pressvest speed cracking help please

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ns49

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hi there i am new to this forum and was wondering if anyone can help.

we use the EP5000 from ivoclar and we mostly provide veneers.

the last 3 times in a row i have waxed up and pressed both small and large investment rings only to have them once press short and the last 3 crack during pressing.

does anyone have any ideas whats going on i have used this for the last 6 months with no problems could it be the batch of pressvest speed? this job needs to be out tomorrow and i have alreaady done it 3 times with only 1 bag of investment left aaarrrggghhhhh
 
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AcademyDL

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Could be a bad batch.

Or if your using the speedvest ... are you mixing for the suggested amount of time?
It has an unusually long mixing time of 2-2.5 mins
OR are you placing in the proper position of your oven on the white tray that is provided
by Ivoclar with the oven and using their plunger with the Alox plunger separator?

I don't know about you but my Alox Plunger usually needs cleaning after a few presses or it doesnt work properly. The plunger may need a light sand blasting since the separator doesnt work that well.

- Justin
 
sixonice

sixonice

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A 2-2.5 minute mix is critical for a smooth, strong homogeneous investment mix. Also be sure that the base you set the ring on (on the press) is completely free of debris or any little pieces of investment that can cause even the slightest bit of rock or off-centerness. Academy gave some great advice on a clean plunger. That thing cannot bind or be tight going down the channel. If you have to clean the plunger, do so with glass beads. Keep using the plunger separator powder on the plunger (I think the stuff works amazing-boron nitrate powder).
Also sure sure the base of your ring is completely 90 degrees. Do not let the investment ring set longer than 60 minutes before burn out. Any longer and the investment actually weakens as it continues to crystallize on the bench.
 
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ns49

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This is what I can't understand I am mixing it for 2.5 mins every times set for 30 in furnace at 850 for 1 hour. Plunger is spottless and we use the separator everytime we do it all to the letter using all of the ivoclar stuff. We get to the end of the cycle it starts to press investment cracks and the crack detection system kicks in and the whole lot is ruined. We have only got one bag left of this batch so hoping the new delivery makes a difference.we have had to cancell the patient for today so has been very frustrating. Thanks for the advice tho any other ideas if it could be something I'm doing wrong would be great
 
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AcademyDL

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if you are doing all that correctly and your using the proper water and liquid ratios my bet is that its a bad batch.
Call Ivoclar for tech support. Im home right now otherwise Id give you the number. Might be different in your neck of the woods anyway.

Get a refund on your ingots and investment for starters.
It gets expensive when it doesn't work.
Your rep should be able to take care of you on it.

- Justin
 
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charles007

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ns49
Are you trimming the top of your ring with a knife, or wet model trimmer. Is your liquid cloudy with beach sand at the bottom !!Any chance that the top of the ring is not level after trimming, trimmed at a angle!!

The many times that my investment went bad, or liquid, it didn't happen on the last 2 or 3 packs of investment. My experience has been that you see it from the 1st pack or into the second half of the box.
Also bad investment tends to set up quickly, but not always..

Charles
 
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SSDS

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Two things you need to do, make sure your furnace has been calibrated and secondly make sure you have ample clearance between veneers. Before you press check your ring to see if there are any fine cracks in the ring. This has happen to me in the past, it tended to happen when i was really busy and did not recalibrate for a couple of days.
Jim
 
sixonice

sixonice

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Alot more good info on the above posts. One more thing came to mind. When pressing the cases, being certain to not press too much wax weight in both rings. 1 small e.max ingot in a 100 gram ring can handle up to .75 grams of wax. 1 large e.max ingot can do up to 2 grams of wax in a 200 gram ring. If your right at the border of a small ring from a weight standpoint, it is always best to upgrade to the 200 gram ring and gain the additonal strength that it provides.
 

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