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View Full Version : Milling machine spindle bull gears quote !



TR
06-04-2014, 09:24 AM
My Herless Turret mill gears are worn. I am looking at getting some custom gears made. Ideally I would like to buy these these gears new, but so far no luck.
I was quoted some AUS $2000 to have the gears replicated which includes grinding and case hardening. I am curious what the USA clients would expect
to pay for custom work like this.

The gears are similar to a bridgeport 81/26 tooth combination, which typically sell for about USA $300 on ebay.

http://i663.photobucket.com/albums/uu354/topari/DSCN4997-Copy_zpsd6a4aa0a.jpg (http://s663.photobucket.com/user/topari/media/DSCN4997-Copy_zpsd6a4aa0a.jpg.html)

boslab
06-04-2014, 10:06 AM
Bloody hell, you could replace the whole machine for that!
Mark

rowbare
06-04-2014, 10:43 AM
I have seen posts of bull gear repairs where they have machined the teeth off the gear and fitted a ring gear to the remaining hub. Would a repair like that be an option for you?

Boston Gear has a wide range of stock gears. They have a distributor in Australia. http://www.bostongear.com/

bob

TR
06-04-2014, 10:55 AM
Ring gear would work well. I will follow it through.
Thanks
Tom

John Stevenson
06-04-2014, 12:29 PM
Why would you even want ring gears ?
There is nothing special in that picture with the exception of the size of the boss on the small gear that could not be machined out of a blank gear.

To fit gears as a ring you need to make sure that they are mounted true and concentric and then worry about how you are going to fasten them, wheras to chop one out of a blank looks to be a simple boring job ?

Peter.
06-04-2014, 12:56 PM
My Denford lathe headstock gear is a delrin ring bolted to a steel hub and it works great. Should be quieter than that combination too, as well as being easy to make.

ironmonger
06-04-2014, 01:26 PM
<<snip>>

To fit gears as a ring you need to make sure that they are mounted true and concentric and then worry about how you are going to fasten them, wheras to chop one out of a blank looks to be a simple boring job ?

'Fastening' ring gears has long been the province of heat and a shrink fit.

Even though I'm a clumsy bastard myself, I have managed to fit a number of ring gears to flywheels, this seems similar enough...

paul

Zahnrad Kopf
06-04-2014, 01:36 PM
It's not clear on this monitor, but what needs to be ground? Assuming it's not the involutes, then I see no reason for that price. You've got your basic blank, bore, install keyway, hob, case carb, and clean. Maybe if You wanna get fancy you can even machine the radiused tooth tops before carbing. ( looks like it on this screen ) $500 AUS + $1501 AUS shipping. Oops. :rolleyes:

Sun God
06-04-2014, 02:20 PM
Converting to belt or chain would be significantly cheaper, and simpler. Adapting Bridgeport gears would be simpler still.

John Stevenson
06-04-2014, 02:32 PM
True a ring gear could be fitted but you have to buy a full gear, cut the centre out and shrink it onto what is possibly a hardened donor gear to finish up with what ? A full gear ? which is what you started out with.

It's a back gear for christs sake, millions of these were made out of cast iron on machines that had seen far better days what what Rush gears or Boston use. Even steel ones ran unhardened.

Which now begs the question what is wrong with the original gears ? doesn't seem to be any teggies missing. Is it a case of it runs at 61 decibels and it *would* be nice if it ran at 60 ?

TR
06-05-2014, 07:01 AM
Which now begs the question what is wrong with the original gears ? doesn't seem to be any teggies missing. Is it a case of it runs at 61 decibels and it *would* be nice if it ran at 60 ?

Good point. There is a touch of vibration when in the low range and lots of noise. I cleaned the gears today and they seem okay. I will seek another opinion. The noise is most pronounced when running CW and one can barely hear anything running CCW. This must be a good clue.

http://i663.photobucket.com/albums/uu354/topari/DSCN5015_zps7acad05c.jpg (http://s663.photobucket.com/user/topari/media/DSCN5015_zps7acad05c.jpg.html)

http://i663.photobucket.com/albums/uu354/topari/DSCN5014_zps77d22c6d.jpg (http://s663.photobucket.com/user/topari/media/DSCN5014_zps77d22c6d.jpg.html)

_Paul_
06-05-2014, 07:30 AM
Could you not just avoid using the backgears at all?

Does you mill have a 3 phase motor? if so you could fit an Inverter and control the spindle speed that way.

From the prices you have mentioned it could work out a lot cheaper than new gears.

Paul

TR
06-05-2014, 07:36 AM
5HP 3 phase motor. Back gears 0 to 500 rpm and main drive about 500 to 4000 rpm.

ammcoman2
06-05-2014, 08:24 AM
Can you flip the two gears around? Then the normally unused tooth faces are in contact. Depending on the way they are set up, this may not be possible.

Geoff