Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 10:00AM |
Registered: 9 years ago Posts: 1,035 |
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the_digital_dentist
I don't get it. You guys will use 3D printed parts for the most inappropriate things, but when it comes to something as simple as the square plugs to fit the tubing, all of a sudden you need machined metal? How about just measuring the tube and 3D printing a solid piece to fit? Tap it in with a rubber mallet then drill your holes and bolt the whole thing together.
For that matter, a piece of wood should work fine, too.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 11:56AM |
Registered: 11 years ago Posts: 1,049 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 12:22PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 01:15PM |
Registered: 8 years ago Posts: 776 |
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cozmicray
Print a block leaving hex hole to insert hex nut -- no tapping
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Not going to get 0.1 tolerance with a hand drill, hacksaw and stuff from the Dollar General
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 04:15PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 07:50PM |
Registered: 8 years ago Posts: 776 |
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realthor
If I understand correctly you are suggesting an aluminum bar (I suppose flat if you are specifying 16x16, square actually by those dimensions). Is such a thing you have at your HW store? I don't remember seeing such thing but will double check.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 07:55PM |
Registered: 11 years ago Posts: 1,049 |
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lkcl
not strong enough. it'll crush and crack as and when pressure is exerted on it from the outside as the bolts are tightened.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 08:29PM |
Registered: 8 years ago Posts: 776 |
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cozmicray
If your going to tighten the bolts that much
may have to use titanium, inconel
Will you be using NASCAR 3000psi air gun to tighten?
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I challenge you to crush a well printed block with a bolt and a standard allen wrench
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 23, 2016 11:52PM |
Registered: 9 years ago Posts: 1,035 |
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lkcl
don't use [pure] steel for the inside spacer: when in direct contact, steel and aluminium react, and the aluminium oxidises within about 18 months - it basically crumbles and turns to dust. people who make and maintain aluminium body cars find this out when things start to drop off the car...
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 02:33AM |
Registered: 8 years ago Posts: 776 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 02:39AM |
Registered: 8 years ago Posts: 776 |
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realthor
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lkcl
don't use [pure] steel for the inside spacer: when in direct contact, steel and aluminium react, and the aluminium oxidises within about 18 months - it basically crumbles and turns to dust. people who make and maintain aluminium body cars find this out when things start to drop off the car...
Aren't bolts and washers Steel too? I don't suppose you're connecting extrusions together using anything else than steel. T-nuts,etc ...?
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 06:33AM |
Registered: 9 years ago Posts: 1,035 |
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lkcl
that doesn't mean it won't be a problem... but like all these things, i thought you might appreciate knowing so that you can also make an informed decision... as opposed to blindly "copying whatever else everyone is doing" and then wondering later why the printer literally falls apart or doesn't work.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 07:19AM |
Registered: 11 years ago Posts: 5,780 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 08:04AM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 12:06PM |
Registered: 8 years ago Posts: 776 |
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realthor
How hard should a bolt be fastened to connect two square alu tubes together?
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 12:14PM |
Registered: 9 years ago Posts: 1,035 |
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lkcl
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realthor
How hard should a bolt be fastened to connect two square alu tubes together?
really, you should be testing it, by buying two bars in the next day or so and trying it out. get two bars, drill holes 10mm front the ends, bolt them together in parallel then prise them apart with your hands. if they bend or they separate even by a couple of millimetres with a mild amount of force, you know you've got a problem that needs to be fixed before proceeding further.
the suggestions i've made are so that you can be absolutely absolutely sure that you can lock the bolts down hard, and guarantee that nothing will move *and* at the same time not be irreversibly damaged by doing so.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 12:19PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 03:39PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 04:26PM |
Registered: 11 years ago Posts: 1,049 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 04:33PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 24, 2016 06:12PM |
Registered: 11 years ago Posts: 1,049 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 25, 2016 05:52PM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 25, 2016 11:15PM |
Registered: 11 years ago Posts: 1,049 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 26, 2016 03:58AM |
Registered: 9 years ago Posts: 1,035 |
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cozmicray
IMHO
Your washer block puts the non-washer hole (drilled thru both sides of tube)
very close to edge of aluminum stock
the worst place to remove metal, weakening the tension/compression web.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 26, 2016 01:22PM |
Registered: 8 years ago Posts: 776 |
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realthor
Considering that 3 tubes will be connected with at least 3 (maybe 6) bolts ... does it really matter that two such tubes can be forced into rotating against each other? I know I can test but I am looking at establishing a minimum amount of fastening force for the actual situation not a theoretical limit that can be achieved if one forces the tubes beyond their working parameters. I mean no offence of course, if anyone it's at fault here it's probably me
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 26, 2016 01:23PM |
Registered: 8 years ago Posts: 776 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 26, 2016 02:41PM |
Registered: 11 years ago Posts: 1,049 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 27, 2016 08:53AM |
Registered: 9 years ago Posts: 1,035 |
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 27, 2016 11:58AM |
Registered: 8 years ago Posts: 776 |
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realthor
If the inside piece (e.g the stack of washers) is the same height as the inside of the tube, 16mm if 20x20x2mm tubes are considered, then there will be no stretching/compressing but in the very crystalline structure of the ALU top and bottom walls, those in between washers. And squishing the solid wall in between washers will take some force.
Re: Coffeetable CoreXY:: new build :: small apartment rep-strap solutions April 27, 2016 12:45PM |
Registered: 9 years ago Posts: 1,035 |