@dc42 said in Nema17 heat, how to deal with it?:

With the belt removed, does the Y motor shaft spin freely?

Not sure what you mean exactly so I'll give multiple answers:

• The motor shaft turns freely if there is nothing connected.
• The motor shaft gives resistance when it's in IDLE 1500mA 30% idle percentage. If nothing is connected to the motor. However it's fairly easy to push through compared to any other motor of the same type.
• The belt is running on the motor shaft. I'll explain my current setup. With some images:

Since my original post I've reduced the friction on the axes quite a bit and that seems to really help in the heat department.

Also took the motors off and it seems I have a faulty motor for the Y axes. If I connect a motor clamp to it and hold the clamp with a tool I can easily make it skip on 1500mA. The motor on the X axes on the other hand is extremely difficult to make skip.

@armatus To be honest with 16mm hardened steal lead screws I would be surprised if they're bent. But I could just be too much of an optimist

A lot of force is needed to bent 16mm stainless steal rods.

@armatus Thnx for the info. Yeah that is quite a bit larger indeed!

If I'm seeing it correctly you're using trapezoidal 12mm leadscrews. I couldn't find those anywhere. Also the T10 trapezoidal leadscrews I found where quite expensive when factoring in good nuts. The SFU1205 I found was only marginally cheaper then the SFU1605. But yeah it might be overkill.

Yeah the drive couples for 12mm to 5 mm are hard to find.

The machine looks awesome! A nice clean design!

I am still planning to test the 3 SFU1605 setup just to know how well that would work.

If it's good, it's good If not I want to use v slot wheels around all vertical beams in the frame. (so 4 guidance rails)

Another thing I'm pondering is whether to use 2020 or 3030 frame components.

@mrehorstdmd From my tests yeah. It makes quite a lot of difference. Quite a bit of heat bleeds out through the heat sinks.

The motors are cold to the touch now. The motors never got hot enough to burn yourself. However the 35-40 degrees was after a 1,5 hour print. So a longer print might produce more heat. The heat accumulation is quite slow.

Edit: Been thinking about this, For the next build I'll be using Alu mounting brackets. Using the frame as a heat sink might actually work.

@vwegert said in Ideas for more realistic bed temperature control:

@dc42 Now I wish I had a FLIR to see how uniform the temperature really is on the surface and how far in I would have to go to get a realistic measurement... A shame that these things are so expensive...

I looked into buying one of those and from I have been able to deduce the precision of a FLIR is not that good. A spot measuring tool is much cheaper and far more precise. Do that's what I use now. It takes a lot more time to measure the whole bed though...

@antlestxp 1.9degree? I'll assume 0.9.

Then you have a setup similar to mine (motor and voltage wise). I'm not happy with the current XY arrangement. The frition is not to bad but still higher then I would like it to be.

Yeah agreed if I do not hold onto the printer when stopping the movement the whole printer indeed moves. But for me that is from 1100mA upward.

The XY arrangement has quite a few contact points with printed linear bearing so probably quite a bit more friction then your setup. (On a single axes I have 5 bearings) also 2 of the rods on a axes turn as well as provide linear motion.

The coolers are keeping the steppers super cool at 1500mA.

I learned a lot from the current build! Even though it has some design flaws it prints WAY better then my upgraded Anet A6.

@antlestxp 4 lead screws would be a option. However the issue with 4 points instead of 3 is that it can be a hassle to get it right and can even lead to torsion in the bed.

Also not sure if the duet wifi can do 4 point calibration.

@fcwilt It would depend on the rigidity of the bed construction. However it is something that has crossed my mind.

Thnx for the insights. I won't be able to give a definet answer if it works or not until I get all the parts and that will be a couple of weeks at least. I will post back with the results.

From my tests with the short SFU1205 I have concluded it has little to no play so it should work fine. However I am working on a lot of assumptions.

@fcwilt said in Z Bed setup with auto calibration, advise requested:

Perhaps they can be purchased but I have yet to see a lead screw that was perfectly straight.

I've ordered one and will let you know. I have a 200mm SFU1205 lying around (from china) and that thing is definitely straight. I do agree that I have never seen a straight trapezoidal leadscrew (only seen 8mm ones tbh).

As for a leadscrew not being intended for it I do definitely agree. I might add a guide to the design.

However a leadscrew is definitely not designed to be mounted on only one end and many printer design rely on that.