Looking for a way to add a good, strong, spring to hold things in place on a print
I have a square frame and will be fitting flat items in it. The frame is in black, the adjustable fittings are brown:
There would be 4 adjustable sides on the inside of the frame. I need one adjustable fitting on each side because the part that goes in the middle needs to be able to be kept in the center. I want to find some way to use some kind of spring action or adjustable like this:
I've thought of using springs, but I need strong springs, since there will be moderate force applied to the tile held in the center of the frame. (Moderate as by hand while working on items held in place in the center - not force like a hammer or mechanical.) I'm also not sure, if I add holes to fit springs into, how to keep the springs from easily popping out.
I'd be up to using a thumbscrew that starts on the outside of the frame, where a knurled top fits, then goes through the frame and attaches to the adjuster, like this:
I'd put in slots to fit nuts at A and B, then use a washer at C. This way tightening or loosening the thumb screw would move the adjustable fittings. The problem is I have a friend who teaches sculpture and other art classes who could use a number of these for classes. I know "idiot proof" is a myth, but I can see his students unscrewing the thumbscrews without thinking and losing them, or loosening the screw to the point where it comes out of the nut in the fitting and then having trouble lining things up and getting the screw and the fitting back in place. Still, this may be the best solution.
The end goal is to make it so, as the printed plastic frame wears down, the adjustable fittings can be tightened to provide the tight fit the frame did when new. The fittings won't ever have to move more than 1mm.
I'm wondering if there is some kind of special nut I could put in place that would not have threads on it and hold the thumbscrew in place. I don't think that'll work, though. I've also tried to imagine a way to set up the fittings so once they're in place, they'll be fitting in place and have a limited range of movement so they can't be taken out of place. I've looked at a number of ideas, but I think this is something I'm just not sure how to fit the parts together. I basically want the adjustable fittings to easily stay in place so they, or any screw or springs used to allow for adjustment, won't easily come out of this when it's in use.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
What about printing the spring as part of the inner part? A simple angled strip could be enough, or multiple. Depends how much force you need. Or a V shape. PETG is surprisingly springy.
I can even imagine a print-in-place mechanism, where the two parts are in separable, while the is the spring between them.
Also, try to search for compliant mechanisms. Those are single piece, locally make only small moves, but the whole thing can do so much. Maybe, you could find some inspiration in those.
P.S. sorry for brainstorming from phone, without actually adding any picture 😃
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
The brainstorming gives me things to look into, so thanks! I had meant to ask about how printed strings would work, something like what you mention, but there was so much to think about and ask about - and also trying to just make sure I could explain what I wanted! - that I lost track of what I did and didn't address.
I have not heard of "compliant mechanisms," so that's something to explore.
I'm not sure about printing in place if it locks the parts together. If this does well and I can sell 'em at the local supply store, I don't want to be printing things where, if a part breaks, you have to buy a whole new thing instead of fixing the problem part. I can certainly use PETG, though, and design parts that will fit together to allow for springiness.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
The main frame B, print holes then insert steel helicoils,
I use this trick all the time. But the "helicoil" kit to suit the thread for the screw requited maybe 3mm 4 mm 5 mm.
I repair so many things in metal and 3D printing, so many years ago I bought the "helicoil" kit that covers the ranges of 3 mm dia up to 16 mm dia.
3 4 5 6 8 10 12 16. mm diameters.
The kits should include individual size Tapping drill, the tap, placing tool, helicoils and the drive knock out.
In your application I would the screw in "grub screws" IE Allen screws without the head.
Normally for example a 4 mm dia screw, I will print the tapped hole to 5.8 mm dia, same size as the tapping drill dia, this allows the helicoil
tap to cut to the correct dimension.
For tensioning, suggest you find an old remote control or anything like a air freshener requiring AA batteries that have the coiled spring battery retainers.
Hope this helps.
PS For printing enclosed holes, I always use the organic support as per the prusa slicer.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
The main frame B, print holes then insert steel helicoils,
I use this trick all the time. But the "helicoil" kit to suit the thread for the screw requited maybe 3mm 4 mm 5 mm.
I repair so many things in metal and 3D printing, so many years ago I bought the "helicoil" kit that covers the ranges of 3 mm dia up to 16 mm dia.
3 4 5 6 8 10 12 16. mm diameters.
The kits should include individual size Tapping drill, the tap, placing tool, helicoils and the drive knock out.
In your application I would the screw in "grub screws" IE Allen screws without the head.
Normally for example a 4 mm dia screw, I will print the tapped hole to 5.8 mm dia, same size as the tapping drill dia, this allows the helicoil
tap to cut to the correct dimension.
For tensioning, suggest you find an old remote control or anything like a air freshener requiring AA batteries that have the coiled spring battery retainers.
Hope this helps.
