Is Knurling a health hazard?

[Mike PooleParticipant @mikepoole82104]

I note that Knurling on items like gym equipment is regarded as a hygiene risk due to skin deposits left in the knurl harbouring bacteria. It maybe worth giving our knurled items a clean now and again. Probably a minimal risk but we often have cuts and scratches on our hands which could provide an easy entry for anything growing in our Knurling. As we are usually the sole user of our tools cross contamination is unlikely but it might save ourselves from something nasty to clean Knurling now and again.

Mike

[Mike PooleParticipant @mikepoole82104]

[MWParticipant @mw27036]

Personally I've never really been bothered by it but I can see the logic in it, not only that but it just doesn't look very nice to make something and the knurl has already picked up a lot of dirt.

I'd just use a wire brush, or acetone is supposed to be very effective at removing grease, Then I've heard about people who lacquer metal which has a knurl.

Michael W

[HOWARDTParticipant @howardt]

I used to design production jigs and fixtures for high volume parts and stopped using knurled many years ago. It is a health hazard if used every few seconds during an eight hour shift as it will wear into the skin. But for odd use in the model shop I wouldn't worry.

[Neil WyattModerator @neilwyatt]

I fear that we will end up living in a totally sanitised world, until one year the whole human race will die because of our under-exercised immune systems.

More than one study has found children growing up on farms suffer fewer infections.

Neil

[Anonymous]

Posted by Neil Wyatt on 15/05/2017 22:34:54:

I fear that we will end up living in a totally sanitised world, until one year the whole human race will die because of our under-exercised immune systems.

More than one study has found children growing up on farms suffer fewer infections.

Neil

Exactly, . Couldn't agree more

[MWParticipant @mw27036]

In theory we already have a gigantic bacterial colony living within all our innards, so anyone who claims to be totally clean is a hypocrite. Our digestion actually relies on this happening in order to bolster the immune system.

Not only that but growing up on a farm would probably be a lot of fun for most kids, so they'd be more likely to feel well even on a bad day. 

 

 

Edited By Michael-w on 15/05/2017 23:14:52

[Mike PooleParticipant @mikepoole82104]

It was a jig fitter that mentioned to me that Knurling is regarded as a hazard but a quick google only came up with the gym reference. What reminded me was I bought a used nippy vice and the knurl was pretty skanky so I skimmed it and re knurled. My mum always says we all eat a bit of dirt before we die, I think we do clean too much and we seem to be breeding a generation who have endless allergies to almost anything, something is going wrong somewhere. I rarely dress minor cuts and abrasions in the workshop and never wear gloves, the only time I use a plaster is to stop the workshop looking like an abbatoir if something won't stop bleeding. Seems to have worked for the last 50 years!

Mike

[thaiguzziParticipant @thaiguzzi]

Posted by Mick Berrisford on 15/05/2017 23:03:45:

Posted by Neil Wyatt on 15/05/2017 22:34:54:

I fear that we will end up living in a totally sanitised world, until one year the whole human race will die because of our under-exercised immune systems.

More than one study has found children growing up on farms suffer fewer infections.

Neil

Exactly, . Couldn't agree more

+2.

[Danny M2ZParticipant @dannym2z]

I was chopping up some chicken breasts for the wok when my friend's 16yo daughter admonished me for using the same knife to chop the carrots, onions, broccoli and snow-peas that were going into the same wok after the chicken had browned.

I was advised all about 'Cross Contamination' which was taught to her at school.

I felt quite sad that her school had not taught simple logic and 'raison de etre' behind this advice.

Imagine the horror when I shot a deer and offered 'Bambi' steaks to the Saturday BBQ.

When the fresh trout started to appear on the menu my friend's daughter finally realised that there are other sources of food than the supermarket and so we caught a few fish.

The sweet girl now has no compunctions about about shooting a rabbit or catching a trout.

* Danny M *

[Tony Pratt 1Participant @tonypratt1]

Seriously guys, have we not got something better to do?

Tony

[Peter KroghParticipant @peterkrogh76576]

Posted by Tony Pratt 1 on 16/05/2017 07:18:52:

Seriously guys, have we not got something better to do?

Tony

What? You're on the clock or something? We're just jawin' away here, passin' the time. I've nothing else to do right now, so …….

Pete

[JasonBModerator @jasonb]

Mike, best clean the end of all your files while you are at it, (not the handle end)

[Mike PooleParticipant @mikepoole82104]

Although Knurling has the ability to collect skin and bacteria I wonder if anyone has ever actually caught anything from one. It is scary the number of times I have seen people leave one of the traps in a washroom and walk straight out the door, I wouldn't want to be sharing a knurl with him, especially as I am a nail biter.

Mike

[JohnFParticipant @johnf59703]

Gee gents always remember you have to "eat you peck of muck" each day just to keep the bodies defence mechanism on its toes !!
Lots of truth in the old sayings !

[HopperParticipant @hopper]

I'd be really really really surprised if someone has actually caught a disease from handling a knurled surface. We worry about all the wrong stuff.

One recent study found that the most germ-ridden surface in most of our lives is the handle of the petrol pump at the service station. Touched by hundreds of people a day and never cleaned, then you come along and hold it for minutes solid while filling up.

[HopperParticipant @hopper]

Posted by Michael-w on 15/05/2017 23:11:32:

In theory we already have a gigantic bacterial colony living within all our innards, so anyone who claims to be totally clean is a hypocrite. Our digestion actually relies on this happening in order to bolster the immune system.

No theory about it. Several kilograms of bacteria inhabit the average human gut. In fact, the number of cells of bacteria in the average human gut outnumbers the number of cells in the human body. So in reality, the bacteria is the dominant lifeform. The body is just there to carry it around. (And to drink beer.)

