Warco BH600G Apron worm gear set

Decided a new thread rather than adding to my 'I screwed up' thread, as it could be of use to others,

Apron Worm Gear set.

Need advise please on the best way to increase the *'whole depth of tooth', of the replacement cone (*hollowed out) gear wheel, by 2.15mm.

The reason, is that having replaced the OEM brass gear wheel with the bronze replacement, I was somewhat "upset' to find that the AFRoM geared motor attached to the Feed Rod just would not budge.

Now that motor worked fine with the OEM brass gear, apart from binding slightly at regular intervals, indicating an alignment problem somewhere in the train.

Reading Howard Lewis' PMs, I was slapped between the eyes seeing all his measurement figures for when he cut his own Gear Shaft.

"Measure the two gears to see if there is a difference for goodness sakes!" I shouted at myself.

Did so and lo and behold the replacement bronze gear has *'whole depth of tooth' 2.15mm LESS than the brass OEM one.
OS dimensions are identical, so that difference means that the Feed Rod is out of alignment with the Gearbox end, as is apparent when connecting it up.
At first I thought it was due to the position of the Bracket that houses the Worm Gear set, so I left the securing cap screws loose, but that did not solve the problem.
Now I/we know.
Problem is I do not have a gear hobbing machine.

Geoff - HELP🙏

*Description from Gears and Gear Cutting by Ivan Law

Oops, forgot to add photos.

I think it might be easier to turn down the worm........but 2mm is a lot.

Or make an identical worm, and turn it into a cutter, and even possibly do the cutting with it mounted in situ if you don't mind the clean up after.

One danger of any manual one at a time correction might be to end up 'non-round' or with uneven teeth that can leave a periodic feed  speed change that shows up on a fine finishing cut.

Edited By Bazyle on 21/03/2016 17:31:44

Geoff,

I probably missed something in the original story, but: Why do you have a replacement wormgear that is clearly not the same shape as the original ?

That dumb question asked ... and following Bazyle's line of reasoning: A cutter made from an identical worm should be your salvation. [is the Worm available as a spare ??]

MichaelG.

Bazyle,

Wonder how much courage I have 🙏

Michael,

That replacement worm gear works fine, is identical to the brass one, apart from the 2.15mm.

Will phone Warco to ask them to look at the other spares, and see if they have spare worms.

More trials and tribulations.

Geoff - Thanks for responses.

.

Apologies for my mis-interpretation, Geoff

I thought the 2.15mm was a dimensional error [i.e. not the same shape as the original] which was shifting the 'Feed Rod' out of alignment and stalling the motor.

... Evidently there is more to the story than that.

MichaelG.

MichaelG,

Cannot find a word for this, but the depth that the replacement teeth have been cut are 2.15mm less than the OEM fitted, hence the binding when the Feed Rod is coupled up to the Gearbox free.

No problem with Gearbox engaged.

Have sent an email to Warco with dimensions.

Geoff - Let's see what they say.

Wonder if a replacement worm might be smaller O D and so match the bronze wormwheel, in case there has been an In Service Design Change. If so, there should have been a note saying "Can only be used as a pair" and not sold separately.

It could be that you have been sent a reject that is anything but to drawing.

WARCO's reply may prove interesting!

If it were a plain spur gear there must be lots of who could probaly sort it out, but being concave is another sort of problem.

In any case, this sort of thing should not happen.  Severe failing in  the Quality Control Department

Hope that you get it sorted, Geoff. Not having a fully operational lathe does leave one feeling exposed.

Howard

Edited By Howard Lewis on 22/03/2016 17:58:54

If the 2.15mm is tooth depth on the wheel things are probably fouling on the crests. Best check which ones. With luck it will be the crests of the worm so it could be turned down a little.

John

-

I'm missing something here.

If the worm wheel is cut deeper, therefore a smaller diameter as it looks from the picture then surely the worm needs to be bigger and as stand should have a hat full of free play and not binding ?????

Warco have said they are investigating.

Will post their response once received.

Ajohnw,

Will do, and thanks for the suggestion.

JS,

I don't know very much about gears, apart from the fact that they mesh together, transmit power and are able to change the speed my car goes, amongst other usefull attributes, hence this thread asking for advise.

Geoff - Gears are 'black art' to me 🤔

Geoff,

You and me both then.

A worm and wheel have to be a certain distance apart to drive correctly.

Now you have stated and the photo's seem to prove this, that the new gear is smaller and therefore with the original worm will have loads of backlash.

But the best advise from the 1s and 6d's is to reduce the worm which will make the clearance even bigger.

You either need an original worm wheel or a bigger worm NOT smaller in my book but unusual in a forum post no one agrees with me, in fact they all lean the other way which makes me think I'm missing something dead obvious here.

Think it's time to put the kettle on and then bore another 100 sprockets out for bearings - sigh.

Edited By John Stevenson on 24/03/2016 16:30:05

If you look above the keyway on the new gear it looks a bit thicker on the flange. The rest isnt necessariy bigger but from what geoff says anyway they didnt cut it deep enough. If it were a changegear lathe it would be easy to cut a new worm to use as a hob to deepen the teeth but the gearbox probably doesnt give the right ratio.

Backlash is not desirable but not such a problem on a feed train i suggest. I,d be more worried about it jumping out of mesh if not in deep enough engageent under load. Hope warco dont leavve it till after the weekend to respond.

TOLD YOU I WAS MISSING SOMETHING.

2.15mm LESS in depth not 2.15mm less in size.

Doh...............................

What you really need to do is offer the worm up to the worn wheel and measure from one side of the wheel bore to the OD of the worm, far side, just say this is 30mm for a round figure.

Then do the same with the new wheel and the difference is the amount it needs cutting deeper.

Thanks John.

Will do.

Geoff - Been otherwise occupied hence not responding sooner.

Problem found.

Found the problem!
It's one of those that you just shake your head at in utter dismay, for failing to recognise what was cause the problem!

Absolutely nothing to do with the set of worm gears, as I at first thought!

It's that bl@@dy spur gear that's out of square and binding.
Only very slightly with Apron off:

**LINK**

BUT locks near solid with Apron back in position:

**LINK**

Either that spur gear has been bored out of square, or the holes for the Gear Shaft, in the Apron casing, have.

No problem with power from the Gearbox of course, there being enough to overcome the binding.

With the original Gear Shaft, there was only a slight hiccup using the first DC motor, but not with the new Gear Shaft fitted.

Have a new more powerful DC motor I will be trying next week.
Had to make an adapted as the motor shaft is so hard I cannot drill it for a drive pin.

I'm now asking myself a single question . . .
Anyone like to hazard a guess as to what it is?

Geoff - Next week will determine if that question is fulfilled.