Cure for Tight Nuts

[JasonBModerator @jasonb]

When there is a need to he does clock them in it is often to 0.01 to 0.02mm, he does not work in inches

[Craig BrownParticipant @craigbrown60096]

Jason, that should say he does not work in bananas

[JasonBModerator @jasonb]

Well not unless he is using that special calliper

[not done it yetParticipant @notdoneityet]

It would be the $20K (note upper case ‘k&rsquo ridiculous price tag placed on that rod in the video hype.- unless it is to some aeronautical standard – that would put me off bothering to watch that. Even so, if it needed ‘saving’, would it still be to the prescribed acceptable standard?

[BazParticipant @baz89810]

I have some reservations about turning all the thread off and presumably screwcutting a smaller diameter thread. The original thread was made that diameter for a reason, is it safe to reduce the diameter?

[Ches Green UKParticipant @chesgreenuk]

Aren't the prices he is quoting in Australian Dollars? ie 1A$ = £0.52 = US$0.67

Ches

[Nigel McBurney 1Participant @nigelmcburney1]

A couple of useful tips I liked was shielding the steady jaws with tape to keep that very hard swarf away from the bearing surfaces,and checking the thread cutting pitch set up with a felt tip pen,

[SillyOldDufferModerator @sillyoldduffer]

Posted by not done it yet on 26/06/2023 08:50:34:

It would be the $20K (note upper case ‘k&rsquo ridiculous price tag placed on that rod in the video hype.- unless it is to some aeronautical standard – that would put me off bothering to watch that. Even so, if it needed ‘saving’, would it still be to the prescribed acceptable standard?

I often think Model Engineers should be sent on a Management Accountancy course to learn it's about value rather than price. Value is is some combination of cost, benefit, and time. Price is obviously important, but it's far from being the only factor.

Whilst price dominates decision making In ordinary life, and many small businesses are successfully run the same way, there's a point at which other considerations come into play. A relative encountered this painfully: he ran a small-business, which he enjoyed thoroughly leading from the front, him and a couple of mates. After the business grew to employ about 15 people, he hated it! Rather than doing the practical work he enjoyed, he found himself managing people, money and assets, all of which were much harder to do than he'd imagined, plus lots of responsibility, and all the aggro. Tragic, but in a business beyond a certain point, the need to manage people, money and assets mean the financial game is often played to different rules. What's worth the money, has to take more than price into account.

In that context, I spent £427 last week buying not very much metal. (Anyone who hasn't bought Brass recently is in for a shock!) Not a sound business decision, but I enjoy Model Engineering, and the metal will keep me amused for at least a year, I hope! Not everyone would have made the same purchase.

Back to mending earth movers, part of the cost of a repair is off-set by the cost of downtime. Machines that work of a living out of action for a few months whilst parts are shipped from the US or Japan cost a fortune, making local repair an option even if repair costs more than a new part. Time is money. Judging by the videos, it appears repairs are about half replacement price, and the work is done quickly compared with importing from abroad. $20000 dollars Australian is a mere £10000.

I've learned a good deal about Hydraulic rams from the videos. They're a mix of high and low-tech. Outside the cylinder, simple and chunky parts are highly stressed with cheap bits designed to break before anything more expensive. Bearings, pins, eyes and end parts all take a hammering, either broken off, bent or badly worn. There's much scope for repairing the chunky parts with a big lathe, big milling machine, big hydraulic press, and lots of skilled welding. Inside the cylinder, the piston and seals aren't too difficult, but the aforementioned damage can make it very difficult to get inside. Changing worn out piston seals – easy on a bench – might start by chopping the ends off to gain access and then welding the whole lot back together again.

Hydraulic cylinders and rods aren't made of ordinary mild-steel. Cylinder steel arrives pre-bored, skived and honed to size. Piston rod is delivered accurately ground to outside diameter. Both are induction hardened up to a depth of about 10mm. Not cheap.

If they have to be replaced, they're machined as necessary to fit the end-parts. Getting through the induction hardening is fun, and after machining the end-parts are then welded on. Not seen a video where either a critically damaged rod or internal cylinder surface is repaired. I guess that's too difficult.

The most accurate work seems to be making pistons. They're turned to a diameter, I guess about 0.05mm, but then grooved to take the O-rings and other seals. The grooves are cut micrometer accurately. Some of the milling is accurate, but much isn't, 0.05mm rather than 0.01mm.

