LittleRP proving to be a waste of time!

Forum dedicated to discussion and technical support centered around the LittleRP affordable, open source 3D resin printer.
hirenashra
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LittleRP proving to be a waste of time!

Postby hirenashra » Fri Jun 17, 2016 7:24 am

Over the past few months of owning it, I've come to the conclusion that it's just not worth this much effort. Over those months, I've probably had three or four relatively good prints. The resin that worked the best was FunToDo Black and I achieved one successful print with the Vorex.

As a jewellery designer I was hoping to get to use the Waxcast formula, so far this has proved to be futile too!

I've tried everything humanly possible to try and get this thing to work. Scored/roughed up the build plate, tried levelling the Z arm to the VAT, gone through 2 sets of seals and FEP, tried different tensions on the VAT...... All useless!!!

I should be doing my jewellery at the bench, instead I'm using it up calibrating the printer to the point that I'm exhausted.

I give up...

I may sell this printer very soon....

Sorry to rant....

HTL
Posts: 101
Joined: Thu Feb 06, 2014 3:19 pm
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Re: LittleRP proving to be a waste of time!

Postby HTL » Fri Jun 17, 2016 9:29 am

hirenashra

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Edit: I have read a couple of your other posts and I believe the problems you are having are because of over pigmented resin or a "high" first layer. If you are doing 80 second base exposures and the parts are not sticking to the build plate the resin is over pigmented and/or the first layers are high (the gap between the build plate and FEP film is too high). My suggestion is to dilute the pigment concentration of your resin. Also you may want to adjust the zero position of the build plate (first layer) to actually touch the FEP film this will insure there are no high base layers. (if your build plate is large enough a trick is to rotate the build plate a bit so that 4 edges of the build plate sits on the lip of the tensioning riser then zero and level from there.
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I am the designer of the vat you are using if it is the LittleRP flexvat. Lets take some time here to do some troubleshooting. I have sold about 140 of these vats to users of all kinds including jewelers who use them successfully every day.

A few questions:

when a print fails how does it fail, does it detach from the build plate, does one side or another not cure correctly, are you having layer failures, please give as much information as possible

what is the model of projector you use

what is your exposure time

are your base layer exposures (build plate attachment layers) the same as the rest of the exposures.

Your post indicates that you might be having a problem with parts detaching from the build plate or layers failing. One thing I can suggest right off the bat is for you to use 3 or 4 very long base layer exposures of 30 to 60 seconds. Long base exposures do two things they thicken the resin cure depth and long base exposures give the resin time to squeeze out from under the build plate into a thin layer since the base exposures are those most likely to present the full face of the build plate to the FEP film. Long exposures will not hurt the FEP film if your layers are of normal thickness. Also, black is a very finicky color for printing, the pigment in the resin not only colors the resin but also controls the thickness and degree of cure of the resin, for example, lets say you are exposing a puddle of clear resin (no build plate) and the resin cures to .2mm thick, if you add pigment and repeat the same exposure test the thickness of the cured layer will decrease depending on the amount of pigment you add, if you repeat this test and double or triple the exposure you will find that the thickness of the pigmented exposures will increase quite a bit less than you would expect, in fact the thickness of the exposed resin will not increase by much no matter how much you increase the exposure. This is actually a very useful property of pigmented resin in that you can have very precise control of your layer thickness and their degree of cure by increasing or deceasing the amount of pigment in the resin. Highly pigmented resins will cure thin layers no matter how much you increase the layer exposure time less pigmented resins allow for thicker layers for a given exposure so pigment "limits" resin cure thickness over a wide range of exposures.

Since you are using black resin the problems you are having may be the result of the resin being over pigmented (layer cure too thin) so you may want to dilute the pigment concentration of your resin, this is how I do it: let your resin sit until the pigment settles out, pour the clear resin into a container, shake up the settled pigment and pour half (more or less) into the clear resin, mix the resin and make some tests. When testing add pigment until you get the print quality you want.

