My first gear cutting adventure...

S

stioc

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Background if anyone finds it amusing-
I'm not sure why but gears are fascinating to me, perhaps it's all the math and theory that goes over my head makes it so. Also similar to single point threading it's sort of like a rite of passage, no? Anyway, so I wanted to try my hands at gear cutting but I didn't have the proper tooling you need to cut gears. I have a 8" rotary table but unless I feel like throwing my back out I usually leave it tucked away under the workbench. Besides I don't have the dividing plates for it either. I did order a $70 DP16 14deg gear cutter set last year. As with most things I took one or two out of the packaging, admired the feel and put them away. I didn't have an arbor for them. Then I got to thinking, hey my used mill did come with a spindexer which I never used...then I realized it was because I don't have a set of 5c collets. So you see like with most things I only have half-ass tooling. Similar to the gear cutters I had also ordered a single 1" 5c collet just so I can touch and feel one lol But here's where things started to come together.

Instead of wasting a few hours watching This Old Tony etc on youtube today I decided to tackle what I thought would be a small step towards gear cutting i.e. making an arbor for the gear cutters and an arbor for the 1" 5c collet to hold the gear blank. Well 6hrs later I had a test gear cut from start to end. Granted it's all aluminum but I was able to scratch the itch.

I decided to keep things simple, no keyway slot etc. I left the cutter a few thou proud of the flange/register so the nut would clamp it down.
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Parting off the nut
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Here's what the final product looks like
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I made a similar arbor for the 5c collet and then cut a gear blank. Having never had to use the spindexer before I decied to check my math using scribe lines. I also decided to be lazy and just use 20 teeth - hey this is just an experiment.

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Finally set the cutter height and hit the go pedal
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All done - after 15mins of repetitive rotations and moving the table back and forth
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Despite feeling beat from 6hrs of machining I was really pleased that even my half-assed plans and tooling came together better than I could've imagined :)
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Sweet. If you had dividing plates or the rotary, would this have been easier? I’m going to be buying an 8” rotary table and am considering getting the dividing plates, chuck and tailstock at the same time.
 
I suppose the effort involved would not have been any easier since I had to make an arbor for the gear cutter but the Spin-indexer can only divide the circle into whole number angles. So if the gear pitch was something that required angles of say 22.25 deg you can't cut it using a spin-indexer.

I think it's a great idea to get the rotary table, dividing plates and the tailstock altogether. Justy size the rotary table to the size of your mill, my 8" rotary table is pretty hefty and discourages me from using it much. I think for my mill I could've gotten away with a 5" like this one:

https://www.grizzly.com/products/Grizzly-5-Rotary-Table/T25937
 
Nice job Stioc. I also get some satisfaction from making gears. A specially if everything works out.
 
Looks good! I've recently headed down this path myself.

A couple of things a noticed in the comments and pictures -

Using a spin-indexer you can cut quite a number of gears. In addition to whole number degree spacing, there is a trick that will give you half degree or could even be used for almost any fractional degree.

I have not tried it (I don't have a spin indexer, I've got a dividing head) - the gist is that you make an additional locating pin, the pin that engages the hole plate and you turn the end of to half it's initial diameter. Of course it will fit the plate hole loosely but your can rotate to either + 1/2 or -1/2 a degree. I'm assuming that the spin indexer has a locking mechanism, you just need to be sure that you are on the correct side of the hole when you lock the head down.

Also your comment about "22.25 deg" spacing - I think you meant 22.5 deg == 16 teeth which is easily do able with a modified pin.

The modified pin trick could conceivably be used for any rational fraction (make a 1/2 and 1/4, 3/4 is go to the next hole -1/4 instead of +, pin set for instance) but keeping track of which fraction you want for each tooth could get quite tedious.

My other observation is - from the photos, it looks like the tops of the gear teeth are pretty fat. Could just be the photo. Typically you calculate how big the blank diameter is and how deep to cut the teeth.

Keep us posted on progress.
I posted on my first gears in the gears and hobbing forum.

-Dave
 
Suzuki4evr said:
Nice job Stioc. I also get some satisfaction from making gears. A specially if everything works out.
Click to expand...
Thanks, I actually remember your post about it when you got a dividing head. I think it was last year some time, that's when I bought a set of gear cutters.

I'd really like to be able to grind a tool with the right teeth profile so I don't have to buy expensive gear cutters for any oddball gear teeth I come across.

rgray said:
Since you already have a rotary table maybe a dividing head like this, https://www.ebay.com/p/AC-Racing-BS...-Jaw-Chuck/23028319575?iid=232805947256&rt=nc would be handy to have.
I have used the angle ability of the dividing head to do angled spur gears. Not the best way to do those but workable.
Click to expand...

Thanks, I've been considering those. In all honesty I rarely use the rotary table since my mill is CNC, however, I keep it around 'just in case' I need to do something and CNC is not an option.

dbb-the-bruce said:
Looks good! I've recently headed down this path myself.

A couple of things a noticed in the comments and pictures -

Using a spin-indexer you can cut quite a number of gears. In addition to whole number degree spacing, there is a trick that will give you half degree or could even be used for almost any fractional degree.

I have not tried it (I don't have a spin indexer, I've got a dividing head) - the gist is that you make an additional locating pin, the pin that engages the hole plate and you turn the end of to half it's initial diameter. Of course it will fit the plate hole loosely but your can rotate to either + 1/2 or -1/2 a degree. I'm assuming that the spin indexer has a locking mechanism, you just need to be sure that you are on the correct side of the hole when you lock the head down.

Also your comment about "22.25 deg" spacing - I think you meant 22.5 deg == 16 teeth which is easily do able with a modified pin.

The modified pin trick could conceivably be used for any rational fraction (make a 1/2 and 1/4, 3/4 is go to the next hole -1/4 instead of +, pin set for instance) but keeping track of which fraction you want for each tooth could get quite tedious.

My other observation is - from the photos, it looks like the tops of the gear teeth are pretty fat. Could just be the photo. Typically you calculate how big the blank diameter is and how deep to cut the teeth.

Keep us posted on progress.
I posted on my first gears in the gears and hobbing forum.

-Dave
Click to expand...

I'll definitely look into the fractional degree trick with the spindexer, I recall Tom Lipton did a video by making another indexing plate for the spindexer but I didn't really watch it beyond the first few mins.

Your observation is spot on about the flat profile. The gear blank was about 1.52" and I decided I wanted to keep the no of teeth fairly min since I was already tired and just wanted to see something resemble a gear before calling it a day lol so I opted for 20 teeth i.e.18deg spacing. I grabbed one of the cutters DP 14 #6 I think without looking up to see the right no cutter. I arbitrarily set the dept to .09" and did it in one pass. I'm guessing the #6 cutter is probably not the right cutter for 20 teeth and the depth is probably too small for that cutter?

I'll go look for your post (there's a gears and hobbing forum here? lol).
 
stioc said:
I grabbed one of the cutters DP 14 #6 I think without looking up to see the right no cutter. I arbitrarily set the dept to .09" and did it in one pass. I'm guessing the #6 cutter is probably not the right cutter for 20 teeth and the depth is probably too small for that cutter?
Click to expand...

# 6 is correct for a 20 tooth. O.D. should be 1.5714 for a 14dp gear.
 
rgray said:
# 6 is correct for a 20 tooth. O.D. should be 1.5714 for a 14dp gear.
Click to expand...

Thanks - did you get that info from the Machinery Handbook or some other source? I created another thread about finding the PA of an existing gear so I'm curious.
 
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