Live Z axis

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jdur
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Live Z axis

Post#1 » Wed Apr 29, 2015 5:32 pm

I just got the B9 up and running and was thinking about creating a live Z axis.

Basically what would happen is instead of the program "slicing" the material, it would have a constant progression through the model. The projector and exposure times would also reflect the movement. I believe the constant movement would adequately prevent the material from sticking to the PDMS but a moving x axis could also be implemented (assuming the entire x/y axis is level). This would allow for very fast prints and theoretically infinite resolution in the Z axis.

I take it this must have been though of and I'm just a newbie with crazy ideas?

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akgold
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Re: Live Z axis

Post#2 » Wed Apr 29, 2015 6:15 pm

Hi welcome to the forums and the B9 world

you theory is sound unfortunately with the type of floor used in the DLP process the layers are cured on the previous layer and the PDMS in the vat window allows an oxygen layer that inhibits the cure to the PDMS well most of the time it does until there is a problem with sticking to the build table, at this point between layer exposures the vat moves side ways to where the dam allows a release of suction that is formed as a result of the last layer being cured. This suction that is formed is really strong and if the Z lifts too soon the vat will go with it or at least it will pick up the PDMS on the vat and it will most likely freeze the Z arm in place due to the suction.
at least I think that is how the theory goes.

now if you try to move the Z are up during the exposure it will not move up.

There are two or three DLP printers in the works now that use this type of printing but they have not hit the market yet as they are both in testing phases.
Here is one that is doing what you want to do.
http://www.gizmo3dprinters.com.au/
I'm so far behind I think I'm First !!

jdur
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Re: Live Z axis

Post#3 » Thu Apr 30, 2015 9:24 am

Suction is only caused when the build table is below the fluid line. If this was such a concern, a pump could be added to the build table to allow resin below its surface.

PDMS sticking seems to be less of a concern since the Z axis is constantly moving. Since there are no on/off exposures, shrinkage would be less of a concern.

Seems like if it is perfected it will be a product improvement all around, rather than just a trade off.

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Robert Howle
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Re: Live Z axis

Post#4 » Thu Apr 30, 2015 10:59 am

Not true. Suction is caused by the last layer in contact with the PDMS. Amount of force to break the suction is determined by the cross sectional area. The build platform itself has nothing to do with the suction.
Dance like nobody's watching!

jdur
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Re: Live Z axis

Post#5 » Thu Apr 30, 2015 11:53 am

Suction is caused by the build table, and its viscosity dependent on the fluid (and the closer you get to a surface the higher it will become). It may not seem like a lot but place the build table in the resin and try to remove it, there will be a force acting on it.

Obviously, there is also suction on the part to the PDMS but the part is usually << than the area of the build table. This is why I recommend still keeping a couple vat sweeps until the build table can reach an acceptable height.

If the Z-axis is constantly moving (with maybe the exception of a couple vat sweeps) and the exposure is constantly on, there should be no sticking to the PDMS. The theory behind that is the resin is more attracted to the cured resin than the PDMS.

jdur
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Re: Live Z axis

Post#6 » Thu Apr 30, 2015 11:57 am

This will call for a higher level of resin to use gravitational force (you could also put the resin under a pressure) to offset the suction.

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Robert Howle
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Re: Live Z axis

Post#7 » Thu Apr 30, 2015 3:43 pm

I am officially out of this dicussion. Thanks.

Robert Howle
Dance like nobody's watching!

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akgold
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Re: Live Z axis

Post#8 » Thu Apr 30, 2015 3:57 pm

Robert Howle wrote:I am officially out of this dicussion. Thanks.

Robert Howle


Me too.
I just wanted to answer the question
I wish you luck on your path and I await to hear about your successes in the future.
If you need any advice as to help on the B9 to print using it's current config. please don't hesitate
I'm so far behind I think I'm First !!

jdur
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Posts: 9

Re: Live Z axis

Post#9 » Thu Apr 30, 2015 5:26 pm

Robert Howle wrote:I am officially out of this dicussion. Thanks.

Robert Howle


Dicussion? I never cursed at you.

