Before I dive into creating an E3D hotend mount for the rostock max that uses a small switch/spring arrangement for the hot end to serve as a probe, I though I’d see if anyone had firsthand experience with such a setup (or had seen an example of one.)
I’ve dug around the internet a bit and haven’t stumbled across the best way to enable the feature in Repetier firmware (or if I’ll have to switch over to Marlin.)
Someone named David apparently originally came up with it, and the person in this video has modified it a bit.
I really don’t know if I want to go the hassle of of installing a servo and a more typical probe arm. I already have a suitable microswitch, and the wire run made!
I’d be afraid that tapping the hotend against the glass surface and would hammer the tip down and eventually create an inward ridge on the bore. @Anthony_Morris Steve Graber posted the video, so he’d definitely have some kind of experience with it.
(Unrelated to the topic itself, but this thread shows up as a YouTube comment below the video as well. I had no idea G+ does this nowadays.)
I’d slow it way down. Microswitches are notoriously inaccur-not-always-tripped-at-the-same-spot-under-dynamic-loads-ate. I think we engineers call it hysterisis. Anyhow, that looks like a bit of a modified peck drilling routine, so I’d slow the pecks down to about 1/4 of what he’s running there and see if things don’t get way more accurate. Or, you know, use a dial indicator.
I’d been thinking of ways to do this myself, however my idea pretty much involved pressure pads on the bed rather than a microswitch on the extruder like that. (cartesian rather than delta) that is a nifty way of doing it. yeah whether tapping it on the glass repeatedly is going to have a negative affect… I duno. it’s a pretty light tap.
I’ll chime in that I’ve had very good accuracy and repeatability using this method. There may be certain hotend tip designs that ‘could’ experience deformation, especially those with very fine pointed tips, but the J-hotend as well as makergear and other common tips have a slight flat machined to the nozzle outlet which spreads the load. Also, consider that we are tapping a metal against glass at fairly low speed and the spring in the microswitch is 80g (2.8Oz), we could surmise that the glass would experience catastrophic failure from point loading long before we reach any force required to deform the brass tip? That’s a lot of speculation of course, but based on actual experience I believe it to be true.
Thanks for the input @Steve_Graber - I’m going to knock up a mount that can be used with a j-head or E-3D and bolted on standoffs to the stock rostock max carriage. Did you use a pen spring on the micro switch? Any hinge recommendations? I see you moved on to machining an adapter, I’d like to stay 100% printed. Any files or design things to watch out for that you might feel like sharing would be much appreciated.
take a look at http://www.thingiverse.com/thing:205036 that I designed for quick disconnect of extruders on an R-Max, It may be possible to modify the top-coupler to use springs and a switch…
@Anthony_White - I have designed some files in plastic for my Cerberus Pup 170 GT2 that fit the j-slot. You can use those and then make your own platform or you can modify the Pup magball platform to your needs. The only caveat is that you need to actively cool the barrel and these parts to prevent them from heating to deformation. If that happens… your printer will work like ass because the hotend will be loose. All the Pup 170 GT2 files and BOM will become available on github THIS week. (I know I keep saying this, but seriously, THIS week… I have only one small change to make…)