PS For printing enclosed holes, I always use the organic support as per the prusa slicer.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
I'm not clear what the advantage of helicoils is over having a slot at B and slipping a nut in there.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
A quick FAG PACKET SKETCH
Use of "Helicoils"
My point being, it is best not to constantly rely on the strength of 3D printing threads
if they are constantly screwed in and out.
Hope this helps clarify the confusion you have.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
Photo added.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
Just as a footnote.
In my years of designing components for the F1, Indy Nascar cars, 2 common materials were used,
aluminium and carbon fiber (fibre) glass.
Anything that needed a bolt to be secured or released regularly (cylinder head bolts for example) always we fitted "helicoils".
On a 3D practical side, designing a hexagon pocket to fit a nut you either find it is to lose, and or worse to tight where you have to
"pull in the nut" with the mating bolt/screw causing the threads to maybe being stretched before doing there job of holding things together is in my opinion a NO NO.
I believe Prusa manufacturing do not go along with this "helicoil"approach for putting high stressed parts together, and those who have bought "assemble at home 3D printers have suffered the agony of placing a nut into a component and hoping the bolt (screw) will align.
Again. just my opinion, any high dollar printer (Prusa) for example, WOW to use a cheap method of holding 3D printed machine IE hex pockets parts is
disgraceful. maybe Prusa will have private valid reasons, I do not know. cost of the inserts ?
I am guessing 80% of this large forum members have never heard of "helicoil inserts and why should they, engineering
is becoming a lost art. The students of today go to engineering colleges at 20 years of age for MORE education and to learn what we learnt at 15 years of age.
and leave with a degree ?? in as we called in the Army clerical paperwork "blanket stackers". But watch out there's a young Chinese person about who is
going to take your job, work and you end up saying Heck WHAT HAPPENED.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
There are times I use printed threads, but rarely on a screw. I have, for example, some conduit connectors for 3" or 4" flexible conduit and my connectors screw into wall plates I make. That's big enough and low stress enough I use 3D printed threads. (Also, those are items of a large enough diameter I can't just use a screw.) But for screws, no printed threads - they're going to break easily! I've had people suggest to use metal screws going into a printed hole with threads, but it'd be so easy to strip the printed threads when tightening the screw, so I never use printed threads to fit against a metal part.
I'm figuring the helicoil could be easily installed with a soldering iron to heat it up and slide it into the hole? I remember several people suggesting that for another issue I had. (I ultimately found a totally different way to do that project and ended up not needing any screws for it at all - so I've forgotten that and might have to look my post up.)
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
Well, there are inserts to use with 3D printing and bolts. CNCkitchen is famous for them...
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
Well, there are inserts to use with 3D printing and bolts. CNCkitchen is famous for them...
I was literally just looking for those before I read your post. I was working on my design and other things and had to go out for a walk to think things over. Then I remembered the inserts people recommended before, but I couldn't remember the name. For those following, it's "heat set inserts." They work with a special soldering iron tip. Put one on the tip of the soldering iron and push where you're going to put it and it melts the plastic, the insert goes in, take the soldering iron out and when it cools the plastic solidifies and holds it in place.
Photo added.
I looked over the photo, which helped me see another issue with what I'm doing: the adjustable pieces will have to, somehow, be fastened in place to make this work. So I may need to make some tracks for them to move on. I like the spring and the adjustment screw, but I think I'll have to stick with one or the other.
Also, your thoughts on a helicoil compared to the heat set inserts in the link above? Not asking to stir things up, just comparing choices.
It very much depends on the application and on the substrate - we are talking about printed matrixes which behave differently to laid, moulded and set plastics.
Helicoils are very useful for structural connections in/through laid glass (my cases are boatbuilding not cars but I suspect many similarities) be aware there are versions designed to be encapsulated in catalytic resins and the centre removed after setting that would NOT be suitable for resin prints, read the label carefully.
Heat set inserts are best for low diameter screws under low to medium stress, especially for enclosures you expect to open from time to time, for one off case closures you may as well print a hole with many perimeters and use a self-tapping screw.
It's in the nature of printed parts that stresses that tend to open the layers are harder to deal with than those that close them so encapsulated nuts pulling closed the layers, especially where reinforced with extra perimeters and washers, will often handle stresses that would rip out inserts.
Printing female threads for metal or nylon bolts does work for medium stresses.
Although it *is* possible to print male and female threads down to M3 - don't bother unless you just want to show off - they will break; printed threads do work at larger sizes but they're better with less acute profiles, I have used them from 4mm with 2mm pitch upwards, above 100mm they are really useful.
Remember that all this depends on the plastic in use. PLA will slowly evade any continuous force whilst ABS and PETG for example, will maintain pressure.
For the OP's problem: You might simplify the process with one fixed and one moving right-angled jaw - so: <0> which would be self centreing and instead of springs line the jaws with TPE cushions.
Cheerio,
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
It very much depends on the application and on the substrate - we are talking about printed matrixes which behave differently to laid, moulded and set plastics.
