Tine Grab Hinge Points on Autocad

[mar]

I am thinking of making a tine grab. Is there any way of figuring out the location of the holes for the hydraulic ram and hinge point by drawing it up on autocad. How do you do it on AutoCAD. Is there any other way of doing it that is not trial and error

 

[clbarclay]

I haven't used AutoCAD, but with other CAD programs you can create drawings with relationships. With that you can.

Not easy to explain just in words, but I have created simplified 2D drawings of things like that where the grab would be show in both full open and closed to show the length of ram required for the pivots or where the pivots need to be to suit particular open/closed lengths.

 

[bkg]

Can you not model the drawing to test operation ie how the ram moves in relationship to brackets or fixed points not used autocad can in onshape ?

 

[mar]

I haven't used AutoCAD, but with other CAD programs you can create drawings with relationships. With that you can.

Not easy to explain just in words, but I have created simplified 2D drawings of things like that where the grab would be show in both full open and closed to show the length of ram required for the pivots or where the pivots need to be to suit particular open/closed lengths.

I think i understand what you are saying. I will give it a go and see how I get on

 

[mar]

Can you not model the drawing to test operation ie how the ram moves in relationship to brackets or fixed points not used autocad can in onshape ?

I only know the basics in Autocad, don't know if you can do that in Autocad

 

[Andrew]

Never used Auto cad but in SolidWorks and SolidEdge make a 2d sketch of the grab and all the pivot points, but leave the rams off. Then copy it twice and use equal length relations on all the lines so you have one drawing of all the dimensions, and two drawings with no dimensions. On one of these add the dimension of the cylinders closed length. On the second drawing add the cylinders open length.
Now you can experiment altering the dimensions and strokes until the grab is how you want it.

 

[Dman2]

Go get a meccano set
Much easier
Well for me anyway

 

[davieh3350]

Draw the grab in the closed position, then copy it an rotate the opening part around the hinge point till it's where you want it open.
Find a ram supplier and see what the closed length and stroke length or their rams are.
Draw a circle the radius of the rams closed length centre to centre of the pin holes, the centre of the circle being from a point at the opposite end from the hinge.... where it looks about right.... then from the same point on the end when it is closed, draw another circle adding the stroke length to the closed length (maybe there's the open length provided) where the two circles intersect is where the pin hole on the frame should be. Go from there and try different positions/sizes of rams till it works

It's great fun to do!

 

[tinman]

Or sign up for a free trial of fusion360 and work fast....

 

[mar]

Draw the grab in the closed position, then copy it an rotate the opening part around the hinge point till it's where you want it open.
Find a ram supplier and see what the closed length and stroke length or their rams are.
Draw a circle the radius of the rams closed length centre to centre of the pin holes, the centre of the circle being from a point at the opposite end from the hinge.... where it looks about right.... then from the same point on the end when it is closed, draw another circle adding the stroke length to the closed length (maybe there's the open length provided) where the two circles intersect is where the pin hole on the frame should be. Go from there and try different positions/sizes of rams till it works

It's great fun to do!

Could you do a basic sketch showing that, I follow some of it but not 100% sure where the centre of the first circle goes

 

[davieh3350]

Could you do a basic sketch showing that, I follow some of it but not 100% sure where the centre of the first circle goes

W

Could you do a basic sketch showing that, I follow some of it but not 100% sure where the centre of the first circle goes

will do one in the morning.

 

[davieh3350]

Could you do a basic sketch showing that, I follow some of it but not 100% sure where the centre of the first circle goes

Done a quick CAD drawing (Cup Aided Design)

Draw the basic frame to the size you want with the grab in closed position, put the hinge point in, copy and rotate the grab part about the hinge point till it's in the open position.
The rams cylinder pin hole is going to need to be above and behind the hinge point of the frame, so the body of the ram doesn't clash with the frame and so it doesn't move the grab at lightning speed and have some power.
The rams rod pin mount can go somewhere along the length of the grabs frame.
As a rough starting point you draw a circle with a radius of the open length of the ram (pin hole to pin hole) with the centre point of the circle in the area of the cylinders pin hole mounting (above and behind the pivot/hinge point)
Where the diameter crosses the frame in the closed position make the rods pin mounting point somewhere on that diameter with enough clearance for the rod. Copy that mount (and a part of the frame (like the line that would be the end of the box section) and rotate and move it to the drawing of the open grab and place it so it's in the same location on the frame.
In the centre of that point draw a circle the diameter of the rams closed length.
Where the two circle intersect is where the pin should go.
Make sure you make changes to both parts of the drawing, not just one.

Hope that's less confusing

 

[mar]

Done a quick CAD drawing (Cup Aided Design)

Draw the basic frame to the size you want with the grab in closed position, put the hinge point in, copy and rotate the grab part about the hinge point till it's in the open position.
The rams cylinder pin hole is going to need to be above and behind the hinge point of the frame, so the body of the ram doesn't clash with the frame and so it doesn't move the grab at lightning speed and have some power.
The rams rod pin mount can go somewhere along the length of the grabs frame.
As a rough starting point you draw a circle with a radius of the open length of the ram (pin hole to pin hole) with the centre point of the circle in the area of the cylinders pin hole mounting (above and behind the pivot/hinge point)
Where the diameter crosses the frame in the closed position make the rods pin mounting point somewhere on that diameter with enough clearance for the rod. Copy that mount (and a part of the frame (like the line that would be the end of the box section) and rotate and move it to the drawing of the open grab and place it so it's in the same location on the frame.
In the centre of that point draw a circle the diameter of the rams closed length.
Where the two circle intersect is where the pin should go.
Make sure you make changes to both parts of the drawing, not just one.

Hope that's less confusing

Thank's for doing that out, it's a great help. When I get a chance some day I will have a trial run.