building a BigRep Rep Strap machine

I’m currently testing my setup with printing the fascinating “Moebius Net” by Bathsheba Grossman.
Its the first testrun which fills up almost the whole 1000mm^2 buildplatform.

The Moebius Net print is about 1/4 done and will need a couple more days to finish. I’m printing with 100mm/s feedrate which also seems to be somewhat max reasonable speed, after that its getting pretty abstract with the current setup (vibration) .

It already consumed about 3 kilos of PLA filament which means that the finished object will have a weight of almost 12kg! O_o Which clearly shows the need for a alternative way to feed the machine.. more precisely a recycling solution.

I solved prior problems with higher extruding speeds and bigger extruded thread diameter with a new hotend design which incorporates a longer melt-channel and two 40w heater-cartridges in parallel with the channel. It heats up in about 5 min. and extrudes very even and clear 1mm PLA threads easily at 100mm/s and more.

But most important, i will exhibit the BigRep machine and hopefully the finished Moebiusnet at the 3DPrintingevent in Eindhoven at 25th october! So anyone interested can see the machine live at the event.

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just some pics of  a skull print.. extruder broke apart on the half way but still looks interesting. i will fix the extruder and try to resume the print.

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Lots of work and progress the last couple of days! After still having a bit of a struggle with the z-axis belt, i added new belt guides which finally solved the problems. I tidied up the wiring and electronics abit and hooked the whole electronicsnest up to a nice big vintage on/off switch, which looks pretty rad! O_o

The first testcube prints actually came out pretty well, even though they clearly show where the machine needs improvement. The x-y axis linear-guide situation is suboptimal, its too heavy and clunky which results in quite some vibration resulting in ripples in the prints. It will get some treatment and redesigns in the next couple of days.

I also couldn’t resist to ramp up the speed and try to print a big skull, which was kind of meant to fail .. but the cause of the fail was at least not the machine shaking apart but my usb-serial adapter diconnecting randomly.. i will look into that and give it a another try.

By the way I’m currently printing on a polystyrol-glass sheet which the PLA sticks very nicely to!

Altogether I’m pretty happy with the first printing experiments :B First prints are really exiting!

it moves! from Krt Crkd on Vimeo.

print test from Krt Crkd on Vimeo.

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At last Movement! Ihave made quite some progress with the machine in the last weeks, the construction is almost complete and all 3 axes are finally moving.

The new design files are here http://www.thingiverse.com/thing:8609

There are 4 x 180Ncm Steppermotors at each corner of the z-drive now, each with its own stepperdriver, all driven by the same step an dir signal. That seems to work pretty well and provides reasonable travel speed for Z. I designed a controllerboard for that which is here http://www.thingiverse.com/thing:8622.
One big timing belt is connecting them and assures synchronous movement of the 4 threaded rods of the z stage.

Belt tensioning is still bit of a topic as tiny angles of the tension-caster will make the belt travel on the pulleys, its a bit touchy but it works. Maybe a spring loaded mechanism would improve this.

Cross spanned steelwires on four sides of the cube provide stiffnes to the construction. We’ll see how that works out in terms of vibration.. the whole mdf parts stuff on the y and x axis is a bit clumsy and could be constructed lighter..maybe with printed parts.. less mass mooved around will allow faster movement.

Even though its still pretty much a prototype and lots of cleanup could be done, the current design finally seems to work, which I’m quite happy about :B

As the first version i uploaded to thingiverse was kind of a concept, i wouldn’t really recommend anyone to work with, the new version could be actually something for you to go for and start experimenting with.

Next thing will be actually starting to experiment with printing, i will order some spools of plastic fillament in the next days. Results will be posted to the blog..

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I am currently rebuilding the drivetrain. Incorperating flange bearings and propperly coutered leadscews. looks much sturdier now, no play anymore.. second chance for the long drive belt

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I’m a little behind with the documentation and updating of the blog.. i’m sorry for that.

Several people asked whats going on or even if the machine is already operational.. thats not the case yet. I’m still struggeling with the Z- drivetrain.. its kind of working but its pretty cranky, which is the result of the rediculously long ( i admit ) belt i currently use. The pulleys i milled from MDF arent optimal either, the belt kind of gets caught on the rim of the pulleys.. have to find another solution for that.

I temporarily  hooked up the motor and the electronics to check out if the 190ncm stepper is strong enough to drive the four threaded rods of the Z-axis, which i wasnt quite sure about either. But it worked out and moved the thing.

Anyhow i think i will switch for 2 motors and 2 belts for the z axis to circumvent the long belt problem. What i also have to do is fabricating some drive pulleys with tapered walls to prevent the “belt getting caught” problem. Im not quit sure how i will do it, i definitely have no money to buy them. Maybe i will make a rapstrap out of my mill for that, and print the pulleys.

Im quite short of resources right now (time and money) so any help and participation is welcomed!

Maybe you flatter the project if you want to see some progress

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Big replicator  successively  materializing

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The design incorporates aluminum-beams which are cheap and obtainable in hardware stores (and recyclable).
The parts you have to produce are all 2D, so you can cut them with a lasercutter, cnc, waterjet or manually.
Of course it also has some screws, washers, bearings etc.

The mechanism uses 4  12mm threaded rods (standard from the hardware-store), driven by timing-pulleys and a drive-belt, to move the xy mechanism, wich is carrying the toolhead, up and down.

It is a concept so a lot optimizing to be done.
Also there are no tools or toolholder designs included, but there is a baseplate where you can fix the tools you want to use.

http://www.thingiverse.com/thing:3093

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