Gearotic anyone else using it?

[Michael Simpson Virgina]

I purchased this program a little while back and have been using it to build gear trains for various projects. While the program seem to work from the surface and has a major wizbang effect when deigning gears. I have found that the output files it generates to be somewhat inaccurate. They work well engough but there is just enoguh error in the angles that it outpts to case some binding in the gears.

IT works better with the cnc where you dont get an exact cut and due to the rounding with the verious bits I tend to get better gear mesh.

I would not recomend the program to laser users.

[Dan Hintz]

Michael,

Have you contacted them about it? It's most likely an issue with compounded rounding errors, so the more steps it takes, the more the error grows. I've considered picking it up, but if I look into it too much I may decide I can write the program myself.

[Kim Vellore]

Oh, I have been using it for the past few weeks and fighting the binding issue. I kept thinking the way the laser cuts it, it does not have smooth edges so it keeps locking. I have to look into it more carefully to conclude. I even got delrin sheets to make these gears and there was still binding... What other program do you use to make these gears? I want to check with another to compare. Kim

[Michael Simpson Virgina]

I have used involute with success. Not as fancy and you cant design gear trains but it does a heck of a job on a single gear. The laser is an exact device and it will cut exactly what and where it is told. That is why they work much more like a printer driver.

These were cut on the CNC very forgiving so they mesh well
http://www.youtube.com/watch?v=wEOrqnsHEt4

These were cut on the laser. They turn ok if you keep them nice and loose. This means you cant use the shaft output drawings. Id you do they will bind.

Bottom line the program needs some work. Its ok to perform simulations but other than that??

I have a very serious problem now. I downloaded the 2.21 version and it has some bugs and the projects from previous versions do not seem to work. I uninstalled it so I could install the 1.65 version and it wont load. Im stuck with the buggy 2.21 for now.


FYI 2.21 also has the rounding errors.

[Doug Griffith]

I've done quite a few gears. I use programs such as Vectorworks to get the geometry and then draw a single optimized tooth that I then duplicate around a central point. I also account for kerf thickness.

Is it possible that the kerf offset of Gearotic is less than what your machine produces? And then there's the kerf angle.

If I mesh gears tightly, I flip the gears in the drawing. Then the kerf angle that's introduced works in your favor.

Michael, one thing I've noticed in this thread is that you consider a laser to be more precision than a CNC. It is actually quite the opposite. A laser is very sloppy by comparison. CNC's are only restricted by cutter diameter and the need to hold down parts. That's if you have a good ballscrew CNC with tight backlash.

[Joseph B. Chritz]

The Grandkids just left and I have a few minutes to unwind so I thought I would take a look at this. I've cut a few gears with Gearotic Motion on my laser and my router, but nothing that needed to be accurate. I was more interested in the imaginary gears.

I downloaded the latest Gearotic Motion and created the default spur gear and output it as a DXF file. Then I created the same spec gear with MasterCam, saved that as a DXF and overlayed them.

The MasterCam DXF was 237 KB (44 lines 638 arcs) and Gearotic DXF was 530 KB (6050 lines).

The MasterCam gear is red, the Gearotic is black. The only noticable difference is at the root of the gear. As the gear rotates this area is just clearance.

When I zoomed in on the contact area I could see a slight difference, but it is less than .0001 inch.

Gears need some clearance to function correctly. I'm pretty sure I would have a problem if I created gears using either of these DXF files unless I shifted the center distance or introduced a clearance allowance using offset contour.

Both programs gave me the gear I asked for.

I would recommend Gearotic Motion, at $75 it's a bargain, especially for the imaginary gears

[Joseph B. Chritz]

Kim,

This is what works for me.

1. Open the DXF in CorelDraw
2. Smart fill the gear (this will give you an outline that CorelDraw likes better)
3. Delete the original, Hairline around the smart fill, turn off fill color
4. Window (tab at the top)
5. Dockers
6. Contour (try .01 outside and adjust as needed)

[Michael Simpson Virgina]

174965

Here is a CDR file. You can plainly see the small gear is off. It does not matter how the program exports it or what program inports it. It is off. Its off enough that you can see it.

I am also using the latest version.

I am in the process of cutting a series of gears on my router and we shall see haw far those are off.

[Kim Vellore]

Joseph, Thanks for the tip. I also figured out another problem I had with my gears, it was user error, I changed the shaft dia and centered to the gear, the problem is if the gear is not symmetric in the Cartesian coordinates I cannot center it in corel pressing "c" and "e", so my gears had slightly off center hole causing binding. I fixed that and it works real smooth. The program itself is awesome, enabled me to do the gears that I had been struggling to do for some time. For reference Art the developer of this program is also the developer for Mach. The program I think is worth a lot more than it costs and real easy to use. Actually I would highly recommend it for lasers. Kim

[Kim Vellore]

Michael, Can you post a X3 version or lower, I could not see any thing in the file. Kim
174965

Here is a CDR file. You can plainly see the small gear is off. It does not matter how the program exports it or what program inports it. It is off. Its off enough that you can see it.
.

