Problems with U1612 Churchill Gear Hobber

Hi all,

I'm hoping one or two of you may be aquainted with this antiquated but very useful piece of kit in my workshop!

It's a 1964 Churchhill gear hobber as already stated. I've been using it for 6 months with no issues, but now I think something deep in its bowels (and Jesus are they deep and ineccesable!!) has gone wrong.

I did my usual set up procedure and proceded to "touch" the hob on the O/D to do a touch-cut, to make sure everything was ok with my set up as I usually do. I then let it run its cycle and checked the marks left for verification.

The first thing I noticed when I came back in to the gear shop to check how things had gone, was instead of a 2MOD 8 deg helix, I had something around 4 deg (approx).

Of course I checked and double checked my settings (which are good) but somethig else has made me believe there is an inherent problem with my machine - I'm hoping that it's maybe a common problem that someone has a quick and easy answer to!

The thing is, this particular model has a "P.I.V" - or positive infinately variable gearbox, so I adjust the cutting feedrate on the run - I noticed that since this set-up problem, when I alter this feedrate it alters the angle of helix aswell - this is obviously not right!

The helix can go from almost vertical at one extreme to about 2/3rds of the required angle at the other end of the spectrum.

Is there anybody here who is familiar with these machines?

I'm fairly new to gearcutting in general, and only do it occasionally as part of my job running a shift of maintenance engineers - and the service guys have quoted me £3000 to have a look and put it right, now thats alot of money right now

Thanks in advance

Mark

A well worth a try, thanks for the views anyway - I guess ill just have to part with the 3Grand then

Macsbig- I'm not familiar with your machine, and I'm assuming that it has a differential for cutting helical gears- if that is the case, did you remember to engage the differential? There should be a lever or knob that locks and unlocks the differential. Some machines have a locking link that you place on the differential change gear studs to lock the differential out for cutting spur gears. I hope this helps. By the way, as far as manual hobber go, 1965 is not that old. Good luck, and please report back when you find your problem.
Dan

Yeh everything is set-up ok Dan (had it verified by an independent scource )

Thanks for the reply, got some guys comming in later today to have a look, hoping that they find something realetively simple and it doesnt cost me the whole 3K lol.

Maybe just and electrical glitch, but the drawings are pretty boobins, cant make head nor tail of them!

By the way, the machine seems realitively rare, it's far more common sibling is the PH1612 which you may or may not of heard of - gotta admit, I'm quite enjoying the the whole gear cutting experience - even if it can get a lilttle frusterating at times!!

My Fellows type 6 Shaper, it seems is a toddler as well, at a mere 67 years young!

No real problems yet with the shaper - touch wood (touches head!) only a bit of routine TLC and the swarf/cutting fliud tray (which is made of cast iron) had previous repair and did fall off again a couple months back.

But my welding guru in the shop has stuck it back together for me and shes chugging away nicely!!

Anyway enough of my ramblings, lets get the radio on and creat some swarf

Who are your service guys?

Churchill Machine tools Mark, think they mainly specialise in the grinding side, but he's bringing one of his gear guru's with him.

Think they also go under the name of Churchill Grinders.

Regards

I would be looking for someone up the Tyneside area cos as far as I know these machines were built in Blaydon.
A phone call to Andy Donaldson at BSA Machine Tools in Birmingham might give you some leads as I'm sure BSA have all the Churchill machines apart from grinders.

Thanks Mark, I'll bear that in mind in the future.

These guys were rocommended by the guy that sold us the two gear cutters, the're here now so hopefully some time soon I'll get to know if my susspisions of the fault are correct!

Regards