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How "hard/tough" are the supposed hard resins for desktop SLS printers?

TwoWheeler

Aluminum
Joined
Jan 25, 2021
SLA, dammit - won't let me edit post title.:dunce:

I am looking to buy a cheap desktop printer to goof around with, making stuff for myself.

Most of what I've seen people printing are figurines and stuff, which I'm not interested in, and that seems to be the focus of the information I'm finding. No one is talking about machining/drilling/tapping the stuff. No one talks about life expectancy.

I want to make functional stuff - bike computer mounts and stuff, and maybe a few things for work, like hold downs, simple fixtures, soft jaws etc.

Would the "regular" resin be ok for stuff like that, or would the more expensive "hard" resins be better? Would a hold down and step block scaled down from a regular 1/2" milling machine clamp - scaled down to use a 1/4" screw instead of a 1/2" - actually hold small parts without breaking or being too flexy?

(Like this: clamp.jpg
 

Jeff_M_PA

Cast Iron
Joined
Oct 31, 2008
Location
San Diego, CA
I'll start by saying that my knowledge is a couple years old. I bought a FDM printer a couple years ago also to goof around with and learn the process. After reading your post, I read up on the SLA process (overview here).

Based upon what I read, if your printer is SLA, then the features you desire (like threaded holes) can be easily printed, so machining the resulting parts would seem less important. Based upon what you describe as your goal to make (which is exactly what I wanted, useful stuff), you should probably consider FDM. The resins are available in a very wide range, fiber reinforced nylon, for example (you need to make a crude dryer to use nylon which is hydroscopic). There seems to be a wider range of available resins and colors for FDM.

If you make a smaller version of a hold-down out of reinforced nylon, it would most definitely be useful for holding small parts. And the beauty if 3D printed ones that you can custom shape them to hold any part you want really well. You have to nail down the shrink you get with each resin and sometimes with each part, but the software makes that adjustment easy. I made all kinds of useful parts with mine.
 

jeffj

Aluminum
Joined
Oct 26, 2011
Location
Southfield, MI
I've used an FDM printer for soft jaws. You really need to do a 100% infill if you print stuff for tooling.
It was for stuff where precision was not terribly important, so I don't know how much it was flexing.

I've not tried the chopped carbon filament on a soft jaw, but I suspect it would work even better.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
I don't have an SLA printer, but did some research while considering getting one (for miniatures). My take-away was there can be a lot of curing issues with the common resins. Gumminess, surface tack, etc. And one of the most common resins apparently can get fairly brittle after a couple of year's exposure to sunlight (basically, going from sticky undercured to brittle overcured).

Based on what I learned, I would not use the resins available for a consumer grade SLA printer for anything mechanical that I cared about. On the other hand, there are definitely filaments available for consumer grade FDM printers which will hold up to a real beating.
 

TwoWheeler

Aluminum
Joined
Jan 25, 2021
Based upon what I read, if your printer is SLA, then the features you desire (like threaded holes) can be easily printed, so machining the resulting parts would seem less important.

I wasn't thinking these items would have an infinite lifespan, but at the same time, I don't want to print a clamp, put a screw in it, tighten it down and hear <CRACK!> the first time I use it! I'm not expecting to put a breaker bar on the screw and torque the snot out of it, just hold small parts, with a small screw.

I used the clamp as an example, because I just made myself a plate with a grid of 1/4-20 holes for holding small, oddball parts. I was going to make some hold downs out of aluminum, but then started thinking about printing them, instead. If I needed something specifically shaped, printing them would be great. On the other hand, I could make a set of generic clamps and if I needed to machine a specific step in the front for a specific job, then I could, and toss them or repurpose them when the job was done. That's why I was asking about machining the material - that, or maybe putting a helicoil or dowel in.
 

Mike1974

Diamond
Joined
Nov 5, 2014
Location
Tampa area
I'm just printing PLA on my home grade $200 printer. I made a clamp (spring loaded however, not a toe clamp style) for a guy to use with his drone controller. Printed c-sunk holes and the pockets for the spring clip. He screwed it down to a piece of aluminum and it did not crack or anything. The screw holes were thru a 1/4" of material.

Not sure what type printer it was years ago, different job. But we printed something similar to a chip fan to suck up sawdust from the cutting tool. The fan had a support ring around the outside, anyways, we tapped it and mounted to a toolholder, built a test fixture and spun it up to like 20k and it worked fine.

edit: might be worth a shot to buy a cheapy and see if that functions for your needs instead of plopping down a chunk of "real" money and finding it's not what you thought.
 

TwoWheeler

Aluminum
Joined
Jan 25, 2021
might be worth a shot to buy a cheapy and see if that functions for your needs instead of plopping down a chunk of "real" money and finding it's not what you thought.

I was looking for excuses - er- reasons to buy one to play with. I thought if I could actually make useable parts with it, then I could justify it. That's why I was asking about the hard/tough resins.

