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SAE all-metal hot end.

Posted by jgilmore 
SAE all-metal hot end.
November 16, 2010 01:14PM
I'm planning on making a stainless steel hot end and of course I'm just going to go to the local hardware store which doesn't really have much in the way of metric stuff.

So I'm going to be drilling out my stainless bolt with a 1/8" drill bit. Do I need to get a 5/16" bolt or will 1/4" do? When I tap a 1/4-20 hole, I like to use a 13/64" drill bit, which implies that the wall will be 13/64"-1/8"=13-8/64=5/64" or about 1mm wall all the way around, less any eccentricity. Which I think should be enough, even given that I'll be using a drill press instead of a lathe. A 5/16-18 bolt uses a 17/64 tap size, which is 1/16 larger, or about 3.5mm extra, so 1.7 wall thickness under the threads. That should be enough to ream?

if I want to ream it out to give a tapered hole, do I need to get a 5/16" bolt? Nophead's bolt was reamed almost completely out, but I don't think I want to get that close, as I need to torque the acorn nut and aluminum heater block onto the end.

Do I need to a tapered hole? Nophead seems to think that tapered holes are just magic, and it's hard to argue with his results, so I'm inclined to say yes, I do need to have a tapered hole for reliable operations.

I'm building it with Baling Wire
Re: SAE all-metal hot end.
November 21, 2010 06:53PM
XCbot has a SS isolator. It works very well.

It took me a few tries to get a good hole drilled through my piece of SS M6. (I had no trouble drilling through a bit of BZP M6 the day before...)

I believe tapering out the bottom made it easier to push melty filament through... rather than push a grippy bit of glassy filament down a cylinder... you push it away from the taper....

Getting close to the groove in the taper isn't about maximizing the taper, but making less of a heat-path upward.. I made mine thin with a dremel.

Details are to be found over a couple articles here: [araspitfire.blogspot.com]

I'm currently printing on my Mendel (that I printed with XCBot), and I'm using a Wade's/Adrian combination.. it works well too. Both print about the same in my estimation... Overbuilding XCBot doesn't seem to have brough any improvement in print. (I believe I'm getting very good prints)


Re: SAE all-metal hot end.
November 22, 2010 02:34AM

Want to do it up here:
http://reprap.org/wiki/SAE_All-Metal_Hot_End? smiling bouncing smiley

-Sebastien, RepRap.org library gnome.

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything! grinning smiley
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