M8 nut sizes

Dave54 · Post by **Dave54** » Fri Nov 29, 2019 8:39 pm

I've just had an odd thing with some metric nuts here. I've got three lots of assorted metric nuts. Bought a couple of boxes from Lidl of offer, and then after using the common sizes (the problem with "sets") I bought a load from Screwfix, again in a set on offer.
So, I wanted some M8 nuts for "Z frame" reinforcement bars on a 3D printer. Printed out the parts, cleaned them up and was ready to go. . .
Except the M8 nuts wouldn't fit the recesses in the printed "finger nuts"
Checked the A/F of the hole. Just over 13mm, so that's fine. Tried a Nyloc I had, and that fitted fine.
So, it turns out that the 8mm nuts in the Lidl sets are about 13.5mm + A/F, seems a slightly loose fit on the thread as well.
Can't see any obvious thread or spanner size near that from a quick look.
I haven't really measured it all properly, as I wanted to finish with the printer.
Any ideas? Doesn't really matter, but I'm just interested to know what size these "odd" size ones are.

Chippo1 · Post by **Chippo1** » Sat Nov 30, 2019 9:08 am

The expected and conventional AF size of M8 nuts is 13mm under the EN standards. But this is not law and there are variations including what I have seen which is the use of an AF 12mm nut on many goods made in the Far East, the norm AF was calculated to give a good load bearing face to the nut and adequate strength. The move to 12mm AF is more than likely to reduce the material input and subsequent weight and cost when making and using huge numbers, cost engineering, on products and uses where loading is not critical to the performance of the nut.

You have slightly over size AF nuts , cheap and nasty I dare say with no obvious rating provided in the form of a KN stamped on the item 4.6 , 8.8 , 12.6 ect

Try an imperial spanner say 9/16 AF As used for 5/16 whitworth ( whitworth bolt head and nut AF sizes were bigger than the equivalent metric. US sizes are different again and my experience of some US products result in a plethora of nut AF dimensions.

So in conclusion , pays yer money and get what you get, there not wrong , but not to your specification!

Dave54 · Post by **Dave54** » Sat Nov 30, 2019 11:46 am

Thanks. Yes, I noticed there are no ratings on them. That figures. Still they're OK for the sort of non critical stuff they get used for by me.
I wouldn't use them on car suspension, although I'll bet there are plenty that have been used that way.
As you say it's close to 1/4" Whit spanner size.
I'll look into it a bit more.

Rorschach · Post by **Rorschach** » Sat Nov 30, 2019 12:13 pm

14mm is quite a common size for a high quality M8 nut as well.

Dave54 · Post by **Dave54** » Sat Nov 30, 2019 12:39 pm

Rorschach wrote: ↑Sat Nov 30, 2019 12:13 pm 14mm is quite a common size for a high quality M8 nut as well.

Thanks. Didn't know that. These seemed a bit slack on the thread though. Still it'd only a length of threaded rod, so it might not be that great itself.
I'll try them on some decent bolts.

Bob225 · Post by **Bob225** » Sat Nov 30, 2019 1:38 pm

Ah a fellow 3d printer owner, is it an ender or prusa printer ? What material did you print the parts from ? ABS ?, if so where did you get your filament from ? Some filaments can shrink by up to 8% i tend to use Colour Fabb yes its more expensive but its very good quality

Is the Kit from china ? it has been known that they use imperial size or that Yanky imperial (4-40 etc,)

dewaltdisney · Post by **dewaltdisney** » Sat Nov 30, 2019 2:10 pm

I wondered if they were Chinese in origin as I had a field mower (Chinese origin) and nuts and bolts were so soft they kept shearing. I replaced the lot with some decent replacements but I did notice that there was an array of spanners needed to get the remaining ones off. I had some screws also that the heads snapped off even by hand driving them.

