Hi got our X1E last week and printing CF PLA and PET CF , really impressed with the finish
I need to print a lot of 1/2” bolts , custom design with a thin head, and Allen key fixture , printed at 100%
I’ve printed 6 prototypes and the thread works great, when i torque it a bit the head snaps off
The hex was 6mm and 3mm deep , bolt head was 3mm thick
I’ve redesigned it to 4mm hex , 3mm deep , and the head to 5mm
Printing tomorrow
Any thoughts?
Would CF nylon be better?
Thanks Dean
Where the threads meet the head is always going to be a weak spot.
You might need to re-design with a fillet to help relieve stress.
Remember, more walls are better for strength then a higher infill.
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When I need strong bolts, I use the cut tool to cut along the length of the bolt and print with the new cut faces down and glue together when done.
I need 3000, so not so easy, i understand what you’re saying
You’ve given me an idea, I have to put a recess under the head for an o ring, i could move that out 1mm and put a chamfer between the head and thread
I’ve also put a 2mm hole down the center of the bolt , more walls
Any thoughts on nylon cf, I’ve only used PLA and pet cf so far
I haven’t used nylon or pet, so I can’t answer that.
If I read that right that you need 3000 bolts, a CNC machining them from plastic or even getting them injection molded might be faster, cheaper, and stronger? And a lot of bolts are already availavle in plastic if these are standard size?
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Layer adhesion at that size is going to be an issue as you’re finding in a vertical 3d printed part (as the thread typically dictates). For a run of 3k you might be better off machining/off-the-shelf methods for reliability in my opinion. Getting consistency across the batch and the time involved is kind of my worry and I’d pass on this job.
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Unpopular opinion - get rid of CF for whatever material you choose. It doesn’t really make the part ‘stronger’, rather the opposite and is more for hiding the 3d-printed looks than function.
Universal plastic bolts are typically made of nylon. If you want the bolts to stay tight over time, avoid plastics that creep (e.g. PLA). If this isn’t an issue and temps aren’t a factor PLA is actually great.
Regarding the snapping head, check the cross section in the head area. The inner hex combined with the ‘thin head’ (assuming it means head height) might not leave enough meat left to allow for load bearing no matter which filament you use.
As others have said - assuming this isn’t hobby stuff (resource limited), printing that amount of screws is an odd choice.
How do we upload images? Then I could show you the bolt
What is the thread spec on the bolt? Diameter of the threads, pitch, etc?
The Upload image icon will bring up a dialog box to add an image. Drag or Paste directly into the message box is usually easier, especially with a good screen capture utility on your computer.
Not unpopular with me. There was a thread recently about CF and its dust possibly being a health/lung hazard and that the CF dust even sheds from filament and not just finished parts. I’ve only got one roll of it as an experiment but it’s the last one for me.
1/2” x 13 unc so a standard thread, I’ve got the thread diallied in good adding or subtracting 0.1 mm
So you like it or you don’t? You say its not unpopular then say its your last roll
See the quote I was replying to.
Wow. If these are expected to be torqued down to much more than an inch-pound of two, you lost already because the form will be trying to stretch it at the top of the threads. Why do these need to be plastic. And for sure, CF isn’t going to make them stronger.
It’s a common size bolt available by the thousands. Check out McMaster-Carr. The link takes you to the flat head bolts with a hex socket drive. The screen shot is just a sample of what’s available. You can typically get a much better price if you call. Especially for 3000.
To get good layer adhesion and hence good strength with PETG you need to print slow and hot with reduced cooling, if the layers cool down too much or quickly it will reduce the strength and possibly become brittle.
As a rule I print between 70-100mm and around 255-265c with part cooling between 35-45% for maximum speed and overhang max around 50-70%.
Here’s my current settings for Esun PETG In white which gives very good strength to my parts. I do adjust them slightly depending on the parts I’m making but this should be a good starting point. Also make sure to do your pressure advance and flow calibrations manually as there’s a 10% error margin on the auto calibration which can make a difference to having settings spot on.
Thanks for the settings, very helpful, we got some printed in PA6-CF really strong