Linear to Rotational Motion Help
Hi,
Before you try to fix this issue, your design has some MAJOR issues.
The first thing I see in this design is a HUGE number of Move commands. This is terrible workflow. EACH time you
use the Move command it will force fusion to do a full re-calculation. Even if you have just done a re-calc. So your
file is basically re-calculating ALL the time.
While there are exceptions, you should almost NEVER have to use the Move command. In this case I can see that the
reason you are using it is to either - shift things around because you cannot see stuff, OR to put them in place in the
Model. As you can see, simply by click and dragging I have dismantled your Model and it will NOT simply go back to
how it was because as soon as I say yes to the inevitable Capture Position request fusion is about to give to me, all
of those parts will be stuck where they are if I hit yes.
Next. See the yellow flag in the timeline on the bottom? In this case it probably makes no difference because it is a
Move, but ANY yellow or Red flags in the timeline need to be fixed IMMEDIATELY. Those things are there for a reason
and are telling you there is a problem.
Your Sketches are not fully constrained. They are simple sketches but unconstrained sketches cause potential
problems later than can trash a design and be unfixable.
You have entire folders full of bodies that are not doing anything.
I am sure that Rob and Linda are lovely people but as component names it means absolutely nothing to an engineer.
Similarly Component 96 means nothing. You will NOT remember half of this stuff if you go back in 6 months time.
What you are left here is a bunch of Bodies and groups of Bodies than will never join up to anything. A bunch of
Components that will join up to something - if you can identify what that is. And a pile of parts that is not a Model
that is useful for anything.
Ok. Lets look at some positives.
I actually like the concept of your design. It is quite Kool. In its present form I think starting again might be the best
way to fix it, but the good news is that if you do it right it will not be the big disaster you are thinking right now.
A few things you need to know before trying again.
DON'T MOVE STUFF AROUND unless you REALLY NEED TO.
- If you cannot see stuff then use the visibility icons.
- If you want to join parts together then use an actual Joint.
There is a difference between Bodies and Components. You need to learn the difference.
- I would STRONGLY advise you to look at the top of the Forum and check out the Pinned Post - RULE #0.
- Any time spent reading the Documentation and doing the embedded tutorials and Self Paced Learning is NEVER
wasted.
Read some engineering books about simple machines. There are many aimed at all levels from Primary School to
University level. Knowing what the six simple machines are and how they work will help you a lot. In this case, and
answering your initial question, you need to change linear motion into rotational motion. You are probably looking
at a screw or wheel and pully.
In this type of design you would normally consider gearing and I would say a Rack and Pinion gear would work best.
Check out Uncle Wikipedia here: https://en.wikipedia.org/wiki/Rack_and_pinion
So lets have a look at how you might have done this design. There are two basic methods, the Origin and Joint
method, and the Build in Place method. Both work well depending on your design methodologies, sometimes one is
better than the other, sometimes you can mix both. Whatever works for you.
Right. New Design; set your measurements if needed (I use mm normally); Name your first Component; Save with
a Meaningful Design Name. Good to go.
New sketch. Lets do the Base first. Pick if you want your Origin to be a corner of the Base or the middle of the Base.
Draw, Fully Constrain and Extrude. Don't forget to decide if all sketches go in the Top Component or within
Assemblies. Both work but be CONSISTANT. I will put Sketches in the Top so when I start the sketch the Top
Component will be Active. When I Extrude I will make what I am making Active. I also like to use Construction Lines
in places I might need later, like the Centre of my Base.
Ok. Lets make the Shoulder. Make the Top Component Active. New Component - call it Shoulder. I am going to use
the Build in Place Method first. Make my Sketch visible again after the extrude. Make a new Sketch, this time use
the top of my Base as the Plane, not the Origin Plane. See how I can see my original sketch through the Base?
I want to use my Construction Lines to locate the Centre of the Base to create the small Platform sketch. To do this
I will Project the parts of this sketch I need into my new Sketch. Press P and click on the Centre Point.
Hit Ok and turn the visibility of my Base OFF, now I have a purple dot. Create a Centre Point Rectangle the size of
the Platform.
Notice how all of the lines are black and the two sketch Icons are little Locks? Everything is fully Constrained.
Finish the Sketch. Before I extrude this one I need to decide if I want just this Part or do I want a Sub-assembly
to try to keep track of things. The Shoulder has two parts, the Platform and the Cradle made of a Left and a Right.
Lets make this a Sub-Assembly.
