The Breakroom > Resources
Gear making.
bogstandard:
I have just watched the most boring DVD. Almost four hours of continuous monotone talking, which to me sounds like a mild Mexican accent, coupled with very close up video.
If you can just get thru that monotone voice, you would find it one of the most informative guides to making gears the easy way.
It is called, you guessed it, 'Making gears the easy way' by Jose Rodriguez, which I think is where the accent comes in.
http://littlemachineshop.com/products/product_view.php?ProductID=2057
It answered a load of questions I had been mulling over for years, and could never get good answers to.
It is well worth watching if you have the chance.
Bogs
John Rudd:
Does this help anyone?
http://www.metalwebnews.com/howto/gear/gear1.html
John Stevenson:
Sorry John,
Got to strongly disagree with you on this one.
it's crap, total crap and before any one says it sour grapes let me explain why.
In no order it's monotonous, the quality of the video is so bad then when they do a close up the teeth could have been angle ground for all you know.
He uses a home made machine that to be honest isn't up to the job, it's part Sherline, part high tensile licorice but the main points are he uses tpi as his model to generate gears because he's using a tap or tap based geometry to generate his hobs [ which aren't hobs in the true sense ]
Gears are measured in DP or module if you are working in metric but he doesn't cover this, neither does he cover pressure angles.
the killer though is he's got the value of Pi wrong in all his calculations so all his maths is for nothing.
Sorry but when you are charging punters serious coin, like 30 quid a throw in the UK for one of these coffee mats, sorry DVD's, you must give value for money.
On You tube is a guy called Hobbynut who has a series of 7 or 8 videos of gear cutting and hobbing.
These are well worth watching, clear precise and full of correct useful information, I see tonight he even has one on corrections to some of the videos already produced.
Download these, burn them to a DVD and throw the Rodriguez away.
John S.
bogstandard:
John,
I tried watching a few of that chaps you tube offerings, but his consistent beating of gums rather than showing anything stopped me from watching them all the way thru. All the articles he did could most probably be condensed into a quarter of the time, if only he could stop using that damned mouth of his and get on with the job in hand.
This DVD I watched however was full of interesting stuff. I am not on about making the cutters, as I know all his tooth forms are a load of crap, and he states that they are not the correct form, but they work for what he is doing. My interest lay in the way he used the hobs, and that to me was an eye opener. Also, I found the video quality was more than acceptable on a 42" plasma.
If you remember, a while ago I was looking to buy a set of gear cutting hobs, and everyone in the know who replied said that expensive machinery was required to use them.
http://madmodder.net/index.php?topic=511.0
In this DVD, the chappie shows how he got around the problem of the complicated and expensive machinery, and achieved very satisfactory results, and I am sure that if I used the correct form of hobs, I could produce correct gears as well, using his techniques.
But to get back to a point that has been raised about tooth forms.
If you are making a set of gears to go onto a small engine or a small workshop tool, does it really matter if the gear forms aren't correct? Surely if they have the right number of teeth and they run together well, does it matter if they are DP20 or MOD1.25? Only if you are trying to match existing setups are perfect tooth forms required, say if you wanted to make a few extra change gears. That is the reason I wanted to use hobs, one hob will cut all gears of the same pitch.
If this is the case, and you are just after making a cheap set of gears for small engines or home shop projects, then I would still recommend this DVD.
There is a large difference in what we need to do in the shop for our own use, and what is required for industrial use, or to satisfy the purists who require everything to be perfect and just so.
If there is anyone local who wants to watch it, I am sure I can arrange a viewing time for you, and then you can make up your own mind if it is for you or not. I won't even charge for the popcorn and coffee.
John
John Stevenson:
--- Quote from: bogstandard on July 17, 2009, 05:40:59 PM ---John,
If you remember, a while ago I was looking to buy a set of gear cutting hobs, and everyone in the know who replied said that expensive machinery was required to use them.
http://madmodder.net/index.php?topic=511.0
In this DVD, the chappie shows how he got around the problem of the complicated and expensive machinery, and achieved very satisfactory results, and I am sure that if I used the correct form of hobs, I could produce correct gears as well, using his techniques.
But to get back to a point that has been raised about tooth forms.
If you are making a set of gears to go onto a small engine or a small workshop tool, does it really matter if the gear forms aren't correct? Surely if they have the right number of teeth and they run together well, does it matter if they are DP20 or MOD1.25? Only if you are trying to match existing setups are perfect tooth forms required, say if you wanted to make a few extra change gears. That is the reason I wanted to use hobs, one hob will cut all gears of the same pitch.
John
--- End quote ---
OK but his method is not hobbing in the correct form as a hob has spiral cut teeth hence the need to gear the hob to the blank, a bit like a jubilee hose clip being tightened.
The method he uses which is also used by hobbynut is a 'hob with concentric teeth that produces a gaer with flats on it, the more cuts, the more flats and the better the quality.
Using this method to produce all the gears in any one range will work, it's nor new and there are some good web sites out there that explain this far better than Mr Rodriguez does.
Here's one from my good friend Tony Jeffree http://www.jeffree.co.uk/Pages/multi-tooth-gear-cutter.htm
And one from Peter Harrison http://homepage.ntlworld.com/peter_harrison/workshop/gearcutting/index.htm
John S.
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