Warco WM250 Carriage Drive Gear Shaft BENT – Help

[Dave Smith 14Participant @davesmith14]

I was happily turning with carriage feed engaged, when the carriage suddenly stopped moving! When I stopped the lathe and disengaged the carriage I found the hand wheel free for half a turn without moving the carriage, then going very stiff and the carriage moving. looking at the cantilevered pinion gear which engages the carriage rack showed the shaft is bent so the gear is engaging/ disengaging. I have no idea how this happened, there was no carriage crash or any bangs. It is going to need a new gear/shaft. My question is how do I get carriage gearbox off and get the gear out with the least hassle, can anyone help please.

Thanks in advance

Dave

[Dave Smith 14Participant @davesmith14]

[Former MemberParticipant @formermember19781]

[This posting has been removed]

[ChrisBParticipant @chrisb35596]

You're going to have to take the saddle and gearbox off I think. But if still under warranty I'd contact Warco first as Bill says.

[Mick B1Participant @mickb1]

I bent the pinion on my WM250V soon after receiving it, by engaging longitudinal feed on a locked saddle when I'd meant to engage crossfeed. It resulted in a very tight spot in carriage movement about every 3 turns of the handwheel.

I lived with this for a while – it doesn't sound as serious as yours – but ultimately found that I could fix it completely with a crowbar! Run the saddle near the tailstock and find the worst tight spot; locate the toe of the crowbar against the shank of the pinion away from the teeth; brace the peak of the shallow bend of the crowbar against the corner of the apron and lever upwards. It took me 3 attempts, but at the end of it I'd cured the problem completely, and so far as I know permanently, at no cost.

However, I'm puzzled by your description. You say your pinion engages and disengages but you don't describe any jams or tight spots, (afternote – read it again, and you did!) so it almost sounds as if the pinion's axis of rotation has been displaced downward, and I don't understand how that could happen without tearing out the carriage to apron bolts…

Talking of which, those 4 caphead bolts at the edges of the carriage are key to dropping the apron. You also have to unbolt the far leadscrew bracket, and pull back the headstock telescopic leadscrew cover, to poke out the shear pin that drives the leadscrew from the geartrain stub. Can't remember anything else offhand. You can then remove the apron gearbox and leadscrew together – take care not to spill the oil. My reason for removing the apron gearbox was that the crossslide shear pin had fallen out into it and got into the pinion that drives the drive pinion, jamming it solid – which sounds nothing like your problem.

I got some helpful advice from Warco, but it didn't sound as if they were familiar with the problem. They might know more about it now – the WM250V was, I think, quite a new or maybe revised product at that time 4 years ago.

Edited By Mick B1 on 02/04/2019 21:19:47

[Dave Smith 14Participant @davesmith14]

Mick

Thanks for that, like you I did about a year ago have a tight spot cured by the crow bar method. Here the gear comes completely out of mesh over half a rotation. When I get it apart I will post some pictures. I will also check with Warco before dismantling it.

Dave

[Dave Smith 14Participant @davesmith14]

All fixed, worst bit was getting the roll pin out that hold the pinion shaft to its mating gear.

[Mick B1Participant @mickb1]

Sounds good – you seem to've had to dismantle more than I did.

Did you find out what caused the bend? Must've been some sort of interference event to have bent the shaft that badly – I wondered if a big piece of debris got trapped between rack and pinion under power feed?

I know the shear pins don't always go – when I bent my pinion shank the leadscrew pin didn't, one of the change gear keyed bushes broke instead. I thought about putting an undercut into the pin, but I keep making the excuse that greater familiarity with the machine makes such incidents less likely.

Edited By Mick B1 on 04/04/2019 21:28:59

[Dave Smith 14Participant @davesmith14]

Mick

There was nothing evident . When It broke I was taken a 0.5mm cut, so nothing big. I agree it could have been something lodged somewhere that moved. Carriage actually runs better now than it ever did. Just got to sort out stiff spot on the x axis on my wm16 now😂

Dave

[Howard LewisParticipant @howardlewis46836]

It is possible that the Apron and Saddle may be a "carry over" from the BH600 / Chester Craftsman / ETR BL12-24.

You will now know that the Apron is quite heavy. I lowered mine, onto a piece of wood, using two M8 studs and nuts, (fitted before removing the final two M8 Capscrews from the saddle. ) I was advised to do that by another poster on here.

If it is a "carry over", the pinion engaging with the Rack is integral with the shaft, and made out of low grade steel that bends easily.

My gear was a 1.5 Mod, 13T. (Making that revealed errors in the chart with my vertex HV6 Rotary Table! ) My replacement was made from BMS, Loctited, and pinned into a piece of 16mm Silver Steel. This repair required a bespoke brass spacer between the pinion and the Apron, to position the shaft, about 18mm long . The pin through the Gear and shaft, inside the Apron was 5mm dia. The 5mm rollpins in the drive to the Power Shaft and the Leadscrew were replaced by 5mm diameter brass, with a 2.5 mm hole drilled through, to weaken them, against the next time that I made the mistake.

(Actually, as part of the repair, I removed the first four teeth of the rack. The first two had never been used, and 3 and 4 were bruised in the crash.. The pinion now disengages just before the Saddle hits the Headstock. )

One other mod to the Apron was to put a nylon bung into the hole on the inner face of the Apron, to raise the oil level. This improves oil delivery to the gear.

A tip for anyone contemplating removing the Power Shaft for any reason, ensure that the key way is at the bottom, before withdrawing it from the worm, to prevent the key from falling out!

HTH

Howard

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