Thread: Kirloskar Lathe

It's imperial. You are starting to see my dilema. Doesn't add up, does it.I just ran another test. Set the lathe up at AY1= .0016 which is the same as .040 mm. Set at 45 rpm, it should advance .072 in one minute ( or 2mm in one minute). It actually advanced .437 (or 11mm) over 5x further. ?

OK, well according to our feeds and speed charts CY1 is four times faster than AY1. I.E AY1 is .2mm pitch and CY1 is .8mm pitch. Given that everything else is fine, i reckon its possible that your gear lever isnt shifting from C to A. I had trouble with this once myself. The lever came accross but the lathe stayed in a different gear.

Is there a way you can ascertain whether this is the case? Perhaps go back up to 500rpm and measure feed in AY1 vs BY1 and CY1.

You could also try AY1 vs AX1 and AZ1.

With those 6 lots of numbers we should have a pattern.

OK scratch that, i just went home at lunch and played around with my lathe and I think I have figured out what the problem is.

I did a test on CX9, should be the fastest pass I can do. Engaged the drive using the feed engage knob, and the feed went about 1/4 of the way that I expected. Engaged drive with the half nuts, and the feed went the correct distance for a 3.5mm pitch.

In short, the half nuts drive the carriage 4 times faster than the "feed engage knob" which is listed at number 21 of figure two on page S-1 of the manual. Could this be your problem????

Brendan

No, I use the half nut lever for threading only, and the feed engage knob for feed operation. I will check out the ABC shifter tomorrow and make sure it is in fact shifting that gear. By placing a mirror under the gear box, I should be able to see the action. Or, I can remove the cover, place the gear in the proper mesh, and then do the tests.

Dang it. I thought i had struck gold. Sometimes with problems like this its the simple things that are wrong.

I reckon if its not the shifter, we can rule out the gears in the box themselves. It just seems too improbable that someone has changed those gears causing a 4x error in feed, yet thread pitches are still OK. As we've discussed, this just doesnt seem right.

So, if the shifter is working, the lathe RPMs are fine, the operater is using the right levers etc then what about the feed engage knob itself. It seems that seeing as we only have one leadscrew for power transmission, and not a seperate one like some lathes do, that given the half nuts and feed knob result in differing speeds for the same gearbox selection, then the feed knob must have a reduction gear in its train. It would be more likely that someone has rooted this gear through abuse (by trying to engage this feed in conjunction with the half nuts perhaps) and thus had to replace it. Potentially with something they had lying around, which could be resulting in the faster travel speed.

A quick check to see if yours is feeding correctly would be to measure travel on AY1 using feed engage knob vs travel on AY1 using half nuts. My half nuts cause the carriage to advance four times further than the feed engage knob. If yours are advancing the same amount, then i'd say someone has screwed with the feed engage knob.

If its not gear shifting problems, and its not feed engage knob, then im officially out of ideas.

I had the apron out and on the bench. The feed works with a worm and gear. The leadscrew goes through the worm, which is keyed. Everything looks original. My last guess, is that maybe the rack and small gear were change somewhere along the way. My rack has approx. 16 teeth along a 10cm length. I know yours is metric, but the pitch should be similar. Would you mind counting your rack teeth, so I can compare.

No probs. Anything I should be aware of before pulling the apron off? I have never done it before.

No, I don't expect you to remove the apron. The long rack that runs underneath the ways of the lathe, that allows the apron to travel from one end of the lathe to the other, when you turn the handwheel. Just measuring the number of teeth in a 10 cm length will tell what I have know. It may be my rack has been replaced with one of a different pitch, along with the small pinion that meshes with it.

Righto, no probs. Ill have a look at it for you tonight.

OK I checked last night, my rack has 16 teeth in a 10cm length, which appears to be the same as yours.

Did you ever test the feed rate on AY1 using feed engage knob vs half nuts? What were the results?

Not knowing anything about these lathes at all,from what I have read it appears that the problem is in the Carriage worm and gears.
Is it possable for the 2 of you to do a comparison on your Carriages.
Worm Diameter and TPI.
Worm wheel Diameter and tooth count.
Large gear diameters in your carriage feeds and pinion diameters.

Thanks for chiming in Pipeclay.

I'd be glad to. How do I go about doing it?

You would have to remove your carriage/Apron.
This may also require you to remove the Leadscrew if the Keyway dosent go the full length of the Leadscrew or if the Key inside the worm is CaptivatedYou maybe abto seperate the Apron from thr Cross Slide.
When you do this work,do it while the Carriage is at the Tailstock end.
Before you remove the apron from the Leadscrew use Timber or suitable packers to support the End of the Leadsrew,it may over time with the unsupported wiegth slightly bend.(Packers about 450 in from the End of the Leadscrew should be fine.) Adjust to suit your needs.
Once the Apron is off it should just be a matter of measuring whats there,they should be visable.
The Pinion for the Cross feed will be on the scew shaft.
At least this way the 2 of you can compare the sizes.
Once you have done this I cant think of anything else that would give Feed variations.