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Neycraft centrifuge problems


#1

I am in dire need of help.

I have been having problems with my Neycraft caster.The crucible
with the molten metal slides forward away from the the heated flask
which then falls out of the cradle. This happens during the time I am
melting the silver, and just when I am about to start the rotation.

When we insert the flask, we make sure it is in the correct slot in
the flask receiver assembly, and that the crucible is firmly pressed
against the flask.There is no mechanism to lock them together. When
we are sure that the crucible and flask are firmly together I start
the melt.

However, midway, or toward the end of the melt, the flask and
crucible separate. Sometimes this happens when I am using the
graphite rod to stir some unmelted grains into the puddle of molten
metal. The slightest, gentlest nudge of the graphite rod in the
silver results in the crucible and flask separating, the crucible
moving forward, and the flask falling out of the cradle. I am very
careful not to nudge the crucible–just the silver–stirring only the
melt and not touching the crucible. Sometimes it just happens
spontaneously. fortunately I am working with a casting buddy and
between us we manage to get things back into alignment.

We set the caster up according to the directions, and sometimes we do
not have a problem, but all too often, we do, and have to stop midway
to make adjustments, meanwhile our silver is freezing into a solid
glob. What is frustrating is that this happens just as things are
almost ready for us to start the caster rotating.

We are using commercial stainless steel flasks, some of which came
with the caster, and others that we purchased and which are sizes
recommended by Neycraft. Also, we make sure that the machine is
balanced correctly for the sizes of the flasks. So that does not seem
to be the problem.

I tried to diagnose the problem today, using an empty (cold) flask,
and to my disappointment, the crucible would not stay firmly against
the flask, but kept sliding forward. What is going on? How can I
correct this. I have a lot of casting to get done, and just don’t
want the frustration of dealing with an obstinate centrifuge, and
certainly don’t want to run the risk of a runaway flask during the
rotation.

Neycraft does not have a website, and there is no on my
manual as to how I can get in touch with them–no phone number or
address. Does anyone have any as to how I can contact
them?

Thanks for your help
Alma


#2

hello Alma, This sounds quite dangerous and you shouldn’t use the
machine until the problem is resolved. There should be a sheetmetal
cradle for the flask to rest in, preventing it from falling out no
matter where the crucible is. I’ve always made them in different
sizes for different size flasks. Do you have something like this on
your machine?

Tom Arnold


#3
The crucible with the molten metal slides forward away from the
the heated flask which then falls out of the cradle. 

Well, Alma, I have no direct experience with the Neycraft
centrifuge, but I looked at the manual online and also just went down
to Frei and looked at a new one. There’s a clip under the crucible
that I gather is supposed to hold it in place - maybe you have an
older model or a missing clip…

There’s something is that doesn’t take an expert, though, and that’s
why it’s moving away. Unless it has grown legs, that force is
gravity. That means that most likely something isn’t level - that’s
different from balance, and the weight of the crucible is causing it
to slide “downhill”.

Checking that with a level and maybe canting the machine so downhill
is TOWARDS the flask should at least help. No doubt you’ll get more
expert advise (I hope), but for some reason the crucible is "falling"
in the wrong direction - that much is clear… Or maybe you have a
bit of debris in the cradle that’s changed the tilt of it, too…


#4

Dear Alma,

I HATE advice that comes from people who only Think that they have
solution to a problem.

So here I go with some of the same advice.

I do not have a lot of experience with the Neycraft casting units. I
would suggest only one thing.

There is a track that all melting crucibles slide back and forth to
the flask in. Take a vices grip pliers or crescent wrench and bend
the track a bit smaller. The melting crucible should still slide back
and forth, but perhaps not so loose in the track. Your stirring rod
or flask gripping tongs should be adequate in sliding the melting
crucible to the flask.

The centrifugal force of the machine should also move it closer to
the flask in the spin casting process.

The only other thing that I could think of is that if there are any
screws that hold the track to the machine that may have come loose.
If so tighten them.

Good luck,
Todd Hawkinson
Southeast Technical College.


#5

Tom, There is no sheet metal cradle below the flask. All that is
holding it in place is the groove in the receiver assembly and the
pressure of the metal bracket that holds the crucible.

