@Mrblom, you still carry the weight/mass of both from the looks of it, the whole idea is to have as low mass as possible consistent with rigidity etc.
Steppers are very cheap, like $6~11US so to have 4 instead of 2 is no biggee. The real cost is the headache of the design and the mainboard and, well is it worth it?
My original idea was to have a quick swap hotend, I might still do that if I cant get the belt layout sane. A job to investigate over the winter (I am in New Zealand) me thinks.
Thanks for input all.....it looks interesting and possible.
Last edited by gzcwnk (15 April 2017 10:13)
hello it will be only a lite extra mass it will only carry one extruder at the time the extra mass will be the center "item" where the belts are connected
check this video https://www.youtube.com/watch?v=FiTmRHkiEUg
Last edited by MrBlom (15 April 2017 10:32)
I drew up the original top end in Fusion360 and the only way I can see to make it work is to swap out the 2040 rail for 2080 and the gantries will be tiered slightly, otherwise you just cant get the belts to pass through each other! No biggee and not that hard to print either.
hello it will be only a lite extra mass it will only carry one extruder at the time the extra mass will be the center "item" where the belts are connectedcheck this video https://www.youtube.com/watch?v=FiTmRHkiEUg
You are doing this on a Prusa i3 type printer? in effect the Z moves slowly so mass isnt an issue so for this design architecture having 2 hotends might be OK as Y is the bed.
Extra mass hardly seems small as it would be in the order of 300~500grammes, hardly small unless using a bowden which isnt any good for flexibles.
For a core XY on the other hand I am moving X and Y and rapidly not just X. Everything I read says keep mass so low I just dont see the point of putting 2 complete moving hotends on Y's gantry as Y's mass is then increased which is what I wish to avoid.
With 2 gantries I avoid carrying the 2nd hotend's mass around when I dont need it. In terms of complexity I need 2 more stepper motors and 2 sets of belts and idlers in the order of $30US. I will need to print 4 parts at about 7hours each part. Then the 2080 rail but since I need to buy more 2040 anyway its only a marginal cost to upgrade to the 2080 for me, I can then cut up the 2040 I have for where I am short.
Just a thought but 2080 is twice the weight of 2040. Can you not tier the gantries by changing the mount and still use 2040? I still can't picture how this is going to work so maybe you can't but it was just a thought..
The gantries are still 2040 they are not changed at all from the original design and yes they are tiered. Its the frame that needs to be 2080 as the double set of belts need to be stacked to pass each other. So this mass does not matter, except the printer's frame at 780mm(Y)x550mm(X)x760mm high is already getting big and heavy. I am trying to see if I can get 2060 to work by having steppers at opposite ends but I suspect not. I am drawing it up in Fusion360 and have the original in front of me....
Ah OK. Out of interest, what is the range of movement on each of the 3 axes for that frame size?