The Shop > Tools
Another 3D Printer
tom osselton:
Could you not drill through and use some of the threaded inserts used in woodworking that are capped?
Joules:
--- Quote from: tom osselton on February 11, 2016, 04:47:25 PM ---Could you not drill through and use some of the threaded inserts used in woodworking that are capped?
--- End quote ---
I looked at those inserts, but decided on a horseshoe shaped alloy fitting with the five threaded bosses machined in, so none of them can spin and I get good clamping force. The whole part above is having a redesign as its a pretty course print, I can route the wiring better and improve the filament cooling fan supports and reduce its footprint with better clamping. Just juggling time and jobs as a rather nice robot arm got delivered a few days back and could be a major distraction if I'm not careful. 8-) But that's another story.
Jorkki:
I received my my kit and have been going through and preparing the parts for assembly.
The hotend mounting really is not something that gives a warm and fuzzy feeling even if I'm not a mechanical engineer.
To complicate that, my effector piece seems to be a not so successful print with deformed rod end mounts so I'll have to trim it down and use some additional washers to make the rod distances equal.
I think the best option would be to order an effector made of aluminium.
At least this one has a 3mm set screw that tightens the hotend directly to the effector plate.
http://www.robotdigg.com/product/396/End+Effector+for+Kossel
Another thing I have noticed is that many of the Traxxas ball joints have quite a bit of play. I know this is a fairly common issue that people have tried to solve by using rubber bands or springs to pull the rods together to lessen the effect, but annoying nevertheless. We'll see how it will affect the accuracy.
Jorma
Joules:
Jorma, you can ignore the play in the ball joints, gravity is working in your favour. The weight of the hotend keeps enough tension to stabilise everything. The only time you will have a problem is when you ramp the speed up. I would suggest this is not a fast printer, but when properly setup, a very precise printer. All my tests indicated very good repetition and quality printing till the hotend worked loose due to crap clamping method. I am working on a solution now.
Wow, I really like that effector plate solution, you have just changed my design focus. :thumbup:
Joules:
Best laid plans of mice and men. I figured I would get this redesign of the hotend clamp nailed, when work rudely interrupted, since last year was very hit and miss, earning toy money has become the priority. So the design got shelved and a quick fix sorted. I modified the original STL file to take a 5mm diameter x 4mm long knurled bush. These are set into the 3D print 2mm from the clamping surface. If anyone wants the new STL file, just give me a shout.
I had to work quick in the workshop as it was freezing and I had about 20mins before my hands stopped working, so no pictures of them being machined. Back inside and warmed up I made use of a cheap table vice I picked up from Aldi, on Friday. Very handy it is too, for holding small stuff like this. Each bush tapped 3mm and the faces cleaned of burrs with a needle file.
I used some packing to spread the load on the working face of the print and pulled the bushes in with a 3mm bolt. The bushes are about 0.15mm oversize with the knurl so they bite well into the 3D print, but hopefully don't stress the walls too much as I wouldn't want them to break loose when clamping this all together.
Here they are all installed and ready to reassemble, then go all the way through calibration again. This I hope will fix the printer for now..... Others plans for update have been pushed well back on the back burner.
Something that has started to interest me is the possibility of moving to a cnc lathe. With my hands being hopeless in these temeratures I am looking at desktop Denford and Boxford slant bed lathes. Anyone local (South Yorkshire) with similar machines fancy guiding/training me in return for CAD design work. If anyone also knows of a working machine requiring a good home !!! I am on the look out for one.
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