We are following the instructions that are in the manual to the
letter. The only instructions are to place the flask in the proper
recess in the flask receiver assembly, and to slide the crucible so
that both it and the flask are pressed firmly together. However, the
crucible slides forward, releasing the flask which drops down
landing on the two rods below. These are the rods that the crucible
slides on. The flask does not rest on the rods, but is about 1/4" to
1/2" above them,depending on the size of the flask. When it falls it
lands on these rods. Fortunately it goes no further, and does not
roll out into the shell of the machine…

The only instructions are to make sure that the flask is secure in
the recessed step receiver and that the crucible is pushed firmly
against the investment flask. But there is nothing that locks them in
place.

Tom, you are right, I will not take a chance using the machine until
this problem is solved. I did some more searching on the internet,
and located a place that I believe manufactures the Neycraft. It is
Densply Neytech.

I shall contact them and see if they can provide some solution.

Alma


#6

Thanks Todd.

The Neycraft comes with a crucible slide lever with a heat proof
knob, making it easy to slide the crucible into place. Problem is, it
does not want to stay there. I will follow your suggestion and try to
get the rods a bit closer together and see if this will hold the
crucible more firmly in place.

John, thanks for the helpful suggestions. The clip under the
crucible does not hold it in place. It is called the crucible slide
lever, and is used to push the crucible up against the flask.
However, perhaps it is supposed to hold the crucible in place in
addition to sliding it into position.

I will check with Frei and see if that is its function, or if there
is supposed to be another clip that would hold the crucible in place.
Or possibly, the crucible slide itself needs adjusting as it lies
directly below the crucible. There is nothing in the manual that
refers to anything thing that is supposed to hold the crucible in
position, but it is something I will check on.

Re: the centrifuge not being level. That was something my friend and
I checked out, but that does not seem to be the problem.

Alma


#7

It sounds like you don’t have the crucible pushed up flush with the
cradle before you spin it. Make sure the flask is resting in the
proper cradle and that you have the crucible pushed up flush to the
flask and cradle prior to release.


#8

Good day to all you Orchid Members,

and to let you know if you should have a NeyCraft Casting Machine
and your having problems with it, you can contact the following.

Product service center
Dentsply neytech division
13553 calimesa blvd.
Yucaipa, CA 92399
Telephone: (909) 795-2461

Sincerely,
Richard Lucas


#9

The problem is centrifuge casting period.!!! I am a small custom
order jeweler with production capabilities and have done both. I am
not sure of

what set up in this thread but melting molting metal in a crucible
and pulling a pin to sling the metal into a moving heated flask that
has to hit the gate of the flask as the molten metal goes from one
to another is gamble. The chance of bad cast is way up there. 90%
plus on vacuum and fear from the sling style centrifugal casting. I
have seen silver and gold on the inside of the protective chamber and
in some cases the walls and ceilings of some shops. Get a vacuum set
up and it is like pouring a cup of coffee, no worries if you follow
the process correctly. I have used vacuum for 25 years and have had a
lot less headaches and redo’s on hand carved models. My 3 cents. PS
you can get a simple set quite reasonably these days and eBay has
them all the time. Give it a chance.


#10

Yeah, Ive used that spin caster before, definatly had me worried at
first. It does sound like the advice so far is right on. That
crucible slide lever gizmo should hold the crucible where you put it.
I’d rather spin cast than vacume any day of the week.

I’ve spun cast for 25 years plus and if I had a failure rate of more
than 1 out of 100 it would drive me nuts, much less 90%. Its like
anything else, you have to learn. Of course I dont vac cast because
of an unacceptable falure rate, hahaha.


#11

Hello, I didn’t read what the original problem was with the Neycraft
caster. I’ve had mine for about 3 years now and love it. Not sure if
this will help or not, but the one issue that I was having with mine
is not being able to seat the crucible firmly to the flask. I had to
take my foredom and do some shaping of the crucible neck in order to
provide good seating. Once you do that, you should be good to go.


#12

Hi gang,

As has been touched on in other bits of this thread, Neycraft spin
casters are a bit weird. They’re not an entirely similar design to
the standard ‘broken arm’ centrifuge we’ve all used for umpteen
years. There are a couple of big differences. The most obvious is
that the splash guard is attached to the main arm, and spins with
the machine. The other big one is how the flasks are cradled. Or not.
The Neycraft has a backplate that has a series of concentric
depressions that the tail of the flask fits into. There’s no cradle
at all. The front of the flask is held in location by the projection
on the nose of the crucible. The crucible sits on a pair of steel
rods, which are a reasonably tight friction fit against a set of
grooves on the bottom of the crucible. The crucible holder (as I
recall it) slides around on a steel bar, and is retained in position
by a leaf spring with a knob on the back.