My wife already told me she'd buy it for me, but I guess I'm just being frugal...yeah, that's it. :rolleyes5:

My employer is in the process of exploring a purchase, and I know they'll buy one a helluva lot better than what I would, so I've kind of been holding out for them, but I may just buy one to screw around with. My boss offered me money for "professional development", so maybe I could tell her I wanted one to learn on in anticipation of the department getting one...and get her to pay for it.:D
 

Conrad Hoffman

Titanium
Joined
May 10, 2009
Location
Canandaigua, NY, USA
I've been disappointed with every printed part I've ever seen, either from a cosmetic, structural or tolerance standpoint. But, they don't call me Hostile Hoffman for nothing.
 

TwoWheeler

Aluminum
Joined
Jan 25, 2021
I've been disappointed with every printed part I've ever seen, either from a cosmetic, structural or tolerance standpoint. But, they don't call me Hostile Hoffman for nothing.

That's pretty much been my experience, too, but my experience has been almost solely with FDM parts - which is why I was asking SLA and hard resins.

One place I worked had an early 3D Systems FDM printer and it was garbage. It was broken more often than it worked, so they got rid of it and outsourced their rapid prototyping. Most of those were just rough mockups or throwaway parts they could make a temporary mold from, but they did get some SLA prototype parts that were pretty nice. At the time it was hella expensive though.

Here, we just had some ABS trays printed to hold circuit boards. The trays had alignment pins so they could be stacked...and almost every single pin broke off. That being said, I could see that maybe with different infill and wall thickness settings, they might have been ok.
 

RCasey

Plastic
Joined
Sep 6, 2019
I have invested quite a bit in my printer so I don't know if a lower cost alternative is comparable, but I have the Formlabs Form 2 and have made several injection molds out of 'Clear' and drill fixtures using 'Grey Pro Resin'. After repeated use I haven't had any issue with threads tapped directly into the 'Grey Pro' material and I am certainly not gentle putting the drill bushings in -- repeated slamming on a hard surface if my tolerances are a bit off.. Of course on a thin section I can purposely snap material off. Might be a bit pricier, but even after several years I am amazed with every print. If you do get an SLA printer, make sure you get a good IPA wash setup because it can be quite messy even if you are careful.
 

LOTT

Cast Iron
Joined
Nov 28, 2016
I don't have a hard number comparison, but some of that resin is pretty impressive. It seems to do better in compression than tension though.

The whole beauty of SLA is the very detailed prints, if you are then drill/tap/machining it you are using it wrong.

We have both FDM and SLA, and the FDM gets used probably ten times as much. A lot of that is speed and convenience, much less involved to get a print. It's a mix of prototypes and fixtures, shop organization, assembly aid type stuff.

SLA shines for making prototypes that you'll be machining for production, but saves all the programming and fixturing of a tricky part. You go from screen to hand and find out of it's going to work quick and cheap.
 

TwoWheeler

Aluminum
Joined
Jan 25, 2021
I have invested quite a bit in my printer so I don't know if a lower cost alternative is comparable, but I have the Formlabs Form 2 and have made several injection molds out of 'Clear' and drill fixtures using 'Grey Pro Resin'. After repeated use I haven't had any issue with threads tapped directly into the 'Grey Pro' material and I am certainly not gentle putting the drill bushings in -- repeated slamming on a hard surface if my tolerances are a bit off..

I said "what the hell?" and bought an Elegoo Mars2 Pro last Friday. It came Sunday. :eek:

I figured I'd start with the cheap, water wash resin.

I screwed up my first test print - didn't tighten the build plate set screws enough and it titled during the print.

I caught it part way through, so I brought the two goofed up parts to work. I drilled a hole in one and it machined fairly well. Then I tried to drive a brass threaded insert in...that didn't go so well. The part broke in half.

Still, for cheap resin, it's a good bit harder than expected.
 

TwoWheeler

Aluminum
Joined
Jan 25, 2021
The whole beauty of SLA is the very detailed prints, if you are then drill/tap/machining it you are using it wrong.

The reason I mentioned that was one thing I was thinking to use it for was to make a generic clamp, and then, if a situation arose where I needed to, I could just cut a step in it the height of the workpiece or whatever. Then I could just print another one, to replace the first one - unlike store-bought clamps. If I ran into the SLA clamp with a cutter - not that I've ever done that - I wouldn't really care.

Or, say, make a special foot for a DeStaCo clamp and maybe drill and tap the backside for a screw to mount it in said clamp....or something.

We don't do real production and seldom ever make the same parts again, so versatility in fixturing is probably what I see as it's biggest advantage.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
I think you'd be happier with FDM using filament of some suitable plastic. SLA prints look much nicer, but if you're planning to clamp/crush something with a printed part, make it with FDM.
 

TeachMePlease

Diamond
Joined
Feb 11, 2014
Location
FL
I've been disappointed with every printed part I've ever seen, either from a cosmetic, structural or tolerance standpoint. But, they don't call me Hostile Hoffman for nothing.