Helicoils are very useful for structural connections in/through laid glass (my cases are boatbuilding not cars but I suspect many similarities) be aware there are versions designed to be encapsulated in catalytic resins and the centre removed after setting that would NOT be suitable for resin prints, read the label carefully.
Heat set inserts are best for low diameter screws under low to medium stress, especially for enclosures you expect to open from time to time, for one off case closures you may as well print a hole with many perimeters and use a self-tapping screw.
It's in the nature of printed parts that stresses that tend to open the layers are harder to deal with than those that close them so encapsulated nuts pulling closed the layers, especially where reinforced with extra perimeters and washers, will often handle stresses that would rip out inserts.
This is something I had NOT thought about at all! Thank you for another bit of info that I had not thought about. That kind of thing is just one more point to consider that helps to make better prints and increase one's experience!
Also thanks on the thoughts about helicoils vs. inserts.
I have printed some small threads and screws - wondering if I could do it and the method I've come up with for doing it by designing in Blender. I don't even have to be super-picky about slicing or printing parameters. But I don't do it and much prefer to use metal screws and add a slot in to slip a nut into place. (I've found it easier to put in square nuts, whether they're in a slot or in a recess. Sharper and better defined corners seem to help more with keeping it from turning too easily.)
For the OP's problem: You might simplify the process with one fixed and one moving right-angled jaw - so: <0> which would be self centreing and instead of springs line the jaws with TPE cushions.
So you're saying maybe make the corners adjustable instead of the sides? I'm not sure I am visualizing what you're suggestion. It sounds like making one corner so it moves in and out and let it adjust to hold what's in the center in place, but that would hold it off center the way i can imagine it.
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
It very much depends on the application and on the substrate - we are talking about printed matrixes which behave differently to laid, moulded and set plastics.
Helicoils are very useful for structural connections in/through laid glass (my cases are boatbuilding not cars but I suspect many similarities) be aware there are versions designed to be encapsulated in catalytic resins and the centre removed after setting that would NOT be suitable for resin prints, read the label carefully.
Heat set inserts are best for low diameter screws under low to medium stress, especially for enclosures you expect to open from time to time, for one off case closures you may as well print a hole with many perimeters and use a self-tapping screw.
It's in the nature of printed parts that stresses that tend to open the layers are harder to deal with than those that close them so encapsulated nuts pulling closed the layers, especially where reinforced with extra perimeters and washers, will often handle stresses that would rip out inserts.
This is something I had NOT thought about at all! Thank you for another bit of info that I had not thought about. That kind of thing is just one more point to consider that helps to make better prints and increase one's experience!
Also thanks on the thoughts about helicoils vs. inserts.
I have printed some small threads and screws - wondering if I could do it and the method I've come up with for doing it by designing in Blender. I don't even have to be super-picky about slicing or printing parameters. But I don't do it and much prefer to use metal screws and add a slot in to slip a nut into place. (I've found it easier to put in square nuts, whether they're in a slot or in a recess. Sharper and better defined corners seem to help more with keeping it from turning too easily.)
For the OP's problem: You might simplify the process with one fixed and one moving right-angled jaw - so: <0> which would be self centreing and instead of springs line the jaws with TPE cushions.
So you're saying maybe make the corners adjustable instead of the sides? I'm not sure I am visualizing what you're suggestion. It sounds like making one corner so it moves in and out and let it adjust to hold what's in the center in place, but that would hold it off center the way i can imagine it.
It sounds like making one corner so it moves in and out and let it adjust to hold what's in the center in place, but that would hold it off center the way i can imagine it.
Mentally rotate your vice 45°...
It depends on the consistency of sizing of the workpieces, if they vary you might need two moveable jaws and two hand-screws to centre it in the X direction while it should self-centre in Y. If the size is fixed one screw should be enough.
Cheerio,
RE: Looking for a way to add a good, strong, spring to hold things in place on a print
Mentally rotate your vice 45°...
It depends on the consistency of sizing of the workpieces, if they vary you might need two moveable jaws and two hand-screws to centre it in the X direction while it should self-centre in Y. If the size is fixed one screw should be enough.
I was doing that - it seemed to me like you were suggesting one corner be static and the other to be adjustable - I couldn't picture that as a way to keep it centered. But doing two corners - yes, that centers it. This breaks the idea I had in my head completely, BUT allows me to do something better, since adjusting 2 corners is MUCH easier than trying to center by adjusting 4 sides!
One thing this does is make using springs to hold it in place problematic. (Or maybe it just makes that flaw more apparent as I imagine 2 "clamps" instead of 4.)
I would LOVE to work out some spring mechanism that, as I adjust one side, moves the other in automatically.
Moving the adjustment to the corners is a great improvement on the idea. It'll take a total redesign of what I'm working on, but it's well worth it because the result is much better!