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ABS or not
Posted: Sun Dec 26, 2021 12:40 am
by GAP
I am looking to printing some of these but the designer states that they must be printed in ABS.
https://www.thingiverse.com/thing:1989545
I do not have and therefore no experience with ABS but I do have PLA.
In peoples opinion is there any reason why I could not use PLA instead of ABS?
Durability perhaps?
Re: ABS or not
Posted: Sun Dec 26, 2021 5:24 am
by philipy
I suspect the 'requirement' to use ABS is more to do with flexibility than durability. PLA can be a bit brittle particularly in smaller sized components and is certainly less flexible than ABS.
However if you have PLA available, it might be worth doing some initial prints with it to see what happens and if it is a problem, the cost of any wasted prinst is negligble.
Re: ABS or not
Posted: Sun Dec 26, 2021 9:33 am
by Trevor Thompson
An interesting question.
Exactly what is it that you want to print? Without knowing what it is it is impossible to answer the question properly.
I use (as regular forum users know) ABS almost exclusively. That doesn't mean it is easy to print with. In generic terms unless you have an enclosed cabinet around your printer it isn't worth the trouble of actually buying ABS filament. It has a tendency to crack and warp while printing - especially if you are printing something tall.
If we know the detail of what you want to print we might be able to see why the designer wants you to print it in ABS.
Trevor
Re: ABS or not
Posted: Sun Dec 26, 2021 10:08 am
by GAP
Trevor Thompson wrote: ↑Sun Dec 26, 2021 9:33 am
An interesting question.
Exactly what is it that you want to print? Without knowing what it is it is impossible to answer the question properly.
I use (as regular forum users know) ABS almost exclusively. That doesn't mean it is easy to print with. In generic terms unless you have an enclosed cabinet around your printer it isn't worth the trouble of actually buying ABS filament. It has a tendency to crack and warp while printing - especially if you are printing something tall.
If we know the detail of what you want to print we might be able to see why the designer wants you to print it in ABS.
Trevor
This is what I want to print
https://www.thingiverse.com/thing:1989545
Re: ABS or not
Posted: Sun Dec 26, 2021 12:29 pm
by GTB
The print in question is a semi-automatic knuckle coupler for those unfamiliar with such things. This one looks a bit like the Willison couplers used on modern cane trams and seems to be designed for use with the LGB coupler mounting.
Graeme,
The design has the centring springs and knuckle closing spring as integral parts of the print. I would assume that is why the designer has specified printing it in ABS. This is an engineering polymer with predictable properties, so the spring parts will be sized to get the requisite spring strengths.
PLA is a polymer that was developed for making plastic bags that would break down quickly when discarded. I've not seen it described as an engineering polymer. As Philip said, PLA has different properties to ABS and odds are that the design will need modification to the springs, so they work reliably when printed in something other than ABS.
I guess your choice is between firing up the CAD and redesigning the print for another polymer, then experimenting until it works reliably, or persuading your printer to co-operate and print the parts in ABS, as designed.
Regards,
Graeme
Re: ABS or not
Posted: Sun Dec 26, 2021 8:44 pm
by GAP
GTB wrote: ↑Sun Dec 26, 2021 12:29 pm
The print in question is a semi-automatic knuckle coupler for those unfamiliar with such things. This one looks a bit like the Willison couplers used on modern cane trams and seems to be designed for use with the LGB coupler mounting.
Graeme,
The design has the centring springs and knuckle closing spring as integral parts of the print. I would assume that is why the designer has specified printing it in ABS. This is an engineering polymer with predictable properties, so the spring parts will be sized to get the requisite spring strengths.
PLA is a polymer that was developed for making plastic bags that would break down quickly when discarded. I've not seen it described as an engineering polymer. As Philip said, PLA has different properties to ABS and odds are that the design will need modification to the springs, so they work reliably when printed in something other than ABS.
I guess your choice is between firing up the CAD and redesigning the print for another polymer, then experimenting until it works reliably, or persuading your printer to co-operate and print the parts in ABS, as designed.
Regards,
Graeme
Thanks,
My printer and I have a love/hate relationship (we both love to hate each other
) so I will not push my luck with ABS at the moment.
Would the springs need to be thinner or thicker to work with PLA?
Another Graeme
Re: ABS or not
Posted: Mon Dec 27, 2021 7:01 am
by GTB
GAP wrote: ↑Sun Dec 26, 2021 8:44 pm
My printer and I have a love/hate relationship (we both love to hate each other
) so I will not push my luck with ABS at the moment.
Would the springs need to be thinner or thicker to work with PLA?
Pretty much describes my experience with CAD programs..........
I've never used PLA for anything but carrying shopping as far as I know, but looking at the properties it seems to be less flexible than ABS, so I'd guess the springs need to be thinner. No idea by how much though, as designing springs is above my pay grade. Philip thinks it is brittle in thin sections, so that probably means a trade-off between flexibility and fragility
My approach would be to print out a couple of sets in PLA and start testing, reducing things by a bit at a time until you are happy with the performance, then make any changes in CAD.
Graeme (GTB)
Re: ABS or not
Posted: Mon Dec 27, 2021 8:31 am
by philipy
GTB wrote: ↑Mon Dec 27, 2021 7:01 am
My approach would be to print out a couple of sets in PLA and start testing, reducing things by a bit at a time until you are happy with the performance, then make any changes in CAD.
Yes, thats pretty much what I had in mind when I suggested some trial prints.
Re: ABS or not
Posted: Mon Dec 27, 2021 9:54 am
by GAP
Printing in PLA it is, I'll just have to perform a large number of user trials.
Good thing the Australian Open tennis starts mid January, SWMBO is a tennis fan and I can do all the testing I want while she is occupied.
Re: ABS or not
Posted: Mon Dec 27, 2021 10:12 am
by Trevor Thompson
I think it is probably worth while trying to get this to work as designed. I am not convinced that changing the material will actually be successful. It really looks like a well thought out set of components.
Lets just think about how you might do it. I assume that your printer is an open machine. We talk about using an enclosed machine for ABS - but we live in a cold damp climate. Printing in ABS requires the material to be kept warm while printing. I presume that you are in mid-summer in a part of the planet which has hot summers. Keeping the environment around the printer warm might not be a problem. The prints are not very tall - I would give it a try in ABS.
This is something you will want a lot of - if it works, so it is worth a bit of experimentation, and it might take less experimentation in ABS than in PLA.
If you do try to print in ABS - I would recommend using a raft - bed adhesion is likely to be your first problem.
Trevor