Alma, it’s been 15 years since I last messed with one of these
things, but my memory is that the crucible itself shouldn’t be able
to move around much on the rods that hold it. If I read your message
right, the entire crucible carrier is sliding away from the flask,
and letting it drop, right?

I can’t recall exactly how that whole thing works, but my memory is
that it’s relying on that leaf spring that sticks out below the
crucible (with the knob on it) to hold the crucible carrier in
position. You may need to bend the leaf spring more ?up? so that it
locks more strongly. (My memory is that you push down on the knob to
slide the crucible carrier forward towards the flasks, and then let
up on it when you want to lock it into position.)

If that is the case, bending it up a little should help. Examine
that leaf spring, and how it interacts with the slider bar, and that
may well lead you to the answer.

FWIW,
Brian.


#13

Alma:

I use this casting machine all the time for teaching. If properly
assembled the flask is very secure with the crucible carrier pushed
up against it. You should test the system by operating it with an
empty flask in place. To understand what I am going to say please go
to the following image on the internet:

http://www.enasco.com/product/8400246

You should be able to click on the above url even though it is very
long.

Note that there are two sets of rods. One set is two short rods
attached to the crucible carrier. The crucible has groves on the
bottom sides that slide between those two short rods. This holds the
crucible securely in place. It should not be merely setting on the
rods.

The crucible and its carrier is then pushed up against the flask
that is centered in the concentric rings on the receiver that is to
the left in the image. The flask is only held in place by the
receiver ring that fits the base of the flask and the pressure of the
crucible carrier that is pushed up against it. It will drop down if
the crucible carrier is pulled away from the flask but that will not
happen because of the friction of the bottom two rods. The carrier
should not slide very freely.

One very important point: The " broken arm" of the machine should be
fully positioned against the rubber stop so that the crucible and
flask is at 90 degrees to the rest of the arm with weight. If you do
not “cock” the arm against the rubber stop it will slam against the
stop when the arm is released causing the flask to possibly fly out
of the machine. The weight should be positioned to properly balance
the machine. With a 2 x 2.5 inch flask you don’t need the weight at
all.

Using an empty flask, wind up the machine three turns and then place
the flask in position. Cock the arm. To release, push the outside of
the drum until you hear the lock on the handle click. Then release
the drum. Try this several times until everything works smoothly.
When heating an actual flask full of metal be sure to get the torch
out of the way and never have your hands down inside the drum after
the arm is wound up and cocked.

If the above description is not perfectly clear, you probably should
find someone who has experience with this machine to show you all the
details. I live in South Carolina, so if you are in this part of the
country let me know.

This particular Neycraft centrifuge is in use for teaching at the
William Holland School of Lapidary Arts in northeast Georgia and at
Wildacres Retreat in North Carolina. It is also used by a local gem
and mineral club in Clemson, SC.

Let me know if you have any further questions.
Fred


#14

you really think that the Mayan, or Aztec Indians had access to a
vacumme casting machine??!! I have been using spin casting for over
20 yrs. and never had ANY serious problems. Vacumme casting is great
and all, but to speak this negatively about a process that has been
around for centuries is a bit irresponsible. I STILL use it every
time I cast. Steve


#15
melting molting metal in a crucible and pulling a pin to sling the
metal into a moving heated flask that has to hit the gate of the
flask as the molten metal goes from one to another is gamble. The
chance of bad cast is way up there. 

An opinion that is a somewhat less than accurate perspective. I done
production casting, well over a million pieces. I have had an
occasional miscast.

I have done hundreds of original wax models of mine and for other
metalsmiths and I do not consider centrifugal casting to be a risk. I
have never done vacuum casting. I never considered vacuum casting to
be a solution to a problem, just another learning curve with
different variables for success, flask temp and metal temp for a
good casting.

Richard Hart G.G.
Denver, Co. 80210


#16

Dear Alma,

The only other comment I can make is that you may have the wrong
size melting crucible. There are several that look the same but have
different bottoms. You might just have the wrong melting crucible.
The Neycraft, I think, has a unique size to the bottom for the style
machine you have. Again, I have looked over these units, but not used
one.

