i.e. can you use other buffs than just the
split laps? 

Gerry, absolutely not - not “buffs”. That would be incredibly
dangerous, and not very useful either. Your posture is completely
wrong, for one thing - the way you would address the wheel.

I assume that you should use Tripoli or bobbing compound for the
first round on a hard lap, would you then go to rouge on a med
lap? 

I could say that there are dozens of wheels and hundreds of
compounds and people use what they like, which would be true but not
very helpful, eh?

There is the MX wheel and I’m sure it has competitors. That’s like
an abrasive cutoff wheel made as a lap. They are expensive,
incredibly aggressive, and extremely wasteful. Also quite dangerous
because of the aggressive grit. They are for production shops
grinding hundreds of rings who also have efficient scrap collection
systems - we don’t use them here, but just so you know.

What we do use is a hard lap with GreyStar, which is a form of
bobbing compound, and a medium lap with white rouge. We also have a
much-worn soft lap that’s about 4" diameter now which is gentler
with rouge for a softer polish. I guess you could use red rouge, but
I got out of the habit of using it at all long ago. White rouge is
faster and good on a lap. I would think that Zam would do well, too.
It’s no different than a polishing lathe - whatever floats yer
boat… Rock-hard laps are useful, but they’re pretty unforgiving -
ditto for soft laps, as they are so soft they can defeat the whole
purpose of lapping.

For platinum I’ll sand with emery, use the GreyStar, go to the
muslin buff with White Diamond just for an intermediate grit, go the
the medium lap with white rouge and then final on a cotton buff. It
sounds laborious but it’s faster than just using wheels, with better
results. I don’t generally do Smurf jewelry but I don’t like hard
edges, either…

Some tips:

Get some 60 grit sanding cloth (tougher than paper) - the stuff on
rolls is good - and a piece of 2"x2" or something wood maybe 6" to a
foot long. Wrap a bit of the sanding cloth on the wood and hold it
there (you’ll find a way…) and dress the wheel top, edge and
bottom before you use it. Do NOT use your fingers instead of wood as
it gets hot instantly. This will create a huge mess, but it’s
necessary to run true. Obviously the sandpaper has to trail the
rotation of the wheel or it will cut loose.

Some people like the bevel face down, which puts the edge at an
angle facing you a certain way. I like the bevel side up, flat side
down… BTW, I also like my bench pin flat side up, bevel down…

Whichever way you like it is fine, but it has to stay that way or
you’ll have to dress the wheel again… Some people also get Magic
Marker or shoe polish and paint the top face black, which increases
the contrast of the split. I don’t care, myself, I guess it helps,
some.

Again - the split lap is incredibly dangerous. Take it slow until
you get used to it. It’s no different than a wheel - if the trailing
edge raises up enough for the split in the lap to catch it your
piece will become a missile. Do not argue with it, it will always
win. It will cut your polishing time in half, though, will far
better results, too.

http://www.donivanandmaggiora.com


#5

I bought a hard felt split lap a few months ago for the first time.
My first impressions are that it needs more adjusting to get it
running true, and it cuts amazingly fast with tripoli compared to
the cloth buffs. Beware, the metal just disappears!

Alastair


#6

OK guys, I have a question or two…

absolutely not - not "buffs". That would be incredibly dangerous,
and not very useful either. Your posture is completely wrong, for
one thing - the way you would address the wheel. 

And someone else said something about carving wood with a chainsaw.

OK, I’ll bite, --Why-- are split laps so dangerous?

I’ve had one for 15+ years, and never had a problem with it. I don’t
generally let students loose on them, but that’s mostly because
they’re liable to burn off way too much metal, way too fast. That,
and they do take a little getting used to, in terms of how you hold
things, and how you approach the surface, but once you’re used to
that, I’ve never had, nor seen anyone have, a problem beyond getting
something tossed every so often. (Far less frequently than any other
normal buff.)

