Free hobbing - a rogue method for spur gears

[implmex]

Robin Robin Robin:
You wrote:
"you werent doing it right

my thread is all about improving the method

I wont waste time discussing why it wont work but will help in ways of making it work

You can lead a horse to the water................

Study the vid and see what you were doing wrong

You think I should take my cues on how to cut gears from this example? (it's from your post #3...last picture)

Or maybe from the Youtube video you linked to?
Yeah I watched it, nice guy I suppose, but not the Gear Guru you suppose him to be.

Tell me, do you even know what an involute profile is supposed to look like?
Were you aware that to legitimately call it a gear, the tooth spaces (and the teeth) should each be as close to identical as possible?
Did you bother to notice that in your example and in the video guru's example you can see differences from tooth to tooth and from space to space with your naked eye?

I'm afraid, Robin, that if you hoped to persuade, the examples you've shown are not persuasive at all.
I'd be embarrassed to put up this kind of outcome on a forum, and then tell me all that I can learn from you about how to do it.

Sorry, bud...you have a ways to go before you get to brag.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
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[Ron Hofer]

2 'l's in 'troll', right?

 

[EmGo]

The problem has been that this method, whilst accepted as producing usable worm gears,

Depends on the definition of usable. As a paperweight, sure. As a worm gear ? Try to sell that to anyone and they'll break your knees.

has never been properly pursued for spur gears

Because no one who has ever made a real gear is that dumb. It's even worse than space cutters ... kinda like using the wrong space cutter while making sure to not tighten the arbor. And maybe let the cutter float around a little while you're at it.

Crap method. Crap parts. Maybe worth pursuing if you're snowed in up the Yukon with nothing but some aluminum cans and an old tap and six more months of winter, but otherwise ...

 

[awander]

Troll Troll Troll Troll Troll

 

[neanderthal mach]

No and just to be REALLY clear, I wasn't talking about the actual Gear Guru's or any other Professional here. For them they have my utmost respect they've more than earned for everything they do every single day there at work or come on here and offer advise I and others can count on. For you.... let's just say you really don't want to know what I think because you have no clue what disrespect even is yet. And don't play purposely dense or EVER try and twist my words because this ain't my first go around with pompous wankers exactly like yourself. I've worked jobs with guys that would have you cowering in tears by the first coffee break just because of your insufferable prick attitude. Your also quoting me while adding your own words to those quotes. Now your starting to piss me off.

Real professionals never need to brag because of what they do every day say's all it needs to for them. So again get it through your fucking head I wasn't talking about anyone but YOU!!!! Is that goddamn clear enough now?

And I'll bet I know more about free hobbing than you do because I understand why the pro's here won't use it on anything where it actually counts.It's a bush league method at best if there's no other way, and I've worked in remote camps and have seen lots of make do shit get done just to get things moving until real parts could be flown in. The standard gear tooth form is and has been optimized over hundreds of years because it's been designed to be as efficient as possible for the duty it's being used in. Any other faked wanna be tooth form will NOT work as well, end of argument. I can cut a working gear with a hand drill and hammer & cold chisel that will sort of wobble around, spin and maybe transmit a bit of power for awhile, but I don't own machine tools for making crap a four year old would be embarrassed to be seen with. I buy pro level equipment because I want pro level results including dividing heads and the proper gear cutters I need to do the work. And I pay attention to what the book recommendations are because they know one hell of a lot more than I do, you very obviously don't. Sort of good enough doesn't interest me at all, it's no wonder the Pros here justifiably laugh at all this cheap ass Harry the Home Shop Hack drivel. This is the third different forum you've played the same tune on and even cut & pasted the same information as well as the same thread title like it's something your proud of. Each time you get the very same result, but everyone else is wrong including professionals that do this shit for a living? Go back to playing circle jerk kid because you've made the absolute worst forum pick of your life.

 

[Mcgyver]

I got sucked in briefly on the other forum, but really, how do you guys have time for Captain Fantastic and this BS?

 

[pavt]

I got sucked in briefly on the other forum, but really, how do you guys have time for Captain Fantastic and this BS?

Cheap entertainment while on the can.

 

[mattthemuppet]

guy has to be a troll, no one can possibly be this much of a douchebag, surely? I laughed out loud when he told Marcus that he's doing things wrong. Still smiling about it as I'm writing this.

Just stop feeding the troll! He thankfully spat the dummy on HSM, hopefully he'll do the same here. I'm all for entertainment, but I'd rather go find a hooker fight.

 

[pavt]

guy has to be a troll, no one can possibly be this much of a douchebag, surely?

You might be surprised. I've had coworkers like that, in person, in real life.

 

[mattthemuppet]

thankfully I've managed to avoid people like that. Plenty of other unpleasant personality traits though..

 

[fciron]

I wonder if I can find the pictures of the bevel pinion I repaired by building up the teeth with an arc welder and shaping them with an angle grinder. Seventy years at the bottom of a manhole is even hard on cast iron.

The water company was able to use it to close a 36"'valve, so it worked.

I won't be recommending angle grinders as the great new way to make gears though.

I also spent several hours at the drafting table studying the Machinery's Handbook and making templates for the tooth shape.