I'm not sure what the 'prescribed standard' is. The parts being mended are treated very roughly and aren't safety critical. I think the only requirement is that repairs last long enough to cover the cost of doing it, plus a margin.

I recommend watching the videos.

Dave

[Nicholas FarrParticipant @nicholasfarr14254]

Posted by Baz on 26/06/2023 09:14:24:

I have some reservations about turning all the thread off and presumably screwcutting a smaller diameter thread. The original thread was made that diameter for a reason, is it safe to reduce the diameter?

Hi Baz, I'll doubt it will make any real significant difference, and in any case they are normally used in a way that the heaviest loading won't be put onto the nut.

Regards Nick.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I also like the idea of checking the thread pitch has been set correctly with a pen.

Regards Nick.

[JellyParticipant @jelly]

Posted by Baz on 26/06/2023 09:14:24:

I have some reservations about turning all the thread off and presumably screwcutting a smaller diameter thread. The original thread was made that diameter for a reason, is it safe to reduce the diameter?

As a craft-trained engineering technician with 20 years experience working on that kind of heavy plant, a strong relationship with various OEM's and OEM dealers (to the point of re-manufacturing parts for OEM's prior to delivery to the customer, when machines arrive in Australia with damage from transit) and consent from the owner of a multi-million pound quarrying excavator…

I think it's probably reasonable to assume that his decision is rooted in sound engineering practice.

If the rod was designed so close to the yield strength that going from 128mm to 125mm on such a long and large thread would be problematic, then I'd say the OEM's design was negligent to begin with 

Edited By Jelly on 26/06/2023 14:51:42

[JellyParticipant @jelly]

Posted by not done it yet on 26/06/2023 08:50:34:

It would be the $20K (note upper case ‘k&rsquo ridiculous price tag placed on that rod in the video hype.- unless it is to some aeronautical standard – that would put me off bothering to watch that. Even so, if it needed ‘saving’, would it still be to the prescribed acceptable standard?

I assume you haven't had to buy spare parts for any large plant equipment recently… The combination of OEM markup (because service is how they make a lot of their money), with logistics costs layered on top if you're not in N. America or W. Europe is a big part of what makes remanufacturing and third-party manufacturing a viable enterprise.

That said, the price of an equivalent piece of steel stock to make the rod would be £15 per 25mm (from M-Machine) so even before the hard-chrome, induction hardening, and grinding which could double to treble the price, a 3m long rod is in the region of £1800 (3500 AUD), so even making a replacement rod would start at $7k-$10.5k australian before machining and welding.

 

This is before accounting for the fact that you might be losing $2k-$4k per day in depreciation alone every day the machine is stood idle, plus the loss of production and/or short term hire-cost which could easily reach tens of thousands of dollars…

Edited By Jelly on 26/06/2023 14:57:53

[Grindstone CowboyParticipant @grindstonecowboy]

The UK equivalent of Kurtis would be the chap at Snowball Engineering – just been watching a video of him making a line-borer for repairing some agricultural equipment.

Rob

[JasonBModerator @jasonb]

Part Two, the new nut

[Simon BarrParticipant @simonbarr48213]

CEE are is definitely my favourite engineering channel on YouTube. I've been watching his stuff for a while now and look forward to new videos each week. The type of work he gets and the machinery he has are things I can only dream of. Despite the huge scale of what he does in relation to things I do I'm sure I've picked up useful knowledge. His use of steadies has shown me how it should be done, not that I've needed to use one yet. I'm self taught and very much still learning to walk the walk. Hugely entertaining stuff.

I can't wait until he starts working on the Huron.

Simon

[Ches Green UKParticipant @chesgreenuk]

Part Two, the new nut

As always, very good stuff from CEE.

The filming and editing gets better and better with each video.

The camera person (Karen) is always looking for new ways to keep the viewer's interest, plus keeping the older stand-bys eg looking down the bore.

I wonder how close she gets to the action?… but I don't see Kurtis letting her endanger herself. It would be interesting to see a 'How we make these videos' from the CEE team.

Ches

 

Edited By Ches Green UK on 30/06/2023 13:09:13

Edited By Ches Green UK on 30/06/2023 13:10:02

[Grindstone CowboyParticipant @grindstonecowboy]

Close enough to suffer from hot chips in an outtake I saw the other day

Rob

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