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Flexi Rex with stronger links

by DrLex Dec 30, 2017
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Thing Apps Enabled

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Amazing!!!!!!!!!!!! I am printing my friends them over and over.

hi can you give me a single link as a model so i can make one myself

I'm not sure how far you will get with this if you don't yet have the skills to make such part from scratch using the dimensions given on the page or by cutting it from the existing model, but here you go.

I loved this stronger version. I made a multi color version for printing on my Prusa MK3 MMU2. Worked great. I will post it. Thank you.

Are there any tutorials that anyone knows of to create this hinge? I have printed many of the various "Flexi" animals I've found on Thingiverse and this model has the superior hinge by far, but I'm not sure how to efficiently model this hinge myself as I would like to create a couple of these "flexis" myself but I don't want my hinges to turn out like so many of the others I've seen here.I want them to be like this Flexi Rex which I consider to be the most fun to play with and definitely strong enough.

is it ok if i make a 10-12in version of this
i want to prank someone

If you want to print a really big one, this may be a better option.

Flexi Rex - separate parts for huge prints
by DrLex

This was my second print ever with my brand new CR10S Pro. I removed it from the bed, and it was incredibly fluid. Didn't feel like a 3d printed toy. I will print many in the future. I love it so much, thank you thank you thank you!

20% infill. Scaled to 50%. Next one will be 200% :D

First one came out great, numbers 2 & 3 (and a TardiFlex) printing now.

Hi I just tried printing this on my Anycubic I3 Mega using default settings from Cura.
Unfortunately after around layer height 0.5-0.9 mm the edges of the links started lifting and interfering with the nozzle causing the links to dislodge from the printer bed.
I am currently using the supplied 0.4mm nozzle.
Does anyone know how to cure this issue?
Thanks Thahir

I have the same printer and the same issue. Tried several settings and dozens of prints.
Could you finally fix this issue ?

If this would really be an issue with the model itself, do you believe there would be 790 reported successful makes?
It is almost inevitable that the links will curl up a little during the initial part of the print where they are printed as overhangs. On a well-tuned printer though, this is not a problem because curling will be limited, the nozzle will push down the overhang every time, and the parts will stick well enough that they are not pushed loose.

Your problem is a combination of poor bed adhesion and excessive curling-up of overhanging parts. If you don't fix these problems with your print setup, you'll have problems printing many other models as well.

If you cannot improve your adhesion and reduce the curling by improving cooling, you could work around it by enabling Z-hop such that the nozzle jumps over the curling parts during travel moves.

Never said, my issues are caused by your model.
I know it's only caused by my printer configuration, but wasn't able to solve it - till now.
Tried also same settings, same filament on same printer model with same gcode like a friend of mine.
Only difference: I print in the basement at a room temperature of 17-18° C, and I'm sure this has an effect on the printings.
It's also not a problem with bed adhesion, as all other parts I print, stick very tight to the bed, so I can only remove them after it cooled down below 30°C.

Solution for me: I moved the model -1 mm down on z-axis, to get more area of the tail tip flat on the bed. Finally I could print it properly with this solution.
My kids love the model and don't care, that I'm missing a few layers.
Thanks for the design and the hints :-)

Sorry, it seemed like you asked to fix a flaw in the model. I do have a bad tendency to feel too easily attacked.
Good to hear you managed to find a solution. You should try enabling Z-hop though, this is likely to avoid the pieces being bumped loose and could come in handy if you encounter this problem with models where you can't use the same workaround.

If you're printing it in PLA, try enabling the cooling fan.

Great model. Turned up really nice. Printing another one just after the first one - with two kids, you can't just print one of these.

I made this with my FlashForge Finder using the standard resolution and it turned out great! I'm very impressed with the design and would love to see more flexi animals!

can you do more of these flexi models?

There are tons of these models on Thingiverse and pretty much everything I could think of has already been made by someone else. If you search for ‘flexi’ or browse through the collections and look for the ones that gather flexible designs, you'll find most of them.

Flexi Rex with stronger links
by DrLex

my printer is a prusa i3 clone,nd it prints are kinda bad,can it handel this?

