Ring size problem

A lost wax capable resin tuned for 70 - 200 micron slice thickness
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Ring size problem

Post#1 » Tue Dec 09, 2014 4:54 am

I have seen a couple other people post similar problems but with no final resolution. by reading all the posts and doing some measuring i have found the problem is probably due to over exposure. My ring rail comes out about .5mm smaller then it should and the overall ring comes out a little larger. for this ring i am using 70xy 75z and regular b1red resin. all default settings. i triple checked my grid calibration and yes i made sure "fit to page" was un-checked when i printed it out. Any suggestions on how to change setting to get a more accurate result. I also noticed this happen with my 1:1 mix using default cherry settings at 50xy but i didn't expect it from the regular b1 resin and default settings. (note: the black ring below was printed with shapeways and is very close to my cad model)
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Image

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Metalcaster
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Ring size problem

Post#2 » Tue Dec 09, 2014 6:07 am

I am also finding the same issues as far as sizing. did the same, full re-calibrate no better ...
However, changing materials got much closer, but material is not castable.

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Ring size problem

Post#3 » Tue Dec 09, 2014 7:27 am

What material did you change it to? Cherry?

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Robert Howle
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Ring size problem

Post#4 » Tue Dec 09, 2014 9:17 am

It is true that there is shrinkage in the layers curing. and post print curing. That is why you scale your models before exporting as .stl. You are never going to get the same finger size as the model. You are beating a dead horse when it comes to b9 resins. I don't know anythng about 3rd party resins. Have been printing on both versions of the B9 and u have to scale.

Anyone that has read the post on this matter is scaling to compensate. Most of the jewelers here scale between 1.5% and 3% depending on the heavyness of the ring. This also helps to compensate for shrinkage with stone setting issues..

Robert Howle
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Ring size problem

Post#5 » Tue Dec 09, 2014 9:59 am

I have no problem scaling up but i think it strange that it's not just the ring-rail that is smaller but as i stated above (and as the pictures show) the entire ring seems to be thicker. That leads me to believe if i lower the exposure time, i may get better results. I was just hoping to get some guidance from a jeweler/ experienced b9 user on changing default settings for better accuracy without underexposing and possibly ruining the resin in the vat. any thoughts on that Robert?

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Robert Howle
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Ring size problem

Post#6 » Tue Dec 09, 2014 10:12 am

I can tell u that I get accurate models (except for shrinkage using 1:1 red/cherry mix. Shorter exposure times and almost eliminates bleed that u often get with the cherry (prob reason for your thickness issues.. I have posted this so many times i have lost count. Best printing for me is 30 xy 30 Z (1.2 machine) 1:1 mix. Other reason for thickness issues include focus, zoom, and over exposure.

The cherry always gave me thicker models and thicker prongs. Especially on micro prongs that were close together. For fine details try the 1:1 mix.

You will not ruin the resin in the vat, just filter, It doesn't go bad from a failed print. And yes lowering the exposure using the MSM might help if expoure is the issue. The MSM is there because all lamps are not created equal.; You may have a lamp that is "hotter" than others.

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Robert Howle
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Ring size problem

Post#7 » Tue Dec 09, 2014 10:17 am

Also looks like the eye sockets are smaller in the B9 print. This looks like bleed. Adjust the MSM down a little, maybe .2 or .1 to start with.

Hope this helps.

Robert
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behold3d
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Ring size problem

Post#8 » Tue Dec 09, 2014 10:43 am

Robert maybe you should start a thread that is titled " Robert Howle's 1:1 resin jeweler setting and procedure"

You probably would still be asked tho ;-)

But i think its more an issue with the search functionality of the form imho

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Robert Howle
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Ring size problem

Post#9 » Tue Dec 09, 2014 10:53 am

Mike is working on making it a default material.. This should go a long way with the issue. The original mix of 1:1 was Justin's, as was the Justin Base, another great idea. I was working with Red/cherry mixes at the same time. Justin was the one that suggested the mix and I have been using it ever since. Just want to make sure that users don't think it was my idea in the beginning. I did notice that as I added the red to the cherry that i had less bleed and crisper details, and exposure times went down. Justin got to the 1:1 mix long before I would have gotten there and saved myself and others a lot of testing. It may very well be that some other mix works as well or better. I really don't think u will get better detail on small design elements with other mixes and I dont' intend spending the time to find out. I am extremely happy with my current results (also the othere jewelers i print for) and dont' think things will change untill new resins are developed (castable ones for me).

Robert Howle
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Ring size problem

Post#10 » Wed Dec 10, 2014 4:44 pm

I assume MSM is the "machine specific multiplier". it took me a second to find it. I never would have known that's where you can compensate for a hot lamp. Thank you Robert.

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Robert Howle
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Ring size problem

Post#11 » Wed Dec 10, 2014 5:56 pm

That is correct. Let us know how it goes.

Robert
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