Minimum X carriage distance from hot end?

I'm building my first RepRap and I was wondering what the minimum distance from the hot end / heater block to parts on the x carriage was so that it doesn't cause issues with warping of the X carriage. I wasn't able to find this from my searches. I did see someone making an open X carriage design to move the RP parts away from the hot end, but is that needed or just paranoia?

Right now I have a mendel-parts v6 hot end (or something very similar, it came in a kit but it looks very close) and a Wade's geared extruder. The extruder is designed for the PEEK to go up "inside" the extruder and this puts the heater block just below the bottom of the X carriage. When I look at that and think that the heater block is going to get hot enough to melt PLA that briefly passes through it I don't see how the X carriage is going to be able to stand a little farther away for long periods of time. Maybe I'll post some pictures tonight so people can let me kniw if it's too close or not.

I have melted/bent a couple of x carriages with my mendelparts v6 hot end, as the carriage is pretty cramped. You might be able to use it if you mount a fan to cool the transition zone of the hot end and the carriage itself.

This open x carriage [www.thingiverse.com] is a great design and have much more space around the hot end. You still need a fan to cool down the cold end of the extruder, or the transition zone on the hot end, as the heat travels up the mounting bolts over time. I suggest you print out a spare carriage of your choice as soon as possible.

It might also be a good idea to look into a lm8uu linear bearing upgrade in the future. I just upgraded the y axis, and it's great!

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-Nudel
Blog with RepRap Comic

I designed the OpenX, so i'd say it's much better than the standard carriage :-)

I've been using it for months with no fan and i haven't seen any warping. I haven't printed with ABS yet, though. Only PLA, so my extruder only gets to ~200 degrees C. I'm also using carbon fiber rods as the rails, and since the OpenX design exposes the rails, metal rails might get hot enough to warp the carriage, potentially.

I haven't had any negative feedback, however, so I'm assuming that these aren't issues.

I also have only printed in PLA, with mendelparts v6 hot end on gregs hinged extruder. The only thing I've had melted/bent was the bottom of the extruder, especially where the trapped nuts from the hot end come in, due to heat going up the bolts. I have mounted a small 5v fan which makes a bit more airflow around the extruder, and have had no warping since.

The open x carriage itself needs no cooling as far as I can tell, and it is truly an excellent upgrade. Thanks a lot Buback!

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-Nudel
Blog with RepRap Comic