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Well I have exciting news. It worked! I dried the nylon for about 5-6 hours in the tupperware, and when I took it out, it was much stiffer than the original nylon, due to lower moisture content (water acts as a plasticizer). I pushed it through a hot nozzle, and it came out with absolutely no bubbles! There is no discoloration, and it comes out smoothly. I have a feeling that it won't clog the no
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galaxyman7
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General
Here is the book on extruding all the different kinds of plastics:
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galaxyman7
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General
I'll do some more research on how to extrude nylon. I did look through a google book, and it said nothing about toxic fumes or plugging. It did say that if the nylon had too much moisture it would react with the plastic when heated and create bubbles. I think the bubbles are not actually steam, but the cyanide hydroxide, and the plug is the left over products. If this is the problem, then drying
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galaxyman7
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General
Hey, I have been working on extruding nylon. It is readily available as both fishing line and weed trimmer line. The cost is much lower than ABS, around $3 a pound here:
Nylon melts at around the same temperature of ABS, so no changes of the extruder would be necessary. Nylon is a very useful plastic, since it has low friction and very low wear. This means it is good for gears, bushings, and any
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galaxyman7
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General
Just found a book on google that is all about extruding plastics! In the preview, it says Nylon must be dried at 230-248 F for 10 hours before being extruded. This isn't a very high temperature so it wouldn't be dangerous to leave the oven on for that long. It seems like this would be worth it if you did a whole spool at once in a toaster oven. The problem would be preventing it from absorbing mo
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galaxyman7
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General
Ok, I just found a post that describes exactly why nylon won't work:
Didn't realize how many other people have tried this.
Many of them said it was sticking to the nozzle and forming a plug. I wonder if this is because they didn't have the temperature up high enough, or if there is some byproduct of melting nylon that won't melt.
Still, the $2/lb price is so tempting. I will try to find out how
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galaxyman7
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General
Well that just ruins everything doesn't it! Does anyone know a way to release the steam?
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galaxyman7
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General
Don't the UP! printers use 1.75 mm line? That is smaller than this. I know Nylon has a high melting point, so it will be harder to get flowing. I did use my lathe to make a test nozzle, and i heated it over the hotplate and pushed the line through. The problem is, when the melted plastic comes out, it is full of bubbles. It doesn't come out cleanly. Of course i could only push it through about a
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galaxyman7
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General
Ok, I just melted some nylon line and some unknown blue line. They both melted fairly easily on a hotplate, without burning. I am not sure what post i saw that said weed eater line is PVC, but anyways, it seems like the plastic would work well for extruding, if you knew the temperature to set the extruder to.
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galaxyman7
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General
Maybe some is made from nylon, but I am pretty sure the cheaper stuff is PVC. Who would be crazy enough to sell nylon for $2 a pound?
As for breaking down into HCl gas, I know it is a risk, but when PVC burns, you can smell it right away. Small amounts of HCl are not enough to do anything to you. You would have time to put the machine outside and turn the heater off.
Does anyone know the tem
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galaxyman7
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General
I was wondering if PVC would work for extruding. Harbor freight has plastic welders for PVC, and I noticed in another post that someone said weed eater line is made from PVC. This weed eater line can be bought on ebay for $16 per 7 lb! That is 2 dollars/pound. Here:
Plus you get free shipping if you buy $25 worth. Also, the diameter of the filament is only .08 in, or about 2 mm. This would decre
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galaxyman7
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General
I am thinking since threaded rod is pretty slow, and the x axis needs to move faster, that I should convert over to belt drive. The arm can keep the lead screws, since the mechanism will go 3 times as fast as the motors are driving it.
Also, I have been thinking about GM3 motors, and I really don't want to deal with them anymore. Their shaft is strangely shaped, the speed isn't very constant, an
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galaxyman7
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Polar Machines, SCARA, Robot Arms
The arm drive has been converted over to a simpler design, driven by lead screws. The rotating base has been changed to linear rails. Look under the other topic.
by
galaxyman7
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Polar Machines, SCARA, Robot Arms
Also, the same seller on amazon sells extremely cheap belts and pulleys. Here is a 519 mm long (20.4 in) belt for 0.16:
amazon
Here is the pulley for only 0.44
amazon
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galaxyman7
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General
For linear slides, I have used teflon lined bushings from amazon. They work quite well on smooth rod and are very cheap, especially when on sale (5 for .44). The same store has tons of other sizes and other cool stuff. Plus if you spend 25 dollars or more, you get free shipping.You can find them here:
amazon
I just epoxied them into some holes on the side of my axis. You just have to use a hole
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galaxyman7
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General
Actually I was thinking that it wouldn't be that much pre-made stuff, but mostly home made solutions adapted from readily available items. For instance, the idea to press two halves of delrin over a leadscrew to make a nut, or using a coupling nut as a motor coupler, or a cheap way to make linear bearings. Things that can be made by anyone without any fancy machinery.
