GEARS - SAME CENTRE DISTANCE - DIFFERENT RATIOS 1

[MRSSPOCK]

Hi.

Does anyone know is it possible to cut involute gear teeth in such a way as to enable different ratios, but keeping the same centre distances?

I mean, suppose I have a pair of spur gears, 20 : 40, is there a way that I can cut a new smaller gear to have 19 teeth instead?

I realise that it would no longer be a rolling contact but slipping.

Is such a thing possible or am I just being silly?

Thanks

 

[MRSSPOCK]

Thanks everyone for your replies.

It all starts to make so much more sense.

I don't suppose anyone knows a way to simulate the rack cutting the gear using Catia V5 ?

I've been messing about with Power Copy but it isn't really a nice way to do it.

I'm only trying to do the simulation to give me a better grasp of how adjusting the various parameters effect the finished profile in reality.

Seeing the physical result, (albeit in CAD land), is really quite good.

It would be just nice to have a macro or something as opposed to using the Power Copy method which is a bit naff.

Thanks

 

[Cockroach]

I found an older computation that I was working on in the day. Typically I would of hacked out the numbers as attached and then roughed it out in AutoCAD in order to get the geometry correct. Once I was certain with the layout, I would of updated it to a SolidWorks model in order to get the various quantities and do a little FEA on it in Simulation. The model coding would then get transferred to the CNC machines and the gear cut accordingly. I can't find any of those source files at the moment, probably archived, I have the machine G Codes, but they would be worthless to you at this point.

Anyway, hope this helps. Good luck with it.

Regards,
Cockroach

 

[MRSSPOCK]

Hello Cockroach.

I'm presently working on a Catia file to try to include all your operations in one hit.

I have got something put together but it's still a bit messy.

Watch this space, but don't hold your breath

Thankyou

 

[Occupant]

I don't have Catia, but if you would drop here all the details of what you are trying to do I could leave a *.dxf file that you probably can import.

 

[MRSSPOCK]

Thanks Occupant.

At this point in time I am just trying to create a macro or similar to create a 3D solid model of any spur gear. At the top of the specification tree in Catia there will be a list of parameters that can be adjusted to achieve the desired result. I don't have a real application for it presently, but it will be nice to know it's there and ready as and when I need it. I realise I have long way to go and lots of parameters still to add, but I've attached an image to illustrate the sort of thing I mean. This really is the bare bones, but it's just to help me figure out the best way to use Catia to achieve the best result. Once I get to that point I will add all the other relevant parameters to the list.

Thanks again for the offer.

 

[dinjin]

I often redesigned only the pinion to mate with the original gear design by using a 50 percent long addendum. It made for a stronger pinion and was very effective acting as a recess action gearing design. This was dependent on the fact that the pinion was the driving member. You may have to design a slightly larger long addendum to overcome the possible proper backlash in the system. Have fun.