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How to stop a sliding drawer

B

bobsmodels

Member
Hi

I have put together a cabinet with drawers. In the assembly I have the drawers constrained so they only move in and out. I thought there was a way to limit the travel. I thought I did it once on a milling machine assembly I did but cannot find it.

Is there a way to stop the drawer when I slide it ? I do not care about the out motion just so it stops ie even with the front.

Thanks


Bob
 
bigseb

bigseb

Alibre Super User
Yes. But its a workaround that involves a disc with the diameter of the drawer travel and a pin on the periphery of the disc that controls the backward and forward movement of a slotted bar attached to the drawer. These items are hidden in the assembly (but not suppressed).

Sorry if that isn't the best description. I've had drinks.
 
swertel

swertel

Alibre Super User
Limit mates are "advanced" mates that even the most popular MCAD programs have only implemented within the past few years. Since this was during the dark ages of the company that shall not be named, I'm not surprised Alibre Design hasn't implemented similar features yet.

Make sure limit mates go onto the suggested features log and include your description for correct application of those mates. Nothing worse than a "working as designed" feature that doesn't work in practice.
 
B

bobsmodels

Member
Bigseb

As soon as you described it I recalled several places where I had done it. One simple one is engine crank driving the piston/rod, same idea. Thanks for the mind jogger

Bob
 
Lew_Merrick

Lew_Merrick

Guest
Bob -- This is an arena about which I have been "complaining" since 2009. Just to be clear. Attached is a (PDF) document I submitted in 2015 (though earlier versions were also submitted). Microscopically more than nothing has been done in this arena.
 

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  • Constraint System Improvements 01 20150308A.pdf
    114.2 KB · Views: 22
JST

JST

Alibre Super User
Limit mates, and "path mates" (where the path is a face or edge that can preferably go across more than one part) are needed enhancements which would make many things MUCH easier.

Add "rotating constraints" where two items can rotate at settable ratio to each other, and you REALLY have something.
 
JST

JST

Alibre Super User
swertel said:
Commonly referred to as GEAR mates.
Click to expand...

Yabbut... also applies to pulleys, so not exclusive to gears as a relation.

Those two would use opposite "sign".... pulleys usually would be a "positive" ratio, as they usually (if not a crossed belt) rotate the same directon, where gears rotate in opposite directions, and would be a "negative" ratio.
 
jaysinn

jaysinn

Member
Yes, this is a feature I'd like to see. I've got an assembly where a cylindrical part is intended to rotate through part of a revolution, and be stopped in its rotation by tabs that I put on the cylinder face hitting "mating" surfaces at the ends of the desired rotation. I'd love to be able to exercise the motion on-screen and have the hard stops work instead of having to visually judge when the tab starts entering into the stop. This would also mean that I could accurately return the cylinder to its "start" position without constraining it to stay there.AlibreAssemblyHardStopPicture.JPG

EDIT: I just read Lew Merrick's "Constraint System Improvements" and absolutely agree with every word he said. He presents the various cases clearly and persuasively.
 
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batejosh

batejosh

Member
One workaround that I use is to use assembly configurations. They may be 'Fully Closed', 'Fully Open' and 'Flexible'. You can use mates to have the drawer closed in 'Fully Closed', mates to have it open in 'Fully Open', and nothing for 'Flexible'. Not perfect, but then at least you'll be able to easily see exactly where it sits at either end :)
 
Lew_Merrick

Lew_Merrick

Guest
My take on this is that we need a "Limited Range" allowance on Constraints. Thus a "drawer" could move between (say) 0 and 50 from a Mate position -- or (say) 0° and 75° allowing both "positional" and "angular" limitations to be applied.
 
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JST

JST

Alibre Super User
Lew_Merrick said:
My take on this is that we need a "Limited Range" allowance on Constraints. Thus a "drawer" could move between (say) 0 and 50 from a Mate position -- or (say) 0° and 75° allowing both "positional" and "angular" limitations to be applied.
Click to expand...
Yes

This, and a few new constraint types would be extremely helpful.
 
JST

JST

Alibre Super User
And those are the ones I am referring to. I am in 320% agreement with you on your list.

Add a "conditional" or "approximate" constraint *, and Alibre would be a really super program. And it needs to be, as otherwise the "free" and low cost CAD systems cover most of what used to be the hobby market. Nobody needs to buy a CAD program for casual hobby use.

In general, to actually spend money on a program, a person has to have the program actually earn some money. And/or has a situation where the CAD models are someone else's IP, or there are other reasons why they cannot be just shoved out somewhere in the cloud.

* .... The constraint I would add is one allowing the constrained feature to be within some error band of the perfect alignment. This mimics, for instance, the alignment of structural steel, where holes are typically made 1/16" oversize above the bolt size, for small bolts up to maybe 3/4". The hole can be out of position by half that in any direction and still assemble OK,
 
T

Toybuilder

Senior Member
bigseb said:
Yes. But its a workaround that involves a disc with the diameter of the drawer travel and a pin on the periphery of the disc that controls the backward and forward movement of a slotted bar attached to the drawer. These items are hidden in the assembly (but not suppressed).

Sorry if that isn't the best description. I've had drinks.
Click to expand...

I believe it's something like this (see attached)...
 

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  • limited linear motion.AD_PKG
    64.7 KB · Views: 13
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