How improve the build table model adhesion

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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#1 » Tue Nov 04, 2014 11:09 pm

I'm testing a new material for the pdms I asked for a suggestion for an expert in plastics, in order to establish a transparent material with a Shore hardness between 40 and 60 similar to sylgard, but with greater resistance to UV. He told me to try it with a transparent polyurethane resin called "PUE 182T "see: http://www.poolkemie.it/prodotti/resine-poliuretaniche/resina-trasparente This resin is more transparent than the sylgard and when is exposed to the UV ray became more transparent!
I re coated the vat with 50 gr of PUE182T, (may be is too much, because pdms thickness after curing is 2,8mm) but the result was great it's look more transparent than sylgard with the same gums consistences.
I tried two print with 30xy 25 z cherry resin default parameters and the first slices of the round model bases remained attached to the pdms, could be happen this because the pdms material is different or I have to change the print parameter? May be over cured?
In order to improve the model adhesion, i drilled my build table with 1,2 mm holes at 0.6 mm of distance one each other.
I wonder is it possible start the print with the build table completely downed on the pdms plane? how can set the soft for do it? This is because the resin is cured in the holes of the build table, has a higher tear strength! This could be a solution to many attachment problems or not? what do you think about? May I go head with this experiments or I'm in totally wrong way because the material is no suitable for the purpose? Have you ever tried such a thing?
Many thanks SERGIO
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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#2 » Tue Nov 04, 2014 11:34 pm

Stupid what you did? You have ruined your build table!!!
Sergio's soul Ah ah
I'm afraid but I hope this is no true! I continuous my experiment may be is better recoat with less quantity 35gr is ok as suggested from Mikej

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mikej
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How improve the build table model adhesion

Post#3 » Tue Nov 04, 2014 11:58 pm

Your build table modification may allow for better adhesion. The downside might be harder to remove the part and cleaning up the table, etc., please keep us posted on your progress.

As for parts sticking to your alternative vat coating (not pdms), it is very important that the material coating have a very high oxygen permeability rating (like pdms), otherwise the resin will simply glue itself to the coating (not good!).
Measure Twice, Cut Once.

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Metalcaster
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How improve the build table model adhesion

Post#4 » Wed Nov 05, 2014 2:00 am

Hi,
I did a similar thing to my Platform. Somewhere, I have posted pictures. the difference is I did not make the holes go through. I thickened the platform by 3 mm so that it would no longer bend. Bending out of shape was a big problem as I had troubles with larger prints falling off the table.
I tested other materials like form 1 grey and some others and the grooved platform made some material impossible to remove. I had to machine them off ,it was so bonded.

I am very sure that will happen with your platform with holes.

Now,The way I have made my new platforms is with 4 mm thick aluminum and machined flat and lightly sanded . ALL materials stick to the platform everytime and it is easy to scrape the patterns off.
I have been using this platform on the 1.1 machine for over a year and on the 1.2 machine for about 1 month. This really helps adhesion a lot if you do it correctly without making it to hard to remove.

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mikej
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How improve the build table model adhesion

Post#5 » Wed Nov 05, 2014 2:06 am

Some users have reported that bare aluminum reacts with and effects the cast-ability of the resin. Just FYI.
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Metalcaster
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How improve the build table model adhesion

Post#6 » Wed Nov 05, 2014 4:52 am

So far, the only thing that has affected the castability ( for me anyhow) is the curing time and the strength of the UV system for curing ... I have been using Oven Cure and UV as many pieces we do are thick . 1 of the trays I have is an aluminum tray. running the tray and the aluminum platform has not caused a problem.
Almost all the other machines on the market use machined,plain aluminum platforms. I have a few of those, but my fasvorites are my 2 B9's

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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#7 » Wed Nov 05, 2014 5:49 am

Yes i did the holes trough the table for this reasons, I think is faster to polish the table with a small tablet plenty of needle than loose the model in the resin! And for this that I'd like to start the print with the table in zero position, but how can do this in the software parameter? Last and no least take advantage because using polyurethane resin called "PUE 182T the duration of the coating is too much longer. So someone could suggest me how start the printing with the table in zero position?
ciao sergio
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mikej
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How improve the build table model adhesion

Post#8 » Wed Nov 05, 2014 5:57 am

The table always starts at "zero" (same position as when you calibrate to sit flush on pdms).
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behold3d
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How improve the build table model adhesion

Post#9 » Wed Nov 05, 2014 7:03 am

My concern is that polyurethane does have better uv handeling ability but does not have the NEEDED release characteristics needed in this method. It will stick to the urethane material ....like glue

