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willmac
02-07-2008, 06:22 AM
Can anyone suggest a good source of information on setting up a typical hobbing machine such as Barber Coleman, Mikron etc. I'm not looking for a basic explanation of the hobbing process or a parts list and diagram for a specific machine (although that would be interesting), but much more the process that you need to go through to set a machine to produce a gear to meet a specific requirement, including those with addendum modification, helical gears etc. I am sure that I have seen a Barber Coleman book that might cover some or all of this but am having some difficulty finding it. I am happy to buy a book if there is one available. If someone has a compilation of this type of thing on a CD/DVD (like John Stevenson's tool and cutter grinder CD) that would be ideal.

John Stevenson
02-07-2008, 07:15 AM
Bill,
We are working on a gear cutting CD but it's a while off yet and will probably run into 3 or 4 CD's to cover the imformation I have collected.
I do have most of the Barber Coleman and fellows books but no Micron books at present.

.

willmac
02-07-2008, 08:44 AM
John -

I hoped you might say something like that. I will order as soon you can get them out. I'm sure I have seen a fairly large Barber Coleman book that covers what I want for hobbing but it is a while ago now. The Fellowes material would be for set up on a gear shaper I guess? Also interesting. How about Gleason material or is that getting a bit too out of the mainstream? I worked in an axle shop for a while producing crown wheels. That was an extremely complex process, that I have mostly forgotten.

Spin Doctor
02-07-2008, 06:36 PM
For the Barber Colemans the whole process is pretty staight forward. All of the info needed for the cutter set-up is generally right on the hob itself. Dtf for Depth to Finish, LA for Lead Angle by which you know how much to swing the hob spindle to compensate. The index ratios for the one I used to use where right on the machine. But as it is a 30-1 ration machine we cut a full set of index gears from 22T to 77T with some others larger than the 77T. That way if we needed to cut say a 53T gear we just put a 30T on the input shaft on the Index gear train and 53T on the output shaft with an idler between them to fit. But they only worked for spur gears and splines. Helicals are rather more complicated as you are progressively advancing or retarding the work in relation to the hob depending on whether it is a right hand helix with a right hand cutter or a lrft hand helix with a right hand cutter. Plus the index ratios and the feed rations are calculated using constants. Any B-C operators handbook should have all of the revelant equations in it. Although there may be things that are specific to each model. The model I am familiar with is the 16 IIRC. Gear shapers such as the fellows are whole different ball game. Even making you own extra index gears for a Fellows is a project as they used a special shaped broached hole in the center of their gears for mounting to the index shafts. It's called "buy our parts". But any mechanical hob versus an electronic one is going to be pretty much a variation on a theme as they operate basedon a timed relationship between the cutter and work.