help with rams / hydraulic cylinders

kevin_mason558

i am trying to develop a lift in work. i have drawn a plate that rotates on hinges, also added in a ram in assembly mode. 
just to test positions of where the ram may be mounted.
used a revolute mate for the plate/frame. that moves as id like
used a sliding mate for the ram that moves in and out
But positioning revolute mates on the ends of the rams does not allow for the ram to be joined to the plate and then extend along using the sliding mate (i haven't made brackets yet because i need to test the positions first to see where the ram will work. i can fabricate brackets to suit at a later stage.

hope this makes sense?
can anyone help with this please

https://cad.onshape.com/documents/dcdc6a1fee7cd38ee55e6fe1/w/5e0d04c60fe635665eb9c535/e/f7a107d8b516d60944829b9f?renderMode=0&uiState=64b05ad040fb7f3a624b5c07

glen_dewsbury

@kevin_mason558
Can you make your document public so a copy can be made?
This looks straight forward but easier to demonstrate in document.

kevin_mason558

@glen_dewsbury
I think I have made it public now
thanks 
I just cannot get them to mate without throwing up errors and separating other mates 

eric_pesty

My guess is that a revolute would over-constrain the ram, try using a cylindrical on one end of the ram to avoid that, and possibly instead of the slider in the ram as well if something is out of plane you may need to allow the cylinder to rotate as well.

Also I noticed you have a bunch of explicit mate connectors defined at the assembly level but most of these are exactly the same as "implicit" ones so don't really add any value (i.e. it seems you are making your life harder for no good reason with these!)

One more tip: you have frames and a cut list defined but you inserted individual parts in the part studio and fixed them... An improvements if you need the individual parts in the assembly would be to group them (and fix just one), or an even better option would be insert the composite part instead of individual frame parts in the assembly.

eric_pesty

One more thing looking at your model: you have a good start in "sketch4" for layout the ram mounting points, I find adding arc (or just start with circles) from the pivot points to the relevant ends is the best way to position your "other" pivot:
Circle around bin pivot and circle centered on ram "fixed" end going through the ram attachment point and where they intersect is where you want your pivot point

kevin_mason558

@eric_pesty I don't know what you mean by the implicit and explicit mates sorry 
am I putting too many mates on things

kevin_mason558

Just to add this I have started fabricating the frame and lifting chute 

was just trying to work out ram positions while we are waiting for delivery 

kevin_mason558

eric_pesty said:

My guess is that a revolute would over-constrain the ram, try using a cylindrical on one end of the ram to avoid that, and possibly instead of the slider in the ram as well if something is out of plane you may need to allow the cylinder to rotate as well.

Also I noticed you have a bunch of explicit mate connectors defined at the assembly level but most of these are exactly the same as "implicit" ones so don't really add any value (i.e. it seems you are making your life harder for no good reason with these!)

One more tip: you have frames and a cut list defined but you inserted individual parts in the part studio and fixed them... An improvements if you need the individual parts in the assembly would be to group them (and fix just one), or an even better option would be insert the composite part instead of individual frame parts in the assembly.

I also don't know about grouping items, I have found I can add them to a folder recently and have used that a few times 

I have been using the parts studio to make a lot of things all building parts off one another 
and I was told I should be using assemblies more. So I'm trying to do this. But because I'm trying to do it at home around work 
I'm usually trying to model/draw something before it's being made within the next day or two. 

I have done some of the training modules but at the moment I'm learning by doing it. Probably not doing things the right way though

eric_pesty

Right,
I find sometimes a 2D sketch is the best way to figure this out, something like this:

https://cad.onshape.com/documents/9a78a5847cc245caac901d3b/w/9959cac71460a6574b6358d2/e/5cd6f62a8b5feb9a24fd430f?renderMode=0&uiState=64b06d79f5c41c233c6c7822

eric_pesty

kevin_mason558 said:

@eric_pesty I don't know what you mean by the implicit and explicit mates sorry 
am I putting too many mates on things

It's ok, you got the job done, I'm just pointing out you are doing extra work for yourself.
See here for implicit vs explicit mate connectors: https://cad.onshape.com/help/Content/mateconnector_a.htm?Highlight=mate connector

glen_dewsbury

Good morning @kevin_mason558
Eric's discussion about about making a sketch to set your initial motion will get you started quickly.
A few more notable points will help to keep organized.
Changing part names makes it clearer to read as apposed to part1 part1 part1.
You made the cut list. This is good. At the same time a composite part was made for you. Using this in the assembly is recommended since it will bring a single item that that needs no further frame mates and can be used for a weldment drawing with a cut list. Any new features that add parts for the frame should be ahead of the cut list feature.
In my example I used mates with offsets to get cylinder connection points before designing brackets. The example allows you to drag the bin up and down to see end results. Can also animate the revolute mate.
As a design note, I would reverse the cylinder orientation. Putting the cylinder on top with rod below offers greater lift capacity when bin is full and less capacity to return the empty bin. As a bonus the rod seals will be facing down to collect less debris on the seal.
https://cad.onshape.com/documents/19af1201ba47247cd6e69c4e/w/965a946ada42f9fd23679b94/e/a14abaaa29c878336de185a4