Check this thing out! i3PRO Need input on Auto level options!

This is coming out, we just finished prototyping it this week, prints like a champ, smooth and quiet!

I'm looking for input on an autolevel setup for it, we'd like to add it, but servo/switch setups seem cumbersome and an induction sensor is not an option due to the PCB bed and Glass build plate.

Thoughts?

Edited 2 time(s). Last edit at 04/15/2015 12:20PM by MakerFront.

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IR or capacitive sensor.

Can you point me in the direction of an accurate/cost effective IR sensor?

Thanks!

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Just one question in general, not to you in specific: why people keep using zip ties for the linear bearings? It is such a flimsy method and any rigidity you can get from the frame is killed there.

Pibot website have the for 5 dollars, and they look pretty good.

[www.pibot.com]

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ggherbaz
Just one question in general, not to you in specific: why people keep using zip ties for the linear bearings? It is such a flimsy method and any rigidity you can get from the frame is killed there.

I thought about that, the V2 version will most likely have all the bearings sandwiched between 2 plates.

In testing this one, we found no rigidity loss as the zip ties hold tight against the metal and the bearings don't move at all! I've picked this thing up and shook it vigorously and nothing changed as far as calibration or tolerances. (not very easy to shake as it weighs 22lbs ha ha)

Edited 2 time(s). Last edit at 04/15/2015 12:36PM by MakerFront.

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ggherbaz
Pibot website have the for 5 dollars, and they look pretty good.

I suppose I could give it a try, it's too bad they don't publish the detection accuracy. Most of the other's I've looked at were not even close to accurate for a 3d printer.

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Any thoughts on FSR sensors? I've used them on a Deltaprintr and they seemed cool, but I'd have to rig up some sort of mount between the bed and frame for them. I didn't want to compromise the strength of the bed frame with flimsy assemblies.

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MakerFront

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ggherbaz
Pibot website have the for 5 dollars, and they look pretty good.

I suppose I could give it a try, it's too bad they don't publish the detection accuracy. Most of the other's I've looked at were not even close to accurate for a 3d printer.

You could check out DC42's implementation tho it isn't cheap.

DC42 dual differential IR Probe

Don't know the cost yet of his new simple design for Delta's etc as he is still working on it but we should know in a few days or so.

Doug

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dougal1957

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MakerFront

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ggherbaz
Pibot website have the for 5 dollars, and they look pretty good.

I suppose I could give it a try, it's too bad they don't publish the detection accuracy. Most of the other's I've looked at were not even close to accurate for a 3d printer.

You could check out DC42's implementation tho it isn't cheap.

DC42 dual differential IR Probe

Don't know the cost yet of his new simple design for Delta's etc as he is still working on it but we should know in a few days or so.

Doug

I'm not really looking for cheap, I am looking cost effective. I don't mind implementing something at a fair price that offers stability and ease of use. Probably the biggest difference between MakerFront and other manufacturers.

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Any thoughts on FSR sensors? I've used them on a Deltaprintr and they seemed cool, but I'd have to rig up some sort of mount between the bed and frame for them. I didn't want to compromise the strength of the bed frame with flimsy assemblies.

You can put it on top of extruder stepper and when pressure push the motor up it will triggered, or you can put it under the linear rod and when carriage flex up will trigger the sensor too.

I'll look into that, I'll probably order some of those IR sensors and give them a shot too!

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My understanding is that Zip ties are used for mounting bearings to minimize alignment errors, if you are sandwiching the bearings between two plates that are solid across both bearings they will have no room to move to "auto" correct alignment, though if you pre-build that part it's less of an issue?

as for auto levelling, your X axis is quite wide as is the spacing of your Z bearings, does this lend itself well to levelling by rotating a single Z motor? or will you raise the whole Z axis?

That is a good point! Maybe the zip ties will stay on this guy. I might even open up the holes to thicker zip ties can be used.

We're using the standard prusa i3 config for this, so both Z motors work together to raise the gantry.

I attached a beauty shot of the 99% finished prototype in bare steel. (waiting on one more part to be cut for it)

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Zerker
My understanding is that Zip ties are used for mounting bearings to minimize alignment errors, if you are sandwiching the bearings between two plates that are solid across both bearings they will have no room to move to "auto" correct alignment, though if you pre-build that part it's less of an issue?

as for auto levelling, your X axis is quite wide as is the spacing of your Z bearings, does this lend itself well to levelling by rotating a single Z motor? or will you raise the whole Z axis?

Edited 2 time(s). Last edit at 04/16/2015 09:53AM by MakerFront.

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As an engineer and industrial designer I follow one principle: do it once and do it right.

I have designed and built 4 printers for my business, I encapsulate my bearings and not once I had to "account for alignment errors".

If a bearing needs to "auto" align, is not following a straight path, and you might have a decent printing machine but nothing else.

You are making a beautiful printer, don't cut corners where you don't need to. Just my honest advise.

