Solved: Joined components don't move together

Anonymous · ‎01-22-2020

Hi,

I searched the forum and found a lot of questions around this, but couldn't find a comprehensive answer that I can use (these threads often end by "I remade it and now it works..."), so I finally decided to ask the question directly.

Fusion360 level : Newbie, watched a loooot of videos and tutorials.

Project :

I'm designing a dolly with 2 purposes: move a camera (light load and smooth moves) or a chain hoist (heavy load) along a beam. So I have a big U shaped steel pieces with rollerblade wheels and ball bearings attached. Design is in attach.

In a nutshell :

I joined all components together, but when I slide the wheel on the rail, only the wheel moves... whatever I try, the dolly itself remains in place (and it's not grounded... ;))

🤔🤔🤔

Components tree is as follows:

- Root

--Cornière (steel angle piece on the beam) - component

--Chariot (dolly) - component

---Plaque_base_chariot (base plate of the dolly) - component

---bord_gauche (left plate) - component

---bord_droit (right plate) - component

--- Roulement 6301_2RS_16:1 (ball bearing front) - component

--- vis_m16_roulement:1 (bolt for the front bearing) - component

--- Roulement 6301_2RS_16:2 (ball bearing back) - comonent

--- vis_m16_roulement:2 (bolt for the back bearing) - component

--- Roue_roller:1 (rollerblade wheel front) - component

--- Roue_roller:2 (rollerblade wheel back) - component

--- Vis_m16_roller:1 (bolt for the front rollerblade wheel) - component

--- Vis_m16_roller:2 (bolt for the back rollerblade wheel) - component

I created joints in the dolly component :

- between base plates and both side plates (rigid)

- between bearing bolts and right side plate (rigid)

- between bearing bolts and bearings (rigid) (they should not touch the rail unless charge is heavy)

- Between rollerblade bolts and right side plate (slider) (for height adjustment)

- between rollerblade bolts and rollerblade wheels (revolute).

- between 1 rollerblade wheel and the steel angle (slider).

Thanks in advance for your help !

etfrench · ‎01-22-2020

Change all of the revolute and slider joints under chariot to rigid joints, then the top level slider will move all of the chariot components as one.

ETFrench

Anonymous · ‎01-22-2020

Hi,

Thank you for this quick answer. I'll try that solution (it's not really important - in the scope of this project) to have the wheels and the adjustment slots "animable",

But this still looks like a "workaround". In my quest for a solution, I watched a lot of videos, and this one among them : https://www.youtube.com/watch?v=C03H_YZHuAI&t=6m50s (starts at 6minutes 50seconds).

In this video, a block revolves and slides around a rod (cylindrical joint), and this rod slides in a slot (slider joint). We see that the when the rod slides in the slot, the block "comes with it"... and there's no rigid joints in there

--> is there an reason why my model doesn't behave like that ?

davebYYPCU · ‎01-22-2020

--> is there an reason why my model doesn't behave like that ?

Your model does work like that. 5mm slider travel for wheel axle bolt, working as expected, after the main rail is grounded.

In other words the front wheel is sliding on the rail, the axle can slide in the slot. Make the two wheels a rigid group the whole model behaves as I am expecting.

Might help....

Anonymous · ‎01-22-2020

Grounding the steel angle did indeed make "miracles"...

But I still put miracles between brackets, since it's still not moving like i'd like it to move. Maybe I'm just being too ambitious for my first designs in Fusion360, but still... it's kind of frustrating because I'm quite sure it's possible to end up with :

- The dolly "rolling" on the grounded steel angle with wheels spinning. (I added a motion link between revolving wheel & slider on steel angle (I actually tried to add 2 slider joints on the 2 wheels (with the idea to create 2 motion links in order to have the dolly "roll" instead of "roll & spin", but it gave an error.

- The dolly limited to a sliding movement

- possible movement in the adjustment slots.

If someone can tell me how, that would be amazing, but I can also live with rigid joints here & there and a still nice sliding movement of the whole dolly... 🙂

davebYYPCU · ‎01-22-2020

What did you do?

The wheels rolling - doesn’t matter,

Wheels sliding and fixed to the rail, - working,

lift trolley up as if suspension, - working.

Need something else?

chrisplyler · ‎01-22-2020

Well, you can't make a Slider joint between a wheel and the angle, and still expect the wheel to turn.

I grounded the angle beam.

I deleted the slider joint between the wheel and the angle beam.

I made a new slider joint between one of the dolly plates and the angle beam.

I set up a motion link between the front wheel's revolve joint and that slider joint.

I set up a motion link between the back wheel's revolve joint and that slider joint. (Alternative would have been to set up a motion link between the back wheel's revolve joint and the front wheel's revolve joint.)

Now it rolls along the beam as expected.

Anonymous · ‎01-22-2020

I still have to try your solution, but just reading it, I get the sense of it... you can't slide & revolve (unless you're burning tires making donuts on a parking lot... ;)) --> slide the plates & make the wheel turn...

I'll try this as soon as i'm out of the office.

Thanks a lot for taking the time to test and explain the way it should be done !

chrisplyler · ‎01-22-2020

You can get both sliding motion AND rotation motion using a Pin Slot Joint. But honestly it's just easier, at least in this case where you have at least one other item in the dolly assembly that can use a Slider, and you already have the wheels set up with Revolute Joints to that other item anyway, to do things as I've described above.

I would only mess with a Pin-Slot Joint if the wheel was sitting on the beam all by itself and needed to roll along alone. Just wanted to make you away of the possibility.

chrisplyler · ‎01-22-2020

Anonymous · ‎01-23-2020

Tested : Works as a charm !

Thanks !