Washer bore sizes

[jwmay]

Huh. Well then I guess I meant grade 8 with 6 marks. I stand corrected.

 

[sdelivery]

Sae are meant to "fit better" use are meant to cover larger holes.
Machinery washers are generally the id of an sae and an od of a uss but much thicker

 

[Parlo]

Go for a screw with a captive washer. Close tolerance.

Thanks Woodchucker. I've found a company in the UK GWR fastners that sells washers with a threaded bore. They are perfect for aesthetics especially if you have spent months on creating an expensive precision asembly. Another bonus is they will really help with parts that are constantly taken apart. Their limitations are that they can't be used unless the thread is up to the head.
I've just found another company that sells plain washers with a nominal size bore which are ideal, Bil castors and wheels.
It doesn't look like I will find the answer to the original question though.

 

[Parlo]

I suspect that washers are made that way because that's the way they were always made. Originally, they were made by a blacksmith pinching the hole over a bolster. He probably gave the punch an extra blow to make sure that it the fit the bolt. Since he didn't like having to check and repunch, he probably gave punch an extra hard final blow. By the time the process became industrialized, a standard was set and that's what we have today.

If there are any questions, ask me about the roast.

Hi,

I took the opportunity to ask about the roast a few days ago, are you able to enlighten me?

 

[RJSakowski]

Hi,

I took the opportunity to ask about the roast a few days ago, are you able to enlighten me?

Sorry, I missed your question. The roast story has several versions and goes like this.

A little girl was watching her mother prepare dinner and asked her mother why she cut the ends off the roast before she put it in the roasting pan. Her mother replied, "Because my mother always cut the ends off. Go ask your grandmother." The little girl posed the same question to her grandmother and her grandmother replied, "Because my mother always cut the ends off. Go ask your great grandmother." The little girl posed the same question to her great grandmother and her great grandmother replied, "Because it was always too big to fit the roasting pan so I had to cut the ends of."

The moral of the story being that things being like they are often are because of traditional reasons that were valid at the time but have no valid reason in the context of our times.

I suspect that may have come to play in sizing washers. Washers have been around since antiquity, individually made to fit a particular need. At some point in the nineteenth century someone decided to industrialize the process and made a decision on the size of the stamping dies and a de facto standard evolved. Later, that, or a very similar, standard was codified.

I share your dismay concerning the sloppy fit of washers and often go one size smaller or just make my own to fit. This thread enlightened me to the fact that there are two classes of fit for washers, both inch and metric. We apparently get the looser fit washers at most retailers.

 

[vtcnc]

I just don't see the need for so much clearance, there must be a reason.

Cost.

A tight clearance, high concentricity washer is more expensive to make than say, a general purpose washer that’s purpose is not primarily concentricity but perhaps say clamping, clearance or locking for example that is not concerned with concentricity.

General purpose washers are made on high volume producing machines that drive unit cost down for global consumption, hence the lower hurdle of tolerance.

More basic information and external links to washer facts can be found in the Machinery Handbook or

Washer (hardware) - Wikipedia

en.m.wikipedia.org

Sent from my iPhone using Tapatalk

 

[Parlo]

Cost.

A tight clearance, high concentricity washer is more expensive to make than say, a general purpose washer that’s purpose is not primarily concentricity but perhaps say clamping, clearance or locking for example that is not concerned with concentricity.

General purpose washers are made on high volume producing machines that drive unit cost down for global consumption, hence the lower hurdle of tolerance.

More basic information and external links to washer facts can be found in the Machinery Handbook or

Washer (hardware) - Wikipedia

en.m.wikipedia.org

Sent from my iPhone using Tapatalk

I don't see how piercing a smaller hole is more expensive apart from there being less weight in the slugs for the scrap man.

 

[WobblyHand]

I don't see how piercing a smaller hole is more expensive apart from there being less weight in the slugs for the scrap man.

For extremely cost sensitive manufacturing, it wouldn't surprise me one bit that those slugs are returned to the manufacturer for credit. So larger holes mean less metal in the washer and they are cheaper, since the slugs are credited.

 

[vtcnc]

I don't see how piercing a smaller hole is more expensive apart from there being less weight in the slugs for the scrap man.

I'm referring to hole tolerance not the size of the hole. When punching off from strip, you have to worry about things like strip width, drift, twist, feed speed, punch speed, tonnage, etc. It isn't just about the size of the relative punch size that we need to consider here when determining cost.

Examples:

Precise punching requires close width tolerances so the web can pass through the die guides without drifting too much and not binding.
Loose tolerances require less setup time where as closer tolerances require more time.
Closer tolerances may require pulling more punches as the tool wears.
More tool changes either requires more sharpening, or more tools.
Don't want to sharpen as much? Get better tool steel = more money.
I could go on about oils for loose, fast punching vs. slower, precise punching.
Cleaning web oilers, rapid feeder settings, etc. require different levels of maintenance, changeover, operator training and settings.

In other words, different tolerances require different process parameters, even on the same machine.

For extremely cost sensitive manufacturing, it wouldn't surprise me one bit that those slugs are returned to the manufacturer for credit. So larger holes mean less metal in the washer and they are cheaper, since the slugs are credited.

This is absolutely true. If you get paid for scrap, and at the volumes you need to be profitable in the fastener world, you need to get paid for scrap or you are throwing profits away. To tie this to my assertion about cost. The amount of scrap you make depends on well your process is defined and how well you execute that process.

We have strayed off track, sorry to derail the conversation, but it is an interesting conversation because this not only applies to the humble washer, but to the most complicated assemblies you can imagine.

 

[whitmore]

I suspect that if bolts were technically able to be machined, then simple washers would also be made using machinery.

This suggests another reason that washers fit loosely; modern bolts are often rolled threads,
and have undersize shanks from 'nominal'; a washer that fits over the (near-full-nominal) diameter
of the threads is loose on the unthreaded portion near the bolt head.

So, it's a thread-forming, not a machining, process that makes the washers as loose as they are.