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    Wieland Zenotec select PMMA milling

    Discussion in 'Dental-CAM' started by saso, May 12, 2018.

    1. saso

      saso Member Full Member

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      Hi everybody,

      these days I have problems with my PMMA fittings. After couple of calibrations all crowns and bridges are too tight so I have to manualy adjust to fit them on the model. This happend with PMMA, zirconia fitting is great.
      Was trying to change settings in 3Shape and also in the machine but it doesn't work.
      So maybe one of you have experienced the same issue and can help me.

      My current 3Shape PMMA settings:
      Drill compensation offset:1,500mm
      Drill radius: 0,600mm
      (milling with new drill compensation and without it doesn't make difference for me)

      Have tried different settings but did not work.
      I am using Wieland burs.

      I have tried changing cement gap but the result is the same, too tight, so I guess cement gap doesn't
      effect the milling.

      Please help,

      thank you in advance.
       
      Last edited: May 12, 2018
    2. Sevan P
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      Sevan P Well-Known Member Full Member

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      Her are my settings on 3shape for pmma, I can on wieland can and mill ok n a mlm ini, vhf k4 and vhf s1 all use wieland carbide cutters as well. Cement gap 0.03 extra cement gap 0.10, smooth distance .50 distance to margin .2 both drill radius and comp are 0.550. All my c&b drop in all the time. My implants and implant bridges I had to play with the strategy for pmma. Zr on all parts is perfect.

      Sent from my SM-N950U using Tapatalk
       
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    3. saso

      saso Member Full Member

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      Thanks Sevan, will try that. But are you changing settings only in 3shape and you do nothing with Wieland settings?

      And using 07, 1 and 2mm burs?
       
    4. Sevan P
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      Sevan P Well-Known Member Full Member

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      Only 3shape. C&b no changes in strategies. 2.5mm, 1mm and .7 and .3 on the 5axis only.

      Sent from my SM-N950U using Tapatalk
       
    5. DentalTechTips

      DentalTechTips Active Member Full Member

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      My settings are 0.03 and 0.07 for the cement gaps. The reason is the burr deflection when milling pmma.

      Sent from my SM-G955W using Tapatalk
       
    6. saso

      saso Member Full Member

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      Yeah, 2.5 burr not 2mm, sorry...will try and hope it's gonna work:)
       
    7. DanM

      DanM Member Full Member

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      Recently WPT support suggested I mill a splint with their special cutters. There's a special milling strategy that mills faster. Started using them for milling all PMMA. Everything is fitting great without any adjustments. Should give them a try.
       
    8. saso

      saso Member Full Member

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      Could you explain a bit more about this strategy and these cutters? If I understand correctly you are milling PMMA with PMMA strategy and using special cutters.

      So, you use this ones for PMMA: Zenotec special cutter S 2.5,1,0.7mm?
       
    9. DanM

      DanM Member Full Member

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      Yes those are the special cutter S burs. The strategy is under PMMA called single cutter. Before I started using these burs I would have similar issues. For crowns I would increase spacer significantly and would struggle to get implants to fit correctly. I switched to Sierra PMMA burs and had much better success but the special cutters from Ivoclar work really well without adjusting any settings.
       
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    10. CoolHandLuke
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      CoolHandLuke 40% titanium Staff Member Full Member

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      milling with 2 flute or 1 flute tools?

      what is your speed? try and stay between 18-25k rpm. less rpm if you have more flutes in your cutters.

      i don't have your specific mill but its not all that different from most others.
       
    11. Sevan P
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      Sevan P Well-Known Member Full Member

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      My Weiland Implant bridge strategy, single flute cutter thing rips so fast! This is for the Select, hybrid Select and VHF S1/S2
      Weiland strat.JPG
       
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    12. saso

      saso Member Full Member

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      Interesting, will test everything and see the result:) thanks for help
       
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    13. Sevan P
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      Sevan P Well-Known Member Full Member

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      Those are stock parameters, I simply copied the strategy then renamed it for a much easier way of using it.

      Sent from my SM-N950U using Tapatalk
       
    14. saso

      saso Member Full Member

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      Tried the strategy for crowns and bridges, works great! Will try an implant bridge soon...
       
    15. saso

      saso Member Full Member

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      So now let me ask you another thing. What are your settings for PEEK, do you mill it also on Wieland?
      If so, what do you do? I assume you have to pick the strategy for PMMA, but I want to know which and which cutters do you use.
      What is with 3Shape settings, the same as for PMMA?

      Thank you for answers!
       
    16. CoolHandLuke
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      CoolHandLuke 40% titanium Staff Member Full Member

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      its not bad, but its only about 40% engagement on your tools. increase the depth to 1.25 and you'll cut a few more minute off the milling time.
       
    17. JMN
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      JMN Christian Member Staff Member Donator Full Member

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      Stupid question time. Why would you not engage the entire cutting length of a tool, aside from not needing to cut that deep. Heat management?
       
    18. CoolHandLuke
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      CoolHandLuke 40% titanium Staff Member Full Member

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      many reasons.

      short answer: its not good to go above a certain amount of axial engagement, nor lateral engagement in the case of Square cutters.

      long answer: the more engagement you have, the more speed you have to give the tool, to create small slices, because without small slices the tool will deform under speed and break. this creates vibration, heat, noise, and may result in damaged parts. so in order to keep a constant Chip Load you must spin the tool faster, or engage the tool less. in the case of semicircular shaped tools such as these, the amount of force the tool can be put under is less, because not all of the ball shaped tool can engage at once. the cutting stroke pushes DOWN as well as Sideways, which means you must restrict your cutting depth to between 30-80% of the diameter of the tool for cutting from an open ended surface or 40-60% of the diameter of the tool for cuts that plunge through the thickness of the material to cut the middle part of the material only.
       
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    19. CoolHandLuke
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      CoolHandLuke 40% titanium Staff Member Full Member

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      this is why it is INFINITELY better to make roughing passes that plaunge, with Square shaped tools. you only put downward plunging force once, and the rest of the tool path is all lateral engagement. far easier on the tool.
       
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    20. Sevan P
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      Sevan P Well-Known Member Full Member

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      I milled a Mesostructure in Trinia on a PMMA strat worked just fine.
       
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