I bought some SS screws from ebay. I think I have been sent the wrong one, but not sure. The invoice says: No.10 x 5/8" (4.8mm x 16mm). The outer thread diameter of the screw measures 3.92mm. Can anyone tell me if this is the wrong size? I wanted 4.8mm diameter, or there abouts.
Non-metric screw size
- Thread starter DiyNutJob
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Probably a No 8 screw instead. What are you using to measure it? 3.92 is within about 7% of 4.2 so probably within manufacturing standards, I can't imagine the tolerances are very good for S/S crap bought off ebay.
I have a cheap ebay class caliper running with ebay battery. It works well. So, don't be a snob! Ebay was terrible at the beginning stages, and now much better. Hence I am buying more and more from them. Their refund process is also very good. So, I will be getting these screws for free. The seller won't bother replacing because of the costs.
The seller do sell 4.2 and 4.8 screws. The bag for the screws isn't marked. So they have definitely made a mistake. You want good tolerances for wood screws? You mad.
The seller do sell 4.2 and 4.8 screws. The bag for the screws isn't marked. So they have definitely made a mistake. You want good tolerances for wood screws? You mad.
Haha, a cheap caliper off ebay, how would you know it woks well, perhaps you checked it's accuracy with a Parkside caliper? I too have a cheap caliper off ebay, it also works well but I suspect it's not very acurate, why would it be, it's cheap and off ebay. But then ebay is so good you tried to buy 4.8mm screws but they sent you 3.9mm!
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Nothing wrong with 3.9 if they are free. How do you know I don't need 4.2/3.9 in the future? This will save me some money and time down the line. You really are mad if you can't see a good deal when it slaps you on the forehead.
Wow you saved a whole few pounds, but you still don't have the screws you originally wanted do you?
I saved 2 weeks in the future, plus a 100% guarantee I get the right screws when I need them. The 4.8 screws are not time critical currently. I am OK up to end of JAN. I would have bought them from china if the delivery times are more predictable. They are 15 days to 3 months currently and outside of my tolerance.
The seller confirmed they would send me the right ones ASAP and I keep the wrong ones. See? Ebay is not so bad. They learnt a thing or two from china. Back in the days, I felt like I was about to get mugged every time I bought from them.
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That's definitely a 4.0mm metric screw, not a no8 screw. No8 screws, nominally 4.17mm, would usually measure around 4.08 to 4.12mm.
A number 7 screw would measure even less than your 3.92.
My experience of actual screw sizes is that they are all over the place. I am OK if wood screw sizes are not extremely out of spec by 0.5mm or more.
D
Deleted member 174758
Maybe if you bought better quality screws you'd find that when you bought a 4mm screw, that would be what you'd get. As to screws being 0.5mm out being OK - sorry, but if you pilot for a 4.0mm in hardwood then find your 4.0mm screws are in fact only 3.5mm in diameter, you'd be screwed - or rather your items wouldn't be...
Screw too small, use a bigger one, or, even use a nylon plug. Simples. I suspect you have never measured the "top quality" screws you bought, or you would know they are all over the place.Maybe if you bought better quality screws you'd find that when you bought a 4mm screw, that would be what you'd get. As to screws being 0.5mm out being OK - sorry, but if you pilot for a 4.0mm in hardwood then find your 4.0mm screws are in fact only 3.5mm in diameter, you'd be screwed - or rather your items wouldn't be...
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How many screws do you buy?
how expensive are a few good quality ones ?
It's very easy to spend a lot of money ( and time) to save a little
how expensive are a few good quality ones ?
It's very easy to spend a lot of money ( and time) to save a little
In a DIY setting, the screw size needed is unknown in advance. So, variety is king. Cheap makes variety possible. I am pretty sure all the screws I have are stated as "top quality" on the box or in the product listing.
Just for the giggles
A 100 pack of Turbodrive 4 x 40mm screws.
Random sample of 20 screws.
Measured with an uncalibrated digital caliper.
Length
Mean = 39.343mm
Standard deviation = 0.1863
With a 99.9% confidence level, the screw length will be between 39.149mm and 39.537mm
A tolerance of around ±0.5%
Shaft Diameter
Mean = 3.888mm
Standard deviation = 0.0365
With a 99.9% confidence level, the srew shaft diameter will be between 3.8501mm and 3.9259mm
A tolerance of around ±1%
A 100 pack of Turbodrive 4 x 40mm screws.
Random sample of 20 screws.
Measured with an uncalibrated digital caliper.
Length
Mean = 39.343mm
Standard deviation = 0.1863
With a 99.9% confidence level, the screw length will be between 39.149mm and 39.537mm
A tolerance of around ±0.5%
Shaft Diameter
Mean = 3.888mm
Standard deviation = 0.0365
With a 99.9% confidence level, the srew shaft diameter will be between 3.8501mm and 3.9259mm
A tolerance of around ±1%
Last edited:
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