tomtomtom123

In some jurisdictions, pedal reflectors are required to be legally road worthy. I have MKS Urban Platform EZY Superior quick release pedals, which only has front bolt holes and no rear holes, so it's not possible to attach rear facing reflectors. Plus, I have the MKS toe cage attached to the front, which prevents front reflectors from being attached. So I decided to 3D print a holder for the reflector lens, that hangs from the back and under the bolts that attach to the toe cage.

At first, I printed a simple uniform thickness plate for the reflector lenses to glue onto. But I thought about it, and they're easy to accidentally break off the pedals, and then I wouldn't be able to reuse the lenses since they're glued. So I decided to print a different design that is glueless, so if the holder breaks, I can print a new one and simply transfer the lenses.

Left = glued, right = glueless






Most 3rd party reflectors are an assembly of a plastic outer housing, and the reflector lens clipped inside of it. It's easy to pop the lenses out.



Almost all of the reflectors I've seen in the LBS and on the big internet bike parts shops, even on the Shimano pedals, are the same Cateye RR-1 model. However, the Cateye reflectors are missing the local certification mark, so I found some other no-name reflector that has the required markings. I don't know the dimensions of the Cateye reflector lens, but I assume it probably has a different length, height, and thickness from the lens that I chose to use. Perhaps someone knows the manufacturer of these lenses?

You can buy 192 pieces of Cateye lenses for $86 on ebay. It comes out to 45 cents per piece, but the entire package for 4 reflectors with housing cost me $3, so the wholesale price must be much cheaper:
https://www.ebay.com/itm/Reflective-...N/192349703971

The glued version

The glued version

The glueless version. It's very easy to slide the lenses into the holder. I designed a small bump in the middle to help prevent the lens from sliding out, but the nuts and bolt that go through the holes will make it impossible for the lenses to fall out.



I expect the holders to break off the pedals once in a while, either from hitting some debris on the ground, or if I accidentally step on the underside of the pedals. I printed the holder in ABS because that's the material used on my printer. It cost me maybe 50 cents to print myself. However, ABS is kind of brittle so it easily cracks. If it were printed with more flexible PA12 nylon on an SLS machine, like with Shapeways, it would be able to bend more before breaking off, and possibly survive. But it would cost maybe $5-6 to print each part with shapeways. Also, maybe it's safer to have the ABS break off in a crash, to prevent the holder from catching onto something and causing the bike to suddenly stop.



Next time, I was thinking about making a new holder with a different design, to place the rear reflector directly behind the pedal spindle, and the front reflector directly in front of the bolts, so the shape of the holder will be a very long horizontal plate, but it will be a bit flimsy and heavier. But it would reduce the change of the holder getting knocked off.

tomtomtom123

Here is the low profile version, which places the reflectors directly in line with the bolts and pedal spindle, so that it's less likely to hit debris from the ground.


I tried to design it so that if I accidentally step on the underside of the pedals, that the weight of my feet won't break the holder. But I think ABS will break. If it were nylon, then It would probably survive. I guess I'll print it out on my ABS printer and try it for a few weeks. If the design is good, I might try to print it in nylon with shapeways. (edit: actually i.materialise was much cheaper [half price], and also cloning 2 copies and connecting them with a ring made it even cheaper to print with i.materialise, about $15 per pair)

elcraft

Would it work for a set of Lyotard "Bernard Thevenet" platforms?

tomtomtom123

The version of the holder that hangs below should work on any platform pedals. But I'll print the new version with the low profile tomorrow and try it. It will contact on 3 places, the spindle body, bolts, and the bottom of the front of pedals, so that if I accidentally step on the underside, it will be less likely to break off.

Technically, the design should work on the Lyotard platform pedals. But the dimensions will be different. The main difference would be the diameter of the spindle body and it's height in relation to the bolt holes and bottom level of the front of the pedals. Plus the distance between the spindle and bolt mounting surface.

noglider 

Well done!

