I have been drawing some parts in cad and wondering if they are cutable on a DIY machine. I am posting a DXF of the file. This is a 15 inch 120 tooth gear. If anyone could cut this and post a pic of the result I would greatly appreciate it. This is for a clock that I am designing.

The tips of the teeth don't touch the sides. zoom in really close and you can see it.

:)

Here's your part Mastercam style.

YouTube - Mastercam Watch Part

The tips of the teeth don't touch the sides. zoom in really close and you can see it.

This must be due to some kind of limitation in solidworks. I tend to notice that when zoomed really close in you can see the gaps but yet the part will still render without errors. Should still be cutable I am guessing. I am using an involute curve that is made from 15 small lines so I am sure that is part of the problem. I cant use regular arcs to form this type of curve it has to be made from lines.

Hi, the tips of the gears DO touch the sides. I found no such gaps nor did I have any problem machining it as you can plainly see in the Video I posted above. Here is a Solidworks rendering of the very same DXF file you posted.

Sorry Mike, but they don't. They're very, very close, but after a couple zooms in AutoCAD, you can see the gaps. I was trying to join them together in AutoCAD, and it wouldn't let me. That's how I found out there were gaps.

Ger21,

He went from Solidworks to DXF. Then I went back into Solidworks, Mastercam, Catia, Cimatron, UGS NX, Pro/E and found no gaps no matter how far I zoomed in. If there were gaps I would not have been able to create the water tight solid that I did in each one of these systems. What version of Acad do you have? There are DXF options for export from Solidworks. Maybe they weren't set right for your version of Acad is all I can think of. Can you post a screen shot of one of these gaps?

The gap is .0000002. I'm using AutoCAD 2007, but it doesn't matter. The coordinates in the .dxf are specified to 10 decimal places. And there are .0000002 gaps.

The horizontal line in the image is the top of the tooth, btw.

Gerry,

How does this molecule sized gap negatively affect you or the manufacturing of this part?

I had assumed it was drawn with a 2D CAD program, and was just pointing out the errors. I didn't know how big the gap was until a few minutes ago.

You mean how "small" the gaps are right? :D

ok... I'll chime in... I opened the dxf file in Rhino cad and there IS a gap.... a very very small gap, but a gap none the less. I cut a few wooden clock gears for a guy here in town once in a while and the gap for me would cause the machining time to go way up. the cad/cam program would look and interpit each line as its own entity and want to run a cutting routine on it. it only took a second to join the outer race into 1 polyline (down from 1920) and now the cnc machine will just follow it around.

also as a side note... remember that those of us that are using a router to cut will Always leave a radius in ALL inside corners. in a lot of cases it wont make any difference but just remember its there when your designing your gears. if the round inside corners are a problem you may want to consider having someone with a lazer cut them and then you will have a true square inside corner.

I'll attach a joined gear file for you to play with. I'll try and cut the gear tomorrow at the shop if things go right

Erik