cheapest and easiest auto bed leveling idea

Hi, I just stumble across this video by Josef Prusa [www.youtube.com] about his cheapest auto bed leveling method by just using 4 tactile switches at all 4 corners.

What I had in mind was to put these switches underneath the bed either at the end of the screws (bottom) or besides the screws. He stated that anything above 300g would trigger the switches due to the weight also it makes the bed heavier by adding another glass and heated bed can't be used.

Anyone up for this thing?

All the more reason because I ordered GT2560 board from geeetech and just found out that the board didn't have aux ports too just like sangui board. also another problem was last night during printing my bed height seems to be at variable height which I thought it's perfectly leveled

We need someone to come out with a self level like the lasers have Amazon self level

This video shows how the self-leveling works on a laser, would be nice to have something like that on our printer

Youtube

Edited 1 time(s). Last edit at 07/04/2015 11:11AM by slanwar.

Well, laser aren't a bad idea but problem occurs when you're using reflective surfaces especially glass surface, might shoot the laser beam to someone's eye. Also unsure if it can detect range of reflective materials.

I was thinking of probably, having a sensor or tilt sensor or perhaps accelerometer/gyro sensor hooked onto all 4 sides of bed (this only ensures the bed are perfectly leveled, no inclinations on either side) then another one probably put on to the carriage for the z axis, then would adjust the left and right threaded rod by turning it manually (my case, using prusa i3)

But still didn't solve auto bed leveling. or should I say, auto z axis distance or something?

The laser won't use the laser to self leveling but a pendulum

Hmm, because the platform uses at least 3 screws , unlike the laser level thingamajiig. My printer, prusa i3 uses 4 screw for bed, the main idea of autobed leveling in marlin firmware (as I understand), will auto adjust the z axis layer height depending on the bed platform if it is tilted slightly. I still don't see the effectiveness using pendulum to auto level the bed. Sorry I might misunderstood you there, currently several issues arise (not related to 3d printer stuff) made me somewhat hard to think =(

I guess a tilt sensor would be nice =x

I always wondered: why not glue small tin foil squares in 4 corner parts of the hotbed glass and connect them to ground, then somehow isolate the hot end from the ground and use it as a sensor terminal?
I think that's the easiest, no?

In fact, I think hotend metal part is already insulated from the ground in most extruders.

Hot glue gun never was a good choice to achieve flat adhesion, basically your idea is to run "electricity" through the hot end then to the tin foil is it?

I've not tried it but common wisdom is that the hot end has too much goop/stray plastic on it to make effective electrical contact.

I did try using FSRs but they're too temperature sensitive to use with a heatedbed at ~120c. I tried all sorts of methods of isolating the FSR from the heatbed but to no success.

My current system uses tactile switches but I use a lever system to amplify the movement of the bed. The tactile switches that I looked at had a stroke of 0.3mm, using levers a movement of 0.1mm on the bed activates the switch.

Moriquendi

Here is one of my idea based on my very first post, sorry for the poor sketches and the late visualizations. The colours are as follow

BLUE = Frame to fix the tactile button/switch
ORANGE = Tactile button/switch
YELLOW = printed shaft fixed beneath the bed

So, how these works also based on the video in my very first post

But I don't know how much weight the bed can hold without pressing the switch, like Prusa himself said that the max weight is 300 gram only before the button will be triggered

Link to image sketch and idea [imgur.com]

I need someone to test out this kind of auto bed leveling type (I lack of proper equipment, ran out of plastic apparently), and you must have these criteria

1. This type of tactile switch/button with base (black box) dimension of 12 x 12 x 3-4mm like this, the blue cap included [www.thanksbuyer.com]
2. Square/box type bed mount (in my case Geeetech acrylic bed mount), not laser cut that looked like skeleton like this [www.replikeo.com]
3. Bed that uses spring on the screw mount because it will be pressed by the nozzle on top of the bed during the auto bed leveling

The switch, will be fitted into the stl file provided below. These probe mount will be mounted underneath the bed, fastened by the spring and locked by the screw hole found there resting on the surface of the bed mount. The 2mm extra wall there will lock itself to the corner of the bed so the switch below won't run away.

Fitting the switch and bracket, requires you to readjusting the bed height to accommodate the total height of the switch with flattened legs. Once everything put into place, with some gaps between the bed and switch, heat the bed up to 110'c or 70'c depending on your desire, turn the bed screw to lower them pressing the switch triggering the end stop, then back off a little bit and let it barely pressing the switch and do this for all the other corners. Other steps may be required for those wanted to retain stock mechanical endstop while those who already have auto bed leveling with glass surface can try this.

One of the biggest drawback I foresee is that, the bed might have different height between 110'c and 60/70'c which is abs and pla by about 0.5mm. This bed leveling probe method I guess are only meant for one material type only that prints on 110'c or 60/70'c only.

Here is small thing you need to do on the tactile switch, straighten the legs to make it flat and do normal wiring (I couldn't imagine how the circuit supposed to be) like Josef Prusa did on his video on first post.

The idea here is to have the nozzle pressing the bed like in the video but enables you to have heated bed feature and theoretically can print more than 300g. Any of you are testing for me, kindly give me feedback on this setup and stl file is still in its experimental phase. I only modeled it based my printer, how the switch supposed to be mounted.

Any feedbacks about this idea and testing are highly appreciated

Edited 2 time(s). Last edit at 07/29/2015 09:37PM by sarf2k4.

Lulzbot mini does auto levelling using an electrical connection through the nozzle and small metal plates in the corner. This works with an automatic nozzle cleaning system. See this video from 4:50
Lulzbot mini

ahh... that's a good one, I think e3d v6 also has one extra screw hole that can be used for this, but don't know how well the wire can hold up to 280'c though, and the metal corner can be hard to get too unless a custom machined aluminum/metal corner for the bed

Just hook up the wire to the cold end part, the cooler. It's an all metal hot end so it's conductive from top to bottom

From what I see in tom's review on printrbot, the other end of the wire hook up at the heater block, I'm not sure whether if it's the sensor wire or the thermistor though, but another think is the round metal plate, casting it won't be cheap for it not to mention a machine to shape it. one flaw is that the glass might break anytime if the bed are very uneven.

Maybe can just use the screw mount for the probe point instead of casting a metal plate for it. just hook another end of the wire just like printrbot, but the other end is directly on to the screw, use a flathead hex screw will do

I'd turn a 10cm wire around the mounting point at the top. When mounting to the extruder it will make a firm contact.

Well, what I always go for is cheapest yet easiest to make