Edited 1 time(s). Last edit at 04/16/2015 01:16AM by ggherbaz.

I'll have to do some testing on that aspect, I understand about not skimping on quality, that makes sense. I have 3 other printers where critical load bearing parts are held in place the same way as this and I've never seen sacrificed quality of prints or stability issues.

This may be in the form of a post-release upgrade kit for this printer, along with some other upgrades like precision lead screws with anti-backlash nuts.

Thanks for the credit! I'm super stoked about this printer!

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+1 on lead screws and anti backlash nuts.

I had some problems with the right hand threaded rod and think the threaded rod part of the Prusa design is a weak spot.

It seems to me an upgrade kit would be really straightforward: new left and right gantry plates (to replace the ones that currently hold the captive nuts), lead screws to replace the threaded rod, and maybe new couplers if the lead screws have a different diameter.

That would be sweet! I'd pay up for that.

With respect to auto-leveling, of the many approaches I've read about this is the one I like the most: [hackaday.com]

Instead of using a sensor to determine where the bed is, it uses the print nozzle itself to zero-set each corner of the bed.

I'd pay up for that too!

Not sure why this old thread has come back to life now...

What is it about your machine that will make people want to choose it over all your competitiors? As far as I can see, it isn't much different from the $300 Chinese kits. You've done all the same things that they did to drive the cost down by sacrificing quality and reliability.

Here's and idea, instead of doing exactly what your competitors are doing, why not make it rigid and use a proper print bed on a proper leveling system so it doesn't need autoleveling?

You have 4 screws at the corners of the bed to "level" it. How can that work without bending the bed/undercarriage? OK, so like all the cheesy printers you're competing with, you put a piece of glass on the bed to provide a "flat" surface to print on after the "leveling" system bends the thin aluminum bed plate. Glass is a thermal insulator and will result in wide temperature variations across its surface. How are you going to get prints to stick to that reliably? Oh yeah, the user can apply glue stick or hair spray. Would it really cost that much more to just use a piece of 1/4" cast aluminum tooling plate for the bed? And would it be that much more difficult to use a 3 point leveling system that actually levels the bed without bending it or the undercarriage?

Two z axis motors? The X axis alignment depends on the Z axis screws staying synchronized. All your competitors use two motors and people have to keep realigning the X axis (though since that is a PITA to do the right way, they usually just align to the bed that requires constant releveling). Why not do something better than your competitors and use a single motor with a belt to keep the Z axis screws synchronized at all times? Then the X axis only has to be aligned once and you can count on it staying aligned so you can do precise/accurate prints with the machine.

Zip ties to hold bearings? Why not just use duct tape to hold the thing together?

You can't possibly beat the Chinese on price. How about trying to beat them on quality- that should be easy...

Edited 2 time(s). Last edit at 11/21/2015 11:43AM by the_digital_dentist.

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

Well, I guess I'm to blame for bringing this thread back to life but I'm not sure what's energizing @the_digital_dentist's criticism.

FWIW, I'll reply to those criticisms as best I can:
1. I chose it over the competition for its price and its quality of construction. I looked around for a long long time trying to find a steel Prusa kit and couldn't find one. The closest I found was a Wanhao which looks like good value but isn't a kit.

2. I don't see what warrants the "drive the cost down by sacrificing quality and reliability" comment. The i3PRO is basically a stock Prusa i3 design made from steel instead of wood / plexiglas.

3. With respect to auto-leveling, I like your idea a lot and agree it would be a great way of differentiating the i3PRO from virtually all the others. I also agree with you that a three point leveling system is a sensible design. On the other hand, the glass build plate is working great for me. I don't use hairspray or glue or slurry or the rest of it - the heated bed helps the filament stick at first and the pieces simply pop off after the bed has cooled down when the print is done. It's true that glass is a thermal insulator and maybe I'll have problems with hot-spots and cold-spots in the future. Aluminum, it seems to me, might have its own issues. I like the fact that I can scrape the glass clean with a razor blade and not worry about scratching the surface - not something I could do with an aluminum bed.

4. The two z-axis motors seem to work fine for me. I'm kind of new to 3D printers so maybe that's just an ignorant opinion on my part but it seems that several cartesian printer designs, including several commercial ones, reliably use two z-axis motors. I don't see how the two z-axis screws can get out of sync unless the stepper motors get out of sync and that seems highly unlikely to me given how much force it requires to get them to "skip" a step.

5. With respect to zip ties to hold the bearings on, I'm of two minds. On the one hand, I would prefer something more engineered. On the other, the forces at work aren't aligned in opposition to the strength of the zip ties so I'm not sure it matters. There are other things about the Prusa design that concern me more, namely the use of threaded rod rather than a precision lead screw.

So net net, I think the i3PRO satisfied my buying criteria really well: a) it's a kit, b) it's a steel frame, c) it uses a widely used and well understood design, d) at a great price.