new VAT that do not work

nicolas

Hello,

i bought two vats in august, brand new.

i have  been using one during 3 months non stop, and everything was fine with it. It is the kind of vat all transparent.

obviously, the vat got sticky and i could not print anymore. So i took my second vat all brand new and i got exactly the same problem, i can not print nothing with the brand new vat, everything stick to it and i can not make one good print.

i do not understand how the new vat can works so bad, can the fep get damaged by the time (the vat was packed in plastic since i bought it.

thanks for your help.

Joseph_Osborn

Depending on the particular type of FEP used in that vat, you will have to adjust your base layers timing. It sounds odd, but if you triple the base layer time you used for the other vat, you should be able to use this vat just as well. For example, if your base time is 8 seconds, increase it to 24 seconds and your print should stick to the build plate correctly. You can use the normal layer times for the rest of the job. I know it sounds nuts, but it works for my stubborn vat.

nicolas

ok thanks i'll try this soon.

nicolas

@rkundla do you have an idea how a brand new VAT can not work ?

i am testing a print with larger time exposure right now but alos bought two new VAT as i need to produce for my business.

A 3 month like time for a VAT is ok for me, but a VAT that do not work at all amaze me.

if you have any advice, i'd be happy.

regards

rkundla

@nicolas 

I think the problem that was encountered had to do with the FEP film that was put on top of the PDMS layer in the vat. Apparently not all FEP film is created equally depending on where you buy it.

You can try taking a small amount of 91% isopropyl alcohol in a dropper, put it in the middle of film in a cleaned out vat, and use your finger to wipe the film around the build region just in case there is any oily contamination of the film. I usually do this to mine after many uses to help clear out any microscopic cured resin that might interfere with the peel process.

Joseph's suggestion is to increase the layer exposure to allow the resin to bond more tightly to the build plate than the film during those initial layers. I've also seen this as a solution if the film to plate interface is not completely flush. This could be do to PDMS levelness or film damage.

I do have to admit that I've stopped using B9 Yellow because I had all sorts of problems getting it to build properly. However, it worked quite well initially. I think my resin wasn't mixed well enough and now I have an overly pigmented resin in the bottle, which requires a lot more light exposure to cure properly. I've moved onto other resin however, so the B9 Yellow is collecting dust in my cabinet.

Another thing you can try if you have access to adhesive-backed FEP film is put a small layer on top of the existing layer in the vat. I've also been looking for some kind of silicone lubricant I could put on top of the film to help with the non-stick behavior, but have not seriously pursued this option.

nicolas

Hello,

that's interesting because i have just opened up a new bottle of B9 yellow. is this resin the problem ?

since september, i have been printing non stop b9 yellow with the same VAT with absolutely no trouble so i am pretty amazed to be struggling so much now with a brand new VAT and new resin bottle.

rkundla

@nicolas it is hard to say if the resin is to blame. The B9 printer traditionally uses a PDMS only vat - no FEP film. I've seen people use Yellow on the Solus, which is FEP only, but most people over there prefer the Emerald resin.

I thought about getting the yellow, but decided to go with the 3DFacture green.

If you want, I can sell you a small bottle of the green if you want to give it a try. Hit me with a PM and we can talk the details.

rkundla

One more tip, does it look like the prints ripped off the plate after some number of layers?

You can try to get some more surface area on your base layers by scaling up your raft/base so get a bigger patch against the plate. That helps resist the sticky resin trying to pull the print off the plate.

If you are running into vat surface/plate problems, a good test is with the printer front panel off, start a print process so the plate moved to the vat. When it stops, look underneath to see how opaque the area is between the vat and the plate. You should be able to see the metal of the plate quite easily and it should be uniform. If it isn't, you have some height variance between the plate and the vat, which will cause some problems with consistent adhesion.

FinalEclipse

Hi @nicolas,

I have had a very similar problem to you, where nothing I do will get the prints to stick to the platform. I realized later that wear and tear of the platform from sanding and removing prints produced micro irregularities which are difficult to spot with the naked eye. These irregularities cause the platform to be imperfectly flushed with the resin vat, causing prints to remain on the vat.

