Another UK build

Re: Another UK build

Postby Nicholas Seward » Wed May 14, 2014 5:12 pm

Nice. It occurs to me that the stiffness required could be accomplished easily with a printed part. Just a printed ring could work. I don't want to go into detail (hard to explain without a pic)
but a printed spring ring will be perfect for the new arm.
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Re: Another UK build

Postby timrwilliams » Wed May 14, 2014 5:15 pm

The other variables which seemed to affect accuracy is the Segmentize Bed Z0 values.
In order to make these measurements a bit easier/consistent, I fitted a micro servo (TowerPro SG90) with the smallest microswitch in my spares box bolted to a horn end. Total mass 12g.
I am still using a Sanguinololu board and driving a servo/switch means I can't fit a LCD panel as well. I hope that when the time comes to try that I will not need the bed sensing unit.
The picture (GUS21) is rather angled but the limit switch trips 0.6mm below the extruder tip.
I am using it in semi-automatic mode - running the extruder down in various positions with a G1 code, and reading the values when the limit switch trips. It is certainly easier to use.
I guess there is a fully automated way to do this, but thats a bit out of my depth.
I was interested in Nicholas' comment in another thread, that the answer to improved accuracy may be in Segmentize. More things to try out?
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GUS21.JPG
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Re: Another UK build

Postby NeoTheFox » Thu May 15, 2014 6:33 am

Oh, this is amazing! You beat me to the probe :D
Great job, are you going to implement it in software now?
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Re: Another UK build

Postby timrwilliams » Thu May 15, 2014 7:04 am

Thanks.
I think using the probe manually to simplify Bed Z0 data collection for Segmentize is about the limit of my understanding. My programming days are long gone.
What I can still do is the hardware, and I think an electronic upgrade with LCD/SD support is the next goal.
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Re: Another UK build

Postby timrwilliams » Mon May 26, 2014 8:17 pm

Progress has slowed but does seem to be getting somewhere.
It all seems to be down to Calibration checking and Bed Zero Matrix measurement. Bed measurement has been made easier by having a semi automatic bed probe and I have been doing repeated testing to get good repeatibility. The most recent calibration piece (GUS25) has all dimensions within +- 2% (though there is a noticable glitch in the vertical arm).
Feeling rather pleased with this I tried a Cushwa Owl (a family favourite) (GUS26). This is 75mm high and took 110 minutes, with no overheating (board/motors/hub). Its not the best owl I have seen but it does seem the right proportions ,even though it is looking the wrong way!!! (see XYZ thread)
I shall have to nail this one down as owls from other printers seem to get given away to admiring friends.
I am using Segmentize as downloaded, I don't have the knowledge to dig inside it.
Apart from more Cal/Bed checking as the arms wear in, I can't think of any major changes I could easily make to the construction.
I have fitted a LCD/SD card controller. As I am still using a Sanguinlolu board with several spare I/O pins used for servo/bed switch, this was more of job than it should have been. I ended up building an I2C interface, but thats another story.
I know I should upgrade the board but I am reluctant to change anything now I have got it working (sort of)
Attachments
GUS25.JPG
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GUS26.JPG
GUS26.JPG (310.06 KiB) Viewed 17118 times
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Re: Another UK build

Postby timrwilliams » Thu Aug 21, 2014 4:41 pm

One of the good moments after building a 3D printer is when you realise its reliable enough to set running and LEAVE.
Up to now I have spent ages hovering anxiously over GUS printing. Recently I was called away for an hour and on return was delighted to find it still printing. Until I looked more closely and found a marked side slip, which I have not come across before. GUS30/31.
I first thought some thing had vibrated loose, but not so. Eventually I worked out that the base plate was the problem. I have posted before that I used a cheap granite chopping board. At 2kg this sits very firmly on the plywood top plate. In this instance something must have jerked it to one side. Easy to fix when I realised. GUS 32 shows a better print.
You see I am still doing Owls. It is the price my family exact for losing a spare room to 3D printers.
This last one is looking the right way, I fixed the XYZ direction (at last).
You may also notice a slight tilt to the print. I think this means I STILL havn't got the Segmentize bed zero matrix right yet. This does seem to need a lot of attention. Although I have speeded it up using a bed sense switch, it still takes some time.
So GUS is up and printing but needs quite a lot of care and attention to set up. But I CAN go away and leave it running.

Regards
Attachments
GUS30.JPG
GUS30.JPG (294.58 KiB) Viewed 17041 times
GUS31.JPG
GUS31.JPG (278 KiB) Viewed 17041 times
GUS32.JPG
GUS32.JPG (312.38 KiB) Viewed 17041 times
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Re: Another UK build

Postby Rasputin73 » Thu Aug 21, 2014 7:27 pm

Wow, nice progress! Love the pics.

What is the dimensional accuracy on your machine right now (excepting the slip of course)? Does that bed sensor switch have a script you run, or is it a more manual thing?

Thanks for the update!
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Re: Another UK build

Postby Rasputin73 » Thu Aug 21, 2014 7:40 pm

Ahh, just re-read your previous post about dimensions. 2% sounds pretty good. Anyone hazard a guess what % is going to be needed for a proper 'replication'? When will we see a GUS able to print itself?

In terms of the bed leveling you said it was "semi-automated" so far. I know that automatic bed leveling is a fairly common feature these days, could other scripts be modified for this? Maybe something normal deltas use, or is the geometry too different?
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Re: Another UK build

Postby timrwilliams » Thu Aug 21, 2014 9:31 pm

Thanks for your interest.

I am not sure my bed probe even deserves to be called SEMI-automatic.
I just put some G-code in Pronterface Buttons to take the head to a number of preset positions and then finish off with the appropriate manual control, the microswitch giving a reproducible end point. The switch is set to trigger about 0.4mm below nozzle. Then G-code returns XYZ.
I am sure there are better and more elegant ways of doing this, but not I fear, by me !
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