Keep the Base invisible. Make the Shoulder the Active part. Extrude the Platform.
The Shoulder now has one Body, but we already know it will have three (or more) parts. We are going to turn this
Body into a Component. Right click on the Body and select Create Component from Bodies. rename the new Part
so we don't forget what it is to Platform.
Now we need the two sides of the Cradle. Make the Top Active. New Sketch on the YZ Plane. This time we will use
the Origin and Joint method. Draw a fully constrained sketch of the Cradle Arm.
Your measurements of this part are quite strange. Lets fix that.
Your part is also not on the Origin of anything. We will use the actual Origin.
Draw the Outline of your shape using the Origin and the Y and Z axis. Use "nice" number unless there is a reason. As
a guide, if you are designing something like this then to the nearest cm is fine; if you are designing a medical
instrument for brain surgery - be more accurate.
Put in a Construction line to help locate our holes. Create our holes, dimension them and make them co-incident
with the construction line. Don't forget to put exactly how far from the top they are and how far apart. Lets also put
a small tab on the bottom to plug into the Platform.
Right now there is nowhere to attach our Cradle Arms so lets fix that. Make sure the Top is Active and start a new
sketch on the face of the Platform. This time we want to project the Body of the Platform onto our sketch.
Turn off the visibility of the Platform and we have the outline of it in purple. Put in some construction lines to help
locate everything. Draw a rectangle inside the Platform outline 70 x 5mm. Put a mid-point constraint with one side
of the rectangle and our construction line. Put a distance dimension for how far it is from our centreline. Now do a
Mirror command of this shape with out centreline.
You should end up with a fully constrained sketch like this.
Turn the Platform visibility back on and extrude our slots 5mm into the Platform.
Notice the Operation is a Cut to a distance of MINUS 5mm.
Lets now create our Cradle sides. Make the Shoulder Active. Extrude the Cradle profile 5mm
Don't forget we WANT it to have the holes. The Operation is New Body.
Turn the visibility of the sketch you just used to extrude back ON. Turn the visibility of the Body you just made OFF.
Make another extruded body.
With Shoulder the Active Component, right click on each of these bodies and Create Component from Body from each
of them.
Turn the visibility of the second Component you just created OFF so you don't get confused.
No we are going to see why I have done this project the way I have. The problem with your design was that it was
just a bunch of components and bodies. They looked connected but they actually were not. I am going to show you
how to fix this. We are going to use two similar types of Joints. Joints ONLY work on Components. This is how.
The first joint is a normal joint. We created our Cradle sides at the Origin and this is where they will stay unless we
Move them. We are going to Move them, but we are going to do it the correct way.
Component One of our Joint is going to be one of the slots in the Platform, and what we want to do is get a little
circular icon in the middle of the slot pointing up. This is the "snap" point of our joint.
Now we want the second Component we want to join together to be the bottom of our Tab on the Cradle Arm we just
extruded. We want that circular Snap to be in the same spot - middle on the surface of the tab.
What we want is for the Cradle arm to go to the Platform hole. Swap around which Component is which if it goes the
other way, just hit undo and try again.
The Cradle Arm is exactly where we want it, we don't want to adjust the position or angle. Hit Ok.
Turn on the other Cradle side visibility and do the same to the other slot. It should look like this.
Change the names of the Cradle Arm so you know what they are. These Components are now permanently joined.
Now lets have a look at the other kind of Joint. The As-Built Joint that we use when we Design in Place.
remember that we built the Base and we built the Platform separately? The Platform is now a Sub-assembly of the
Platform and two Cradle Arms that are all Joined. Righ now, it you turn the visibility of the Base back on these things
will look like they are joined but they are not. You can drag them around.
Make the Top Component Active. Turn on all visibilities. and it will look like this.
Simple job next. Everything is in the right place so lets join them together.
This time you want an As-Built Joint.
Select the Platform (NOT the Cradle as it is already joined) and the Base.
Now it is all joined together. This works with all of the other joints you will need. There are different types of joints
but the basics are all the same. Pick your Snap Points, adjust if necessary; pick your Joint Type and it should work.
I will attach my file so you can have a look on the timeline how I did it, but this is the workflow that you want.
And READ and DO the Tutorials in the Documents and Self Paced Learning.
A few guidelines.
Sketches should be simple and only do one or two things.
Planning is important.
Know what Component is Active and When you need to Change it.
Joints are ONLY between Components.
If it isn't Joined then it is a thing floating in space.
Cheers
Andrew
