Magnetic Joint Improvements

posted 2 May 2014 12:46 by David Taylor

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Before After     For those of you that have been following along, you would have known that my original tool end contained 6mm gutter bolts, with Neodymium magnets on each end, covered with heat shrink. This worked well for a while but then the heat shrink seemed  to get a bit loose, causing some of the balls to move around a bit. This caused wildly inconsistent prints. I tried to give the balls a seat by adding hot glue and while that improved things, the heat shrink would sometimes actually come off the tips of the gutter bolts. Cable ties over the heat shrink improved things a little more, until the ball just popped out of the hot glued seats. So it was time to find a real solution. I drilled a 2.5mm hole in each chrome ball, threaded it to 3mm, and locked each one in place with a lock nut. How to drill into a chrome ball bearing You have to grill your balls. ;-) I tossed mine into the braai (Barbeque for you non-South African's). A normal charcoal braai. Drop them in, make sure they don't fall out of the hottest bit of the fire and continue cooking your food as usual. Leave them in the hot ash until the next night (The idea is to let them cool down slowly). Some people suggest heating them until they are white hot and then putting them into hot sand to cool over 24 to 48 hours. Looks like a normal braai works just as well. They do however come out quite hard still. I broke 3 taps threading 6 balls. They also loose there nice chrome shine, but the end result should be a solid, consistent connection, which weighs a bit less due to the lower volume components. Before After 106 grams (3.7 ounces) 71 grams (2.5 ounces) The fact that I have magnets on the bottom and top of the balls also wasn't a good idea. The magnets seemed to interact with each other at certain angles reducing the holding power randomly. Getting rid of the bottom magnets in this case should also improve things. Next steps: Testing, and then do the same with the trucks at the other end of the diagonal rods.

Tool Carrier [almost] fully assembled

posted 10 Nov 2013 22:25 by David Taylor   [ updated 10 Nov 2013 22:30 ]

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On Saturday night I ended up smoothing down the laser cut parts, which now fit together nice and snug, and assembled the Tool carrier.   Everything seems to be lining up as designed.   Only thing left to do on the tool carrier is to thread the clamps (shown at the top of the image above) with an M3 tap and then it's done.   My E3D all metal hot-end should be arriving soon (Hopefully this week) and then this section should be mostly done.   I'm picking up my Ramps 1.4 board and components on Tuesday night together with 4 2A Pololu drivers, so the rest of the week will probably consist of soldering (if only I had one of these: http://www.thingiverse.com/thing:69729. I will have as soon as I've built my printer ;-)

Laser Cut parts

posted 31 Oct 2013 06:43 by David Taylor

I just got back from EcoLaser in Alberton where I picked up the first parts I ever had laser cut. (Click to see full size image)   I sent these guys the dxf files I created using OpenSCAD and specified the fact that I needed the big parts cut from 3mm aluminium while the small bits should be cut from 4.5mm. They quoted me R 26.16 for a set. I had to get 6 sets to fulfil their minimum order, but at least now I have a couple of sets I can experiment on. They fit my trucks perfectly.   When I was shopping around for quotes I did ask for a quote to have the same parts CNC'd. The quote I got back was more that R 1500.00 for one set.   Stephan from StreamlineCNC was nice enough to send me the reply below when I asked him to explain the big difference in price: The different methods used in machining and laser cutting make it very difficult for me to compete directly with their pricing. In the case of the Tool Carrier, for instance. They would likely cut all their 3mm alu orders from different clients together. The plate lies loose on the bed of the machine and once cut, the parts just need to be picked up and delivered. On the cnc I need to write a cad program which is not as basic as for their machine. I need to clamp the alu plate down to cut it, so in your case it will need a jig with tapped holes made specifically for your plate which I will likely not use again. This also need a cad program to be written for specifically and a separate piece of alu to be cut out of. I need to load the tools in the machine for that job. It might be that some of the tools needed will already be in the machine, but not always likely. Then that set of tools need to be calibrated and that program loaded and orientated to the piece of material. Although your job is not a very complicated one, all these operations have to be done before we cut. That is also the reason that it gets less expensive the more parts you do in one set-up.  Stephan did warn me that the laser cut parts are much worse quality that what you would get from laser cutting thought. (Click to see the full sized image)   These parts are going to need quite a bit of sanding and filing before they can be used.   I've also bought an E3D-v5 All metal HotEnd. Now if only international and South African shipping was as good as RoyalMail.

Tool Carrier

posted 17 Oct 2013 23:09 by David Taylor

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I spent a bit of time designing a tool carrier. I.E. the hot-end carrier. I've seen loads of these printed, but I'm trying to keep the printed parts on my printer to a minimum until I actually have a 3D printer. All the guys I do know with 3D printers are just too busy so I spend allot of time having to wait for them, not to mention any rework required if a design was wrong.   I figured if I made one from aluminium, I could make this with a bit of work at home. For the fun of it, I decided to get a quote to have the parts laser cut and was pleasantly surprised: To have the carrier cut from 3mm aluminium and 3 clamps cut from 4.5mm aluminium (See pictures below) would cost me a grand total of R 26.16 (1.65GBP or 2.66USD). I was shocked. I thought it would be at least 2 extra zeros to that number. Needless to say, I'm not going to make them manually.   4.5mm is however not the required 4.6mm I need to hold a hot-end securely (http://reprap.org/wiki/File:Jhn_nozzle_holder_v5_metric.jpg) so I decided to see what it would cost to have a slightly better version CNC'ed. This would allow me to cut the clamps from 6mm aluminium and then have a perfect 4.6mm height machined out. I'm still waiting for quotes from two local companies that I've asked. (I hate the fact that South African companies do not deal well with e-mail. Unless you phone them, you never get anything out of them)   Anyway, below are some pictures of the designs done in OpenSCAD