I put yellow reflective tape on my pedals, facing front, back, and outside side.

tomtomtom123

I printed the new low profile design. Here it is. My estimated dimensions were overall good, but missed by around 0.2-0.3mm in some places, but it was good enough. I had to use DIN 439 thin nuts because I couldn't get normal DIN 934 nuts onto the bolt because the bolts were a little bit too long and the gap to the spindle body was too narrow to fit the nut through. I used 25mm long bolts because I used 3.5mm of washer to push the toe cage forward, but if I didn't do this, then I could have used 20mm long bolts and normal DIN 934 nuts would have fit, and the 3D printed part could have been 5mm shorter in length. It was a very tight space, so I had to use tweezers to get the washers and nuts onto the bolt.

It was also a very tight fit for the 3D printed part to slip onto the bolts, because the curved "pedestal" on the 3D printed part that conforms to the curved surface of the pedal spindle body makes it necessary to bend the 3D printed part to get it over the spindle body. I was afraid that I might snap and break the 3D printed part in ABS material while trying to get it on, but it survived. Nylon with SLS printing would be more flexible and stronger, so should be easier to install.

Since the 3D printed part is somewhat large, there was some warping and shrinking around the edges of the part, due to heating and cooling in my cheap FDM 3D printer. SLS printing would be very precise with no warping. Because of the warping, 1 of the 4 reflector lenses were loose, so I added a few layers of masking tape on the back of the loose lens to thicken it and create a tighter fit.


One other thing that I did in the past was to shave the tabs on the inner side of the pedals so that I could bring my feet as close as possible to the crank arms. Rough cutting with proxxon/dremel tool and then finishing the surface with a metal file works ok, but it took me a very long time because the metal file I was using was extremely dull.

tomtomtom123

I tried stepping on the underside of the pedal to test what would happen, and the junction connecting where the wall for the reflector slot to the main flat "plate" cracked, because of bending stress. So I revised the design to add curves to the "plate", and reinforced the junction with the walls. So the crack should not happen there again. But FDM ABS is still brittle, so I expect the wall where the bolt passes through to eventually crack under stress. I think it will definitely have to be printed in nylon on a SLS machine for the part to be durable.

tomtomtom123

I printed the revised version with curved ends. I raised the front by 2mm, and the rear by 8mm. But as you can see in the images below, the rear reflector was recessed too far into the pedal which blocks some of it's visibility, so instead I decreased the change to 5mm for the next print. For the rear reflector, the curved surface and reinforced walls connected to the spindle "pedestal" should help prevent the walls from cracking when the part is stepped on. Usually when stepped on from the underside, the load from the foot will be placed on the rear reflector near the spindle, so the front reflector shouldn't have any problems except when hit by debris from the ground.

My printer nozzle got clogged, so the print got cutoff the top, but at least enough came out that I could still use it. I've now sent the new model to be printed in stronger and more flexible nylon on a SLS machine. I'll get it in 2 weeks.

2_i 

The design still looks pretty vulnerable, but who cares - this is very nice progress. Congratulations! I ride plenty at night and know from experience that reflectors make a difference. However, many otherwise good pedals lack reflectors or have them mangled. This is a very nice development. Incidentally, I have an offer of a 3D printer for the price of putting finishing touches to its construction and making it available on occasions to the donor - presumably I should look into it.

tomtomtom123

Well, FDM printing will always be somewhat brittle. Some materials would be stronger than others, but with FDM, the big weakness is the adhesion between the XY layers in the Z axis, because as you print each new layer on top, the layer below has already cooled down. There are also internal gaps where the nozzle misses to fill in, so the parts are not completely solid. With FDM, some types of materials warp more or less than others. ABS needs an enclosed heating system, which I do not have on my cheap printer. I put it in a cardboard box and pump warm air into it with a heater.