What I don’t like about them is the whole unit spinning & not just
the casting arm. At least this is what I remember about the one I was
thinking about trying.

The machine I have used for the last 40 years or so is the Lucas
Brand. It is the best you could find.

Best regards,

Todd Hawkinson
Southeast Technical College


#17
I did some more searching on the internet, and located a place
that I believe manufactures the Neycraft. It is Densply Neytech. I
shall contact them and see if they can provide some solution. 

Another big problem with this machine is that the most critical
moving part is made from aluminium and is located just under the
crucible. The slide fixture/receiver holder melted last week
(students!) and loosened our receiver part.Most dangerous! Why this
most critical part is not made from steel is just mind boggling. When
you talk to them please report this critical design error. This
machine should be taken of the market and the maufacturer should
replace this part for all machines sold, or they might face big
lawsuits.

Peter Deckers, New Zealand


#18

Carl, Thanks for your suggestions.

I have a vacuum caster as well as my Neycraft. I know that many
prefer the vacuum and get excellent casts, and I certainly don’t want
to imply that one is better than the other. I am just talking about
my own experience.

I have used both, and find that for me the centrifuge is easier to
use and gives me better castings. I have never had any molten metal
flying around as I weigh my models and measure my metal very
carefully.

One of the problems with using the vacuum is that as I do not have
an electromelt, I have to melt my metal in a crucible.There is a time
lag between the time I get the flask from the kiln, set it on the
vacuum, and get my metal melted. Perhaps this is why I have not
gotten good results from the vacuum.

Following the recommendation made by a friend, I have tried heating
the flasks an extra 100 to 200 degrees to allow for cool down, set it
on the vacuum, and then began the melt, but this did not seem to
help. Also, I find it difficult to make a smooth pour from the
crucible into the flask.

I know there are ways of rigging a holder for the torch enabling one
to keep it on the melt while retrieving the flask from the kiln and
setting it on the vacuum, but so far have not been able to make one
that I believe is safe to use.

I considered getting an electromelt, but they weigh 13 lbs and this
is a heavy load to lift and make a smooth pour. A friend who is about
my size finds that the weight of the electromelt makes it difficult
for women with small hands and wrists to get a smooth pour.

Hence my preference for the centrifuge—which worked fine until it
developed its current problems.

Alma


#19

Tom, Thanks a million for your suggestion about modifying the neck
of the crucible. That seems to be the problem. I had just gotten this
crucible, and was concerned when I purchased it, as the neck was
different from the one I had been using. The clerk, however, assured
me that it would work with my Neycraft, and said he had sold dozens
to Neycraft owners and had not heard of any problems.

Following your suggestion I have modified it with my Foredom, and
now it fits, and seems to hold, but just to be on the safe side I am
ordering several new crucibles from Otto Frei who claims that theirs
are the only ones that fit the Neycraft 4X4. Sure hope so.

Thanks again for pinpointing the problem as being the crucible. The
problem only arose with the new crucible, and I am surprised that I
did not recognize that this was the item at fault.

Alma


#20

Neycraft problems solved

A great big thank you to all who took to time to offer valuable
suggestions and help with the problems I have been having with my
Neycraft. It is the crucible. It is a new one which I had just
purchased as my old one was getting quite cruddy looking. At the time
I made the purchase I mentioned to the clerk that the neck was
different from the one I had been using. It was fatter, and rounder.
However, he assured me that it would work with the Neycraft, that he
had sold dozens and no one had any problems. When I assembled it, I
noticed that there was a gap between it and the crucible holder, that
did not exist with the old crucible. However, it just did not dawn on
me that it might cause a problem. Sometimes the obvious just eludes
one.

Tom mentioned in his post that he had modified the neck of his to
fit more securely, so I took my foredom and reshaped mine. Now it
fits, and seems secure.

However, I am not about to take any chances with it and have ordered
several new crucibles from Otto Frei who claims that theirs is “the
only one that fits the Neycraft 4X4.” That is a big claim,and even
though there may be other crucibles on the market which are being
sold as fitting the Neycraft, I want to be positive that the one I am
using is the correct one.

So thanks again to everyone. I appreciate all the help.

Alma