This is not exactly true. While still nominally 4" MK4/MK4i wheel is slightly smaller in diameter than the MK3 billet wheel. Enough that for a perfect fit the overall tread length would want to be adjusted.
Below are the drill patterns for that I use when making the SDS predrilled tread. All the holes are drilled with a 5.5mm drill bit. I find that the final holes end up a bit smaller than the drill bit size.
I have not figured out the official tread specs for 1" wide 3-ply black Neoprene, but I would expect the overall length to scale by the same factor as it was the 1.5" width tread this would result in an overall length of 11.341".
One reason there’s been much discussion on this topic is that some batches of the blue nitrile had serious issues with delamination. This is the worst we saw – one or two matches on new treads:
Hi Patrick. Sorry to post on such an old thread, but I just wanted to ask, the McMaster link you shared has a black backer, but everywhere else I look it has a brown backer. Did you change suppliers or something?
220016 - SDS (came preinstalled onto spare wheels), August 2021. This stuff was awesome. We wish we could get more.
220111 - SDS (precut and drilled spare treads), March 2022. This stuff crumbled at a mid-layer within the rubber, NOT at the interface between the rubber and the fiber backing.
220127 - SDS (came preinstalled onto spare wheels), April 2022. This stuff appeared to be the same as 220111.
190276 - McMaster 5994K9, May 2019. This stuff appeared to be the same as 220016.
Any idea if 5994K9 purchased today is the same stuff? Might be worth the investment to cut our own tread if it’s the same as the old black-backed SDS tread (totally not just to go with our color scheme…)
In our experience the black Neoprene tread we currently sell (which is 5994K1) is better than any of the blue nitrile / blue Buna-N materials.
5994K9 is blue with black backing and it is better than the orange backed blue nitrile that we sell. The orange backed blue nitrile material we sell is from a different supplier. Once stock is depleted it will be discontinued and we will only sell the best stuff 5994K1 Black Neoprene.
Yes, if you order from mcmaster you will need to develop a method for slicing the tread into narrower strips.
We have clamp jigs we’ve rigged up to rip the tread on our bandsaw at a consist width. We first free-hand bandsaw to length (maybe a bit oversize), then rip it in half to get two 1.5" strips. Having a bandsaw makes the job a lot easier and safer than using box cutters on this tread.
After making coupons with the right length/width, we drop it in a hole-drilling jig to make the mounting holes.
This would probably be a good case to make a little jig to hold down the tread, to keep the blade centered in the tread, and to help keep fingers away from the blade…
I saw your jig for cutting black neoprene tread on your website and followed the onshape link, do you happen to use the Patrick W black neoprene jig or the Harrison D jig? Thanks!
