overextend margins-3Shape

[SteveD]

Is anyone else getting overextend margins? Seems to be most evident on chamfer type preps. We see them on both printed and slm cases. Any input would be helpful. Thanks

 

[Ryan Gottlieb]

Can you post a photo?

 

[shane williams]

The only way you can have over extended margins is by marking it wrong in 3Shape. The mill or printer will manufactor whatever you design. Are you printing yourself or sending out for the crowns to be printed? Maybe the printer is creating copings that are a bit to large and creating an over-extended margin. You said this usually happens on chamfer preps, so it doesn't happen on any other case? If it's happening on one style of margin and not the others, I'd say it's the tech scanning and not the printer. Thats the only thing I can think of?

 

[SteveD]

I must need more posts, before i can upload attachments.

 

[SteveD]

Oh if life were so easy! I have looked at the margin marking, looks right on. It's infinitely software or something were missing. I'm trying to upload pics, hopefully will have that figured out soon.

 

[CoolHandLuke]

ah, now the picture is clearer.... steved created two threads and forgot to include these details in the photo thread. so steve i will bring your photo to this thread and we can continue discussion:



now, as to the Over extension of this margin, in what sense are you seeing overextensions? laterally as in the margin is too thick? or gingivally as in the margin is further below the line on the die than it should be?

because if it is a trifle with the margin being too thick well some manufacturers have it set like that to ensure that 1st run copings are not (or ar minimally) remade in house. something like an ounce of medicine being worth a pound of cure....

however if the margin line is simply too far down the die, well thats a design flaw; your 3shape worker bee will need a bit of retraining.

 

[lcmlabforum]

?
some manufacturers have it set like that to ensure that 1st run copings are not (or ar minimally) remade in house. something like an ounce of medicine being worth a pound of cure....

Can you elaborate?
LCM

 

[rkm rdt]

That looks like cad cast.

 

[DMC]

Could be parameters for the extra material on margin.

The angles are wrong, and actually extend the margin.

This is possible, no?

 

[chocybunny]

Did you design this on your 3Shape or did you have this designed else where ?
If you did in house then there are some settings you can adjust let me know and I will let you know what your settings can be changed to.
If you have sent this out then possibly to avoid having chips and razor thin margins this was bulit out is easly adjusted with a high speed and diamond bur carefully around the margin.

 

[CoolHandLuke]

?
some manufacturers have it set like that to ensure that 1st run copings are not (or ar minimally) remade in house. something like an ounce of medicine being worth a pound of cure....

Can you elaborate?
LCM

some manufacturer's margin setting are set thick at the margin line (in some cases AS thick as the coping) to prevent visible chipping, and nearly guarantee that the 1st coping they mill will be quality enough to ship.

which is sloppy and cheap and underhanded and all sorts of bad practice. CAD CAM is supposed to save us all time and effort, but this saves nothing.

 

[SteveD]

This is a 3Shape in-house design. Sent out for SLM. Thickness of margins is manufacturers recommendation, take very little time to finish.On our printed and milled parts we get nice thin margins. What has me and the designers confused is we get slight over extensions on the margins. I sat with them again yesterday, were margins are set look good. Can there be some setting or combination or settings were missing?

 

[martintay]

This is a 3Shape in-house design. Sent out for SLM. Thickness of margins is manufacturers recommendation, take very little time to finish.On our printed and milled parts we get nice thin margins. What has me and the designers confused is we get slight over extensions on the margins. I sat with them again yesterday, were margins are set look good. Can there be some setting or combination or settings were missing?

Are the copings really loose ?

 

[SteveD]

No, they fit well.

 

[Janae_CADCAM]

IF I am understanding you right, I think you are saying that the margin is in the right place it is just a little thick. I had that problem in the beginning and started to decrease my Margin offset. I've been happy with lowering it down to .10mm. Depending on what verison of sofware you are using, you will either find the margin offset on your spacer settings or under your advanced settings where you are choosing which library to use for your crown you are designing.