Solidworks Gear Mater

[Maximusmountain]

I have messed around with it for ages. I have come to no avail. Solidworks2009. sp3.0. Windows XP.

I really need the gear mate to work, i know the gears work together as i made them in Gaalad (some milling software) so i know they fit exactly and i cut them out on a laser to physically test that they work and they do! However, solidworks doesn't really like acting like normal gears would. It seems to me that i have to select cylindrical objects, as lines are not enough. If need be i can cut corners off etc but as it is already exact (the middle circle and you big circle on the outside have the same centre point) it is very important that i can keep them in the same position.

 

here is a picture of my gears, its mainly the one with internal and external teeth that is causing me the grief.

http://picturepush.com/public/2877422

[shift1313]

how are you restraining these in real life? Is the shaft the center gear rides on fixed? is the OD of the large gear fixed inside some sort of bearing?

 

One thing you can do is suppress any mechanical or advanced mates you have and start a motion study. You need to have at least a Basic motion or Motion Analysis(not animation) for this to work. You can apply contact mates between the gears and apply a motor to the drive gear. The contact between them will drive it.

 

Mechanical mates for gears are only mathematical relationships with circular edges. You could possibly get yours to work by driving the medium gear on a path and applying gear mates for the rotation.

[Maximusmountain]

how are you restraining these in real life? Is the shaft the center gear rides on fixed? is the OD of the large gear fixed inside some sort of bearing?

 

One thing you can do is suppress any mechanical or advanced mates you have and start a motion study. You need to have at least a Basic motion or Motion Analysis(not animation) for this to work. You can apply contact mates between the gears and apply a motor to the drive gear. The contact between them will drive it.

 

Mechanical mates for gears are only mathematical relationships with circular edges. You could possibly get yours to work by driving the medium gear on a path and applying gear mates for the rotation.

 

Real life, the centre one is constraint by an axel. the outside it constaint to the axel but is losely, so that it can turn. If im honest there is normally a second one to keep it taught to stop it falling apart, however, solidworks can ignore this for the time being (Y)

 

the drive gear.. yeah.. would it not be effected by the first object i put in there is now stuck, happens with all assembleys i try, the first object is solid.

 

so i should create a centre line for the middle gear, which i can then constraint to the other two, and then set the gear mates so that i could roate in a motion study with a motor?

[shift1313]

For it to work you need to have an axle drawn for the center and for the larger one. make these axles fixed by right clicking and making sure they are fixed(not Float). Apply concentirc constraints so your gears can rotate freely and a coincident constraint between all their faces and a plane to hold them all together.

 

Honestly im not sure what is going to happen with the mates without playing with the model. Is this just for fun?

[Maximusmountain]

so the axel would be the first component in therefore that would be fixed. however surely just the coincidenst would be required after the first axel? and how would i get the middle one to turn then? because thats the one im really having trouble with..

[shift1313]

okay i drew this real quick. The teeth are off but this is how i did it. I drew a base plate. I made this a large OD circle that had a counter bore in the middle for the large od gear. It also has a shaft in the middle for the small gear. I then added mates to hold everything together as i described above and started a Motion Analysis. I added contact mates between the gears and drove the red gear at 20rpm.

 

here is a short vid

 

http://filebox.vt.edu/users/maperez/stargear.avi

[Maximusmountain]

but then i also have the problem that i had to begin with, i cant figure out how to gear mate the red to the green, and the green to the blue, everything else is all well and good. thanks for all the help though

[shift1313]

are you expecting to drive the outside gear with the inside gear?

[shift1313]

so the axel would be the first component in therefore that would be fixed. however surely just the coincidenst would be required after the first axel? and how would i get the middle one to turn then? because thats the one im really having trouble with..

 

 

The first component is fixed but if you right click on it, the drop down menu will say Float, if you click that you "free" the component. You can right click on any component and Fix them.

[Maximusmountain]

for my DT project it will vary, i will be driving the inside with the outside being driven, and then on some the outside will be driving and the inside will be driven.

[shift1313]

so the axel would be the first component in therefore that would be fixed. however surely just the coincidenst would be required after the first axel? and how would i get the middle one to turn then? because thats the one im really having trouble with..

 

 

The main plate is fixed, the red gear is concentric(edge selected) with the axle in the center. This fixes it to the face of the plate and lets it rotate. The green(middle) gear is only mated with a coincident constraint selecting the face of the gear and the face of the plate. The blue one has a concentric constraint and is free to rotate in my animation(it moves just a little).

 

In this setup the red gear will drive the green one if you create a motion analysis and add the cam/contact mates. To do this with standard mates im not sure. You will probably need to create a path that the center of the green gear follows and add gear(rotational) mates. The catch is this doesnt accurately depict what is going to happen like the motion analysis.

 

This seems like a modified sun or planetary gear set but you are missing an estra idler gear in there between the red and green on the other side. The red needs to drive a set of 3 or 4 gears that drive the green gear.

[Maximusmountain]

yeah i didnt realise when doing it in galaad that it didnt work, it is a modified sun and planet, its also a little modified epicyclic gearing system, which is also another one of my ideas. so i should add them in the motion analysis to get them to work, that makes more sense. Ill have a stab at it tommorow in DT, cheers for the help

[shift1313]

No problem. There have been a few posts in here that i have placed screen shots of the setup. At the bottom of the screen is a little tab that says Model, and one next to it that should say Motion Study. When you click on that tab it will bring up your options/timeline. From there you need to change the drop down box from Animation to Motion Study. The contact mate is a little cam/lobe icon and there is also a motor icon to drive the gear.

 

When doing the motion study you can also analyze several things like input/output force/torque. It may be useful for your final report:)

[Maximusmountain]

When doing the motion study you can also analyze several things like input/output force/torque. It may be useful for your final report:)

 

Dont think ill need solidworks for that, i have the ratios and i have the torque data for the 5%ile and the 95%ile (damn projects demand that i have them >.

 

Thanks for all of your help though, I shall give it all a try out, i will also be sure to come back and show the finial solutions

[Maximusmountain]

looks like i managed to get it to work

Cheers for the help!

[shift1313]

cool. Looks like you have a few problems still too figure out. Im sure you know but in a typical planetary setup you have a gear in the center to drive, some planet gears then an outside gear thats driven. You need at least 1 more green gear for the assembly to be stable and not want to bind up. And im not sure how you are going to setup input/output with a setup like that. You almost need another interior gear. What is your focus with this, meaning what are you trying to accomplish?

[Maximusmountain]

cool. Looks like you have a few problems still too figure out. Im sure you know but in a typical planetary setup you have a gear in the center to drive, some planet gears then an outside gear thats driven. You need at least 1 more green gear for the assembly to be stable and not want to bind up. And im not sure how you are going to setup input/output with a setup like that. You almost need another interior gear. What is your focus with this, meaning what are you trying to accomplish?

 

yeah after seeing that ive put in a 3rd inside gear to make it more stable, its still very glitchy, but i know its ok in real life as ive lasered it out and its not glitchy like it is in solidworks (

). The gear that would be slap bang in the middle of the big outside one is going to be attached to a metal rod. the outside one is going to be driven by a human hand. Lots of these layers means that i get lots of different gearing ratios for my geared screwdriver. this is just for one of my 6/7 ideas that i shall be cadding up, so should be interesting