As far as using it as a normal buffer, I’ve done that too. It’s just
a motor with a buffing spike on it. It’ll spin anything. Perhaps not
in an ideal orientation for most work, but it is just a buffer set up
at an angle. When I was just out of school, that was the smallest
buffer I had, so it went on the road with me, and was my workhorse.
Worked great, even if I did have to stand sort of sideways to it to
get a decent angle. (Make sure it’s spinning AWAY from you, and the
usual rules about buffing on the downspin side of the wheel apply.
Much more so, in fact.) Worked great for hard felt inside ring buffs.
It was really easy to see down inside the ring while polishing. (Also
great for inside goblet mops.)

I’ll cheerfully admit that there are some body positioning issues,
due to the way it sits, and there are other issues about how dropped
items get ejected (or not) that are a little entertaining if you
don’t think them through before hand, but why all the paranoia? I’ve
even banged my hand into the edge of a spinning flint-hard split lap.
It cut the skin almost instantly, but it didn’t do the sort of damage
you’d expect from a saw. It just buffed a groove into the side of my
thumb. Not especially deep or ragged, and aside from cursing up a
blue streak when the alcohol hit it, I barely noticed. Bandaged and
back at work in under 5 minutes, healed and forgotten in a day or
three. Didn’t even scar. (Frankly, not any worse than I’d expect from
banging into the edge of a non-split flint lap on a normal buffer.)

So, what’s the deal? My undergrad professor was paranoid about them,
so I’ve always been careful with it, but I’ve never really
understood the reason for all the fuss.

Seeking Enlightenment
Brian.


#7

Hi Gerry,

Well I broke down and bought a split lap polisher, now I need some
help on how to use it. 

I really think the lap is an indispensable tool so congratulations on
your purchase. I use a 6 inch Rock Hard lap, I put the flat side down
(lettering up) and use a black magic marker to blacken the top
beveled edge (that makes it easier to see the piece you’re lapping
on the underside). I use Gesswein’s Grey 800 (item #215-0045) as a
compound rather than Tripoli (Gesswien #215-0300) because I think it
cuts a bit more quickly. I also have a separate lap with rouge but I
almost never use it, I just stick with the one lap. When I’m done
lapping with the Grey I can hit it lightly on the buff with rouge
and get a nice high polish that maintains the crisp edges I created
on the lap. I use that lap for gold, platinum and palladium without
changing it. I know that purists and text books will tell you to use
separate laps but I have not encountered any problems using the same
lap for everything. I do use different buffs for gold and platinum
however.

Mark


#8

The best tip I can give you is to darken the top surface of your
split lap wheel with a black magic marker so that when it’s spinning
as you work the jewelry is more visible under the wheel. My favorite
is bobbing compound, it’s greasy but does a great job with a hard
wheel. Polishing is an art, not the grunt job as many think it is.
Oh, and have a good source of light shining through your wheel.

Margie - carving animals that stand on the face of a dime
www.mmwaxmodels.com


#9
I've even banged my hand into the edge of a spinning flint-hard
split lap. It cut the skin almost instantly, but it didn't do the
sort of damage you'd expect from a saw. 

Well, Brian, I’d say you answered all your own questions there… ;}

For myself I would agree that there is a “paranoia” about the lap
that’s not deserved. My own take on it would be more like “We’re not
in Kansas anymore.” I think part of it is that it’s largely a
professional machine, and only some people are really experienced
with them. I agree with you that paranoia isn’t called for, but then
again for someone who just bought one and has never used it before I
think that a dose of respect IS called for. But as you say, once you
get the hang of it, it’s not a big deal. You get used to the smell
of burning flesh after awhile – again, ;}

As for using other wheels - I’ve never done the things you describe,
but I’m the sort of person who might, in a pinch. I’ve seen shops
using inside ring buffs and other things on them, too. That doesn’t
mean it’s a good way to polish, though. I think it could be taken as
a given that if it were as or more effective than a buffing machine,
that’s how we all would polish, but we don’t. As you say, it’s all
about posture…

http://www.donivanandmaggiora.com


#10

Forgive my ignorance, but I’m puzzled as to what a split lap
polisher is. I’ve looked them up when they’ve been mentioned before
and they looked the same as or similar to ordinary buffing machines.