My solution was this: once the platform is lowered into the vat and after it has been pushed downward three times, carefully and gently push down the platform slightly. You will see that there's an allowance of a millimeter or even more before the springs compress. While doing this, fasten the vertical locking knob immediately and try a print.

Hope this helps!  

Chris

nicolas

Hello,

i made a new test that failed.

i followed the instructions above, so i cleaned the fep film with alcool, i mixed well the b9 resin and turn the printing plateform as i had been printing on the same side since 10 months or so.

as you can see, the print is almost for the supports and very bad for the part, so i do not understand.

i will try to change the exposure settings, but i still do not understand where the problem comes from.

rkundla

I assume that is the base plate and the print is firmly attached, right? Also you stopped the print mid-way?

It looks like overexposure in some regards and underexposure in others. On your computer, which video card do you use and have you verified that your HDMI depth setting is full (0-255) ? May not apply to Intel graphics cards. I know with Windows 10 this value can be reset unexpectedly. It is worth double-checking.

Can you post the details from your resin profile with the times, etc.? Also, please refresh my memory with the slot position, which projector, did you change any of the settings, etc. 

A good test is something like this model from Thingiverse (http://www.thingiverse.com/download:872736). 

It is a fine feature test with nine spikes on a square mount. I would space these out on the build plate and use it to see which sides print better than others due to light distribution or other environmental issues.

nicolas

Hello,

i did not stop the print midway, i let it finished the print 100%

What is the hdmi depth feature, is it on the pc or the projector i have to check this ?

i use windows8

rkundla

What were you trying to print since it looks incomplete?

The HDMI depth is a setting in your video card driver on the CP. What video card are you using to connect to the Draken? nVidia, ATI/AMD or Intel? I'll look for some info based on your setup.

rkundla

I decided to try my B9 Yellow with the Vivitek and the flex vat. Using 60 second base layers at 25 micron, which I used in the past, I was not getting anything to cure let alone stick to the plate.

I just projected a solid square on the vat without the plate and it took 2.5 to 3.0 minutes (150-180 seconds) to get something I could scrape off the FEP. Since I am down to the dregs of my bottle, it is probably no longer chemically balanced and is essentially worthless. I will have to throw it away. :(

nicolas

Hello,

i made a successful print yesterday, i increased 50% the exposure time for the base layer and the print layer.

so 45 s for the base layer and 22 s for the print layer.

i am goind to make some more tests today and see what happens.

rkundla

@nicolas glad to hear you were able to get a print to come out. Those types of settings seem like what I used previously, but maybe my resin is low on photo-initiator and it cannot cure the resin fast enough. Either way, the bottle is toast so into the garbage it will go.

I may have to get a bottle of emerald to give it a try and see how it works with the Draken.

nicolas

Hello,

i made a good print yesterday, with those settings of light exposure send in my last message.

But it seems the supports moved, i have no idea why.

because i changed the VAT and the resin bottle at the same time, it is difficult to be sure where the problem comes from the FEP film of the VAT or the resin.

rkundla

@nicolas glad to see the print looks 100% better.

If they appear to be in the same plane, it means the print moved.

Either it is due to unstable supports or movement in the build plate/printer during the printing process.

Check to make sure the build plate does not wiggle when tightened down. Also make sure the printer is on a solid surface to prevent it from wobbling or bouncing due to the motor movement.

I do not use CW to make my primary supports. I used Rhino/RhinoGold, so I set a pretty thick base in the bottom center approximateley 3 mm from the base, then add some additional supports along the bottom of the ring to stabilize it. That usually helps.

Don't forget to support all overhangs or else they will not print correctly. It looks like the signet top part shifted as well. Sometimes you need internal supports between the flats of the band to keep it solid.

nicolas

hello thank rkundla.

i'll try do use support on rhinogold as i use it too.

to you use clayoo or other extension ?

rkundla

@nicolas I haven't really tried to make something with Clayoo, but it is quite powerful from what I've seen. Works best for organic designs with more curves.

I made a support for rings I keep as a template:

Works pretty good for supporting the ring base and is easy to cut off with a saw and sandpaper.