3D printing surface finish help

[6axlepwr]

I just came back from visiting the JB Hunt Library at NCSU here in Raleigh. They have a 3D printing center. Definitely not useful for what I need, but I did get some useful information.

Before I go on, I have to put in this for the safety police here. DO NOT do this indoors. Do this in a well ventilated area like outside. There, that should squelch and safety posts. BTW, I stripped three more Kato shells using the motor tool and 91% isopropyl alcohol. Worked just fine and no injuries.

Get yourself a small single serving crock pot. Put enough household ammonia in it and heat it up. Use some sort of method that you can put the part on and then lower it in as well as remove it without touching the part yourself. Sort of like how french fries are made with a fry basket. I was told it only takes a few minutes and the ammonia acts like an etchant and smooths the surface. I was told that once you master this process, you can get the surface smooth as glass in many instances.

You can also use ammonia to fix cracks.

[bbussey]

What does it do to the surface relief in a scale as small as N?  I suspect that this would be problematic in that regard.

[wcfn100]

Crap, I just threw one of those out.

I would imagine this is material dependent.  What were they using it on?

What does it do to the surface relief in a scale as small as N?  I suspect that this would be problematic in that regard.

If it's consistent enough, you could compensate on the drawing (he says in his best bbussey voice  ).

Jason

[6axlepwr]

We were talking about the fine print lines. I would think though it would diminish stuff like bolt heads and small detail such as that. I have not seen it work, but I would imagine a lot depends on the soak time.I would also think that it would round off sharp edges a bit.

[pnolan48]

What is the concentration of the ammonia? Is this plain household stuff (5-10%) or more industrial strength (>25%)? Neither would be especially safe without precautions, but the reaction times would certainly differ. I think concentration would be important to know before trying this.

[Sokramiketes]

I've heard of Acetone for ABS printed models... but Ammonia is a new one. 

http://hackaday.com/2013/02/26/giving-3d-printed-parts-a-shiny-smooth-finish/

[peteski]

I love these threads!   
Also, there are many different resins used for 3D printing. Is the resin used in FUD printing the same as the stuff used at NCSU?  Did you actually try this on some FUD printed piece or are you waiting for others to be your guinea pigs? 

[Dave Schneider]

I too was wondering about the various resins. I have a couple of spare FUD pieces (handrails) with which to experiment. Where does one get ammonia?

Best wishes, Dave

[havingfuntoo]

I am going to change my name from Havingfuntoo to Motherhubard. If you are going to heat it, heat by using a water bath where you bring the hot/boiling water from a kettle where the water is heated well away from the task at hand. I think I would probably also have a covered container to hold the Ammonia water mix.

Don’t heat over direct heat.

This is an interesting turn up, I wonder if it is residual wax that is being glazed over rather than the build material being changed??

[6axlepwr]

I was told to use regular household ammonia. The kind you can get at the grocery store for cleaning. The response from this group has brought up good questions. Ones I would not have thought to ask. Especially about the type of material to use the ammonia on.

As for what type of material the ammonia works on, I am not sure. The technician did nto specify, but now that I think about it I can only imagine that he was referring to the type they work on at the lab. Guess that means I spoke out of line with information that is not 100% accurate. My apologies. The NCSU lab does not use stereo lithography. There machine uses a wire feed type of plastic or resin that works like a regular printer. It melts the wire and feeds through a print head. The resolution is not that great. Finest is 100um layer. They had some samples from the two types of machines they use. The line (layer) definitions were very pronounced. The machines they use are Makerbot Replicator 2 and one called Uprint. they both use a PLA filament. The test parts they had were of a much harder material than what I have gotten from Shapeways (FUD).  I do not use Shapeways anymore so I do not have anything to try the process out on. I was hoping the NCSU lab would produce good quality items, but not the case. Especially for N-Scale. At least with FUD, you could painstakingly work the finish to something useable. With PLA filament, no way.

Please take no offense, because I am not offended. This is my first ever forum retort, but your smart a$$ remark needs to be addressed. If it gets me kicked off the forum. Oh well life goes on.
No, I am not waiting for anyone to be my guinea pig. Peteski, is it possible in your opinion we should not even bother posting information we learn? It was my understanding that these forums were to share information and then discuss it. If you would not mind though, please post a list of rules that you would like us to follow so we do not insult your intelligence. Or should we first submit our posts to you for your approval?

I do not know about others, but to me these forums are as if we are all sitting around together discussing modeling. Someone might say "hey, I heard such and such......" and then we discuss it. Or "I was told this process would work on such and such...." and then we discuss that. Without being berated by self appointed overlords. If there is a safety issue, it can be addressed to us without being a  . Such as possibly, " I would like to offer up a word of caution on heating ammonia." Then explain why or your experience with it such as has been done on other forums I have been on with people who ARE experts in chemistry and kindly explain the why and why not of it all or the precautions to take. So I would like to ask you Mr. Peteski and anyone else with your all knowing attitude to put it away and possibly contribute to the conversation. If I am wrong, point it out with experience or proven knowledge. I will say "thank you for letting me know and educating me on the subject". I am here to learn too.

[Sokramiketes]

Don't worry about Peteski, Brian.   You're lucky he read your entire post and understood it.  Usually he kinda half reads and then posts some incoherent thought afterwards. 

[peteski]

Please take no offense, because I am not offended. This is my first ever forum retort, but your smart a$$ remark needs to be addressed. If it gets me kicked off the forum. Oh well life goes on.
No, I am not waiting for anyone to be my guinea pig. Peteski, is it possible in your opinion we should not even bother posting information we learn? It was my understanding that these forums were to share information and then discuss it. If you would not mind though, please post a list of rules that you would like us to follow so we do not insult your intelligence. Or should we first submit our posts to you for your approval?

If you think that mine was a smart-a$$ remark, then you don't really know what a smart-a$$ remark looks like.    I was simply posting my opinion about the information you posted.  I wasn't even the first one who questioned it.

My opinion? Of course.  Isn't it ok to present one's opinions on the forum? I read your post (several times, just so I didn't miss or misunderstand anything), then I commented that the information you provided seemed to be really haphazard and incomplete.  If you said that you were told (or you personally verified) that throwing bunch of Shapeways FUD printouts in hot ammonia works magic, I would have been happy as a Microtrains collector in Microtrains factory!  But as presented, to me, your info was just as valid as something I would read in National Enquirer.  That's just me...

EDIT:  If your post stated that either you only learned about this technique but haven't tried it yourself, or that you used it on some of the Shapeways FUD-printer parts and it worked perfectly, then I would have had no problems with that.

[wcfn100]

If you think that mine was a smart-a$$ remark, then you don't really know what a smart-a$$ remark looks like. 

Like you and mockery.

I was simply posting my opinion about the information you posted.  I wasn't even the first one who questioned it.

Here's your post:

I love these threads!   
Also, there are many different resins used for 3D printing. Is the resin used in FUD printing the same as the stuff used at NCSU?  Did you actually try this on some FUD printed piece or are you waiting for others to be your guinea pigs? 

What's the opinion part again?

Jason

[Philip H]

Guys,
I'm not a mod, and I don't play one on tv.  But really?  Again we have someone trying to share knowledge, who even issued the apparently now required Don't Do This at Home caveat, and we're still busting each other's nuts.  Ask for clarification when clarification is truly needed - but otherwise can we please start acting like grown ups around here?  I got tired of my toddlers acting better then the Atlas crowd, I really hope I don't see a repeat here.

[Alaska Railroader]

Is Bestine, the obvious to me, not applicable for this RP project. No heating necessary and it works wonders on the wax residue, especially on FUD.