I want to cut my first gear

So, the set of gear cutters I ordered are M1.25, PA20 Bore 22 mm. I'm looking for a R8 arbor for this. I've contacted a few eBay sellers asking about their products and can't get a decent answer. Search on eBay: "USA 22mm R8 Shank Milling Arbor Gear Mill Cutter Holder Toolholding 7/16-20" for what I'm thinking.

I'm assuming this will work?

I asked if the arbor was keyed and didn't get a response. Can anyone help here?
 
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Don't know, but could be a language issue. Try asking if they have a slot or key to keep the cutter from moving. Unless you are doing heavy cuts not sure if the key is necessary. Kind of like the infamous R8 key...

That being said, I'd look for one with a keyway. Keep us posted, I need to get a 22mm arbor for gear cutting as well. The ones that I see are pretty large and have a huge left hand nut and extension below the cutter.
 
It looks like these Chinese arbors are pretty much the same everywhere. I couldn't find a picture of one taken apart, so I went out in the rain for you. You're welcome.This is a Chinese 22mm from Amazon. It says "22mm R8." I put my caliper on the key, and it was about 0.235".

1661085292257.png

As to the other thing we were talking about, I have this feeling that any kind of bushing or bearing that rides along the teeth on the rack will not fare too well. I started thinking about how you could make a roller bearing to ride on a toothed surface, and I started to think about a pair of idler pinions. It would be a kind of wacky design, but they would roll along the teeth no problem. Shrug.
 
I've got one of those arbors like the picture MM posted but for slitting saws. Some of my blades don't have keyways, so I pulled the key out. Those arbors aren't much good for slitting saws. Way too much bulk below the saw but probably work fine fore a gear cutter.
 
I just ordered from Amazon "NEW 22mm R8 Shank Milling Machine Arbor Fit for Milling Machine Bridgeport".

It's strange that none of the pictures I could find show the arbor with the nut off like dewbane has shown.

Here's my email contact with an eBay seller:
Me:
Can you confirm that this will hold a gear cutter with a 22 mm bore? Also, does this arbor have a keyway?

Them:
It could not hold a gear cutter with a 22mm bore.
It could hold 20mm one.
And it has a keyway.

Am I missing something here? I'm getting so many mixed messages on this. Both eBayer I contacted said it will not fit. I think they are misinterpreting my question. I think they are referring to the thickness of the cutter?

Anyways, I'm hoping this Amazon arbor will work with the gear cutter set I ordered from China.
 
It should fit your cutters. A 22mm shank will hold 22mm gear cutters. If you look at these listings they say dimensions are within a cm! This means that they don't know what they are selling. Ie, they certainly are not machinery savvy. Anyways, I ordered a similar one from AliExpress and will find out in a couple of weeks.
 
Ok. Thanks, WobblyHand.

So, I've been thinking of tq60's post about supporting the pinion side of the rack and I think he is 100% correct. I looked at my arbor press and the rack is supported on all 4 sides. I also watched mrpete222's video on a rack and pinion build (nutcracker) and he did the same.

I am adding an adjustable block on the inside to support the rack on the pinion side. This will allow me to move it slightly as things wear or if I miscalculate the dimensions. Assembly drawing update to follow....
 
Here's an update to the assembly. I added a U block that encompasses the pinion and allows adjustment. Hopefully, this is enough to support the rack on the pinion side.

Assy3.jpeg
 
It looks plausible. I'm not sure about aluminum on aluminum violence, and who will be the victim. If the rack gets chewed up over time, that's a comparatively hard part to make. If the U-block gets chewed up over time, you can just tweak the adjustment. Seems to me the way to pick which thing is going to wear first is to put some kind of bearing material on the parts of the U-block that contact the rack. Some kind of high density plastic, perhaps. Or back to my other idea, a couple of idler pinions that roll with the rack and just freewheel.

You could always skip al that and just keep it in mind if you have to remake parts down the road. I'm not an engineer, and I tend to massively over-build things.

I envy your skill at making stuff with CAD. I've tried to get my head around FreeCAD and Fusion 360 over the last couple of days, and I am still working from unwritten plans contained only in my head, or maybe the odd crude pencil drawing, because I only have so much free time, and I am not within the same galaxy as actually producing usable renderings with either program. I tip my hat to you.
 
dewbane said:
It looks plausible. I'm not sure about aluminum on aluminum violence, and who will be the victim. If the rack gets chewed up over time, that's a comparatively hard part to make. If the U-block gets chewed up over time, you can just tweak the adjustment. Seems to me the way to pick which thing is going to wear first is to put some kind of bearing material on the parts of the U-block that contact the rack. Some kind of high density plastic, perhaps. Or back to my other idea, a couple of idler pinions that roll with the rack and just freewheel.

You could always skip al that and just keep it in mind if you have to remake parts down the road. I'm not an engineer, and I tend to massively over-build things.

I envy your skill at making stuff with CAD. I've tried to get my head around FreeCAD and Fusion 360 over the last couple of days, and I am still working from unwritten plans contained only in my head, or maybe the odd crude pencil drawing, because I only have so much free time, and I am not within the same galaxy as actually producing usable renderings with either program. I tip my hat to you.
Click to expand...

Yes. I see your point, but my arbor press is steel (or iron) on steel (same materials for both rack and guide). So, I'm doing a similar idea except softer materials. And this is only pressing on bottle caps. It's not an arbor press expected to exert tons of force.

I've never seen idler gears used to support anything, but it could work. Usually gears are set apart a calculated distance with some small clearance. Idler gears wouldn't have that luxury. Don't know if that would work.

It took me a long time to get decent at FreeCad. I started with F360 and quickly realized the free version would be not here forever and switched to FreeCad. The learning curve is steep on either one. FreeCad has its issues like all CAD software. The biggest one being the topological naming issue, but F360 had its issues too. Just keep using it and using it and it will get easier and easier. I still need to lookup how to do things every once in a while. Since it's free forever, you'll never had to worry about licensing. Use it for personal or commercial use. No problem. Sorry for the long response. I'm a big proponent of FreeCad. Each release gets better and better. I had an issue with the A2+ workbench and posted it on the FreeCad forum. The developer responded and fixed the issue!
 
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