3D Printed Boot Grommet
 

Enthused by Ronin's thread on boot grommets, but not wanting to cut the wiring harness (because its a bit short) I finally got round to designing one for 3D printing. I can't do flexible materials yet, but after some examination the cable actually doesn't move very much at all so I've printed this prototype in PETG (polyethylene tetrapthalate glycol-modified). This is basically the same stuff pop bottles are made of so fairly robust and waterproof, although a bit of a bugger to glue.

I made it in two parts so it could be attached from either side, and the handy thing about FDM 3D printing is that the layers tend to lock together if you get the clearances right.

CAD model:

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

First prototype:

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

Tweaked it a little, made a second prototype

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

Fitted it in place:

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

From the inside - I removed the tail light so I could see what was going on

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

Now glued together with silicone. Polyurethane panel adhesive would be better, but I didn't have any so I'll see what the silicone does.

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

Same sort of deal for the boot lid, but this is just a single piece which presses in place since you can't get to the other side. This one needs warming up a bit with the hot air gun to soften it as the panel isn't flat. I pressed it in place while it cooled, and then stuck it in with silicone.

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

This is in General Vod btw who is off to be a daily driver in a week or so, so the new grommets will get well tested +++ I will report back on how they last.

Brilliant work. +++ (worked out a price yet?)

Talking of movement, the lower grommet into the wing is pretty static but not the upper one.
I've cable tied the cable/tube to part of the hinge mechanism so that movement at the boot lid end is minimal and just sealed it with mastic.

If you send me the .stl file or what you have then I can print it for you in flexible filament (ninjaflex). I am designing grommets for the aerial and the central locking rubber boots at the moment, since I have issues with both.

I did a quick and dirty CAD in Tinkercad for the aerial last night:

Attachment 22771

Attachment 22772

As you can see in the second pic, the ninjaflex is quite flexible.

What are you using to do your CAD?

Thanks. I have an E3D Hemera sitting on my desk waiting to go on my CR-10 so I can print TPU and nylon eventually. Just haven't got round to it yet :rolleyes: I tried it accidentally on my Ender 3 when a supplier sent an incorrectly labelled sample. It printed, but welded itself to the bed!

I use Fusion360 for design. You're welcome to this STL if you want to have a go at printing it in Ninjaflex. I'm not sure how it would behave with that though as it's designed for PETG so it locks together (to an extent). I would expect ninjaflex to require adhesive, although this requires a sealant of sorts so maybe not that different. I would make the design quite different to print in ninjaflex from the start though so I may send you a couple of STLs to play with when I have time to tweak it.

This is what I'd do for TPU:

http://forum.a8parts.co.uk/attachmen...1&d=1579513423

Each half would clip over the cable and then be bonded together with polyurethane sealant. The completed thing could then be pushed in to the panel like the original.

You'd need support round the groove to print this though, unless you printed it vertically with support under the rebate. I don't know how TPU behaves with support though.

I have an Aldi Cocoon Create 3D printer (don’t laugh) which has been heavily modified to improve the print quality. I have got access to a Lulzbot Taz 6 and lulzbot Mini 2 at work.

My printer has a glass bed and PEI sheet which definitely stops the flexible filament sticking so much to the bed. It also has a Microswiss all metal hot end which has made printing with flexible filament a LOT easier.

If you make the 3D model to be a tight fit then I would think that you would be able to get away with simply pressing the part into the round hole with no adhesive needed. This has seemed to work with the aerial prototype that I printed last night. I poured water all around it and it does not seem to leak into the boot at least. Perhaps sealant would be prudent though +++

I am learning how to use fusion 360 but it makes my head hurt! I need more time to get the hang of it. Any files that you want to send my way would be appreciated. I can send the finished products over the drink if you like!

That looks perfect! I am beginning to suspect that you are some kind of genius MJ...:D May I ask how long you have been doing CAD?

In fusion 360 I have designed some jigsaw like connectors for multi piece objects that work quite well. It would probably work for TPU as well.


http://forum.a8parts.co.uk/attachmen...1&d=1579515342
This groove was printed with supports and was no problem to clean up (ninjaflex).

I've been doing 2D CAD for about 25 years, but 3D for only a year since I bought my CR-10S. From a 2D background the leap to extruding a 2D object in to 3D space is fairly simple, but Fusion is very different to AutoCAD despite both being made by Autodesk. I did my first 3D object in Tinkercad too but quickly found its limits and moved on to Fusion360.

Check out a chap called Lars Christiansen on Youtube - he has some great tutorials which is how I got started +++

I'll upload these STLs on to my web server and pm you the links shortly :)

That looks flipping brilliant! Well done MJ +++

Now onto the D2 fog light grills! :)

Not sure if they are still available but aerial grommet part number is 4A5035539 and I should have one if I can find it as I bought one but never got round to fitting it before gearbox failed