Peppersass wrote:Caution: In case it isn't obvious, this mod is designed for the Monolith Conical, not the Monolith Flat (and maybe not the Max, either, but I don't have one of those to check.) However, with some patience and care it can be adapted to work on the Flat.

After Neel put a pair of these in the mail for me, I realized that there could be differences between the Monolith Conical and Flat portafilter holders. And, as I found out when the mod pieces arrived, there are indeed differences. I would have realized it sooner had I examined the photos in this thread more carefully, but I didn't.

The biggest difference is that the horizontal fork support channel is open-ended on the Conical but not on the Flat. That means the retaining pieces can't slide into the channel from the ends. It also means the small vertical strut that holds the piece in the channel prevents insertion into the channel on the Flat.

Figuring I had nothing to lose, I cut off the vertical struts. That allowed each piece to slip into the channel from the rear, and luckily the topography of the piece matches the shape of the Flat's channel. The fit is tight enough that the piece has to be snapped into place, but once that's done it slides freely in the channel. Unfortunately, without the vertical strut it isn't held very securely and can be pulled out fairly easily. Fortunately, wedging it against the end of the channel with the associated fork holds it in place.

Unfortunately, this means there's only one fork width that works, and it wasn't quite wide enough to accommodate my bottomless portafilter. Part of this is due to the fact that the fork channel is closed at both ends, which reduces the available width by a few millimeters at each end. So I shaved a bit of plastic off the inside edges of the mod pieces where they contact the forks in the channel, just enough to widen the gap to fit the PF. The mod pieces could accommodate a narrower PF by using some shims on the outer edges of the mod pieces.

The other difference is that the forks on the Flat are slightly longer. I was able to get around this by shaving off some plastic from the inside surfaces of the retainers. This was tricky because removing too much plastic would cause the pieces to sag and not retain the PF, while removing too little would prevent them from springing back enough to hold the PF in place. I ended up with a decent fit by shaving a little at a time and slightly bending the arms to keep them from sagging. I ended up with a situation where I have to push each retainer up to snap into the proper position, but they stay there. They do bend down when I insert the PF, just like in the video, but they don't spring back up automatically (one doesn't, one almost does.) So I have to push them up, which snaps them into place. From there, they prevent the PF from falling out of the forks, which is the most important feature. When I remove the PF, the retainers bend down without my needing to help them, just like in the video, but they have to be pushed back up into place for the next time.

All in all, I like it better than my 3M tape mod, which sometimes doesn't work. Also, it works quite nicely with both my bottomless PF and my spouted PF, which is a little narrower.

This experience has caused me to consider finally getting a 3D printer to see if I can design a set of retainers that will work with the Flat. Dealing with the fork length issue should be straightforward, but dealing with the shorter closed channel problem isn't, making it difficult to find a shape that will provide a little more width but still securely hold the retaining pieces in place. One idea would be to dispense with having the piece slide in the channel and instead have a tab with a hole that allows the piece to attach to the fork with the screw that holds the fork in place (a longer screw would be required. The piece could have a hook that slips into the channel from the front on the other side of the fork that keeps the piece from rotating. It could be thin enough to allow a fork width that would accommodate even the widest PF.

Any recommendations for a 3D printer in the $500 range that can do a good job printing these?

Perhaps the subject line of this thread should be changed to include the word, "Conical".