Thread: Gaston Defour no.220 universal head spiral bevel gears

Hi,

I have a damaged (chipped) spiral bevel gear and i would like to know what are my options to fix this. can this be repaired or should i find a replacement (standard replacement parts)? i don't know much about spiral bevel gears and if i can find standard pairs that match this one.

Thanks in advance.

That company went out of business around 1970. I assume it is metric since they were made in France where the metric system was invented.
Bil lD

if i can find standard pairs that match this one

.

Unlikely in the extreme. The simple reason for this is production machine tool parts are designed (and processed) for their application. Its not like the maker went down to the gear store to find a pair that might work

As far as volume production of such things, the tens of millions of matched spiral bevel ring and pinion rear axle gear sets produced by Ford Motor Company up at least until 1948 come to mind

There are a few compagnies dealing in used spares for a Dufour (not defour) in france
Search for: "Fraiseuse Dufour PIECES DETACHEES"
But they willtry to sell you the whole head probably
I know of a compagny in Hungary who can make you a new set But that is a long distance away
(always replace both gears) If you get new gears comes the problem of adjusting them

Peter

Thanks for the replies and info, I'll try and contact the French and hope for the best.

Regards.

If you fail to find a replacement Dufour part, there is still some hope. If you very carefully measure the dimensions that the gear set must mount (bores, ODs, axis centerline offsets, etc) and work in (the open area envelope inside the head), and the tooth ratio of the existing gears, you can have a custom gear shop produce a new set. The new set almost certainly won't be compatible with the existing set (!!!) but could be a fine functional replacement.

What do these gears do? can the ratio be changed? I assume more then manualy tilt the head from time to time as the changing jobs require. I understand Bridgeports are known for stripping the worm gears that tilt the head.
Any chance of welding in a new tooth and machining it to match.
Bill D

Originally Posted by Bill D

What do these gears do? can the ratio be changed? I assume more then manualy tilt the head from time to time as the changing jobs require. I understand Bridgeports are known for stripping the worm gears that tilt the head.
Any chance of welding in a new tooth and machining it to match.
Bill D

That is obvious the gear that drives the mainspindle And no. Welding is not going to work
I doubt it is ever possible besides a realy low speed low torcue applicatin on mild steel

Peter

Originally Posted by sfriedberg

you can have a custom gear shop produce a new set.

In practical terms, no. The price for one pair would be higher than ten complete machines. We aren't talking helicals or even herringbones here.

You could replace them with straight teeth, but you don't want to. Even that would not be at all cheap. I see 30 hours in a set of straight bevels like that, probably more. And they'd be second-rate when you were done.

However .... these days, there is a maybe. DMG have been 3d contouring spiral bevels for a while, on really big sets. Find the software that does this and you could possibly mill a pair.

I am pretty sure even rfq-ing a set from people doing the big ones would come back with a price beyond acceptable, but you can always ask.

There are only a couple of places in the US even capable of quoting these parts now, much less making them.

Possibly it would be feasible to model a set of skew bevels then mill those. If it were mine, I'd probably go that way.

What do you propose to do with the machine? If it for light, occasional work and there is only one tooth damaged, I would re assemble and keep an eye on it. You don't know how long the tooth has been damaged, perhaps many years ago. Replacements as a "one off" will be horrendously expensive and you do say you don't know much about bevel gears, which will need to be accurately assembled to run correctly. If you can get a used head complete that may be the way to go. Check the gears on it though, they may be worse than yours.

Here's a few possibles ...

Pay Gleason to do the workup, then buy this program ($375, cheap) to dump the numbers in to create a model

Bevel + - 3-d Gear Models and Software

Model it in Pro/E

Accurate parametric modeling of spiral bevel gear based on CAD software Pro/E

Model and program cutter paths, generic

Manufacturing method of spiral bevel gears based on CAD/CAM and 3-axis machining center

or figure it out for yourself (free !) from the following article

A Practical Approach for Modeling a Bevel Gear : Gear Technology March/April 2015

I'd probably go with the skew bevels, should be similar process but easier. Much easier.