Resin Printers - Review in hand

I've got a new 3D printer to review, I won't say much except that it's a resin printer.

Costs of resin printing are getting close to FFD printers opening up the prospect of much greater dimensional accuracy and finer surface finish to a lot more of us.

It would be useful for me to have some thoughts on resin printing from readers/forum members - I'm especially interested in any aspects of the machine/process you'd like to be covered.

Also, my understanding is that basic resins are a bit fragile for engineering parts. I'm interested in looking at tougher and flexible resins for longer term testing, so any suggestions welcome.

Neil

I'm not printing yet but I'm doing plenty of design stuff atm.

Very manual, with consequent slowness

If anyone has personal knowledge of a cheap decent handheld 3D scanner on the market this would massively speed up maker efficiency for 3D printer users

Some years ago I purchased a hand-held 3D scanner, which was subsequently returned because it really wasn't up to the job. I subsequently used photogrammetry in the form of Autodesk's 123D, which worked well but unfortunately is no longer available. There are other such (free) systems available that I haven't tried. The most challenging thing about 3D scanning and photogrammetry is the process of editing and refining the resultant mesh file. Meshmixer works well, but is not very intuitive to use.

Hi Neil,

I'm the convener for the Gauge One 3D circle forum at **LINK**

You'll find quite a bit of chat about resin printers and resins there, including this post from just yesterday on 'tough' resins **LINK**

I suspect that you will know the author: he is very experienced with resin printing and I trust his judgement.

As an aside, our main goal is the production of CAD models for railway items - I kept meeting folk who had 3D printers but couldn't get on with CAD sofware, so we try to design accurate CAD models for them to print. Our (new and slightly under construction) website is at **LINK**

Both the forum and the model repository are completely public - you don't need to join anything to access them but you would need an account if you want to post a message or upload a CAD model. Quite a few of our members are members here too.

Adrian Johnstone

Hi Neil,

Interested in the cleaning up process and also how easy it is to just walk in and print something. My existing FFD printer can be untouched for a couple of months and then (usually) springs immediately back to life.

The resin printers I saw a few years back gave the impression of being a potentially very messy process and not suitable for e.g. alongside my desk in my office.

Simon

The big interest for me is using 3D prints as patterns for lost-wax casting. At this stage I'm finding that FFD prints lack surface finish so a resin printer offers promise - BUT can it produce patterns in a material useful for lost-wax? At the moment I use a material called Moldlay from the USA which seems to give the foundry less trouble than PLA

Chas

Like Chas, my interest would be in making foundry patterns. Working from other peoples patterns I have had many patterns presented to me that have been 3D printed and completely useless except that I spend hours trying to smooth them due to the tiny ridges left by the printing process. Could one print in a wax type substance that could be melted and burnt out ? Can you lost wax process with PLA ? Noel

Thanks for the thoughts folks.

I know you can get SLA resin with a high wax content specifically for lost wax casting.

Cleanup seems to be something of an issue, the review will look at that. It seems the resin can sit in the printer for about a week without ill effects. I have got a washing and curing machine, but obviously that's for prints not the 'vat'.

Those links are useful too.

Rather like when I explored FFD, I'll start with what I'm supplied which is a standard resin and chiefly 'decorative' parts for models. In fullness of time, I'm keen to explore the potential for making working parts with the better definition of SLA.

I've enjoyed my first experience of the supplied slicing software. Hoping to do my first print tomorrow! Wish me luck.

Was the original SLA machine the vitrifying vat in Carry on Screaming?

Neil

For lost wax, I used a 0.001" layer height and a new nozzle with PLA.

I recently took part in a study to compare a few different additive manufacturing techniques with the aim to finding the best solution for prototyping injection moulded mechanism parts - The result just proved what we already knew and had been doing for years...STL

The output of FDM is well documented now and didnt score highly in this exercise. Visible steps and lack of ability to print fine detail meant some of the parts were not usable. I have an Ultimaker at home so was not surprised by the result however I was pleasantly surprised at how good the Ultimaker prints compared to the more industrial machines....very much user dependant!

By far the most usable was STL. These produced smooth parts with an accuracy or ~0.1mm which is in the ball park of injection moulding. The parts went together well and the job was done. Even parts done on the desktop Formlabs machine gave good results. The tough resin produced good functional parts for some of the wearable parts we were looking at.

I purchased my Ultimaker for strong functional parts for model aircraft but for model engineering and scale detail I would go with STL, probably a Formlabs machine - as seen in the Hornby series on TV.

I heard that changing resin and clean up of the machine is a pain? how practical is it to do a single small print compared to FDM.

Obviously the material is sensitive to UV so how well does it perform outdoors all day? assuming painting helps here? I currently outsource all my STL prints for work and have been advised to not leave them by the window for more than a few hours as this will degrade properties.

