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Will a Barber Colman #3 cut worm gears?

Cory

Cast Iron
Joined
Feb 9, 2007
Location
Sterling,VA
I am interested in cutting bronze worm gears for my antique Porter Cable sanders. I have researched some and heard that the Barber Colman #3 gear hobbing machine will do this.The gears I want to cut are 2" in dia and 5/8 thick with 21 teeth.I think the worm has a 4 start thread but not real sure. I need help in choosing a machine and the best place to have hobbs made. Also how do you figure out the dim. of the gears?I am new to this and not a machinit by trade but very interested in making these gears.Please help me out. Thanks agian,Cory
 
There is a book called "gear cutting practice" by colvin and stanley (??). HAs a lot of good info.

Ash gear can help with the cutters. Better have deep pockets.

I believe the B-C will do it. I have the vertical feed attachment for mine to do it but never installed.

Not sure about the 4 start part.
 
Thanks for the reply.So you have B-C #3? If I buy a B-C#3 and it does not have the vertical feed are you willing to sell yours?How old is you machine and where did you get it, how much was it?Are these the best small gear machine to get?
 
A BC #3 or the later 6-10 models (later cousin) look to be about $5000 from dealers, more or less.

Then prepare to buy the change-gears, as those above usually come with none. $25-50 each.

Then prepare to buy hobs...probably $300-500 each.

Then buy hob-arbors to match the hobs, those might be $500-1000 or you can make your own.

Then you have to be able to turn the gear blanks to .001" of nominal on OD and ID, and they must be concentric.

You must create workholding for the blanks, another lathe job that has to be accurately done, either turn the B&S #9 taper or use collets and a straight shaft.

I'm not trying to pour cold water on a noob's dreams here, but these are in fact the steps you must consider and be prepared to spend $$ on before you can make Prototype Gear #1.

If you made that first gear and had spent less than $6000, it would be a small miracle, unless somehow you manage to pry the machine out of the hands of an unsuspecting owner for less.
 
Where could I find this machine? I have looked all over the web and everyone wants 10,000.00 for the machine.I am looking for all the help I can get positve or negative so bring it on! I am not a machinist by trade but work in a prototype shop where we have a lathe and mill.I am very interesed in making these gears so any input is welcome.I have a machine I found the guy wants 3750.00 with all the gears,good price? Does the machine have to have vertical feed?Is vertical feed manual or automatic?
 
Way before you ever buy a machine, you need to get Ivan Law's Gears And Gear Cutting and understand everything in the chapter about worms and worm gears.

Then you won't need a BC to cut a few worm gears.

The only justification for such a machine is to make enough gears on it to get your money back. That will be a whale of a lot of gears Cory.

John
 
I think if you spent your money on a good dividing head complete with plates and tailstock and could grind a form cutter you could be making a few prototypes for $500-1000. It will take awhile to get thru the learning curve and all the indexing, but I think you'll end up with a serviceable result.

John has given you excellent advice, a BC is a production machine, the books have sections on cycle times and how to maximize production...
 
How else can this worm gear be made? Metal lathe,vertical mill? Has anyone run a Barber Colman #3 gear hobbing machine? Once the BC machine is set up with the right hob and gears it is ready for production?
 
How else can this worm gear be made?
Read Ivan Law's Gears And Gear Cutting

John
 
Can a dividing head work on a vertical bridgeport mill?Do you still use a hob to cut this gear?I am a beginner so please be patient.Thanks,Cory
 
I have made them on a Barber Colemen, I, thats right ME, was the down feed attachment :)...they paid me 4.50 an hour to downfeed. And blow the chips out and hold a piece of paper under the hob to see when it stopped making dust. These wormwheels were for L&W chuck dividing heads about 1985.

We also made a couple 1 offs with a horizontal mill, a dividing head, and a single tooth cutter, those wormwheels are not perfect because they have no helix (alto the teeth are cut at an angle), but they work OK, and far better than the torn up ones they were made to replace :)

the job IMHO is better done on a horizontal because you built the flycutter on an arbor and use the overarm support so the one end isn't just hanging out in the breeze :)

Bill
 
Any old crap universal mill.
Shaft encoder off a scrap Fanuc lathe.
Contactor box off a scrap Guildermeister lathe
$140 worth of electronic bits to go inside.
Reduction gearbox off an electric motor
Stepper motor to drive it.
Bit chopped off an old Myford leadscrew, fluted and hardened as a hob.

hob%20indexer20.jpg


Here's one I did earlier.
 
Re reading your post again and you don't even need to go to this trouble.
If you are only making the one type of gear then all you need is a gear train from the arbor to the Gearbox like in the picture above, That box is 40:1 ratio so you need a 40 driving a 21 to get the gearbox to generate 21 teeth every revolution.
How ever this only works for a single start worm.
If yours is a 4 start worm then the ratio need to be 4 times faster so you want a 160 driving a 21 or a compound train.

Can you get an old worm and get flutes ground into it as a hob ?
 
Cory, are you intending to go into production, or just make a couple gears to fix up your own tools?

It is very possible to free-hob worm gears with nothing but diy tooling, but it will take a bunch of ingenuity and experimentation.

Here's one I made for my old Jet 1024 power feed.

Gear-Making.jpg


Graham
 
When making replacement gears, I find cutting chips the easy part. What about establishing axial pitch, pressure angle, pitch diameter, tooth thickness, any tooth form modifaication, and some way to inspect accuracy? (Willbird=BCR?)
 
John, WOW!

gnorbury,
wuz all enthused, have a 6" rotary table that I bought new in the early seventies, perfect other than stripped worm gear. Looked doable until I realized that each of those 85 or so hob teeth have very accurate looking relief angles, (duh), ground, (or?), on both sides and not a visible nick on any following tooth, with what, .100" or so between? Please share.

And please Lord, don't let it start with. "very sharp chisel and jewlers loup..." or "check with your significant other for an emery board...." times 170!

Very impressed Bob

Edit, on further inspection, did you get away with just top relief?
 
You guys sure know the tricks of the trade.In gnorbury's picture of the home made hob how do you figure out how many flutes to grind into the worm after you make it?What is the best material to make these out of so you can temper them?Does the speed of the mill have to relate to the speed of the gear box?Or the speed of the cutter is a constant and the gear box sets the tooth pattern.What about the feed into the cutter?Can this DIY hobb be used in a lathe, and the gear be set up on the crossfeed?
 
Cory, the explanations to your questions are long, sometimes very long. Buy the books mentioned above and read them. You will be light years ahead.

A B-C is a producion machine. FInd an old horizontal mill they are cheap. I think I have a spare out in the shop.
 








 
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