[paul mott]

I have been using Gearotic for a couple of weeks now and I think it is just great. The software is still under development and bugs are being found and fixed as further developments are being made so ultimately this is going to be a fine program, so I recommend just being patient.

If you wish to laser cut accurate gears then there are a couple of important factors which must be taken into consideration.
1) The tool diameter has to be set to the final kerf width - this then applies the correct offset for the profile tool path.
2) The laser has to be able to cut a perfect outline perpendicular to the surface all around the profile.

We looked at cutting acrylic a little while back and the “Eurolaser foot” brought into question the edge finish that can be produced with a laser. If this sort of edge finish is unattainable then any gears cut will just not be accurate enough to run without binding or having tight spots.
I cut these non-linear gears as an example and they run just fine. (just for reference, my machine has fine adjustment for setting the vertical cut plus a theoretical resolution of 8,128 steps per inch)

Paul.

[Michael Simpson Virgina]

Here is a close up of the teeth. No matter how it is created or what is used to import the angles do not change. The bottom line is the teeth created in the program have some issues and in many cases this will cause problems.

The bigger the gear the less of an issue.

I would give you the exact specs on the gear but in fortunatly I upgraded the program and its no longer compatible with previous gear projects and it wont let me revert back to a previous install.

Its obvious that the program will be a real cool program once completed but if you need to create acurate gears now then look at something else.

[Doug Griffith]

That's so bad it should still be in Alpha. Looks worthless to me.

[Joseph B. Chritz]

That's an easy one.

At the top of the screen is an icon for settings. When that opens there is a setting for gear point distribution. The default is .001 inch. When I set it to .25 inch there are fewer points on the gear, but a much coarser shape.

I agree with you Doug, that is worthless, but with more points the gear it becomes a lot better.

[Doug Griffith]

Much better but...

It sounds like the gears are composed of polylines and not arcs. I, personally, prefer an arcs approach. Otherwise there may be stepping and at the very least a kerjillion points that would make it unwieldy to deal with.

[Joseph B. Chritz]

Can't argue with that, it would be nice if we could get the DXF file with mostly arcs. Read my post from last night. I created the same gear with Gerotic Motion and MasterCam. Gerotic DXF had 6050 lines and MasterCam DXF had 44 lines and 638 arcs. The difference between the gears in the contact area was less than .0001. The root area was a little different, but that's was clearance and shouldn't affect the operation of the gear.

The main reason I like Gearotic Motion is the imaginary gears, some guys have done some really wild things. I would trust Gearotic Motion to output an acceptable DXF file. If there were a problem I would expect it to be fixed quickly.

[paul mott]

Very strange.

I can laser cut these Gearotic gears with true involute teeh shapes and they mesh and run just fine. Perhaps you guys should switch to using the 2.5D milling GCode.

Merry Christmas,

Paul.

[Michael Simpson Virgina]

OK you fixed it for me. I Just created a 9 gear set for a clock that will do Hours, Minutes, and seconds. With the gear point distribution set to .005 I get nice smooth gears which will work in both plastic and wood. On my CNC or laser.

If I export a gear at .005 I can rotate the gear and the teeth will line up perfectly. Cant do that when set to the default of .25. I for the life of me dont know why the default is so coarse.

Thanks for the input. Once again I can continue my project thanks to the this forum.

I have posted on the manufacures forum the other bugs. I hope they get them fixed as I just found a couple more.

[Michael Simpson Virgina]

I have a complete set of gears cut and they turned out pretty good. The next problem I am encountering is that the shaft holes are allways too close together makeing the mesh too tight. Do any of you know of an adjustment that may make the shaft holes create a looser fit.

[Joseph B. Chritz]

There is a lot of information about gear backlash on the internet.
The information we are getting from Gearotic Motion is with zero backlash.
To function smoothly some backlash is needed. Too much or too little backlash is not good.

It’s up to us to build in the necessary backlash, either by adjusting the center distance or cutting the teeth deeper.
It changes for different applications and gear sizes so we can’t have a “one size fits all”.
You can do it either way, but I prefer to leave the center distance at the nominal value and cutting the gears to run smoothly.
I do that by offsetting the contour.
Please see my post above about the technique I use with CorelDraw that works for me. The offset will have to be adjusted for the backlash desired.

[Michael Simpson Virgina]

Thanks. I just thought we could do some tweaking in GM to get a better shaft layout. I use GM (Gearotic Motion) to get play with my gear ratios but I like using corel to layout the gears. I know with corel I can cut with my CNC or my laser and things will line up.

Another issue I had was that I have a gear set that mates up with a previous train. IE minute hand over hour hand. While I got the gear ratios down the sizes were off. I used the shift feature in GM to tweek the size a bit. Is this the best way of adjusting the siaze of the gears? I know in the program involute there were many more adjustments I could use.