SRAM PF30 Crank Preload Adjuster Compatible System
Description
TL;DR Tested. Works. Slice somewhere between 0.15mm and 0.28mm. I recommend 0.15mm, 3 shells, and concentric infill and surfaces. No supports needed. V4 is the best. The hardware required for V4 are three M1.6 * 8mm screws with three standard hex nuts. The printed adjuster thread is different than the original. FreeCAD file included. So what is here? 1.) I made a copy of the original adjuster. The stl file for it is included, but it is not setup for printing. The thread was made using FreeCAD's Thread Profile workbench. I didn't find any references that listed the original thread size. I measured a minor diameter of 32.3mm and a thread pitch of 0.75mm. 2.) My main goal was to make a replacement adjuster that included some kind of metal threaded fastener instead of a stupid self tapper. My first modified version is included as an stl file only. It is a little bit larger than the original adjuster, is easy to turn by hand, and is designed for FDM printing. This was designed for M1.4 * 5mm hardware. If you really really want to reuse the original thread sleeve, maybe try this print...if you also have some M1.4 hardware laying around. This is really stretching the limits of the M1.4 hardware. I broke off some hex cap bolts before switching to philips. It is also a bit too much stress in the thickness of supports around the clamps. I had one fastener pull through the print, but this was also printed at 0.28mm layer height instead of 0.15mm. 3.) After some of the issues with V1, while riding, it dawned on me that I should just replace the factory spacer and thread sleeve on the non drive side and make a two part assembly instead. The extra design space would give me the room I needed to bump the hardware up to M1.6 while still keeping the diameter small. The original adjuster is 49mm. The V4 version is slightly smaller. 4.) I mostly wanted to stop stripping out the rusty screw from the original adjusters that I've replaced half a dozen times, and wanted to stop having issues with preload every time I ride in the rain. For this reason I tried to make a little cover and some plugs that cap over the bolt holes. The plugs have little pockets to make them removable with a sharp tool. They also have retention built in. I'm personally using stainless bolts, but they are still slightly magnetic, so a little extra protection seemed like a good idea. Additionally, the nuts are inserted from the inside thread side of each part and the screw holes are blind. Be careful about how you slip the nuts into their slots. A nut hex point needs to be pointed out from the slot opening. In other words, the sides of the nut in the slot must be flat as the nut is pushed in. While the nuts have a slot for insertion, once they are in position, the screw will pull them into a fully enclosed recessed seat beside the slot. The slot is sized 105% larger than the final seat. Be careful not to damage the adjuster thread while inserting the nut. 5.) You will also need my little tool for adjusting the preload. It has a center hole for inserting a precision screwdriver or any other ~3mm diameter object. It also has a side slot for a 19mm box cone wrench. These are available if you would like to set preload in a way that you can feel the tension and position of the adjustment. 6.) I included a bunch of spacers and premade sizes. If you have a crank that only came with a 13mm spacer on the drive side and have trouble with your front derailleur travel, print out a range of spacers. Setup your crank as close to the frame as practicable. Once you find a good setup make a single custom spacer for both sides. For my Felt AR I ended up using an 11mm on the drive side and a 3.8mm NDS spacer. In conclusion, I have only ridden V4 for 2 days and around 50 miles so far, and all revisions for 6 days. I do not expect to have any issues but if I do, I will not hesitate to take this page down or make changes accordingly. I'm an ex-buyer for a chain of shops, and have ridden very close to daily since 2009.
Statistics
Likes
0
Downloads
0