Well, I bought a cheap SLA and while I haven't set it up yet, these are prints from other users of the same printer.

anycubic-photon-3d-printer-objects-1-1500x1000.jpg


sdumoosea3d01.jpg


IMG_1507.jpg


anycubic-photon-3d-printer-objects-5-1500x1000.jpg


photon-s-24-1024x683.jpg


You can color me impressed and hopeful.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
There's no question that SLA makes prettier prints than FDM. It's why I was considering an SLA printer to make miniatures. But that doesn't mean SLA prints would be a good choice for custom clamp blocks, to take the recent example above in this thread.
 

aarongough

Stainless
Joined
Oct 27, 2014
Location
Toronto, Canada
I have been trying to find a solution for low volume production of printed parts for a while... I have a part that is very simple: a belt loop adapter to hold my knife sheaths sideways. Having these parts SLS printed in nylon by a 3rd party like shapeways works well, but the cost is silly for such a simple part, about $16 per part.

I have a delta style FDM printer at home and spent a good while playing with different materials and tweaking settings to try to get a part that looked ok and was functional, however even after lots of tweaking the resulting parts never really looked good enough to be something that I would want to send out to a customer.

A couple of weeks ago I bought an Elegoo Mars 2 Pro to see what I could do with a resin printer, this is the result:



The part on the left is FDM printed in carbon-fiber reinforced nylon. The part on the right is off the resin printer.

My initial attempt was a bit delicate as the part walls were just too thin, but after beefing them up to about 0.080" thick I am unable to break this part! This was printed in 'esun hard tough' resin which I coloured black by adding black UV resistant pigment sourced from SmoothOn. I am not a fan of the esun resin though as it has a pigment in it that tends to clump, I will be trying out the SirayaTech 'BLU' resin next and I think that will be a winner.

Cost of this part as printed is $0.86 each and the printer can actually produce them quite quickly! Because the LCD screen type resin printers cure each layer in a set time regardless of how full the layer is, I can just fill the build volume with parts and it will print in the same time as a single part. I can print 10 of these in just under 2 hours at 0.05mm layer height.

Parts off the resin printer just scream 'professional' when done right. You can print textures right into the part to make them look even better:



^ this was an example with a hex grid embossed into the surface of the part in CAD. Unfortunately I made the walls too thin and it was too delicate. I also printed it right on the build-plate which is why it has the 'elephants foot' on the near side, I've found always printing on supports gives much better results.

After seeing MANY other 3D printed parts at trade shows and so on, these are the first ones that I've seen that I think genuinely look good.

Hopefully these will be my first production 3D printed parts! I am doing some durability and UV resistance testing at the moment. Hopefully the opaque nature of the print will make them more UV resistant!

-Aaron
 

aarongough

Stainless
Joined
Oct 27, 2014
Location
Toronto, Canada
Help me with the math here.
5 parts per hour and $0.86 each as total cost to make.
Bob

I guess I should say $0.86 each in material costs? Is that what you mean? To get a total cost you'd have to include a percentage of my fixed costs, as the printer occupies space (about 1/2 square ft on a bench), and uses electricity (only about 40W).

However the number of parts per hour doesn't really figure into the cost as there's little to no labor in the parts and everything runs unattended... Post-processing would take about 2-3 minutes of hands-on time for a batch of 10 parts, so the labor involved really is minimal.

EDIT:

Other potential costs involved in the process -
1) LCD screen replacements... The screen is a consumable and needs to be replaced every 2000 hours or so at a cost of about $100.
2) Alcohol for washing parts
3) Labor for post-processing
4) Amortized cost of machine and post-processing equipment

The printer was $330. A screen replacement is about $100. Let's assume it totally dies at 4000 hours of print time (unlikely), amortized cost per hour is about $0.107

The alcohol (ethyl or isopropyl) is a consumable but you don't use much. Let's say 25ml is lost for each print. The stuff I buy is about $6 per 500ml, so cost per print there is about $0.30

The process is not at all labor intensive assuming you get the supports bang on. Let's say 5 minutes of handling time cleaning the resin tank, blending and coloring resins, removing from the build plate and curing. At $60 an hour that's about $5

Post-processing equipment (magnetic stirrer for alcohol washing and UV curing station) was about $250. Let's assume that dies every 4000 hours of print time. Cost per hour about $0.0625

So, detailed total cost for a batch of 10 parts:
Resin: $8.60
Alcohol: $0.30
Printer amortization (@ 2.5 hrs): $0.266
Post-processing amortization (@2.5 hrs): $0.155
Electricity (2.5 hrs @ 40W @ $.21/kwh): $0.021
Labor (5 mins @ $60/hr): $5.00

Total cost for 10 parts: $14.33
Cost per part: $1.43

Even at double that I think it would still be a bargain! Especially given that it's not a specialized process. I can print a mix of parts simultaneously or in series, and use the machine for short-turn prototyping as well!

-Aaron
 








 
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