Author Topic: Bevel Gear Mill  (Read 1598 times)

Offline Joules

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Re: Bevel Gear Mill
« Reply #50 on: August 28, 2020, 05:44:06 PM »


Now this is intriguing to watch, note the hob seems to have two teeth offset so it can machine each side, not sure about the profile at the end.  As the gear is very broad the tooth profile almost looks like a tapered Acme form.  A blunt Meccano gear
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #51 on: August 28, 2020, 08:51:59 PM »
It doesn't look like the spindle changes its vertical angle. If so and there are two teeth they would have to move towards each other as the mill rotated into the cut, making a tapered space.

One possibility for achieving that might be a rotationally fixed core spindle acting as a tapered cam, inside an outer rotary spindle holding the teeth. The inner spindle driven by a linear actuator. That might force the teeth together or apart at a timing and degree determined by the CNC program feeding that cam.

I dunno, maybe something like that......
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #52 on: August 28, 2020, 09:01:03 PM »
I wonder if you could have a cnc "wobble spindle" to cut both sides of the tooth space in one revolution?  :loco:
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Offline WeldingRod

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Re: Bevel Gear Mill
« Reply #53 on: August 28, 2020, 10:17:04 PM »
I think spiral bevel gears can be hobbed...  not totally sure, though!
That would be even more complicated  ;-)

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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #54 on: August 29, 2020, 10:59:55 AM »
It might actually be easier.

But this is getting to the point where my brain hurts!

I'm pretty sure the two things I will be trying out are a mill (possibly mounted on my new lathe) with involute profiled teeth (probably with a homemade cutter) and a zinc alloy casting from an existing bevel gear. Those seem like the simplest (and quickest) for what I have on-hand for equipment and capabilities.

The rack tooth generation method has great appeal, so maybe some-day I'll try that, and likewise building a hobbyist gear hobbing machine like the Jacobs or the JS Eley machines -- both shown in older Model Engineers, has always been something I wanted to do.
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Steve
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Offline WeldingRod

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Re: Bevel Gear Mill
« Reply #55 on: August 30, 2020, 02:52:16 PM »
It looks like face milling spiral bevel gears is done with a shaped cutter (normally multi-tooth) moving in a circle and cutting on the end.  Think hole saw.  This is tipped and tilted to get the geometry to work.  You plunge it in once per tooth space.  It looks like a single tooth cutter would be ok, just slower metal removal.
Actually sounds pretty straightforward for what you are interested in.  One setup, two cutter head angles for the right and left spirals you need, and tooth indexing.
This gets away from the tapered tooth generating problem nicely!

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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #56 on: September 04, 2020, 01:59:23 PM »
Look what came in the mail today! A brand new, in ancient metal cornered unopened box, still factory taped closed, inside Cosmolined, and anti-rust paper wrapped, National #5 20P bevel gear mill w/7/8" arbor hole.

I believe (not absolutely sure) that this will cut bevel gears in the size range and tooth count I'm interested in. Which is about an inch dia 16 tooth, more or less.

Even if it doesn't, it was way cool to just crack that box open for the first time after who knows how many years since manufactured! The first person to look inside and unwrap that little treasure! Fun.....!  :ddb:

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Steve
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Offline awemawson

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Re: Bevel Gear Mill
« Reply #57 on: September 04, 2020, 02:48:24 PM »
Well don't tease us man - open the box and SHOW us  :clap:
Andrew Mawson
East Sussex

Offline Lew_Merrick_PE

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Re: Bevel Gear Mill
« Reply #58 on: September 04, 2020, 03:11:31 PM »
I think spiral bevel gears can be hobbed...  not totally sure, though!
Hi WeldingRod  --  Yes, I served my Apprenticeship in a Tool & Die shop "across the alley" from Western Gear.  Making hobs was a (moderately) common task.  The set-up to use such hobs was fr from trivial.  --  Lew

Offline tom osselton

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Re: Bevel Gear Mill
« Reply #59 on: September 04, 2020, 05:36:20 PM »
OPEN THE DAM BOX ALREADY!  :D Ebay find?

Offline vtsteam

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Re: Bevel Gear Mill
« Reply #60 on: September 04, 2020, 06:28:43 PM »
Jeepers! :whip:



 :beer:

yes, Tom, the Bay
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Steve
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Offline shipto

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Re: Bevel Gear Mill
« Reply #61 on: September 06, 2020, 04:49:14 PM »
Sure I read somewhere these can do bevel gears: http://www.lathes.co.uk/jacobs/
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #62 on: September 06, 2020, 06:23:42 PM »
Yes, Shipto, that's the machine I've always wanted to build -- the version in Model Engineer, not the College Engineering version, which does not do bevel gears.

But on the second page of this thread, engjas mentioned a second Model Engineer gear machine by JS Eley, that I hadn't seen before. I like that one. too. Some day I'm going to build one of those two.
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #63 on: September 22, 2020, 10:04:27 PM »
Well my two bevel gears arrived from China finally today. I must say they do look shiny, and I was particularly pleased to see they threw in an extra gear with the pair!
I love it when a Plan B comes together!
Steve
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Offline Joules

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Re: Bevel Gear Mill
« Reply #64 on: Today at 12:40:49 AM »
WOW, just don’t be tempted to plant them and grow more....   They could be “Bevel Not Gear Weed”
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #65 on: Today at 09:52:11 AM »
I find I can pretty much get by with just two words these days: "What the.....?"
 :bang:
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Bevel Gear Mill
« Reply #66 on: Today at 10:02:20 AM »
Obviously, I'm going to have to make them myself. I'm slowly working my way back to getting a usable shop, and the time to work in it.
I love it when a Plan B comes together!
Steve
www.sredmond.com