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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#10 » Thu Nov 06, 2014 11:45 am

Sorry Mikej but i believed that in order to realize the first layer the table raise up from the pdms base of the z thickness!
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mikej
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How improve the build table model adhesion

Post#11 » Fri Nov 07, 2014 12:49 am

That would be the ideal case, but real life is seldom. :)
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Eddie J
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How improve the build table model adhesion

Post#12 » Fri Nov 07, 2014 4:12 am

I think if you make the print adhere to the table better - this is going to be a moot point. Since by the sounds of it, the new VAT coating will still cause each layer to stick while printing, meaning that the part printing may warp or bend or be more likely to fail or have the supports snap away.

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tim.yoshi
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How improve the build table model adhesion

Post#13 » Wed Nov 12, 2014 10:14 pm

I tried PU - no luck here. Resin sticks to it.
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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#14 » Thu Nov 13, 2014 9:30 pm

Hy tim use this tips before print before fill the vat with resinTry to spray on the vat coating the silicone spray Fresil or teflon spray and tell me what's happen!

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Robert Howle
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How improve the build table model adhesion

Post#15 » Fri Nov 14, 2014 7:11 am

I for one don't understand all these "stick to build table" itterations. Never had the problem if all is calibrated well, base layers not too thick, etc. Good luck with your project.

Robert
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akgold
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How improve the build table model adhesion

Post#16 » Fri Nov 14, 2014 2:33 pm

I never had the problem either until last week after reading this post about it.

I also leave my seat at the hockey game when my team is behind and I want them to score.
I'm so far behind I think I'm First !!

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Metalcaster
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How improve the build table model adhesion

Post#17 » Fri Nov 14, 2014 5:13 pm

I don't think this issue shows up at all when running 30xy x 30um, however, running with much bigger platforms like 100xy x50 um or any of the larger settings, the flatness of the platform can become an issue. Some platforms are flatter then others. I have 3 platforms, 2 were not flat which I added metal to and then machined the surfaces flat. These platforms work perfectly at any size. Any issue on large sizes on these platforms are due to parts sticking to the pdms and destroying the PDMS quickly. That could be caused by settings or just the fact that you have a tremendous amount of suction on the pdms . Since the part is so big I seem to think the X motor can't pull it loose.

The third platform was flat when i got it until I had a large print stuck to the PDMS like it was glued. By the time I got the material un-stuck,the platform was no longer flat. I did not realize it and lost a lot of time trying to figure out new settings to get things to stick again. Checked flatness, fixed the flatness and the platform works fine again. If you can rock a flat steel rule diagonally across the platform on large grows, you will have some issues.

Something to check. ... once you calibrate your build plate, take it off and check flatness... if you put pressure on the plate as you are tightening the screws, you could bend the plate and cause problems.
Unfortunately, there are apparently very few of us running larger prints and those of us who do, don't have the benefit yet of help with settings. I am hoping with the new glass coming out that some good experimentation will be done on large parts first to test the new glass coating and to get some settings that work well.

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Robert Howle
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How improve the build table model adhesion

Post#18 » Fri Nov 14, 2014 5:18 pm

Mike will be testing full build table size solid blocks probably because release is the issue that has to be proven at all resolutions. At this pt i don't think jewelry size items are a problem. Will no more as i test print using the new coated glass.

One of the reasons AK took down the order info on the coating and glass was so more testing can be done to determine exactly what uses are going to be recommended.

Robert
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ROSITAGIOIELLI
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How improve the build table model adhesion

Post#19 » Sat Nov 15, 2014 11:44 pm

May be drilling the build table as I did is the solution to the adhesion forced caused by vacuum effect when the table raise up from pdms, this happen over most when you use the b9c to produce jewellery and not only as model maker see the pic
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Metalcaster
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How improve the build table model adhesion

Post#20 » Sun Nov 16, 2014 2:57 am

It is definitely not necessary to drill holes in the platform for adhesion. Mine are simply a thick 3mm plate of aluminum glued with marine epoxy and machined/sanded flat. Easy to do and its a permanent fix. The exposed aluminum has no effect on the resin for casting.
If you do make holes in it, the b9 red can be pulled off , but other materials will bond to the holy platform permanently. I already did this experiment a year ago and had too much adhesion with holes. However, sanded perfectly flat has worked without any failures for almost 1 year. Adding the extra thickness of aluminum helps to guarantee the flatness and make sure it won't bend again.

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