Why the groove mount?

[dbarrans]

Why do all the hot ends I've seen on the web have a mount that cannot be secured? The stock Rostock Max hot end depends on a single nut staying tight, and groove mounts seem like they were designed to make their attachments fail.

I'd think it would be simple to put a horizontal disk at the top of the hot end with three equally spaced holes drilled vertically through the disk, all one piece with the cooling fin area. This could be securely fastened to the platform using screws, and wouldn't rotate when swapping the nozzle or tightening the joint between the heat block and the thermal break.

- dan

[cambo3d]

explain why they would make there attachments fail?

jhead groove mount is universal and has been working great for me.

I guess it all depends on how the end user decides to mount it. I've seen some that just press fit, i've seen some that have a lock plate.

the jhead mount that I made has a lock plate and is secured via 3 bolts. I dont see it failing anytime soon.

also for the seeme hotend, I used locktight on the nut to keep it from loosening up due to heat changes. Never had a problem with it since. Even if you had a horizontal plate. It's still possible to rotate the whole assembly because of the way the seeme hotend is designed. The hotend is not a single piece design, you have the nozzle, bottom hot end piece, the peek insulator, and then the top piece.

[dbarrans]

I'm talking about the top piece. It pretty much depends on friction to keep it from rotating. If the top piece had an integral disk with three holes to bolt it to the melamine piece rather than using a single knurled nut, there's no way it would rotate.

A groove mount depends on friction to keep it from rotating too. It just doesn't seem like a good starting point, and I was wondering how it came about.

- dan

[dbarrans]

Here's a sketch of what I'm talking about.

- dan

[dbarrans]

Well, of course it'd work better to bolt the disk to the bottom of the melamine piece to avoid the need to take the hot end apart to mount it.

How did you bolt in your Jhead? Did you drill holes in the groove mount for the 3 bolts?

- dan

[cambo3d]

Well, of course it'd work better to bolt the disk to the bottom of the melamine piece to avoid the need to take the hot end apart to mount it.

How did you bolt in your Jhead? Did you drill holes in the groove mount for the 3 bolts?

- dan

like this
http://forum.seemecnc.com/viewtopic.php ... 370#p13154

http://forum.seemecnc.com/viewtopic.php ... 390#p13215

http://forum.seemecnc.com/viewtopic.php ... 380#p13168

[dbarrans]

What keeps the hot end from rotating inside the kossel mount?

- dan

[daftscience]

What keeps the hot end from rotating inside the kossel mount?

- dan

Friction. The groove mount I'm using for my E3d is a very tight fit that get's tighter when you bolt it down to the effector.
I'm currently using This one

This is another good one. It has to bolts that go into the grooves and help hold the hotend in place. I didn't like it because it was big, and the bolts damage the groove.

[Polygonhell]

There is no real force trying to rotate the Hotend, so it's unclear why you would complicate the mount when friction is sufficient.

[dbarrans]

It just seems a weird way to design something that's subject to lots of vibration and high acceleration in random directions for hours at a time. I would have started with something involving screws rather than friction to hold it all together. Seems like something that depends on friction alone would work itself loose after a while.

Yes, I know *all* fasteners ultimately use friction, but at least screws have the mechanical advantage of leverage to help hold objects in place.

- dan

[Polygonhell]

I would guess the current groove mount originated with the JHead, it's popularity is likely what established it as a standard.
I've personally never had an issue with a Hotend rotating and causing an issue. So my assumption is the design is sufficient.
If I were looking to redesign the Hotend mount today I'd probably try and make changing out as easy as possible, integrating the electrical connections. I think there is a really good case for using different hotends for PLA and other plastics.