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    Milled Bridges Rocking Again

    Discussion in 'Metal' started by NickB, Jul 18, 2016.

    1. NickB

      NickB Member Full Member

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      Well, today I sat my ass down and WATCHED the waxers sprue everything. Turns out they are heating up the bar in order to bend it, then spruing the bridges to it after it mildly cools.
      So, this is likely the main reason that the bridges are warping. Today, I made it known to them that they need to cut the bar if they need to bend it, then either glue it back or use wax
      to reconnect it. But they must let it set up and cool before spruing onto the bar if they do this. We'll see if this fixes the issue.

      I will still post photos today or tomorrow to show how they are sprued from the machine as sometimes I use a stabilizer bar.

      Nick
       
    2. DanM

      DanM Member Full Member

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      Can you mill in a CAD Cast type material that they can't warp
       
    3. 2thm8kr
      Devilish

      2thm8kr Beanosavedmysociallife Full Member

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      When I had waxers that were giving me trouble with this sort of thing, I would make them cut and solder the cases.
      It only takes a few times to get properly waxed and sprued cases or you end up with an ace solderer.
       
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    4. NickB

      NickB Member Full Member

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      Such as? I only know of wax alone. Ive heard of some using PMMA but not sure if that would work or not. Plus PMMA material is much more expensive
      than the wax material (so Ive been told).

      Nick
       
    5. NickB

      NickB Member Full Member

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      Here are the photos from the spruing when I use the stabilizer bar.

      20160719_103025.jpg 20160719_103135.jpg 20160719_124340.jpg
       
    6. adl

      adl Active Member Full Member

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      Try direct spruing from the pontics only with individual flush head s for the abutements . It works like a charm every time .
       
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    7. DanM

      DanM Member Full Member

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    8. user name
      Question

      user name Well-Known Member Donator Full Member

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    9. JMN
      No Mood

      JMN Christian Member Donator Full Member

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    10. kimba

      kimba Active Member Full Member

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      DEGUVEST GF and ARGIVEST speed
      both work with our milled wax which is Wieland. I use deguvest for bridges but to be honest the speed vest works well for shorter span ie 3 unit bridges, but I have never tried it with larger spans I just feel better with a slow burnout for larger spans , but that is not scientific , just the usual technicians voodoo.
      glad you have appeared to have sorted it. Interestingly , my guy always understood English well when discussing pay rates , but seemed to have more difficulty when taking technical direction!!
       
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    11. vurban210
      No Mood

      vurban210 Active Member Full Member

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      Your issue is 100% spruing. That bar is a huge mass of metal and is so close to the bridge that when it cools there are some massive forces going on that are warping the bridge. Not trying to be a pr!ck but honestly, there is so much wrong going on there it is a wonder your bridges ever fit.

      I could go on and on, but it would be hard to express in written word. I would be happy to help anyway I can and I can also put you in touch with someone that is a casting guru.
       
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    12. Solid

      Solid Member Full Member

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      maybe he thinks you are just a show off. Did you tell him what exactly he was doing wrong?
       
    13. Solid

      Solid Member Full Member

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      How can a long span bridge "break in 2 spots" just because of firing it on 3 unit bridge program parameters? you may get porcelain under fired but not breaking the framework???
       
    14. Sevan P
      Twisted

      Sevan P Well-Known Member Full Member

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      Sold Zr doesn't cool down as fast as our think. So when your small unit program has a cooldown down of 1min and you long span program has a cooldown of 12 min then yeah the Zr straight sheers clean. And the case has Zr lingual with each connector was well in size.

      Sent from my SM-G920V using Tapatalk
       
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    15. kimba

      kimba Active Member Full Member

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      Tell him what he was doing wrong ?? No , it's just my hobby to waste my time and materials by making 6 high gold metal frameworks with someone who was insisting it was not him , but the materials I had been successfully using in my laboratory for years!! Judging by the tone in your question to seven P let me guess, you are a young technician who knows a lot and everyone in the laboratory is just picking on you
       
    16. Solid

      Solid Member Full Member

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      cheer up.. nothin wrong of showing off;))
       
    17. Solid

      Solid Member Full Member

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      Manufacturers generally note the slow cooling for veneering YSZ, some emphasizes only the last cycle that is the glaze. slow cooling by definition can't be more than 50c/m and mainly to avoid delamination. as for fracturing the framework itself I 'd like you to elaborate more on that since never happened with me and used to do 8-10 units a day including opaque and adjusting frameworks whether 3 unit bridge or full arch. many zirconia porcelains fire at 800c and find it hard to believe if the muffle opens at 800c without slow cooling to 400c then to 23c that will cause fracture
       
    18. NickB

      NickB Member Full Member

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      That photo shows what the machine mills out when I add the stabilizer bar. Its just one solid piece and not sprued with wax. And I cut back the bar to reduce that suck back effect.
      Today, after showing how to properly sprue and invest to these waxers yesterday, we had two big bridges that fit really well. One waxer tried to heat up the entire bar to bend it
      for a full arch bridge that was milled yesterday, and she sprued it without allowing it time to set and cool. I made it known that this is a big no no. They seemed to have gotten
      the point. As for the length of the sprues on the photo.....Ive tried to make them longer in the software, but it simply wont allow me to do so. All I have control of is the thickness
      of the sprues.
       
    19. user name
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      user name Well-Known Member Donator Full Member

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      When I used to cast, any sprues/rods that were heated and bent weren't used for 24 hours. I always had a few in the drawer that were bent for future use. In my experience, even a cold water dip and some time in the fridge isn't enough. They have to sit along time to fully lose memory.
       
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    20. TheLabGuy

      TheLabGuy Just a Member Full Member

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      Yeah, I've said this is spruing technique since day 1. Glad you finally seen what they were doing.
       

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