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Bike Lamp Mount

by MaximSachs, published

Bike Lamp Mount by MaximSachs Mar 1, 2013

Description

I needed a lamp mount for my bike. This is what I came up with.

See the video of the creation here: http://www.youtube.com/watch?v=Ts9hvJNGRZM

Designed in catia: 45min Print time: 80min

You can find the optimized mount by pachek here: http://www.thingiverse.com/thing:67312

Recent Comments

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Thank you very much! That looks fantastic!
Sorry I made a silly mistake! I was removing material from inside so it wouldnt clamp! :) I modified the parts so now should be OK (30mm internal diameter). I have replaced the models in the link

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License

Bike Lamp Mount by MaximSachs is licensed under the Creative Commons - Attribution license.

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Just for practising I have created a Finite Element Model based on yours. I have applied a 0.5 Kg Vertical force on each Fixing Hole (total 1kg) which is way too much above the light weight, but can be considered as an "accidental" load while handling the bike. For Fused Deposition Modeling ABS Plastic I have used the average tensile strength of 18 MPa (as extracted from this nice article: ode11.com/publications/sme_rp_2001.pdf)

Results are here: plus.google.com/photos/110411608784812538591/albums/5860057738063507825?authkey=CLjkreTaptL5_gE

Maximum Displacement is 6.4 mm on the extremes

Maximum Von Misses Stress 1.39 Mpa, thus not permanent deformation (18MPa) is achieved. Maximum Displacement is 6.41 mm on the extremes.

If adding a 1.5 mm radious as shown in the images the Von Misses Stresses and displacements are slighly reduced, The Images have an scaled factors to exagerate the distortions

This is not of course accurate (the full set of analysis) since Im a beginner on this subject
WOW! That is incredible! Thank you very much. I think now we can say that the bikelamp won't fail. Since my design is waaay over designed, it would be interesting to see how far I could reduce thickness before plastic deformation occurs. What program did you use to simulate the stresses?
Yes you right, the nice approach would be to reduce the thickness as much as possible. Which weight you calculate for the light itself? do you feel the printed part as overthick, structurally?
I didnt do any calculations before designing, and just overdesigned it, since the weight difference is almost neglegible on the bike. Also the predictions of the load for the actual printed part is very hard to make, since it is not printed as a solid piece. Unfortunately I dont know how to convert the printer stl code back into a 3d model to run tests on it.
The area where reduction of thickness is most interesting to me is the mount to the actual tube of the bike. It is so strong, it cannot deform when pushed against the tube. So during assembly I had to remoove the tube run it through the mount and put the tube back in place in the bike. It would be nice if the mount allowed enough deformation to be pushed against the tube so it snapped in place.
I understand, overthickness made impossible to bend the part without breaking it. According the Finite Element software you would need to apply 30Kg of force (15 Kg on each side!) to open the hinge the enough 30mm for inserting it around the bar:

lh5.googleusercontent.com/-uwNqUUFBVT8/UVTGPbbCJ4I/AAAAAAAAQVg/HWL3xdW0acg/s1019/15mm+Displacement.jpg

Moreover doing so you will break it since the max stress would be 90Mpa when the tensile strength of the material is around 18Mpa. you can see here the obvious area where it will break on red

lh4.googleusercontent.com/-Qx0cSwfk7sI/UVTGPNj383I/AAAAAAAAQVc/5RAeqtCQRQ8/s983/15+mm+Von+Misses+90+Mpa.jpg

Being ABS it wouldnt be permanent deformation, but a brittle fracture
very interesting! Also I should have mentioned I used PLA to print the mount. I think it should be less brittle. How thin do you think I can make the thickness to safely fit it around the bar?
Now I cant find the Fused PLA mechanical caractheristics, but assuming are the same as ABS (and this is conservative since you say is less brittle) reducing the thickness down to 2 mm you can open the necessary for assembly without breaking (max stress around 7Mpa over 18Mp for fracture), only applying 1kg per side which I think is achievable:

lh4.googleusercontent.com/-vsiMM5Hm5iI/UVTOfkQ7kcI/AAAAAAAAQV4/xMwui_bseX4/s909/02.jpg

I also wider the original opening so less bending is needed (now is 12,5mm)

lh6.googleusercontent.com/-rIx7xa6Wq-Y/UVTOg9cdUkI/AAAAAAAAQWA/iXEkR088e4g/s788/03.jpg

Thus for achieving the 30 mm bar only 8.75 mm displacement should be enough

lh3.googleusercontent.com/-iy444NXHUFc/UVTOdbCV3zI/AAAAAAAAQVw/UuJI1MNsw7o/s943/01.jpg

I have uploaded the modified 3D Model here (if it is OK for you)
http://www.thingiverse.com/thing:67312

There is a considerable reduction of the material as well as the print time
Thank you very much! That looks fantastic!
Sorry I made a silly mistake! I was removing material from inside so it wouldnt clamp! :) I modified the parts so now should be OK (30mm internal diameter). I have replaced the models in the link
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