Does the name lap mean that rather than mops and buffs where you
polish using the edge which faces you, the laps are hard flat
surfaces to which you attach various abrasive discs, such that you
use the flat surface at the side rather than the edge? Always wanting
to learn.

Helen
UK
http://www.hillsgems.co.uk


#11

Hi Helen,

A split lap is a polishing motor that is mounted on an angel such
that you can see thru the wheel at the surface below as you polish
it.
It has a light from the top and you polish from the bottom. It gives
yo the ability to get very flat crisp surfaces.

Here are some pictures from Stuller to help you visualize this. The
hardness of the wheels comes down to personal preference. I have seen
people mount the felt wheel on a regular polishing motor and try to
work it sideways but that is Not a good idea.

Mark

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#12
Forgive my ignorance, but I'm puzzled as to what a split lap
polisher is. 

Helen - and others, no doubt - At first I passed this one by,
thinking others can answer as well. Then I thought up the following
long-winded reply that might actually be useful to some. ;}

Let’s back up a bit… Lapping is a process where mating surfaces
are worked using abrasives. Mostly people think of lapping as a flat
thing, but that’s not necessarily so. Faceted gemstones are cut and
polished on laps - flat lap, flat facets. Telescope mirrors are made
by lapping a convex tool into a concave blank of glass. Machinists
use lapping machines for aerospace quality work. The interesting
thing about some lapping processes, like mirrors, is that the tool
and the work lap each other, and in so doing they reach an
equilibrium of surface that can be near perfect. Fascinating stuff,
that. When you lay a piece of sandpaper on top of your polisher and
rub the edge of a bezel on it, you are lapping it. I get all long
winded here because it’s a fundamental fabrication process - it’s a
good thing to understand.

The split lap is called that because, if you’ll notice, there are
slits cut into the wheel. That means that while the wheel is running
you can see through the wheel to the work underneath, like a strobe
effect. And yes, it works quite well.

The value of the split lap is speed, and part of that speed is
quality - it allows the user to pump out quality work fast. Any flat
surface can be lapped in seconds or something more, and not only
that, it will be “perfectly” flat. Machinist laps go to.000001", and
split laps don’t do that… But a wedding band with a flat edge
can just be put entirely on the lap, and the whole side will be
polished flat in one operation - no ripples, no facets, no rounded
edges, bang. In a production shop using speed methods, a raw casting
of a wedding band can be completely finished on the lap in 5-10
minutes, depending on the shop and the worker. That’s also very
wasteful, which is why good a good scrap sysem is essential.

And the surface doesn’t have to be flat like a wedding band. A ring
with a split shank and a flat surface on the side can be lapped by
"walking" the lap down the slope of the side - curved surfaces can
be lapped by a skilled worker, and any faceting removed on a wheel.
I use white rouge on a medium lap on any surface it will reach,
because it doesn’t cut, it just polishes - fast, flat and crisp.

So, the final answer to the question of what it’s good for is that
it’s good for anything flat, which is a very, very common surface in
jewelry. It may not be a final solution, but having a true surface
to take off from is a huge benefit, too. Not for everyone, not
essential to most people, but real handy…

http://www.donivanandmaggiora.com


#13

I don’t use the flat side of the split lap. Truth is that any hard
flat lap on a regular polishing lathe will product that type of flat.
No matter how one works it, the edges will lose their crispness and
become somewhat rounded off.