DWD

Chippo1 · Post by **Chippo1** » Sat Nov 30, 2019 5:28 pm

Standard M8 are 8.8:high tensile

Socket head M8 are usually 12.6 ultra high tensile

Lowest normal stuff was know years ago as “farmers pattern” or wrought iron nuts and bolts , soft as cheese now these are rated at 4.6, suspect some of this cheap stuff is that or lower KN rating

14mm is odd size to and not the norm for 12.5kn stuff, we are just going down the tube of do what u like ignore standards

Dave54 · Post by **Dave54** » Sat Nov 30, 2019 6:32 pm

Bob225 wrote: ↑Sat Nov 30, 2019 1:38 pm Ah a fellow 3d printer owner, is it an ender or prusa printer ? What material did you print the parts from ? ABS ?, if so where did you get your filament from ? Some filaments can shrink by up to 8% i tend to use Colour Fabb yes its more expensive but its very good quality
Is the Kit from china ? it has been known that they use imperial size or that Yanky imperial (4-40 etc,)

Only had it a couple of weeks. Steep-ish learning curve.
Printer's a Balco 3D Touch from Aldi. Fairly good reviews. It's apparently more or less the same as a Wanhao i3 Plus.
I've been printing PLA from this supplier.
https://bit.ly/37OP6Fs
Good results so far. Only one minor jam after a problem with a print, it appears to print about right dimensionally. Good price too. The brackets for the reinforcement that's the subject here fitted first time after minimal clean up. The four 3 mm allen pins holes for the top brackets were spot on, as were the hexagon recesses for the nuts. Pity the first lot of nuts didn't fit!

All great fun, but time consuming.
To be fair the machine worked pretty well "out of the box" once assembled.

Dave54 · Post by **Dave54** » Sat Nov 30, 2019 6:39 pm

No doubt about it that standards seem to be going by the board. A lot of this Far Eastern stuff is OK if they keep the quality control tight, and perhaps with a bit of fettling.
A good bit of it's less than perfect though.
To be fair these nuts and bolts have been used for non critical stuff around here, and have been fine. Same with the use on the printer. The nuts aren't rated, but they don't need to be for this application.

Bob225 · Post by **Bob225** » Sun Dec 01, 2019 1:29 pm

They have come down in price My i3 Prusa was nearly £500 back in 2014/5, mine was a very steep learning curve so was my 2nd machine then i saved up and purchased an Ultimaker 2+ thanks to the euro have gone up in price by around £800 !!

Here's a few links

https://shop.3dfilaprint.com/

https://www.dream3d.co.uk/

https://ooznest.co.uk a small business with very good customer service one of the few openbuilds suppliers in the UK

https://openbuilds.com/ Very good forum

https://ultimaker.com/software/ultimaker-cura Cura one of the best print programs

https://www.thingiverse.com/ says it all

https://www.ebay.co.uk/str/Kays-Fasteners I have used them for years very good quality for the money

If your going to print ABS (heated bed is a must) Look at getting some BuiltTak it works much better than Pritt stick

I have just finished a project - 1:14 sidewinder missile for a UK YouTuber as well as another batch of shopping trolley Keys

I hope this is of some use

Dave54 · Post by **Dave54** » Sun Dec 01, 2019 2:18 pm

Cheers Bob. I'll have a look at those links. Useful.
I'm using Cura, and Thingiverse.
That's where the stabiliser kit came from. Working very well too. Printing as I type. Got rid of the wobble.
Both the Prusa, and the Ultimaker look excellent machines. (Already looked at them.

)

I only really got this one out of interest. I can see the potential though. See how this one goes.

Bob225 · Post by **Bob225** » Sun Dec 01, 2019 4:15 pm

I do my own designs in Fusion360 what's free for hobby use, it outputs to stl files or a program like Cura or Meshmixer, Meshmixer is worth a play with especially for adding supports and morphing objects

You may have seen some of my renders on the forum

Just another gauge pod/mount

: yaris_pod1.png (68.94 KiB) Viewed 3968 times

3D print (please excuse the bad pic)

: pod print.JPG (36.14 KiB) Viewed 3965 times

Dave54 · Post by **Dave54** » Sun Dec 01, 2019 7:07 pm

Nice work.
I've been learning Freecad. That's quite a steep learning curve as well though. I like to use open source software where possible.
I might well have a look at DesignSpark from RS though. It looks quite good.
I'll have a look at Meshmixer. Thanks
It all takes time though.