Using Muffler sealer to fill gap between heater and metal block

Hi,

I have purchase a relatively cheap "JHead" hotend from amazon. When i purchased it, I do know it is pretty cheap and could be a knock off. Today, when I got the hotend, I noticed there is a gap between the heater and the metal block (metal block drilled hole radius > heater radius), but the heater is held securely with a screw. I was wondering I should use some thermal compound (muffler sealer) to fill the gap to enable a better thermal conductivity?

Thanks

Edited 1 time(s). Last edit at 10/12/2015 03:37PM by andrew.ngai.

Not needed.

So the gap between would not affect the performance?

As the inventor of J-Head hot-ends, I am going to tell you that these "knock-offs" are not really J-Heads. They just use the name to game the system and sell their junk. Here is a link to the wiki page with real J-Heads ---> [reprap.org]

Buying cheap knock-offs does not encourage the developers to develop new products or to even keep selling what they created.

Best Regards,

Brian

That is not even a knockoff of a J-Head, its its own product. If you want a J-Head buy a real one, if you want an all metal version look at E3D, Prometheus, etc.

EDIT: OK its not its own product, but it is a knockoff of something closer to a E3D.

Edited 1 time(s). Last edit at 10/12/2015 08:00PM by zerodameaon.

wow, I didn't know that it is a completely different design just having the name on it. Where would you recommend I get myself a legitimate JHead?

Yes the gap will affect performance. Air is a thermal insulator. You are measuring the temperature in the block and the heater is insulated from the block by a layer of air, so the heater will have to run much hotter to get the block heated to whatever the set temperature is. There will be a time delay between turning on the heater and the temperature rise in the block (beyond the delay due to the mass of the block). Putting the heater in broad contact with the heater block will allow it to run cooler for the same set temperature which should extend its life. The heater block will respond to changes in the heater more rapidly, so temperature regulation may be better.

I don't know how the J heads are made, but the E3D v6 has a slot cut in the block and a screw clamps the heater block to the heater in broad contact. It is secure and transfers heat quickly from the heater to the block.

Edited 1 time(s). Last edit at 10/12/2015 08:15PM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
andrew.ngai
wow, I didn't know that it is a completely different design just having the name on it. Where would you recommend I get myself a legitimate JHead?

Check [www.hotends.com].

Best Regards,

Brian

Muffler sealant actually is a good idea, we've often discussed the best thermal grease/compound for this issue.
-Olaf

My opinion and 50 years experience with electronics. Thermal paste is for transferring heat away to keep parts cool. At heater block temp it will dry out a lot faster. Replaced many failed transistors where the paste dried out. The gap is really same and has a very minor effect on temp. My heater blocks heat up to 240 c in 45 seconds and stays there. The thermistor is right next to the nozzle where it should be. Muffler sealer is for stopping leaks and becomes hard.
Might have trouble replacing you heater.

Putzer,
are you trying to say, that dry thermal paste is worse for heat transfer than an air gap?
IMHO, everything "solid" is better than air. ( even toothpaste would do )

I agree, that it would be difficult/impossible to remove the heater cartridge, when we'd use muffler sealant. But usually the cartridge is defect when we had to remove it, so we can just drill it out.
-Olaf

Freeze your Heater Cartridge, heat a copper tube, tap the cartridge in. Drill your heater block accordingly. It may be possible to use some copper braid.

Thermal paste is suppose to be used to transfer heat to keep things cooler. Only that, when it dries out it can flake off onto your print.