[HOWARDTParticipant @howardt]

Its alright to make light of the question but when someone suffers from skin problems, dermatitis, then it is no laughing matter. I am sure those people would prefer the designer to give some thought to handling rather than ignore the potential health problems. I agree we all have to eat some dirt,I do on a regular basis, and have knurled fittings in my workshop. But I was answering for the full time work place, were handling is for thirty five hours or more a week not the odd minute a month.

[HopperParticipant @hopper]

Howard, definitely knurling is not a good idea on a production jig handled constantly for an 8 hour shift. Like rubbing a file on your hands all day long, to be sure. We used to use that Plastidip stuff on the QA clamps on car body spot weld jigs etc that operators were doing up and undoing all day long.

I think though if a person has dermatitis they might be best to wear cotton gloves when handling gym equipment. What is the alternative? Slippery bars on 100kg weights while bench pressing and someone loses their grip?

[Anonymous]

You can't catch Dermatitis, Psoriasis etc, from another person. It's either genetic or from various irritants and allergens .

If you suffer from similar then you make your own choices to minimise the risks be it barrier creams, gloves etc, skin/bacteria from a knurled surface isn't going to affect it, though other irritants things like oil might. It's all common sense, I get a particularly nasty type of Psoriasis. I know what I can and can't do and how to do it, I don't need 'elf and safety to tell me what I can and can't touch,.

[MuzzerParticipant @muzzer]

When you wash your hands you turn the tap on with your dirty hands, wash them and then….turn off the dirty tap with your clean hands. What do you conclude from that? Then of course, you leave the room by grabbing the dirty handle on the way out.

"Washing" hands is simply a process of dilution, not cleansing. The closer you are to places of contamination, the filthier(?) they are. Luckily our bodies are used to dealing with sensible concentrations of bugs.

As for knurls, unless they are poorly made ie have swarf and splinters hanging off them, what is the worst that will happen? The ingrained "dirt" is just grease and muck unless you work in an abattoir or sewerage works. The risk from long term ingestion of grease and oil is not from bugs but from the impurities in the petroleum derived oil and grease itself. This seems to increase the risk of developing cancers of the digestive system, bowels, lower gut and the neighbouring external bits like your ball bag and ring piece – particularly if you are handling used engine oil which has higher concentrations of nasties like pyrobenzene. These originate in the petrol and become dissolved in the engine oil. So burning (reclaiming??) used engine oil in furnaces, heaters and engines is really not recommended.

Murray

[Steven VineParticipant @stevenvine79904]

Forget the knurls. What about the handles on supermarket shopping trolleys. Ugh, I can't bear thinking about it. Think about it next time you go (and take a rag)!

Steve

[MWParticipant @mw27036]

I mean, hygiene is important it's saved an awful lot of people but it shouldn't rule your life. Just a little bit of common sense attitude towards it and you're fine. no need to do anything else.

I worked in a factory where my hands used to get a bit sore and they had this special green tape you can put round your fingers and it sticks to itself but it's not really tacky to anything else. To make a kind of "make-shift cast" around your finger.

I would say most employers would do something about it if you found some sort of repetitive action on the shop floor was giving you gripe, they just aren't always aware of it. 

I'd like to see the man who could lift a 100kg weight by himself that would be enough to do the back in of most people, outside Arnold Schwarzenegger territory! 

Michael W

Edited By Michael-w on 16/05/2017 15:33:19

[Fowlers FuryParticipant @fowlersfury]

Too true about supermarket trolley handles : – [

We could continue this ad nauseam (literally) but consider if you can public toilets for some perspective. We usually need to touch a contaminated handle to enter. But how many men then wash their hands before releasing the one-eyed trouser snake? Business over and hands washed but now with hot air dryers, residues & viruses are circulated with force for all to inhale. To exit the place we now have to touch the inside door handle which has been grasped by ……and so on.

The human race would have died out millenia ago if we couldn't tolerate some pathogens on our skin.

But consolation is at "hand" for model engineers thanks to the oligodynamic action of metals. Herewith one quote from the Abstract Zentralbl Bakteriol Mikrobiol Hyg B. 1985 Dec;182(1):95-101.

"The oligodynamic action of the pure metals aluminium, antimony, bismuth, cadmium, cobalt, copper, gold, iron, lead, manganese, mercury, nickel, platinum, silver, tin, titanium, and zinc on Bacillus subtilis (1 strain), Enterobacteriaceae (26 strains), Legionellaceae (13 strains), Micrococcaceae (6 strains), and Pseudomonas aeruginosa (4 strains) was investigated using an agar diffusion test. B. subtilis and Legionellaceae exhibited the highest susceptibility. The apathogenic micrococci and staphylococci were more susceptible to oligodynamic action of some metals than S. aureus. The group of gram negative rods was the most resistant."

Another publication offers "Many infections can be spread by doorknobs. Brass doorknobs disinfect themselves in about eight hours, while stainless steel and aluminium knobs never do. Unvarnished brass doorknobs therefore tend to be more sanitary than stainless or aluminium doorknobs. The effect is important in hospitals, and useful in any building.[3]"

Only brass & copper then for knurled handles ?

[Brian GParticipant @briang]

Posted by Fowlers Fury on 16/05/2017 16:12:08:

…

Only brass & copper then for knurled handles ?

Silver has even better anti-microbial properties. Judging from how it turns (I used to prepare electrodes for a quantometer) I think it would take a lovely knurl as well

Brian

Edited By Brian G on 16/05/2017 17:27:01

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