Why don't you just try? It will take only about 2 hours and less than a dollar in material.

Is it necessary use support in a big scale?

How long it takes to print?

You could probably have printed at least 4 waiting for this answer! Of course it heavily depends on the settings you use.

So much fun. I love it! Printed perfectly on my Ender 3 Pro

Thanks for this design. It inspired me and my sons TardiFlex.
Because they Love Flexi Rex and they like tardigrades.

Your hinge's indications were used as a base for the design.
Many thanks for your explanations, they saved me from many trial and error sessions.

TardiFlex - The flexible tardigrade with stronger hinges (& keychain!)
by jp_math

Printed last night on my new Ender 3.
It's my second successful print from my printer.
thanks for the project, turned out great
off the bed, most links were loose, I did have to 'pop' only a couple loose.
used Cura as Splitter, printed at 2mm changing only the initial layer prints speed from 30 to 20.

Brilliant item ! It's a great way to demonstrate how FDM can create objects that would otherwise be impossible via moulding. My kids are intrigued at how it's possible to print interlocked chain links !
The 3D model itself is very well produced, so huge thank to its designer. This was one of the first items I printed on my 'out the box' Anet A8 and it gave me a lot of confidence that I've set it up OK. My only 'issue' was that the bottom layer was all fused, but I think that's because Cura added a raft (not sure that's the correct term). I've now started using Simplify3D which is giving me even better results than before (and the support feature is great) so I will try this model again.

Quick question, presumably both sides of this item should print off with entirely separated chain links which are not fused by a base layer ?

Nothing is supposed to be fused. The model should be flexible and require no clean-up the moment it comes off the print bed.

I'm printing on the Ender 3 with the Bullseye Petsfang mod and I'm noticing the first few layers (however not the very first layer) is curling up alot as it prints.. have any idea as to why this is?

Are you enabling the cooling fan on the first layers? Don't do that, only enable it at the third or fourth layer. Also there may be simply too much cooling, try reducing fan speed if possible.

Oh.. I'll try it again whenever I get the chance

Printed on my Alfawise U20 in draft. No raft or brim. Printed beautifully. No clean up needed... just jumped off the bed and flexed away. Printed 5 copies and gave them to all the kids in their Christmas stockings. Apparently Santa 3D prints toys too. Thanks for the file!

I printed this out with a 0.8mm nozzle (150%) and it was pretty good. A few vertebrae were fused, so I might try it again and under-extrude it a bit. Very cool model thanks!

This is probably the most satisfying print I have done so far. Lifted off the bed with the slightest of touches from Mr Leatherman knife and worked perfectly. Absolutely love it and so will the grandchildren. Many thanks for the stl.

Nobody has problems printing without rafts? I have tryed several approaches in Cura or Simplify 3D and cant print this part (no issues with other parts)

I am using an ender 3

i dont recall a 'raft' option, but i'm new.
I printed, as my second print, only changing the initial layer print speed from 30 to 20, printed at i think 'draft' mode of 2mm
using HatchBox Red

I did mine on an ender 3, in cura, with a brim, .15 and 15% infill and it came out fine.

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Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App
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Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App
Comments deleted.

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App
Comments deleted.

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App

Thank you for this thing! Thumbs up to you!

  • Posted with 3D Geeks Thingiverse Browser App

Anyone have a problem with the print shifting when printing at 150%? I sliced in Cura 3.6 (beta) and around the layers where the spine spikes begin the extruder just moves over and begins to print on air. happened twice in the same exact time in the print. has to be sliced wrong, at least that is the only thing I can think of.

I have just tried this print and once at 140% and once at 100% and rotated 90 degrees and it failed in exactly the same spot.. just above the spine on the last 4 links of the tail... seems very weird... not sure if STL issue or Cura slicing issue or if the pieces are moving off the bed (had it printing overnight so don't know that part)... I printed these a couple of days apart with some other basic models printing fine in between. I think I will try a BRIM to remove the part moving from the equation.

