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| PeterE builds a 3d Printer |
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| PeterE:
nrml, Thank you very much for your kind offer, but I found out that there are at least two persons at my job with their own machines and one of them is printing my parts right now. If anyone of them refuses I will take your kind offer. BR /Peter |
| PeterE:
Time for an update. The ordered parts are slowly arriving and the bits that stop me are the printed ones. My workmate swamped by jobs so I just have to give him some slack but I know the bits aren't that far away now. The parts ordered via ebay have basically arrived so let's have look at the goodies: The first picture shows the paper template I intend to use as stencil for putting a name on the printer, thought that would be kind of fun. Next "bag" contained the electronics. An Arduino Mega, a shield card for stepper drivers, the small display, five stepper drivers of the most common type and, cables and connectors to join them all. All at a bargain price as mentioned above. Next is a kit of mechanical parts, that is bearing of different sorts, Flex couplings, toothed belt with gears and a specially treated M8x60 machine screw used as filament feeder. Stepper motors are a must and even a bit expensive, these came to me from Italy . The shipment also included cables but I missed adding them to the photo. Another parcel from China contained the extruder nozzle with heater and thermo resistor. The fan was also included as you can see. the heatbed looks like below. It can be used for both 12 and 24 V DC. It will be mounted beneath a mineral glass plate that will be the actual build bed. Size is about 200x200mm. last week the three end switches used to mark the end of travel for each of the axis. The last picture for this time shows the threaded bars and smooth rods I will be using to put the movements together. From back to front. 2x1m M10 stainless threaded rod, then a 1m M5 stainless for Z-movement, and finally a bunch of stainless smooth rods 8mm dia. These smooth rods keep th h9 tolerance so should work well with the bearings. Still to arrive are the printed parts as said, together with a large graphic display to replace the smaller one - I missed the difference from the beginning but the overall cost is OK anyway. More pictures when the build commence. I will of course keep track of cost during the build but prefer to wait until finished to get the tally right. BR /Peter |
| picclock:
Hi Peter Good to see the build log continues. Do you have the part number or info on your motors? I found it difficult to get ones with optimal characteristics, and in the end settled for nema17 LDO 42sth38 1684AC, (2.8V, 1.68A. 1.65 Ohms, 3.6Kg.cm torque - spec attached) which I purchased from SemiU in the UK. They are pretty std 5% 200 step jobs. The voltage of the motor does not really matter as its the current which drives, and the faster you can change the winding current the faster the motor speed, hence my intention to drive these from a 24V source (its all about the inductance :med:). Saw a video on youtube about a printer which layed carbon fiber yarn in with the plastic (nylon in this case) to massively improve mechanical characteristics. It sounds a lot better than than using filament with carbon fibre particles embedded. link: (no affiliation) Will be very interested to hear about any snags or issues you encounter. Hope to start my build log soon. Best Regards picclock |
| PeterE:
Hi picclock, Yes, the build log continues, but slowly. The set of stepper motors I bought are these http://www.ebay.com/itm/301698572024?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (scroll down to the specs.) This is the first time I am using stepper motors so have to guess a lot (to say the least), anyway they are here now so these will be the ones that goes on. If I find them too weak I have to get other ones, but the specs looked OK as far as I could judge. I will take smallish steps through the build and include photos on the way, and of course add things i find as awkward or odd or anything that don't feel right, as well as those things that goes well. That video was interesting. Something to keep in ind for more complex bits - if I get that far. Waiting for your build log as well ;-) BR /Peter |
| picclock:
Hi Peter I think the motors are all but identical. I am assuming 360mN.m is 0.36Kgs force at 1mm, which equates to 3.6Kg.cms. If so they should be fine. The amount a stepper deviates from its controlled position is caused by the lamination tolerance plus the load you put on the motor. Lamination tolerance is unchangeable, however by minimising load you should be able to get close to that figure. The 3.6kg.cms figure is the point at which the motor rotor will have moved so much that it will likely step to the next available position. Choosing a motor for optimum performance is a tricky thing. On the one hand you want loads of torque so that you can maintain positional accuracy, but that comes at the cost of much higher rotor inertia which limits acceleration. So at best is an educated guess. I think the Y axis is the one to watch out for, as this will accelerate the highest weight load. I weighed the assembled x axis filament feeder with motor and attached head/fan (minus bearings, carriage and rods) and it came out to 480 gms (picture), which is a high load for the X axis. I intend to use a bowden tube setup to minimise this load, but its something to bear in mind as this will hopefully be traversing the x axis at a fair rate and may cause frame issues. Best Regards picclock |
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