Leg Developer End Pieces
So I have a Marcy Multigym leg developer, and it is an ideal all in one bench that has an attached leg developer, the problem though is that the everytime I get on and off the machine, the foam covers on the leg developer pieces fall off.
This is due to the end pieces that hold the foam in wearing out, they are a friction fit and don't hold very well, so I wanted to try and see if I could solve this by 3D printing something
I took the following screen shot from the product website, as you can see the leg developer in the image [1] is very similar to the one I have.
Its quite difficult to make out in that image, but the foam parts of the leg developer are held on by plastic press fit pieces, which are easily removed when a little pressure is applied to them. The problem with this is that to get on or off the leg developer part your leg rubs on the foam and that friction is enough to pop those pieces out
I put this down to general wear and tear and examined the pieces that came with mine and after about a year of use (20mins a week) they have become so loose they just fall out with the slightest pressure
I think this can be put down to general wear and tear as opposed to a defect but as you can see in the close up below of one of the end pieces, it is worn down quite significantly, enough to cause them to no longer grip:
Now I could just asked the company I bought it from who has a great warranty team to send me a replacement, but I thought this would be a great opportunity to again improve my 3D printing and design skills, so instead I initially tried to create a like for like replica (with some personalised touches):
Rather annoyingly I 3D printed some tests of these but the results weren't great, I found it diffcult to get a snug fit and sitll experienced the same problem of the piece rapidly wearing out and falling out.
So I came back to the pipe tool within Fusion 360 to create a better version:
My Idea with this was to have a threaded insert that would press fit, and due to the large contact area stay in place, or if that didn't work I could reinforce it with glue/ epoxy. Then to have a screwable end cap that is screwed in tightly
The reason I wen't down this road is, that it is important to make sure that the end pieces are easily removable when you actually need to, for servicing of the foam/ metal roller pieces inside them. So glueing the original pieces in place isn't a viable option.
I printed this design (Galaxy Black PETG) and it seems to be holding up well:
I've used it a couple of weeks now and all seems to be good. Its important to note here that these end pieces are not weight bearing so are ok to 3D print without carrying out much testing on as if a piece breaks its unlikely to lead to a scenario that could be dangerous. I just want to mention that because its important to consider that with 3D printing! :-)
Initially I printed the flat design you see above as a test for the thread piece, to minimise the amount of waste of the PETG but in the end I liked the minimalstic style of the design so I kept it in the final product.
[1]"Marcy SM-4008 Smith Machine Home Gym with 140kg Weight Set Bench", Exercise.co.uk, 2021. [Online]. Available: https://www.exercise.co.uk/marcy-sm-4008-smith-machine-home-gym-with-bench-and-140kg-weight-set. [Accessed: 23- May- 2021].