I am gonna agree with what DrLex mentioned, the end of the tail appears to have come loose from the bed causing the print to fail.
What happened to my two prints, the print head shifted and began printing over half air and half print. This occurred around 3/4 of the prints completion, and also happened at the exact same spot on both prints. Before printing the second one I had even looked at the layers, nothing seemed out of the norm. I have S3D now, but have yet to try and slice it in there to print.

I dont think it is a file problem, either Cura didnt convert the model properly, or my printer didnt read them properly.

With 740 reported makes and the knowledge that for every person who did the effort to post their make there are probably at least 10 who didn't, don't you think it is a bit implausible that this file has an error?
Your problem seems to be poor bed adhesion. The hinge links do tend to curl up a little at a certain point during the print, but this is not a problem if the pieces stick well to the bed. If they don't, then the slightest bump of the nozzle against the curling-up bits will push the piece loose and it becomes a mess.
If you have this kind of problem with this print already, you can expect more demanding prints to fail too. The curling-up of overhanging parts can be reduced by enabling the print cooling fan. Proper ways to fix the poor bed adhesion depend on the filament type and the bed surface. If you can print this torture test without problems, you won't have problems printing this Rex or other things.

Warp Test for Print Bed Adhesion

Printed with 0.6mm nozzle. hard first layer (minor holes) even at 200% scale.
3 walls - 30% Infill. the head is too heavy. the legs should be abjusted a bit further front. (5-8mm more).
So it's a very good design and my daughter love it.

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Spine fused except for neck. How do i fix it?

Try some simpler test prints to check whether you don't have stringing or over-extrusion problems.

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I love this, printed it in 200% and it looks amazing - it stands proudly on my work desk

Hello there! i just want to let You know that this print has great relaxing properetieson on autistic kids. I have few in my class and they are more calm if they have one of thease on their hands, and it is super serious. You shuld look in to it mate! And thanks for great job!

Is anyone else having issues with the top layer being too thin? It seems to be thin for me even if I tell it 4 top layers? Could use some guidance. My kids love this model and I'm printing them for their classroom prizes when they earn enough points. I print at a .2 height and 3 perimeters. I have been telling cura 4 bottom and 4 top but the top still seems thin. Thanks for the improved links as the ones I have printed so far have survived my 3 year old for several days. He sleeps with flexy rex.

4 layers should be enough for .2 layers. You should check if you're not under-extruding, this could cause the top layer to have gaps. If the filament you're using has a diameter that is considerably smaller than 1.75mm (or whatever the nominal diameter should be), too little material will be extruded unless you determine the actual diameter with an accurate caliper or micrometer, and configure this diameter in your slicer. Also if the filament is rather soft, you may need to increase the extrusion multiplier.

Thanks, @DrLex I will be selling these at the craft fair in my school. I have printed your and the original attribution paper. I really like the design.

Thank you for this thing! Thumbs up to you!

  • Sent from 3D Geeks: Thingiverse Browser for Android

Printed it in clear petg came out super.

No response so far, and it seems eBay doesn't want to make it easy to report things like this. Given the fact that this is just a small parasite, and my only contribution to this model are the improved hinges, I don't think I'll spend the effort to have my name added in small grey letters to a temporary eBay page.

Yes, I can see it from the details on the hinges. Even though it is an obvious rip-off (there is only about 60 cents worth of material when printed in a premium filament), the license doesn't prohibit selling it. However, it is in violation of the attribution requirement. The articulated slug and butterfly also sold by this person do have a tiny grey attribution message, most likely because someone already contacted the seller about that.
It is pretty annoying to see that some find it too much asked to add a simple attribution even if the model itself is for free. What's so difficult about that?
Thanks for bringing this to my attention!

Love it! My 3 year old son takes it anywhere.

I know it would probably take quite a bit of time but would there be a way to design one for girls? A Flexi-Rexi perhaps? Leave the fierce face but add a bow on the head or something? My daughter would kill to have one in pink! Just a thought!

With my new Prusa i3 pro B, at scale 100%, all the pieces are fuse together.
I still need to adjust the flow and few other things of my printer, but my advice would be to use a higher scale.

Despite all, the t-rex is really nice!