The parts that I will receive in 2 weeks are nylon from a SLS printer. The printed parts from this machine are several times stronger and also more flexible, and better resists impact loads. It's printed with nylon powder, using a laser to melt the layers. The powder is heated to near the melting temperature, and then the laser pushes the targeted powder over the melting temperature. The entire box is kept heated the whole time, and then after the job is done, the box is cooled down slowly to prevent warping. The layer thickness is also around 0.12mm so it is much more accurate, and the Z axis is not too much weaker than the XY. In contrast, my cheap FDM printer is set to either 0.2 or 0.3mm layers, and the nozzle squirts inaccurate squiggly lines with shaky motors.

The commercial SLS printer that's used by the company that I ordered the parts from is supposed to cost over $100,000 including setup and training costs. Some companies charge very low prices to print your parts on their printers, usually because they have an automatic software that will squeeze as many parts as possible that will fit into the print job, and keep the printers running 24 hours. A human just needs to swap a fresh box and replace the powder. However, the patent for this type of printer supposedly expired a few years ago, and there have been kickstarter projects with cheaper miniature versions for a few thousand dollars. But printing with plastic powder would be very messy and possibly unhealthy without a cleanroom. The powder is 60 microns (0.06mm), which is even finer than wheat flour.

(Edit: Oh, seems that some of those kickstart projects failed. And some of the new companies that actually offered working SLS machines went bankrupt. I guess there is a reason why the good machines cost over $100,000.)
https://3dprint.com/188101/low-cost-...ser-sintering/

2_i 

Death of a couple in a befriended family was attributed to CO emitted by a 3D printer, but there was a deal of ambiguity there. The case made some news.

tomtomtom123

It was supposedly false reporting

2_i 

We know the family and to the best of my knowledge the printer was never eliminated but never fully pinned down either.

tomtomtom123

So I thought about it, and a bent sheet metal part would make more sense. Here is what it would look like. I'm sure that MKS could do this easily for very cheap with stamped metal, with their own machines.

I checked the price for the local laser cutter, and 4 pieces (for 1 pair of pedals) costs $6 per piece ($24 per pair of pedals). 40 pieces and the price drops to $1 per piece. 200 pieces and the price drops to 50 cents. This doesn't include the bending service. I don't know what they charge for it. I don't want to get into the business of selling these things though.

Anyway, the weight of these 2 parts in sheet metal is around 12g per pedal. But you'll have to add the extra weight of the plastic reflector holder and their small screws and nuts, so maybe it's around 16-18g.

The 3D printed plastic part that I previously made is around 16g, plus nuts and longer bolts is also maybe around 18-20g per pedal. So the weight difference isn't much. But the sheet metal would be stronger, less likely to break, and more low profile so that it fits between the gaps in the underside of the pedal so that when you step on the underside you don't actually put weight on the metal plates. Except you'd have to bend the metal yourself, or pay extra for their bending service.

Lasercutting also sometimes leaves burn marks and globs of melted splatter material. It's fine for private use, but not good for selling.

2_i 

The fragility is in the long arms that need to hold the reflectors. What about bolting to the sides of the pedal, at least one of the reflectors, or to the top with recessed bolt heads. Even hooks going to any openings there could stabilize the structure.

Incidentally, when you glued the reflectors, what glue did you use? My impression was that teflon was used on the underside of the reflectors, to facilitate sliding, or some other hard slippery plastic, making it hard to glue.

tomtomtom123

Running the holder along the outer side may be possible, but I think it would be more likely to get caught in something on the side instead of the bottom of the pedal, and I think the size limitation of running it on the side requires it to be made of sheet metal instead of plastic. It's only possible to bolt something to the side through the slot where the toe cage strap slips through.

Bolting through the holes in the top is a bit difficult because you'd be stepping on whatever fasteners used to attach them.

I used 2 component polyurethane epoxy glue.

tomtomtom123

I got the SLS nylon printed parts today. 2 pairs. I painted one pair because the printed material has a porous surface that absorbs water and dirt. It's much stronger than the FDM ABS parts.

rumrunn6

fascinating