Making Spur Gears

Has anyone had success cutting spur gears? I’ve tried many different variables, torch height, amperage, and speed but can’t get it dialed in. I’m trying to cut 1/2" steel, but haven’t had much luck. I’ve been working on 3/8" thick pieces, and they are better, but still having the same issues. The top (pierced side) looks great, but the underside is not as defined. I’m also getting a curve along the side of the teeth.
Parameters are 15 IPM, 0.060" cut height, 3/8" thick steel, 45 Amps, 15 tooth gear (6 diametral Pitch) or diameter 3 inches across.
I’ve also tried going slower with lower Amps because I read somewhere that it helps make a more accurate cut. Approximately 32 Amps, at 7 IPM, cut height of 0.035", but having similar issues.

I’m a new user so I can only put one photo in at the moment.

Welcome to The Forum what plasma machine are using?
And what kind of consumables are you using with that plasma?
What air pressure are you delivering to your plasma?

Thanks for the welcome! I’m using the RazorWeld Cut 45 CNC, with Hypotherm 45a electrode and 45a nozzle (220669 and 220671). Currently delivering around 85psi of dry air (we have an air dryer at our shop). Here’s a picture of the underside of the gear.

Are you using any feed rate optimization in your tool paths?

What is the current conditioned of your consumables?

Consumables look good, and I am currently NOT using any feed rate optimization. I didn’t notice that option in Fusion 360 until you mentioned it. Thank you! Do I need to increase my air pressure? I’m not sure if it should be higher for thicker materials.

I would say 75 PSI would be about right for the razor weld.

Maybe a member with more experience cutting thicker materials with the razor weld can chime in.

Do a 40 to 60% reduction in inches per minute in the feed rate optimization section of fusion 360.

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Slowing down and keeping amperage the same will result in less bevel. It may result in more dross, but that should crack off easily.

If you reduce amperage and speed, you will probably get the same result as you’ve been getting.


@ds690 That is a good point. The OP needs all the amps.

With my hypertherm of 85 I switch from 45 amp consumables to 65 amp consumables at quarter inch and I switch from 65 amp consumables to 85 amp consumables at half inch.

I was looking at some of my fusion 360 add on today and it reminded me of this post.

here is a good add on for fusion 360 to make gears.

@ChrisR how did you ever make out with this?

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Thanks for the help! Luckily I have the Solidworks Tool box and they have gears in there too. It’s nice to know how to make them in Fusion 360 too though! I haven’t had much luck making gears like I was hoping, but I think it’s just that we don’t have a torch powerful enough. It the mean time I’ve been CNCing them out of aluminum. Thanks again for the help you guys! I was just trying to make really big gears that wouldn’t fit on my CNC.

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