People (including me) have printed this at 75% scale without problems. You need to tune your print settings. If you already have problems with this model that has quite forgiving tolerances, it will be a lot worse on finer models…

I printed at 50% and it worked, I have one at 100% too and they look like a parent and child pairing. Printing in PLA on a Taz 6

I know, indeed I have specified that my printer is new and that I have to adjust some settings.
For people like me, I suggest to use an higher scale. The t-rex is nice and it worth the time required.

We made these as prizes for a charity event. The kids were thrilled. By far their favorite choice of prizes.

This is a great design! I made it for one of my young cousins. I was worried that it would not be able to withstand rough play, but It seems to do so very well thus far! How hard is it to apply such hinges to an otherwise unhinged model?

It will probably depend a bit on the model. The basic idea isn't difficult: just cut slots at the desired locations, and add the hinges. I have added some hints and the dimensions of the hinges used in this model to the description (because have seen some new models that still use weak hinge designs).

Love this. Just sent you a tip. Hopefully you get it all, instead of only a 50% cut from Makerbot.

My wife runs a therapy clinic. Young kids get to pick a toy from toybox as a reward for good behavior. They've bypassed all the other toys and keep coming back to this one. And this one lasts because of the bigger hinges. Well done.

How hard would it be to apply bigger hinges to another model, like the new articulated butterfly that is now featured?

Thanks for the tip! It's mostly PayPal that takes a share, MakerBot bundles the tips in a monthly pay-out to reduce the share lost per transaction.

The butterfly could be rather easily improved by adding some extra material to the outer ring of each hinge, which is the weakest part. There is no reason to flatten this part, because it has to rotate around the axle anyway. I had a quick go at this for one hinge, but doing it for the entire model will require a few hours of tweaking and fiddling. I might do it someday if I find the time.

I shrank yours to about 80%, which for some reason all the women and kids think is much cuter. No idea why! The same treatment for the butterfly makes the rod the weakest point.

I'd love to learn modelling well enough to modify the butterfly. If you ever decide to do it, let me know and I'd love to follow along!

Printed on my MP Select Mini at 120% scale, printed beautifully. No grinding or fusing issues at all. Niece and nephew love it - thanks for the upload!

Do we need to print this with support?

See the ‘Print settings’ section. The answer is: no.

Any problems with 200%? Will try it this evening, when it should work.

200% turned out great!

No, the bigger your print this, the easier the print.

What are the tolerances for this?

I'm not sure what's the purpose of your question, but the most important dimensions and clearances of the hinges can be found below, in my reply to burt_23 from Feb 11 2018.

This is my favorite print so far. Printed beautifully at 150%, I will be making more. Thanks!!

Thank you for the great model. Printed perfectly!

Thanx Dr.
I printed two very nice ones on a Monoprice Select Mini at orig size with Hatchbox green filament.
They both flex just fine.
Layer height = 0.02
Top/bottom & shell thickness = 0.80
Print speed = 60
Nozzle = 210 deg
Bed temp = 60 deg

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I printed two very nice ones at orig scale with Hatchbox green filament. Layer = 0.02, Top/bottom & shell thickness = 0.8, Print speed = 60mm, Nozzle temp = 210, Bed temp = 60 deg. It flexed fine right off the build plate and seems strong enough for a five year old.

I've printed a couple of these but end up breaking them trying to flex it! Has anybody got any tips on how to separate the links?

See the reply I made below on the question from @Aurora_Borealis.

Try scaling the model up! I printed a big one (160%) and the hinges wrok perfectly :)

Did you print them with 3 perimeters?
I printed one and the links turned out stiff ... I am printing a bigger version at the moment...

Thanks. I tried scaling to 140% and it worked perfectly!

Hey, very nice model.
I printed one and the hinges are pretty stiff, the first one the head doesn't move. What settings could I change?

This really should move freely the moment you take it off the build plate. You shouldn't even hear a crack when you try to move the parts for the first time. Some things that might be causing parts to become fused:

  • Stringing: can cause connections between the gaps. Try one of the many stringing tests available on Thingiverse, many of them also contain some hints to avoid stringing.
  • Over-extrusion: would need to be pretty severe though, but doing a calibration test would be a good idea nevertheless.
  • Curling up of overhangs: try an overhang test (again, many can be found on this site). You may need a cooling fan to combat this.
  • Poor bed adhesion: if one of the parts detaches from the bed mid-print and is pushed around by the nozzle, the hinge will be messed up and become solid. If necessary, print with a brim or raft to get better adhesion.

