Acetal Resin

AJEL

AJEL

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That looks more like a partial flexable sprue diagram.
flexables
[/URL][/IMG]
 
A

Allan

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But this sprue is framework? And arcade (splint),this sprue is correct to?
 
AJEL

AJEL

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I have seen some voids when the bi/canine area has no sprue for splint as in brux appliance (they make a super brux appliance especially for bulimia individuals.)
I will check with Kriss I believe he uses a double bar to improve complete flow, I simply add a sprue to that area sometimes with a vent. This is for a bite opening to determine verticle for reconstruction for a LVI case.

ai1123.photobucket.com_albums_l546_Ajels_flexables_IMG_2104.jpg
ai1123.photobucket.com_albums_l546_Ajels_flexables_IMG_2104.jpg
 
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A

Allan

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This yellow stone, is of high expansion? OR not?
It can be normal stone
 
AJEL

AJEL

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The model the waxup is done on is expansion stone (Hi Tech 800-859-2006),the model is sealed with Thermoplastic model separator from CDM. Articulated & waxed to bite. I use regular yellow beta gypsum to hold the model in the bottom of the flask, the next layer I like a bubble free stone, I use "flask it" from Garreco Garreco Gypsum, that will just cover the occlusion then I use a top to make deflasking and not damaging the occlusion easier. I use a Chicago Pneumatic Air Scribe # CP 9361 one with a chisel & one with a pin tip. to clean up the stone around my dentures, implant cases & flexible cases. get the 9361 not the cheap 710 it doesn't work for our purpose.
Hopefully the next postt will be either Sol from Flexite Flexite Products Page who called while I was typing this or Alan with his success.
 
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Allan

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But why do you use flask garreco?? Flask Garreco not support injection!
 
AJEL

AJEL

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The Flask-it material flows well no bubbles, separates easily & is supported as it is 9000psi compression with only .09% expansion. Most injection specs (that I have seen) require 8500psi compression in flask with less than .12% expansion. Now for acetal your model will have expansion stone 13000psi compression strength with a 1.1% expansion.
 
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Allan

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Ajel, you could do a video on youtube explaining how to create an arch (splint) Acetal.

Wax
Invest (Gypsum used)
Injection

This video does not yet exist on youtube

I suggest to you, my friend!


Thank you!
 
AJEL

AJEL

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Snap on problem

This UTUBE is something I know nothing about doing. :hmmmm2: I have techs over to my little lab but haven't taught clinics since the MAC (Mid American Conference IDLA). This subject could be subject to DenMat ]Why Snap-on Smile | DenMat.com Legal problems. I as a removable technician have to do a lot of different things to scratch out a living, :banghead:these LVI style biteopeners R a small portion. I have been doing these biteopeners with a variety of materials starting with Astron Vinyl in 1980's. My major income seems to come from CLEARSplint TMJ/TMD appliances.(who would ever think people could be stressed in this economy?:censored:) I do Acetal frames in lab & send to Bertram for CoCr frames for my partials. My dentures balance whenever I am allowed to, & I do many repairs especially in this economy. In over 40 year I have seen & worked on many attachments & have always kept notes on problems & benefits I have seen with them. When I took Kriss class at his nice lab in VA I took copious notes & pictures (he did not give me waiver to publish only for my own use.)
From your picture I note U R dark skinned what did you think of my http://dentallabnetwork.com/forums/f2/special-waxes-ethnic-8757/
thread. I have used the wax from the last post and it handles ok but U have to order 5lb min. Alan R U also doing dentures in your laboratory?
 
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Allan

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Yes, I do dentures in my lab, flex, resin .... now wanted to get to do this acetal, my great difficulty is to invest the piece gettin dirty, follow what you gave me in the post, making the sprues aspect of collar, but it seems that the cast is too much messing vesitbular even going separator before injecting, I'm thinking it's the rock! Honestly, I'm thinking that I'm including the stone is very hard! When the material is injected, I'm thinking that he is joining others in stone


What stone do you use? Type 3? and to close the flask? type 5?
 
j_marks101

j_marks101

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Valplast has a few gypsum products for duplicate models and investing flexible thermoplastic resins. Accu-Val is a type 3 yellow stone with 0.3% expansion for duplicate models; helps improve the fit after processing. They also have Val-stone, a die stone with I think 13,000 psi compression strength that keeps its physical properties with high heat and high pressure during injection. Works great for Valplast, I'd imagine it works well for acetal as well although I will never touch that stuff in my lab! Water/powder ratios are crucial - its amazing how few denture techs pay attention to that stuff, they think it's only for investments and c&b guys
 
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Allan

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The smell of the acetal is horrible, burning eyes and smells of formaldehyde!

Someone already noticed this?
 
araucaria

araucaria

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The smell of the acetal is horrible, burning eyes and smells of formaldehyde!

Someone already noticed this?

never noticed these issues. have you checked heater temperatures?
and ventilation, extraction, safety data sheets of manufacturers, risk assessments, gmp, etc ?
 
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Allan

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Duracetal , i injection with 220° Celsius and 20 minutes
 
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Allan

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Anyone here have any photo model invested in the flask with sprue?
 
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Allan

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I have seen some voids when the bi/canine area has no sprue for splint as in brux appliance (they make a super brux appliance especially for bulimia individuals.)
I will check with Kriss I believe he uses a double bar to improve complete flow, I simply add a sprue to that area sometimes with a vent. This is for a bite opening to determine verticle for reconstruction for a LVI case.

ai1123.photobucket.com_albums_l546_Ajels_flexables_IMG_2104.jpg



Anyone here have any photo model invested in the flask with sprue?
ai1123.photobucket.com_albums_l546_Ajels_flexables_IMG_2104.jpg
 
K

Kris S.

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If you are smelling the chemical smell and it is burning your eyes the material to boiling in your machine. The temp. needs to be lowered I would say 30C. Boiling the acetal will make to acetal brittle, discolor, have bobbles and have a great deal of shrinkage.
 
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Allan

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Kris Ok, so I'm pumping at 210 ° C, will decrease to 180 ° C?

Correct?
 

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