Anybody ever cut a hot end in half to see the inside cross-section? How’d you do it?
I’m trying to capture the behavior of the filament inside in the middle of a filament change. So I don’t want to melt or mangle the plastic inside the stainless steel heat break. I don’t have any cutting devices with flood coolant, unfortunately. So heat generation may be an issue.
Oh, and I’m probably going to need to cut a bunch of these, so minimizing manual labor would be nice
Ideas:
Use my mini mill and spray the hell out of some WD-40 to try to keep it cool
Rough it down in stages with with a dremel, bench grinder, hand-file, and wet sanding (ulgh)
You’ll need to go really slow to keep the heat down.
I remember seeing a 3d printed motorized hacksaw jig. Something like that would work, it will take a long time, but work really good. Could even get a small pump for cooling.
Given the kinds of printer spares I have on hand, I could probably build a “1D printer” (camera slider) and gcode it back and forth to run a saw using less time and money than it would take to build that DC gearmotor thing.
As @Ashley_Webster says, Sanj and I have cut a great many hotends in half!
If you don’t take crazy deep cuts heat buildup is not an issue when cutting the aluminium. The volume of stainless is so small that you don’t need to worry about heat there either. But do use the lubricant.
The only real pieces of advice you need are:
don’t cut below the halfway line on the mill, it sounds obvious, but doing so will result in the heartbeak jumping out and potentially breaking the tool. I speak from experience!
find a way to support the assembly whilst cutting. This may mean milling a jig for your vise, or using an old heater block on the cold-side of the break.
From there if you need to get down to the centreline then I think you need to get out the sandpaper.
Like @Joshua_Rowley says just go slow. The other trick we use is “poor man’s liquid nitrogen” (upside down aerosol air duster) which you can use while cutting to stop the plastic melting. Strongly prefer milling over abrasives, as milling generates much less heat and is generally quicker and easier. However if you’re cutting up hardened steel nozzles abrasives is the only way to go. As Josh says when you’re close to the centreline, fine grade grit paper to polish gives the best results for observation of the innards.
@Jason_McMullan There are plastic flow simulation tools for injection molding and industrial extrusion (eg making PVC pipe) but they’re expensive and very specialized. It’s really hard to simulate polymer melt flow accurately during transient conditions like retraction and material swaps.
@Griffin_Paquette That video showed a hacksaw and a vise, and was a brass+PEEK hot end, which is a bit less appealing with a stainless steel heat break.