BTW I use yellow resin, I find that it gives me the best control of layer thickness when I tweak the pigment concentration.



HTL
Last edited by HTL on Fri Jun 17, 2016 12:21 pm, edited 1 time in total.

hirenashra
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Re: LittleRP proving to be a waste of time!

Postby hirenashra » Fri Jun 17, 2016 12:14 pm


HTL
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Re: LittleRP proving to be a waste of time!

Postby HTL » Fri Jun 17, 2016 12:58 pm

Hiren

I am not sure if you were using my vat so this is some advice for people who are using or are considering using self printed vats:
If you FDM print a vat the infill value of all of the parts should be very high absolute minimum 50%, I suggest using the highest infill you can manage or even solid because these vats have to be able to highly tension the FEP without distorting and they must clamp the FEP tightly. Lightly tensioned and clamped vats will not work well . My new larger vat in fact uses an aluminum base plate and clamp plate (see the current top post at ) because I found that LittleRP sized vats are about as large as you can go using all plastic and still maintain a high tension on the FEP (BTW my vats are solid cast polyurethane, a very rigid plastic).

Double gasket the FEP film, use a gasket above and below the FEP.

When you tighten the clamp plate make sure the gaskets are fully crushed

Tension the vat until when you strike it (the vat not the FEP, you will make dents in the FEP) it makes the sound of a high pitched drum.

HTL

hirenashra
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Re: LittleRP proving to be a waste of time!

Postby hirenashra » Fri Jun 17, 2016 1:09 pm

Attachments
IMG_20160617_173714.jpg

hirenashra
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Re: LittleRP proving to be a waste of time!

Postby hirenashra » Fri Jun 17, 2016 1:12 pm

How do I zero the build plate with the default build plate? It's not that big.

Also, how do you lessen the pigment in heavy pigmented resin?

Just to add, I'm using your VAT. I don't have facilities to print my own unfortunately.

Thanks.

HTL
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Re: LittleRP proving to be a waste of time!

Postby HTL » Fri Jun 17, 2016 2:42 pm

see the second to last paragraph of my first post, it covers diluting resin pigment.

Increase the tension on your fep, it appears to be low (make sure the gasket and FEP are tightly clamped, the gaskets should be fully crushed).

you may need to raise you vats zero position a bit. You will have to consult the LittleRP documentation for this but try increasing the vat tension first

HTL

color65
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Re: LittleRP proving to be a waste of time!

Postby color65 » Fri Jun 17, 2016 5:12 pm

Hello,
I am not a LitleRP user, I have a mUVe 3d printer, but I have had similar problems with castable resins like B9 Cherry and Emerald green. These resins has a big viscosity and to be sure that the first layer will stick to build plate, I made a modification of G code for the first layer. The trick is to add a big pause before exposing the first layer, if you home your build platform to the bottom of the VAT and wait about 1 minute you will see how the amount of resin between plate and FEP significantly reduces. This is helpful in case your first layer not sticking to the build plate, if your print fail after 50 or 150 layer, there are many other reasons, like FEP tension, exposure time, mechanical issue,etc.

HTL
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Re: LittleRP proving to be a waste of time!

Postby HTL » Fri Jun 17, 2016 5:43 pm

The very high FEP tension my vats are designed to produce tend to take care of the resin "squeeze out" problem even on base layers especially if you use long base exposures (the base exposures and regular exposures can be different in CW). The .005 (.127mm) FEP used on my vats is an extremely tough material, you will probably break the vat before you split it under tension .

BTW the flexvat should sound something like this (strike the vat rather than the FEP though or you will get dents in the FEP, the vat shown is an old prototype) the name of the game with flexvats is high tension.

hirenashra
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Joined: Sun Mar 13, 2016 3:25 am
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Re: LittleRP proving to be a waste of time!

Postby hirenashra » Sat Jun 18, 2016 5:37 am

Last edited by hirenashra on Sat Jun 18, 2016 12:52 pm, edited 1 time in total.


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