CNCDudez RepStrap Version 2.0

Managed to get Version 2.0 of my RepStrap finished before Christmas but did not get time to release some pictures.

Just now waiting for some new Stepper Drivers to arrive and then will post up a video.

We tested each Axis with other drivers as it was built and tweaked each Axis until we got the speeds we wanted.






More pictures can be found on the following thread:
[www.cncdudez.co.uk]

Cheers

Sean.

Great looking machine. Not sure I understand the design of the front area where all of your wires are leading. If you put a keyboard there it would look like a steampunked computer terminal.

Very interested to hear about the speeds your getting. I've made some similar decisions to you in my build, but i'm not printing yet. If you think about it while posting details, I'd be interested to hear your thoughts on why you're getting faster speeds. Rigidity, motor/belt orientation, etc.

Thanks, and nice work.

Hi Brian

> Great looking machine. Not sure I understand the
> design of the front area where all of your wires
> are leading. If you put a keyboard there it would
> look like a steampunked computer terminal.

It was to just keep it all neat and in one place. I have got so many machines with wires trailing everywhere that I just wanted it kept all strapped to the machine.
I am going for dedicated heatsink boxed stepper drivers also, which take up a lot of room and will probably fill that space.

If all fails we could bring back Robot Wars and enter it


>
> Very interested to hear about the speeds your
> getting. I've made some similar decisions to you
> in my build, but i'm not printing yet. If you
> think about it while posting details, I'd be
> interested to hear your thoughts on why you're
> getting faster speeds. Rigidity, motor/belt
> orientation, etc.

The main thing I found for speed was making it Rigid to stop the shaking when moving that heavy mass of an extruder/stepper on the X-Axis.
I messed around with the bearing mounting height for the carriage and wizzed it back and forth until we got it just right.
We only move about 230mm on the X-Axis the Firmware maxed out on the speed, due to the ramping settings. It never really got to the max speed. We increased these settings in the firmware to the point where you may of well as waved goodbye to ramping !

But at the end of the day we know we are not going to print at these sort of speeds. It is fun seeing it move at 500mm/s and nice to use for travel but it was more to see how fast in can push the printing in the future. Like other fast machines out there printing at 60mm/s would be a nice goal.

The Z-Axis height goes to over 200mm in height and again we wanted the least shake when it was down at Zero point or high up in the air. We did not wanted to go for the Box design, so played around with the spacing of the rails till we were happy.
This frame got torn apart and rebuilt a few times over the weeks and the main challenge was trying to keep all the steppers within the frame footprint.

We ended going for 12 Tooth drive cogs and 10mm wide belts that are more rigid and less flex than the 5mm wide belts. We kept to Nema17 motors just to keep the size down really and the torque of these are more than man enough.

The dual steppers on the Z-Axis and Dual Ballscrews were a luxury really and we probably could of got away with threaded rods or the cheaper trapezoidal thread/Brass nuts.
But they are very accurate with near Zero backlash and just no friction when lifitng the weight of the X-Axis.

Just now waiting for new Stepper Drivers to arrive and will post up some videos.

>
> Thanks, and nice work.

Thanks and Regards

Sean.

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[www.cncdudez.co.uk]
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Thanks for the explanation Sean. Makes sense and I'm a bit encouraged about some of the design decisions I made. I started off making a Mendel Max but couldn't get comfortable with the triangular frame design. I understand how the Mendel Prusa landed on the triangle, but that doesn't mean I agree with the design. When I was building out my frame for the MM the triangle just felt wrong. Those nice extruded aluminum pieces just scream to be set at 90 degree angles.

Like you, I've also mounted my z-axis motors at the bottom, but instead of your wiring solution I have a large space under the build platform for my wiring and electronics. Here's an older picture. I haven't taken one lately but recent changes are a larger area under the build platform, z-axis motors and threaded rod mounted, and y-platform in place. (Jealous of your screw rods, something to consider for a later version)



Again, nice work on yours. It's a great looking machine, and no one is going to complain about faster prints.

Brian

Hi Brian

The link to the picture does not work for me as it looks like it is a forum attachment and you have to be a member to view.

I got to agree that keeping the electronics out of the way and neat and tidy is the way to go. But as this is a protoype I wanted to have the electronics out in view, so I can tweak the setting and also show what has gone into it.

I am using individual steppers and a new Sanguino-Breakout PCB I made.

Look forward to seeing some pictures of your frame.

Regards

Sean.

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[www.cncdudez.co.uk]
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Thanks, I'll know better next time. Let's see if these pics work. Hopefully these will give you an idea on where I'm going. Not rocket science and not nearly the same level of finesse you achieved, but you can see we did land on some of the same design decisions.

Hi Brian

Looking good that end.

I like the way you are attaching the rails, saves drilling and making sure the holes are spot on and that is the nice thing about using extrusions, you can easly bolt thing on using t-nuts and bolts.

Good luck with the rest of the build that end, will update the thread when my final bits arrive.

Regards

Sean.

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[www.cncdudez.co.uk]
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brianblanton Wrote:
-------------------------------------------------------
> Thanks for the explanation Sean. Makes sense and
> I'm a bit encouraged about some of the design
> decisions I made. I started off making a Mendel
> Max but couldn't get comfortable with the
> triangular frame design. I understand how the
> Mendel Prusa landed on the triangle, but that
> doesn't mean I agree with the design. When I was
> building out my frame for the MM the triangle just
> felt wrong. Those nice extruded aluminum pieces
> just scream to be set at 90 degree angles.

I built a cubic frame (for a completely unrelated project) from 20x20 aluminium square profile and 3-way commercial plastic corner pieces and it's a lot more rigid than any M8 rod frame. I've been toying with the thought of designing simple printer axis attachments for a frame like that (gantry X-Y and built plate moving in Z). It would be completely scalable, you would only need to change rod and belt lengths to adapt it to any size. I don't really see any other reason for the triangle frame than achieving the rigidity for a threaded rod construction.

Got it wired up today and it works better than I thought.

I used the latest Marlin Firmware along with the Breakout PCB I layed up based on the Sanguino design.
Had to tweak the Marlin Firmware because of it's hort pulse width when using externall steppers, but not a problem.



Video showing rapid moves of 550mm/s and printing at 200mm/s

[www.youtube.com]


Cheers

Sean.

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[www.cncdudez.co.uk]
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Hey Sean, I checked out your video and the speed looks good. Again, nice work on the printer.