(Developer of the now famous Cerec Birkhoff Effect which has been incorporated into the new 3D software!)
3/24/08 Doc Hemp UPDATE!! This morning I had 4 cerecs to do on a patient that flew in from Arizona ... Got all ready to mill the 1st one and got a "Milling Unit Not Ready" warning ... tried everything .... rebooted both main computer and milling unit ... It was working perfectly last Thursday and all I did was change the water. Then Called Mikey in Germany .... He suggested everything I already did first and then had me re - upload the software to the milling unit ... that was it ... He diagnosed that the battery in the milling unit motherboard was going bad ... lost it's memory over the weekend ..... Damn he's GOOD! ... here are his follow up instructions and photos ....
Hempster,
Also attached please find two pix of the little battery on the milling unitīs care-control motherboard. This battery may loose itīs capacity over the years, so over a long weekend the milling unit may "forget" the software, which results in the "milling unit not ready" error warning - thus requiring a new software download.
Itīs a CR 2032 Li-Mn 3 Volt battery... (It comes in many brands, i.e. .. Sony, Varta, Maxwell, etc. and is in stock in all USA battery stores for around $3) .... maybe we should put this on our "how to maintain your milling unit" website?
Hope the big quadrant case worked out well! Hey, it was good talking to you!
I CC this to David Lawler, since he also has one of the early Cerec 3s.
Cheers
Mikey
A Doc Hemp Note To open the motherboard compartment loosen the one screw at the top center And Pull the outer edges of the 2 black plastic tabs toward you to slide the mother out.
10/09/07 UPDATE! .... More photos at the bottom of the page ... Doc Mike doing my milling machine service (and 3 wonderful Cerecs on me - Zero sensitivity!) The maintenance is very easy to do especially if you can actually see someone do it once.
Hempster,
please put this on your web site instead of my former "no service ever
needed" statement! In fact, this grease job is the only thing that needs to
be done on those older mills! And the service techs usually never do this!
Cheers
Mikey
Dr.Horst Michael Birkhoff
Grünstr.2
41516 Grevenbroich
Germany
doc.mike@t-online.de
... how about a second hand mill?
- we specialize in used Cerec machines!
-----Ursprüngliche Nachricht-----
Von: doc.mike@t-online.de
A few days ago a friend of mine who also has an older Cerec 3 told me
that after milling his machine "lost a drop of oil".
Funny enough, my own machine also started to drop oil (well, so does my
Harley and I donīt care! ;-))
Both our machines have several thousands of millings on their belts. I
checked with the hotline, secret agents and deep throats and hereīs what
I found out:
1. itīs not oil. Itīs water mixed with rust.
2. The problem was partly solved 2 or 3 years ago when Sirona changed
the tank lid to a tupperware-style design. Now the tank does not leak
any more.
3. The motor and block shafts run thru a thin white teflon bushing which
again is encapsuled in a metal/plastic housing. These pieces cost about
$ 2.- or $ 3.-.
They are the same like in Cerec 2. But with Cerec 2 the block shaft was
vertical so when the teflon bushing got bad water would run into the
electronics and destroy them. So, part of the yearly service for Cerec2
was to exchange that bushing.
Now comes the funny part: With the motor and block shafts now all
mounted horizontally in Cerec 3, Sirona engineers relied on that these
bushings would NEVER have to be replaced (because no water would get
into a horizontally mounted shaft bushing). They designed them to be
non-replacable! BIG mistake. They do deteriorate and leak over time.
What Sirona will do then is sell you a completely new milling unit
insert... costs several thousands of bucks plus labour.
While a new milling unit insert MAY make sense after the warning at
30000 minutes of milling appears (because of worn-out parts that affect
milling precision and fit), it is no a joy to have this kind of
expensive fun on relatively young machines.
So here is what you (or your technician) should do - in both scenarios -
if a) machine leaks or b) to prevent leaking:
Open machine at least once a year. Put a little new grease*** on the
shafts. This little bit of grease is only used to thin the old hardened
black grease and then rub it all off. Now put some new grease on the
shafts, especially in the area between the big toothed wheel and the
milling chamber bushing (see red arrows on pic # 978).
Actually this IS part of the yearly service plan, but itīs often
neglected. In fact, itīs the ONLY thing that is REALLY important in the
service plan! (all the other small things like rubber stops, new tank
etc. is just b.......!)
On heavily used machines, this should be performed more frequently. Itīs
the old hard grease that makes the bushings leak. New grease will seal
them for a certain time.
On pic # 985 you can see what happens if you or the tech donīt properly
spread the grease over the shafts: water will leak from the milling
chamber down to the motherboard housing. Will give you trouble sooner or
later!
*** The grease you need is:
Chestertons 622 White Grease. This is a pure mineral oil grease with
Teflon* added designed for applications where a clean, nonstaining, food
grade lubricant is required.
It is a superior, multipurpose product that conforms with FDA
regulations 178.3570 and 177.1550 for food machinery use. It is
certified by NSF as an H1 lubricant and can be used in federally
inspected meat and poultry plants. It is a long lasting, non-hardening
lubricant that withstands washout from water, steam, food or fruit
juices.
Chesterton 622 White Grease is virtually tasteless and odorless. When
used on food processing equipment, users can be assured that the
lubricant will not contaminate finished products.
NSF Certified
Food Grade, H1 Lubricant
NLGI #2
Excellent Water Resistance
Teflon* Fortified
Kosher Certified
*Teflon is a registered DuPont trademark.
all you need is some torx bits and a screwdriver that holds them. For
those of you who want to do it themselves, please make sure
1. to switch off the unit before opening it, pull the plug! Be careful
not to damage the thin door magnet switch cable that is attached to the
front plastic flap (when taking it off)
2. be extremely careful not to let dirt or dust or grease get on the
back of the timing (=big toothed) wheels where they meet the light
barriers! (and of course the light barriers themselves)
See attached pic: The little black square is the upper part of the light
barrier, and the back of the wheel runs thru it!
3. Of course this will void your warranty... so if your machine still
has warranty call your service tech and ask him to bring the white
poultry grease for service! ;-))
Cheers
Mikey
Hempster .....
This last photo shows the position of the light barrier... to make sure
that people do not place grease or other dirt there! Otherwise the shaft
would not find itīs "zero" position any more!
Cheers
Mikey
10/09/07
More photos added here below
Flushing Your Milling Unit with Water (another important maintenance item)
(1) Periodically when the tank is emptied to be re-filled with water and Dentatec solution first fill with plain water.
(2) Then go to start->all programs -> Cerec -> service -> maintenance only -> start water pump. Now let run until it stops (about 3 minutes).
(3) Empty tank again and then re-fill with water and Dentatec.