Hmm, the only thing I cannot exclude is stringing. But I only see tiny bits ...
The bigger version I printed works perfectly :)

Well, stringing is usually the least of these problems, and I also have problems eliminating it with certain types of PLA in an all-metal hot-end. If you wiggle the parts around, and poke in between the gaps with a needle, you can usually break the strings easily. A quick pass with a hot air gun can also help to remove the strings (but be careful not to melt everything!)

I've been watching my MPSelect Mini v2 for the last while. I sliced it using the Cura for Mac v3.2.1 and I've paused it a couple of times to try and get some of the excess material out. I can see that there are sections that are going to need dremel love - might end up fusing - something to do with the back ridges. I've verified the STL file is great. IT IS NOT the model at all - something the printer or Cura is doing, so I'm going to experiment a bit. Will post photos when it's done.

It seems that Cura had the support setting turned on. It popped off the bed and was a prefect flexy rexy just needing a bit of cleanup. Ok, a lot. I have sliced it again making sure that the supports are turned off, and I'll see how it turns out. I'm also going to try some other software and see how it behaves.

Great design and the kids loved it. Stands well and moves. So fun!

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This looks great. I'm going to eventually try to mod it so it can hold a desk cable or pen or something.

Hi thank you for this model.
sorry for my english, i speak french.
I printed a couple for my kids and they love it. Now they ask me for another dinosaure!
I can try to create it with Catia V5 but I need some information. What is the clearance you give arround the mecanism?
You design it with what kind of software?
Thank you again and have a nice day

I did not design the original model, I only modified it, and I did this in Blender (which is not the easiest program to work with). I cut up the model and reassembled it with improved hinges. I attached a diagram with the most important dimensions if you want to create something similar.

Ok nice thank you, i will try something :)

Noob question, I'm starting on 3d printer with a new matter mod-t, how do I set perimeters on Cura 3.xx ?

You can enable ‘wall line count’ in Preferences -> Settings to be able to specify this. Otherwise, you could set wall thickness to the nozzle diameter times the number of perimeters (although I'm not sure this will always do what you expect).

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Good job. I printed 10. I just couldn't stop.....

Really great job! after printed, pulled out from hotbed outstanding flexible and with stronger joints.

Tks for this remix!

Printed perfectly on my Monoprice Mini. Great design. Thanks!

I am not sure if it is just me, but it does not print the tail until 4-5 layers up hence ruining the tail. any tips?

Judging from the 49 successful makes so far, it might be just you. What software and settings are you using? Are you printing this at normal scale? If you get a preview of the print, are the layers also missing there, or is it just your printer that skips them?

I use cura, and I print on a monopolize select mini v2. So update: I tried printing again and this time it only skipped the first layer of the tail so I quickly put a piece of painters tape down and you can't even tell it missed a layer. I'll have to keep looking in to why it skips. Thanks for the file.

It may be that the model is not sitting flat on the bed in Cura.
I just printed it at 100% and 200% scale and both finished perfectly.

Printed perfectly! Awesome design, I would love to see more Flexi Creatures.

Does this scale up well?

Question to the upscalers.
Is a 7,5 hour print duration ok for 200%, or have i some settings disguised?

Yes. I made a 285%, the biggest that would fit on my print bed. Works perfectly. He also prints great down 40%.

i printed it at 50% and most of the hinges was sticked together, but maybe its my printer calibration, im too noob! but it printed well at 65% with same settings!
i bet if your printer is fine tuned you can print it fine smaller

I printed at 100% and 200% too (will post a make shortly) and both turned out great.

Yes, someone just made a 200% size print of this.

Flexi Rex with stronger links
by Ciruelo

Well that I bust out laughing - riding a roomba. Good one. Now I will HAVE to try one at 200% JUST to ride mine.