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Feasibility question - cheapskate extension

Posted: Wed Aug 05, 2015 3:16 pm
by BenTheRighteous
Let me start off by saying I'm happy with my printer's build volume but I understand there are others who aren't. For those people - how crazy of an idea is it to print out some extensions that sit between the cheapskate and the delta arm axle? I feel like moving the axle out by a few cm would help the print head reach farther and satisfy the people who feel like they need the extra volume.

What would the disadvantages be? Off the top of my head, I would wonder how precise the printed extension would need to be, and if a printed part would be appropriate for that or not. Also, strength might be a factor. I could see bad things happening if the extension were to break in the middle of a print job, but then again I don't know what sort of force it would have to stand up to, so maybe it's not an issue.

Overall, yay or nay?

Re: Feasibility question - cheapskate extension

Posted: Wed Aug 05, 2015 3:24 pm
by KAS
Would the effector lift as it swings in a negative angle directly under the tower?

Re: Feasibility question - cheapskate extension

Posted: Wed Aug 05, 2015 7:35 pm
by Earthbound
KAS wrote:Would the effector lift as it swings in a negative angle directly under the tower?
I think the firmware is okay with an arm swinging past vertical. As long as the firmware can do the math correctly and nothing mechanical is binding, the effector will remain level.

The negative impact of moving the carriage axles closer to the center of the build envelope is that the golden triangle of decent Z height calibration gets smaller.

Re: Feasibility question - cheapskate extension

Posted: Thu Aug 06, 2015 12:00 am
by BenTheRighteous
That's a valid point, but I think if you're trying to reclaim the extra width, that means you're trying to print outside the golden triangle anyways.

Re: Feasibility question - cheapskate extension

Posted: Thu Aug 06, 2015 12:25 am
by bvandiepenbos
Weird things may happen to speed/acceleration as arms pass the zero vertical point.
Interesting thought, who knows until you try, it may work.

What about printing larger platform instead?

Longer arms is probably the best solution.

Re: Feasibility question - cheapskate extension

Posted: Thu Aug 06, 2015 1:26 am
by ZakRabbit
bvandiepenbos wrote:Weird things may happen to speed/acceleration as arms pass the zero vertical point.
Interesting thought, who knows until you try, it may work.

What about printing larger platform instead?

Longer arms is probably the best solution.
If given the choice between longer arms, and spacing the pivot away from the trucks, my gut tells me longer arms would be best. I wonder what a smaller diameter effector with super long arms would accomplish? Is that not heading toward some "ideal?"

Re: Feasibility question - cheapskate extension

Posted: Thu Aug 06, 2015 2:41 am
by Earthbound
I would be concerned about the stability of a small diameter effector. The vertical distance between the center of mass of the hot end and the horizontal center line of the effector needs to be a minor fraction of the effector diameter. Reducing the diameter of the effector makes the fraction larger. Keeping the fraction small minimizes the leverage that the hot end can exert on the effector during a change of direction or if/when the nozzle snags. Maximizing the stability of the effector is one reason I keep my hot end in a stock (above the effector) position.

Re: Feasibility question - cheapskate extension

Posted: Fri Aug 07, 2015 8:36 am
by BenTheRighteous
I agree that longer arms is the best option, but those would be more difficult to print a solution for. Also the only aftermarket arms I'm aware of are the Trick Laser CF arms, and they're the same length as the stock ones.

I've heard there are other options on eBay, but if it were me, I wouldn't want to go down that route.

Re: Feasibility question - cheapskate extension

Posted: Fri Aug 07, 2015 9:43 am
by bvandiepenbos
BenTheRighteous wrote:I agree that longer arms is the best option, but those would be more difficult to print a solution for. Also the only aftermarket arms I'm aware of are the Trick Laser CF arms, and they're the same length as the stock ones.

I've heard there are other options on eBay, but if it were me, I wouldn't want to go down that route.
Trick Laser now offers CF arms 300 and 325 length. And still 269 stock length.