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gear hobbing /spline cutting ? school me

D.D.Machine

Stainless
Joined
Dec 10, 2003
Location
poulsbo, wa, usa
I`m looking at picking up a gear hobb machine but don`t now mutch about them .I`m making shafts that have 21 to 40 splines on them but there all 30* pressure angle and 24 pitch so I think one hobb well do them all?
biggest shaft is 2" od and up to 40" long

what machine should I be looking for?
Thanks
Duffy
 
I`m looking at picking up a gear hobb machine DO IT but don`t now mutch about them YOU'LL LEARN BY DOING.I`m making shafts that have 21 to 40 splines on them but there all 30* pressure angle and 24 pitch so I think one hobb well do them all? YES
biggest shaft is 2" od and up to 40" long GEEZ THAT'S A WHOPPER

what machine should I be looking for? HM, LITTLE BIGGER THAN I WOULD KNOW... SURE SOMEONE ELSE DOES
Thanks DE NADA
Duffy
 
Hi Duffy,

For a spline shaft you want a horizontal mill with an indexing head and an involute cutter of appropriate geometry. You'll probably have to get one custom-made for the 30° PA (are you sure about that???).
 
Duffy,
You don't mention quantity. Hobbing is the way to go if the quantity is there. An old Barber-Coleman hobb is not that exspensive, it's the cost of the cutters that will kill you. Get a hold of somebody like RPI (http://www.repair-parts-inc.com/renew.htm). Have them quote you a turn key set-up. This should include machine, cutting hobbs, and training.

I'll tell you right now, if you aren't doing several hundred splined shafts per year, you can't afford to be in the hobbing business. I haven't even begun to talk about gaging. This can run thousands of $ for every size shaft.

If you don't have the volume, look into sending the work out. There are plenty of shops out there that do spline hobbing. They have both the cutters and the gaging.
JR
 
An early Barber-Colman No. 3 or the latter 6-10 is your best bet. If you locate a machine, make certain you get all the index, and speed gears, and the correct hob arbor.
 
10 fingers,
IIRC, the #3 only has a 1 7/8" spindle hole. I'm not sure about the 6-10. We've got 16-16s which have about 3 1/2". Duffy didn't say how long the splines are so...

You guys that are reccomending gear cutters on a horizontal have never been around a BC hobb. If you have all of the change gears and attachments, there isn't much you can't do with one. I've seen triple start "threaded" shafts made on a BC! The best thing is - one pass and you're done.
JR
 
JR, I don't know about the low cost part. I emailed Repair Parts about that BC 6-10 built in 1926, and labeled as a "good starter" machine a few months ago and the quote came back around $5K.

I guess it's not bad if you've got work lined up but I was somewhat amazed at the price. There's another dealer in NC that's got a corner on the market too...amazing numbers of hobbing machinery at similar prices. I think a mid-1950s model 6-10 came back close to 10K.

-Matt
 
Matt,
That's why I said earlier that you must have some quantity to get into hobbing. Either that or a pile of money that you want to get rid of. You can spend $10K just starting out. There are plenty of job shops that do gear making & hobbing.

If you do have a pile of money, I am available for consulting. The number to call is BR-549. :D
JR
 
what I`m doing is 4x4 axles and shafts for the mating of trans and tranfer cases ,,, 90% of my spline work is under 2" dia and 10" long .
these shafts do not fit tight, right now I`m just milling them with a cutter I make using TPG inserts but I`m tired of cutting one spline at a time. this week I`m making 50 shafts that got 34 splines on one end and 23 on the other. next week it well by 34 and 32 same size run. so right there is 6150 cuts.

its geting old real fast
Duffy
 
Duffy, for a used Barber-Coleman with change gears, and a couple of hobbs, you're going to spend $8-10K. Now, if you see this as a continuing business, that's probably a good investment. In the time it takes you to make 2 passes, a hobb can cut one end complete. Once you have them set, you can load shafts and just start it then walk away. Those 50 shafts are probably no more than 3 days work on a hobb - both ends.

If you plan on doing 100 shafts/month. Paying $10K for a hobb is probably less than a 1 year payback vs having them made. Comparing to how you do them now, it's probably less than 6 months unless you don't pay yourself.
JR
 
Duffy, we do similar work here for performance off-road and drag racing. Are the splines you are milling involute form? If just straight sided, they will not work as intended. The beauty of the involute form is that regardless of backlash, the spline will self center under load. Suggest you get a copy of ANSI B92.1-1970
and attend one of the gear industry classes.
 
This ought to be the time I come in and ask about the mill you've been using until now... Ever thought about making a hobbing unit to fit it? It must be pretty big, and you must already have a decent indexing setup... Now all you need is a drive shaft with a couple of uni-joints to drive it 'round. A gearbox thereinbetween to give right number of divisions, and away you go. Or a drive shaft with a worm on it, and master worm gears with the right number of teeth for your job attached to the shaft.

This sort of thing has come up here several times. Do a search.
 
Looks like I may be needing some home-schooling too. ;)


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:D
 
Well, isn't that just the cutest thing you've ever seen? What's it going to be when it grows up, a 16-16?

From the pictures, it looks to be in good shape. Maybe 1" through the spindle? Do you have a chuck for the spindle nose? Change gears?

I'm not jealous! I'm not jealous! I'm not jealous!
JR
 
The hobber came from Kearney State University in Nebraska who seemed to be the original owner based on crusty old documentation from Barber-Colman to a CNC shop in Neb. to me. It looks like a little creampuff but it's every bit of 1800 lbs...a lot of solid cast iron in the base. The motor is a 2hp 1200rpm monster and has a triple V-belt drive.

I've got about 15 change gears for the tooth timing and maybe 8 change gears for the feed, 3 hobs, I've got about a dozen more hobs from ebay sniping.

Conflicting info on the panel between 230v and 480v so I opened up the jbox on the side of the motor...crusty old wiring but I think will work, 230v.

The belt guarding is the most intricately conceived cast piece I've ever seen, and the most confounding to take apart...not sure how it actually comes off because it entraps 1 belt and I can't see inside how that belt is released.

Right now I'm in the wiring & cleaning phase, someone long ago did most of the hard work by applying rust preventative to every exposed metal surface, so it's just dirty.

John S, just rub it in ;) .

-Matt

PS: I should add that this seller I think hit the high-water mark as far as crating. Made special T-bolts from 1-1/2" x 1-1/2" x 1/4" thick square washers and threaded rod to firmly bolt the machine to the 2x6 base, electrical taped all swinging covers shut, reversed the handwheel on the far side to protect the crank handle, packed all the change gears and hobs in individual bubble wraps and then screwed down a 5 gallon pail inside the crate, and all the bubble wrapped items inside. Packed the documents in a cardboard box, and marked the HEAVY and LIGHT END on the crate in large letters. Only thing they missed was the little arched cover in the front, and that merely fell off with no damage.

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