The real beauty of the split lap, beside the ability to watch more
closely what and where is being polished, is the ability to stay
away from the edge while polishing the surfaces. By using the beveled
side of the lap, one can concentrate one’s polishing on the surface,
saving the edges for last. One can produce the very sharpest possible
edges this way.

Bruce D. Holmgrain
JA Certified Master Benchjeweler
goldwerx.us


#14

Thanks for the info re split lap polishers Mark. I think the link I
followed the first time was a mistake as it showed a picture of a
conventional polishing lathe. I get it now, thanks.

Helen
UK


#15

Brilliant, thank you John. That was a very clear and understandable
explanation of lapping. I do love the whole trying to get flat,
crisp surfaces but am happy to lap using sandpaper on a flat surface
for a while yet. If I ever become established, I will consider a
split lap polisher as I have a healthy respect for power tools and
always approach them with caution to avoid injury.

Thanks to yourself who have offered answers to my query.

Helen
UK
http://www.hillsgems.co.uk


#16

Bruce:

So you’re buffing (lapping) on the -top- of the flat lap? (the angled
bit towards the edge.)

I can see how that’d concentrate your contact in one area, but don’t
you find that it makes your surface concave unless you’re very
careful? Now the real question is: are you running the lap upside
down, so the angled bit is down, or are you running it flat side down
and working on top?

I’m not entirely sure I agree with you about the advantage of
working on the angled bit, but I want to find out what you’re doing,
and try it before I make up my mind. (Methinks the geometry isn’t
quite right, but I’m willing to try it first.) (I’ve never had any
problem with rounding my edges by working on the flat (bottom) side
of the lap.)

Cheers-
Brian Meek.


#17

Alberic,

The beauty of this tool has a lot to do with the illusion of an
extremely flat surface.

While it is true that if on concentrates all of one’s polishing
efforts purely on the surfaces, some concaving will occur. My
experience has been that there are surfaces where there is some
advantage. Flat or pipe bands are a case in point. Swiping the
outside surface of the band against the beveled surface of the lap
will produce a truly machined appearance. One has nearly perfect
control by watching the polishing as it is taking place. By saving
the surface junctions for last, one can produce the type of edge only
seen on diamond facet junctions, thus producing a machined
appearance.

I keep the beveled side on the bottom and almost never use the flat
side of a split lap.

I realize that this is counter intuitive. I really only learned it
from someone that was taking far greater advantage of the split lap
than I could.

(I've never had any problem with rounding my edges by working on
the flat (bottom) side of the lap.)

That’s what I thought, too, until someone showed me the difference.

Bruce D. Holmgrain
JA Certified Master Benchjeweler
goldwerx.us


#18
Now the real question is: are you running the lap upside down, so
the angled bit is down, or are you running it flat side down and
working on top? 

Brian, I assume Bruce will reply for himself - but more
generally… As I said earlier on this thread, I also like to use
the flat side down. Some consider the angled side to be the work
surface, though - couldn’t tell you what the manufacturers say. If
you look, you’ll see that if the flat side is down, the work suface
is angled to the user. If the angle is down, the work surface is
roughly parallel to the bench top, and I suspect they want us to use
it that way. I like the large surface of the flat side,
though…Since the whole lap is the same material, it’s really a
matter of preference and even habit…

http://www.donivanandmaggiora.com


#19

Good morning,

One more dumb question and I promise I’ll leave this subject alone.
I just rec’d my lap and I think I’m doing something wrong as I can’t
see all that well thru it. When I’m using it I can barely see an
outline of the piece I’m working on.

Any suggestions, different light maybe or different light position?

Thanks
Gerry


#20

Hi Gerry:

The light needs to be directly above the wheel (so as to shine down
through the splits). It’s best if it’s a florescent light, as the
strobing of the light should synch up with the spinning of the wheel,
and give you a pretty clear view in certain spots. (I’ve used mine in
daylight, so the strobing isn’t required, but it sure is nice when it
works out.)

FWIW,
Brian Meek.