The problem with the wiki i
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galaxyman7
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General
I am not that great at editing wikis. I think the website is better because the library isn't only for reprap. It is also for other builders. I am just posting here because I know a lot of the people here have some really cool tricks up their sleeves from working on all this stuff.
Also, I just posted instructions on how to make a motor coupler from a coupling nut. I use this on my milling machi
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galaxyman7
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General
Hi, I just wanted to see where everyone got their basic components for mechanical projects. I am constantly searching for cheaper and better ways to make these components. These are some components that make up most of the price for making a machine like the reprap, or a CNC milling machine. I think if we find cheap, reliable sources for each of these components, we will have a base from which to
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galaxyman7
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General
That is a really cool idea! The print would be slightly angled though, since when the arm moves across the surface, it will also being going up slightly. This can be compensated for with a slightly angled print bed. Also, getting the motor to rotate that precisely would require a stepper motor with very small increments, or a servo with very fine positioning. It might be worth it to use two cheap
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galaxyman7
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Polar Machines, SCARA, Robot Arms
Unfortunately I have no dial indicator. I just made my drill press into a make shift lathe, so I might be able to make some aluminum couplers. I was also thinking I might be able to drill out a coupling nut and use that. I have done that with my milling machine and it works quite well. I will work on this after finals are over in December, then I will have plenty of time. Meanwhile I will keep tr
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galaxyman7
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Polar Machines, SCARA, Robot Arms
Do you think it just isn't fast enough or what? I am pretty sure it can hit the speeds that a mendel can, because it has commercial lead screws rather than threaded rod. This means less friction and therefore quicker acceleration. Also, lead screws give much higher accuracy than belt drive. I really don't know why no one has done this.
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galaxyman7
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General
Sorry I haven't been on in a while, but anyways...
I am having trouble with the motors on the arm. The assembly kind of wobbles as it moves. I think it is because either:
1. The coupler isn't connecting the motor to the rod very well. The GM3 motor has a strange shaped shaft so it is hard to get concentric with the threaded rod.
2. The nut holder and/or motor holders aren't held to the pivot bol
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galaxyman7
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Polar Machines, SCARA, Robot Arms
Actually the cheapest possible printer is probably the Mantis 9. It is under $100. Look it up on google. It has the parts list and where to get them, and it is pretty easy to build. They have full video instructions on how to assemble it. I think they might sell kits but I'm not sure. It is actually a CNC mill, but it can be easily converted to printing. You would just need to attach an extruder
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galaxyman7
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General
I think the best bet for making powder out of scrap plastic is to use router bits or drill bits. I have a cnc milling machine, and it can easily reduce plastic to powder, especially HDPE. I think a row of rotating router bits would easily reduce the scrap into powder, even if it was a strange shape like a milk bottle. You could power all of the router bits with one router using belts and pulleys.
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galaxyman7
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General
I have built almost all of the mechanical part of the arm. I have replaced the plastic parts on the arm with plywood, which makes the arm much more stiff. It now has both of the arm motors attached along with the threaded rod and nut holders. When I hook it up to 12V it runs great, and smoothly moves the arm. The last thing I need to do is tension the x-axis lead screw so that it doesn't wobble w
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galaxyman7
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Polar Machines, SCARA, Robot Arms
Hi, I have been working on a robotic arm reprap here:
and I was also thinking about the extruder I am going to use as well as the plastic. I have tons of 12 X 24 X 3/32 plastic sheet lying around, and I wondered if I could cut it into strips and use it to extrude. I could use this copper pipe fitting:
and squish the large end down to a 3/32 X 0.3 slot. I would cut my plastic into strips 0.3
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galaxyman7
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Mechanics
I have updated the wiki page for the robotic arm. It now includes some of the part files and pictures.
It can be found here:
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galaxyman7
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Polar Machines, SCARA, Robot Arms
I think you might be able to simply edit the STL or STEP file by hand and change the size. It might be encrypted or something though, so who knows.
By the way, I made some motor holders for the GM3. I have attached the STL and STEP files.
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galaxyman7
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Polar Machines, SCARA, Robot Arms
Ok here is an updated STL model, along with a .STEP file. I tried an IGS file but it was too big. By the way I am not very good at editing wikis, so I have no idea how to change the pictures and ect..
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galaxyman7
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Polar Machines, SCARA, Robot Arms