Lost wax prints are very popular at the moment and outsourcing 3D prints is expensive because the process is slow and raw material costs are high so printing your own pattern may save money but we should not forget the casting knowledge required to produce a good pattern so some level of learning should be expected before receiving wonderful usable lost wax castings - probably scope for another article!

I would have thought wax patterns were very forgiving of design as with lost wax/pla you don't have to think about how to get them out of the investment so undercuts and no draft are not a problem like they would be with traditional non burn out patterns used with sand.

Michael makes a very valid point ! Even if you have a perfect 3D pattern, you have a long way to go to getting a good casting, if your casting it yourself.

For me 3D printing took a severe knock when a printed assembly was left in a warm car on a sunny day - I had a seriously mis shapen useless lump of plastic ! Noel.

More interesting comments.

I would imagine UV resistance is high as the polymers are 'set' by exposure to UV. If you don't have a UV curing device you can simply leave the prints in sunshine (not an easy option in Wales this March...)

Cean up etc. is all going to be part of my learning process. I expect an initial review, followed by a what I've learnt from using this machine.

Also, given the interest mentioned above, I've been discussing an article on 3D scanning with new hobby level scanners that are sub-£1,000.

Neil

Noel Shelley,

PLA is often recommended for 3D printing to produce castings for lost wax. My experience is that this did not work at all well and resulted in a high percentage of spoiled castings. I don't however know if this was due to lack of knowledge on the part of the foundry. Certainly things were much better using MOLDLAY. I could not simply change foundries because there are no foundries here in Australia that will lost wax cast in stainless in the smallish quantities I need.

In my case I make motorcycle parts in stainless steel and I need to get the best finish and detail I possibly can. Otherwise the work involved is prohibitive e.g having to polish out lines resultant from poor 3D prints. Especially when these occour in hard-to-polish areas,

As usual It is all a matter of horses for courses. I don't doubt that the castings shown in Neil's photo are suitable for his requirements but they certainly would not be OK for me.

The comments made by Jason in this post are spot-on correct! The process of 3D prints to lost wax castings has many advantages - you just have to make it work

Chas

As Chas says - use the right product. There are filaments designed for the lost wax process but cost twice as much so if you just use PLA you may waste your time as it doesn't burn out so well. Less critical on full size than a 1/24 model.
Next problem is surface finish on FDM which can be rough so for 'conventional' mould making the sand sticks to it. Just like you can't make a pattern out of raw chipboard you have to clean it up and provide a smooth surface. Again less of a problem on a full size loco wheel than a Gauge 1 one.

FDM printing isn't designed for making watch parts so don't expect fine details on your 00 scale wagon. If you want to count the rivets use resin as the process is based on mobile phone screen pixel size - about 2 thou square. But you don't therefore do everything with resin to get detail when not needed as it can be slower.

Horses for courses. (and it is Cheltenham race week after all)

I've got limited space and I don't want something messy. Real world practicality would be a key area of interest to me, and ease of setup for a novice.

I downloaded two stl files to help calibrate my 3D printer. The Ameralab print is a small city about 20mm wide by 10mm deep and 15mm high. The Resin XP2 validation is a flat plate about 40mm square by 1.5mm thick. Thats one point five, not 15, with designs on it. Looking at certain features on the prints you can adjust your printer settings to suit. Well worth it. I did print parts to use as patterns with green sand, so lots of pounding. If the pattern was fairly small I printed it as a solid. If getting a bit on the large size, I would use my cad programme to turn the pattern into a shell, then fill the shell with car filler, cheaper than resin.

Lee Webster,

Your technique of filling a 3D shell is illustrative of how versatile 3D printing can be. It would work well for sand casting but not for lost wax process because the filler would not melt out of the "wax" casting,

As Bazyle says above, the 3D prints must be smoothed for best results - all very well for 2 or 3 prints but a considerable pain if you need to fettle 20-30 prints. I do find that I never get the same quality of product using 3D prints as I get from Silicone or aluminium/epoxy moulds.

Maybe resin casting will overcome the limitations of FDM printing for my purposes - I await Neil's article with interest and I hope he covers the possibility of making prints for lost wax by the resin process

Chas

As you don't need a strong pattern to resist the Pounding Lee mentions when using lost wax you simply print a pattern with minimal internal structure so less resin used and less to burn out.

If you are doing 20 or 30 sand castings with FDM then better to print an oversize master pattern and cast an aluminium pattern from that which can have it's surface refined and then used to cast the rest. If lost wax then if the part allows print a negative mould and make a batch of waxes or make a silicon mould from a resin print and make waxes in that.

Making a negative mould is very interesting! as this would make multiples cost effective.

3D printing brings manufacturing readily in to peoples homes and once CAD is learned is very simple and relatively cheap. If casting aluminium patterns was an outsourced job it would be far too expensive and likely go on the CNC milling machine as machining aluminium is cheap - obviously machining steel and cast iron is a different story.

....if you can do everything yourself then the only cost is your time....