I know you guys are doubters but it seems like a real possibility. My theory is with a moving Z axis and live exposure you will always have a slightly uncured material at the surface of the PDMS. As you probably know from your wisdom, the PDMS or CH3[Si(CH3)2O]nSi(CH3)3 sole purpose is to place oxygen on the surface to inhibit the polymerization of the resin which I assume is a free radical system. The reason for the VAT sweep is probably to remove the suction force you speak of as well as clean off the surface of the PMDS, rather than to re-oxidize it. There is also the possibility of using plasma to etch the surface creating a silicone dioxide layer on the surface (inhibiting the free radical system from curing), although I don't know if that will change the solubility of the resin on the PDMS surface.

You guys are in the mind set of slicing material and exposing it to UV light which is clouding your judgement IMO. You need to think of the slices becoming infinitely small to understand it.

Anyhow, it's just a matter of trying it. If I am able to do it I will rub it in if I am not I will not tell you about it lol.

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akgold
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Re: Live Z axis

Post#10 » Thu Apr 30, 2015 6:09 pm

you have just repeated everything I said using different words. if you know this info why ask about it?
as per your comment regarding cursing no one said you cursed and no neither one of us are cursing at you.
English is not your native language I take it?

a discussion is the exchange of ideas and information or compare results that is all we were doing but you seem to want to argue about nothing. IE: dis·cus·sion
dəˈskəSH(ə)n/noun
noun: discussion
the action or process of talking about something, typically in order to reach a decision or to exchange ideas.

we have no doubt in time this method of individual slice exposure will migrate to continuous exposure as I have shown here already.
if you want to pursue this method using a B9 we are all waiting to hear your result.
not many us are here to just talk theory most of us have jobs to do related to printing the items.
so helping people on a forum as much as we do is strictly to see others succeed as well as we do.

good luck and please refrain from reading between the lines or misinterpreting words of a discussion.
I'm so far behind I think I'm First !!

jdur
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Posts: 9

Re: Live Z axis

Post#11 » Thu Apr 30, 2015 6:20 pm

akgold wrote:you have just repeated everything I said using different words. if you know this info why ask about it?
as per your comment regarding cursing no one said you cursed and no neither one of us are cursing at you.
English is not your native language I take it?

a discussion is the exchange of ideas and information or compare results that is all we were doing but you seem to want to argue about nothing. IE: dis·cus·sion
dəˈskəSH(ə)n/noun
noun: discussion
the action or process of talking about something, typically in order to reach a decision or to exchange ideas.

we have no doubt in time this method of individual slice exposure will migrate to continuous exposure as I have shown here already.
if you want to pursue this method using a B9 we are all waiting to hear your result.
not many us are here to just talk theory most of us have jobs to do related to printing the items.
so helping people on a forum as much as we do is strictly to see others succeed as well as we do.

good luck and please refrain from reading between the lines or misinterpreting words of a discussion.


Lol I was just being a grammar nazi because he spelled it as "dicussion".

I will post results when I get them. I also have a job as I am president/ceo of a company that does a lot more than jewelry and my goal is only to help out the community (if I solve a problem I will gladly share it). I would rather spend some time now to be able to print in a 20th of the time. I started the thread hoping for ideas/suggestions rather than to be shot down. Or if someone has already tried it they could share their experience.

Thanks

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brumbaer
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Re: Live Z axis

Post#12 » Fri May 01, 2015 4:48 am

The idea is not new. It has been brought to broader attention under the catch phrase clip printing some weeks ago, the hubub is just receding.
It seems that the suction/adhesion problem is not solved by making minuscle steps only, as there is no product announcment imminent and all samples are of models that have small cross sections and gurantee free flow of air and resin.

Go ahead create a prototype, it will not be very difficult and can be done in software only, as long as your happy with 5um z steps. If you want finer steps you have to do some minor hardware changes.

We are all (I assume) eager to see and adopt your solution, so please keep us informed about it's progress.

Please note English is not my first language, so if this post sounds anything but neutral, it is not due to intention, but the language barrier.

Bexley
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Posts: 215

Re: Live Z axis

Post#13 » Fri May 01, 2015 7:37 am

Just encase the entire printer in a vacuum tank. No air pressure = no suction.

Of course, the resin might begin to boil...

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