by muzz64 Aug 11, 2017
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Brand new to 3d printing. I had no trouble printing this but I can't get the raft off the dino. I got most of it off using an Exacto knife, screwdriver, pliers etc so the legs and mouth now open but I might have hurt it in the process because they open and close but there is no 'spring' action.

I then tried making another without the raft but it didn't stick well enough to my build plate and when I went downstairs to get a drink I came back it was floating in the air attached to the extruder :-)

Thanks for your message and this is all part of the learning process.

Firstly you need to look at your raft settings. The 'raft to model spacing' is the clearance you need to change to make the raft break away easier. However, it can't be 'too easy' or the print won't stick adequately to the raft. There is also a technique to getting raft off easily and it comes from running a blade cleanly straight down between the raft and print... don't come at it from an angle. That will make it harder to remove.

As for he spring action you need to make sure you use more shells and infill. From memory 3 shells and at least 35% infill should be used. The point being more material = more strengthen and snap if you flex it. If you can use a 'linear' infill pattern than is also worth applying.

Lastly, there is no substitute for a precise slicing app and accurate well set up machine... and using quality filament. All of these things affect the result and particularly with things like this that have fine clearances and need well formed sections so they flex.

Minisaurs or Minisaurz?

Yes in hindsight I should have made it a "z" creation... :-)

I like the look, but when i printed it the legs and jar are moving, but doesnt spring back... it shouldbe this way ?

Sorry to hear your having trouble with my Minisaurs print. No they shouldn't be this way. If they are well printed the jaws will be springy when you flick the legs... they snap closed. This suggests a few possibilities:

(1) Your slicer is not seeing the spring part designed internally. If the print file generated does not include this the jaw will rotate and be floppy, not springy.

(2) Your machine does not 'bridge' well. This is essential to build the internal spring that runs inside from the back of the tail to the hip area. For good bridging you need PLA and an effective filament cooling fan.

(3) Filament can make a lot of difference... more than most people realise. There is lots of low quality filament out there that don't deal with things like this well.

I hope this helps. All the best.

Muzz64, love your design! Question, have you ever thought about maybe adding a plastic spring to the design in the belly of the Rex to add more tension to the bite even more than the spring effect or lever effect of the tail, leg and jaw assembly.

Hi Chris

Thanks for your feedback and I'm pleased to hear you like my designs. I tried several different plastic spring locations / methods when developing this and settled on the version as posted. Well printed files should result in jaws that snap and the spring movement is limited so ensure there is next to no chance it will break during use (PLA is brittle and will crack when bent too far).

The spring extends from near the back of the tail... joins the leg/hip then extends from the other side of the leg/hip on to the lower jaw. It needs length in the spring component to achieve enough flex so it bites / snaps. When I tried alternatives with less length in the spring and/of other configurations the result simply wasn't as good.

My prints all have a definite 'snap' to the jaw action if you hold the Minisaur by the tail and flick the leg... scaled up 120% helps as well compared to the standard scale (...but many people on here like small prints).

Comments deleted.

Why do you recommend a raft?
Considering you print in pla, I don't see a benefit in printing with a raft.

Up to you but I usually recommend it as some users report damaging their prints when removing them from the build plate if they don't use it. A good (well sliced / set-up) Raft should allow far easier removal of the print off the build plate plus easy removal of the model from the Raft. Mine is like that and the base surface is usually still pretty good as well.

If you're confident about getting your print off the build plate undamaged without Raft than do it...

All the best!

Oh that explains.
I have never trouble with object removal. I print on aluminum with hair spray and after the print I put the plate in the freezer. Always pops off with no damage!

I print on glass without any glue or spray and when it cools down, it pops of from itself.

Also with abs?
I use kapton foil on top of the alu plate.
I have different top plates for abs or pla.

I print on glass with PLA, PETG and ABS. Works for all materials. WIth ABS sometimes it could be, that a corner gets a little bit rounded, but it sticks pretty well. YOu need a heated bed of course, for all materials if you just print on glass with no additional glue.

PLA will make it snap better but it should be okay with ABS as long as your machine bridges well... the should work out well.

All the best

Brilliant Muzz. Love this evolution and look forward to the next! Brilliant use of the legs.

Thanks... as I'm sure you've seen I already had my Z-Rex design but this works in a completely different way and allows it to have a better bite and jaws that really snap when flicked right... and the body is fully enclosed. From my point of view a significant improvement.

Someday you'll have to reveal the Magic you use for designing these things!
I took a look at the layers in S3D and theirs some interesting things going on with the jaw mechanism. :)
Pretty awesome!!!
Thanks for another great design!

Thanks... pleased you like my latest things that bite!

Yet another terrific and fun design from muzz! The kids are going to love these. Appreciate the excellent and humorous pictures you post with your designs.

Cheers for muzz :)