Another UK build

Re: Another UK build

Postby timrwilliams » Sun Mar 30, 2014 9:53 am

Progress of a kind-
I finished calibrating individual arms and wiring up the motors and endstops. The only spare board I have at the moment is a Sanguino with ATMEG 644 flashed with Sprinter, and Pololu stepper drivers. I realise this is probably not ideal, but I wanted to try GUS in action. After some firmware adjustment I was able to sort of control GUS using Pronterface - Homing , X/Y/Z manual movement and G code entry.
I rigged up a dummy hot end to get the right sort of clearance and was able to measure twelve or more bed zero positions.
After a couple of false starts with the G code preprocessor I produced a processed G code file which worked under Pronterface and performed quite credible dummy hot end movements (a GUS pulley) - 28 minutes.
Much still to be done.
I need to decide either to take the board (RAMPS with Marlin) and Bowden extruder from a working Delta, or build some new units.
By the way, the print surface is a cheap granite board from a kitchen shop.
The Pololu drivers are 1/16 microsteps and give cal values of 61.5 steps/mm for all three arms. The current limits are set at 1A which seems enough for this limited test.
I couldn't spot any cyclical errors due to pulley deformity, but perhaps I did not do enough accurate measurements. I was so keen to get on.
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Re: Another UK build

Postby timrwilliams » Thu Apr 03, 2014 7:57 pm

I can hardly believe I am writing this. First print this evening.
I took your advice on calibration and finished the extruder/hot end.
Its a 30mm three limb calibration piece and by no means very accurate. The X/Y limbs are not quite 90 degrees and the Z limb is too big with a pronounced curve. So more fine tuning to do. But its working!!
I will write more on the construction details soon.
Many thanks to Nicholas and everyone for design/advice/encouragement.
Attachments
GUS6.JPG
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GUS5.JPG
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Re: Another UK build

Postby Nicholas Seward » Thu Apr 03, 2014 8:16 pm

Woot!!!! That is huge!
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Re: Another UK build

Postby tommythorn » Thu Apr 03, 2014 8:37 pm

Congratulations, that looks good!

I noticed the plate mount for the J-head. Is that to avoid problems with the heat for the hotend?
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Re: Another UK build

Postby timrwilliams » Thu Apr 03, 2014 9:24 pm

Thanks
Yes- I could have mounted the J- head in the lower hub, but that seemed to obstruct some of the PEEK fins. So I contrived an adaptor (green) with the metal plate having a dual function (I hoped) of securing the hot end and as a heat sink. I have only run this for about 30mins so far which is not long, but the metal did not seem to get too hot. I hope the PEEK fins are doing the job, but I am prepared to put a fan on if necessary.
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Re: Another UK build

Postby NeoTheFox » Fri Apr 04, 2014 5:01 am

You are doing great! And also very fast, I belive you made it print faster than everybody on this forum (maybe exept for GUS 1)
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Re: Another UK build

Postby timrwilliams » Fri Apr 04, 2014 8:40 am

Thanks -

It helps being retired and having good advice/examples from the forum.
I shall spend today thinking, and writing a ' GUS To Do' list
I usually print an owl as a test piece. But I think I need much more fine adjustment before that happens.
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Re: Another UK build

Postby ChrisK » Fri Apr 04, 2014 9:40 am

wow Tim, awesome! in local parlance, proper job.
cant believe how quick you went from deciding to get stuck in to working, printing machine

oh, it's kinda customary in Simpson circles to print a squirrel as a test piece. sure Nicholas or one of the others could point you to the appropriate file as I am no-where near printing at the mo
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Re: Another UK build

Postby timrwilliams » Fri Apr 04, 2014 9:53 am

Thanks Chris -
It was seeing your prints set me off!!
I have found the squirrel file. At the moment it would come out tall and thin!
Hope you continue to make progress with your build.
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Re: Another UK build

Postby timrwilliams » Sat Apr 05, 2014 6:48 pm

As custom suggests, I tried a squirrel print. The first attempt, at full file size stuttered and interrupted and I stopped. This sort of error I have come to associate with slow communication between software and firmware I need more work on that, - upgrade firmware/baud rate.
Scaling to 60% seemed to work better, (you can see the mark of the first go on the blue tape.)
The dimensions are clearly wrong (looks more like a cat) the Z height is about 12% too large. Its encouraging that most of the layers are well aligned vertically, so the mechanism is sound it's the calibration that's out.

After about an hour's printing the temperature of the metal J-head fixing plate was 45C, so it looks as if the adaptor I made up allows reasonable cooling of the PEEK body. Probably the metal plate could be replaced by a printed one.

Sadly I think I have to stop this fun printing and -
- Recalibrate individual arms with better attention to linearity.
- Upgrade Board to RAMPS and firmware to Marlin at higher baud rate.
Attachments
GUS8.JPG
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