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SLA or FDM what are the pros and cons of each?

swamp dweller

Cast Iron
Joined
Jun 10, 2010
Location
Central Florida USA
The more I research 3D printers the more confused I get.We are a plastic injection molding company and want to prototype plastic parts before we build the molds.The majority of our parts would be considered small,about the size of a 10-32 X 3/4 bolt to the size of a quarter or golf ball at most.I'd like to get something that will hold about .002 tolerances for fitting prototypes together that need to be assembled and also have a decent finish. Every manufacturer says their product has high accuracy and great finishes but I'd like to hear from real users of these products and the problems and praises they have. I see a wide range of material costs and wonder about the cost to operate and maintain these machines after they are in use. From what I've read it looks like SLA produces a better finish and more accurate parts than FDM. What do the actual users of these technologies have to say?
 
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The more I research 3D printers the more confused I get.I'd like to get something that will hold about .002 tolerances for fitting prototypes together that need to be assembled and also have a decent finish. Every manufacturer says their product has high accuracy and great finishes but I'd like to hear from real users of these products and the problems and praises they have. I see a wide range of material costs and wonder about the cost to operate and maintain these machines after they are in use. From what I've read it looks like SLA produces a better finish and more accurate parts than FDM. What do the actual users of these technologies have to say?

Are you asking about plastic or metal 3D printers?

If plastic, Resin (SLA) seems to be the way to go for surface finish, filament (FDM) is what I use (Low cost and easy to work with) the surface finish can be quite good once your settings are dialed in, one of my cheap hobby printers can consistently do .05mm Z steps and he top and bottoms of the prints are smooth as glass in PLA, I have made parts with (coarse) threads that work perfectly, pieces that slide seem to work fine as well, perfect for prototyping within reason, you're not going to have much luck with parts smaller than say 10mm unless you have a big budget. My $600CAD printer will do small parts decently at very slow speeds, but require some attention afterwards (sanding down edges, sometimes there are little strings).

With 3D printers, you get what you pay for... sometimes... My highschool had a 3D printer that was $14,000 that claimed accuracy to 0.01mm and had no settings to change, and my hobby printer out performed it after being set up and dialed in...

If you are willing to take the time, a hobby printer can be just as (or more) effective than an expensive one.

FDM Pros:
- Cheap material (I pay $25 per KILO of filament)
- Easy to use out of the box (With limited accuracy)
- Easy to clean (no resin all over the place)
- Adjustments are very simple
- Software is usually good (I use "Cura")
- Some models with multiple heads can print different colours or in different materials at the same time (Meaning you can make a brittle PLA part with a flexible Nylon part or coating)
- HUGE community support groups

Cons:
- Frustrating if you don't have the patience for fiddling with it.
- Supports sometimes leave a messy underside (some printers compensate by using a separate support material that washes away)
- There will always be Z level ridges (The plastic bulges out slightly and makes rounded levels from each pass, usually not an issue, especially if you do some post work. but hey don't look the nicest)
- Too many printers to pick from (Many, Many knock offs, including mine, some are great, some are not)

I hope this helps!
If you have any more questions, feel free to ask!!
 
I have a lot of experience in the medical field using 3D printers. For the hobbyist, FDM is usually the cheapest method but the resolution is poor and materials are limited. But you can get into one like the Dremel, Maker Bot, RepRap, Cube, Solidoodle, Dimension etc for very little investment and the parts are okay for what they are.

If you want good resolution then the SLA printers like the 3D Systems SLA 7000 or Formlabs Form 1+ are worth a look. In addition to the cost of the machine you also have to consider the cost of materials since the resin is not cheap. These eliminate the need for supports during your build but require post-curing.

A good compromise between the two would be a polyjet printer like the Connex Objet or Stratasys Dimension. These create fully cured models which eliminate the need for post-curing, but do require cleaning the supporting structures with a water jet.
 
If you're going for the size of a golf ball at most and you want functional prototypes, I would absolutely go with SLA. Most hobby level FDM printers are going to have a minimum layer height of .1mm and a nozzle diameter of around .3mm or larger. That means that's your minimum feature size on the Z and XY axes, respectively. If you're injection molding things with thin walls or snap fits, and FDM printer will likely be frustrating because of how easily the parts snap between layers and how none of your snap fits are quite the dimensions you designed them to be. Yes, SLA can be a little messy and a little more frustrating, but I've talked with people who prototype injection molding parts and they constantly use their Form 2 while their Makerbot lays dormant.
 
If you're going for the size of a golf ball at most and you want functional prototypes, I would absolutely go with SLA. Most hobby level FDM printers are going to have a minimum layer height of .1mm and a nozzle diameter of around .3mm or larger. That means that's your minimum feature size on the Z and XY axes, respectively. If you're injection molding things with thin walls or snap fits, and FDM printer will likely be frustrating because of how easily the parts snap between layers and how none of your snap fits are quite the dimensions you designed them to be. Yes, SLA can be a little messy and a little more frustrating, but I've talked with people who prototype injection molding parts and they constantly use their Form 2 while their Makerbot lays dormant.

+1 to this post.

My first thought was "Absolutely SLA" from reading the OP. The minutia of features on the parts all but eliminates FDM from being a candidate at all.
 
Most hobby level FDM printers are going to have a minimum layer height of .1mm and a nozzle diameter of around .3mm or larger. That means that's your minimum feature size on the Z and XY axes, respectively.

My cheap FDM 3D printer will do layers of 0.05mm without problem (haven't tried anything smaller as I don't have the patience) my printer has a 0.4mm nozzle, but I can upgrade it to 0.1mm or 0.075mm

In theory since most of us work in machine shops we could make nozzles as small as we want and just change the settings in the slicer :)
 








 
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