Build Your Own SLA/SLS

Do you have any updates on this FEP yet? I'm anxious to hear how it works for you.

Hi guys,

tried the "Ikea" vat tonight, 0.05 FEP stretched firmly but not very very tight.

-After a few seconds of exposing the first layer (just a square about 3x3cm) , the FEP film started to bulge, a little bit like plastic becoming too hot. I was just 10 seconds into the first layer, projector is 20 to 30 cm away from the FEP, i placed my hand and cannot feel any heat.

You can see in the picture attached, from underneath the vat, the reflection of the vertical extruded alu profile is not straight where the film has bulged. I removed the resin and released the FEP, it seems permanently deformed. I'm using maker juice G+ black.

I'm not sure what can cause the FEP to deform like this. Bought the FEP here:
http://projectsinterestsandetcetera.com/store/


Do I need to place a glass underneath the FEP so it cannot deform ? Or do i need to stretch it very hard ?

Puzzled.

If your FEP is not under a good amount of tension it is not going to be flat and you are going to get sagging in the middle of the vat floor. BTW you got the FEP from me and it works flawlessly on my rig but I have the film under tension ( http://projectsinterestsandetcetera.com ... iagram.jpg - http://projectsinterestsandetcetera.com ... p-flexvat/ - http://projectsinterestsandetcetera.com ... oing-work/ )

HTL

Thanks HTL, I will find a system to make it more tight.
But Im still puzzled by this bulge. If you got a minute and a piece of FEP to spare, could you try printing just one layer without much tension, just to see if you also get the bulge,

Thanks

Hugues

Tension is the key to this type of vat. .005" FEP is a tough material it will not split under tension unless it is stretched 300 or 400 % or more. Tension makes the vat floor "rigid" just like a piece of glass, this tension combined with a sufficient "squeeze out" time between exposures (giving the resin time to flatten between the build plate and vat floor) has given me 100% successful printouts 100% of the time since I built my vat (this was no way near true before). If you can find a way to tension your vat the return will be have hassle free printing long term.

Note: the "squeeze out" time I mentioned, depending on the tautness if the FEP is the same or slightly longer than your normal layer cycle time (my cycle time with squeeze out is 3 - 3.5 sec. exposure + 7 sec. combined vat tilt/build plate rise fall/squeeze out time for 75 - 200 micron layer thicknesses, 67.5mmY X 120mmX ).

BTW I like your bike (ex owner 79 honda 750)

HTL

I second the need to have a tension device. I too use .005" FEP and it will easily 'sag' without tension. I tension mine until it sounds like a drum. I've become pretty good at sensing the correct 'pitch' of the sound it makes when strummed making sure it is equal across the entire surface. I once had big issues with not sticking to my build plate and it was due to not tensioning enough.

Will definitely design a system to increase tension.
Thanks for the info on squeeze out time, clear.
You mention vat tilt, I was under the impression your vat was fixed and not tilting. The one I'm building is fixed. Can FEP work with a completely fixed vat ?

My printer was originally built with a tilting vat (I was using Qsil on glass for the vat floor) and I just never stopped using it. Most people printing with flexvats do not use tilting. I will probably run some parts this weekend with the tilt turned off to see if there are any differences but I will probably still use the tilt for printing parts that have very large flat areas.

Would a combination of a glass base and FEP film work to eliminate all the bulging if one has a lot of resin sitting in the basin? If this would work I would assume that it will have quite the advantages: simple cheap design and would have both the advantage of a hard bottom basin and a flexible one.

I'll give it a try when I can as I already scratched the sylgard coating on my newly acquired dlp printer.