 

[mattthemuppet]

I fixed up a chuck pinion recently - missing tooth and worn teeth either side of it - by having a friend fill in the gap with his mig welder and then I ground the teeth shape with a Dremel. Looks a little (a lot?) ugly, but it works fine for this application.

 

[52 Ford]

I fixed up a chuck pinion recently - missing tooth and worn teeth either side of it - by having a friend fill in the gap with his mig welder and then I ground the teeth shape with a Dremel. Looks a little (a lot?) ugly, but it works fine for this application.
View attachment 332352
View attachment 332354
View attachment 332355
View attachment 332353

Looks good! At any rate, it ain't wrong if it works!

 

[52 Ford]

I wonder if I can find the pictures of the bevel pinion I repaired by building up the teeth with an arc welder and shaping them with an angle grinder. Seventy years at the bottom of a manhole is even hard on cast iron.

The water company was able to use it to close a 36"'valve, so it worked.

I won't be recommending angle grinders as the great new way to make gears though.

I also spent several hours at the drafting table studying the Machinery's Handbook and making templates for the tooth shape.

Not that it matters at all, but what electrode did you burn when you built up that pinion?

An angle grinder can be a "precision" instrument if you take your time with it!

 

[oly2brf5]

guy has to be a troll, no one can possibly be this much of a douchebag, surely? I laughed out loud when he told Marcus that he's doing things wrong.

Bit of a sense of deja vu here. This idiot has just been banned on a UK model engineering forum for insulting remarks and accusing members who have clearly made working gears by old school methods (dividing head and horizontal mill) of being dumb armchair pontificators. He started on that forum bullsitting on VFDs. When I queried his comments (I used to design VFDs for electric vehicles) he told me I didn't know what I was talking about. He most certainly is that much of a douchebag - the sooner he leaves the better.

Andrew

 

[zimbo]

Robin,

Good to see a fellow country man here. When you get bored of playing around and need any precision gear cutting done, see Dave at Jmann Transmission or Emanual at Paddock Gears. Both in workington, Hre. PM if you need contacts.


Sent from my iPhone using Tapatalk

 

[modelmakerblue]

I am posting this thread topic to see if there is any interest in this obscure practice.
The very mention of the subject seems to rattle cages and bring out some very thin skinned machinists like I was talking heresy

To summarise
Its a method of cutting gears without the complexity and cost of a manual dividing head and formed milling cutter or even worse a head geared to a mill spindle and using a hob cutter

Let me say up front that I have the greatest respect for the science of gear technology and its practitioners. Its a very complex subject and has some highly skilled manufacturers who hold much of the expertise that is well beyond the home hobbyist

What I propose for discussion and experimentation will in many ways tear up the rule book and start from scratch

This method has been used to make wrom gears and this is a well documented procedure with ample vids on YT. I dont propose to elaborate on the area save to say that making spur gears is no more than an extension of the method (which has got some bad press in the past mainly IMHO due to faulty implementation of the technique)

I have been experimenting in this area and have produced some encouraging results - even successes. I will offer to post pix and vids of my work and invite others to try the technique and report

Up front
This is a Cheap Charlie method that can knock out gears in minutes
These gears - at this stage wont be to accepted DP/Mod standards (yet) but they will make quasi involute forms and can be assembled into a meshing train that seems to work
At present the method only produces Mod 1(ish) 30PA pieces and is only suitable for light duty low power xmission on non ferrous mtls
These might suit a model maker or experimentalist. The wheels are likely only to work amongst themselves but that may not be an issues - for example making a set of change gears for an old lathe

I think the method can be extended to perform reliably to meet des criteria eg No of teeth, and predictable Pcd but it needs skill and experience

I welcome the participation of open minded machinists but I wont be producing reams of explanatory words as the convolutions of the subject will be one big turn off, put a picture is worth...............
and even better get your hands on when much will become clear

for me very much work in hand and I believe there are others on this board who have been down this path


Hope this doesnt start a forest fire

Robin (no affiliation to Batman)

I don't know how you find time to peddle this CRAP on multiple forums?
Tony

 

[oly2brf5]

Good to see a fellow country man..............

I hate to disappoint, but in his rambling on the UK modelling forum there was nothing to suggest that he was based anywhere other than in the UK. He used a completely different name there as well.

Andrew

 

[Scottl]

Free range chickens good.

Free range gears? Not so good.

Maybe next thread he can school us on ways to improve a HF 7x10 "lathe".

 

[fciron]

Started with a nickel rod for cast iron repair (Lincoln 55NI I think). Preheated with big propane torch to spit sizzling temp and tried to keep the temp up the whole time. (I have an IR thermometer now, so I preheat to 500f and keep above 300f.) Used a needle scaler and wire brush on the angle grinder between passes.

Nickel rod is pricey and likes to leave hard to remove chucks of slag trapped in crevices, so I switched to 7018 rod after a solid base was laid down and I ran out of NI rod.

I think that's it. It was a while ago. Angle grinder was precise enough, when we laid my pinion on the matching wheel they found in their boneyard it rolled around nicely and tracked correctly which gave me confidence that it wouldn't lock up in use. (That meant I didn't have to do the big gear in equally bad condition that they dug out of the hole.)