Comments on: Understanding Metric Bolt and Screw Grades (and Head Markings) /understanding-metric-bolt-and-screw-grades-head-markings/ Quality Bolts, Screws, & Studs Thu, 04 Sep 2025 14:56:33 +0000 hourly 1 https://wordpress.org/?v=6.9.4 By: Frank Rizzo /understanding-metric-bolt-and-screw-grades-head-markings/#comment-7175 Fri, 09 Feb 2024 00:40:48 +0000 /?p=348#comment-7175 In reply to Richard.

What? 0.8 mm is not about 20 tpi, not at all. 20 tpi is 1.27 mm pitch, which yes, is very close to regular M8x1.25

]]> By: Joe Pinchback /understanding-metric-bolt-and-screw-grades-head-markings/#comment-7022 Mon, 29 Jan 2024 21:23:51 +0000 /?p=348#comment-7022 In reply to Patrick.

Patrick, check out this blog post. It has definitions for many of the terms we use: /guide-to-fastener-terminology/

]]> By: Patrick /understanding-metric-bolt-and-screw-grades-head-markings/#comment-6986 Sat, 27 Jan 2024 20:58:53 +0000 /?p=348#comment-6986 Very well-presented information. Easy to follow and understand. One addition that would make this perfect is a short list of definitions of some of the more technical terms used, just so it isn’t necessary to go look them up elsewhere. Otherwise, nicely done.

]]> By: Patrick /understanding-metric-bolt-and-screw-grades-head-markings/#comment-5097 Thu, 07 Sep 2023 08:46:43 +0000 /?p=348#comment-5097 In reply to Paul Mathews.

I have one of these bolts with the marking 8.8 W G. My socket wrench set only goes up to 14mm what size do I need to unfasten this screw/bolt?
It’s part of my walker the wheel section.

]]> By: Paul Mathews /understanding-metric-bolt-and-screw-grades-head-markings/#comment-3209 Wed, 08 Mar 2023 20:43:11 +0000 /?p=348#comment-3209 In reply to Alexander Iliev.

12 approximately 44% stronger than 10 mm

]]> By: Jason /understanding-metric-bolt-and-screw-grades-head-markings/#comment-2599 Sun, 22 Jan 2023 15:30:12 +0000 /?p=348#comment-2599 I have a bolt, M14x1.5, that only has the following markings on the head: “DS” with the number “9” underneath. How do I tell what grade this is? It came from a piece of Korean equipment.

]]> By: Mehmet /understanding-metric-bolt-and-screw-grades-head-markings/#comment-2057 Mon, 28 Nov 2022 14:40:27 +0000 /?p=348#comment-2057 Hello,
What is the font of marking? Times new roman, arial or another fonts are okey?

thx.

]]> By: Jack /understanding-metric-bolt-and-screw-grades-head-markings/#comment-1081 Sat, 13 Aug 2022 22:37:51 +0000 /?p=348#comment-1081 In reply to Carl P Padowitz.

Mahle head bolts for Mazda Miata 1.8 L are marked VRG and 72.9. What does this mean? Are these TTY bolts? They do not appear to have the typical reduced cross section, so I need to know.

]]> By: Richard /understanding-metric-bolt-and-screw-grades-head-markings/#comment-487 Mon, 15 Nov 2021 21:57:06 +0000 /?p=348#comment-487 Funny. I was trying to match a bolt to a shackle; 5/16″ or 8 mm, neither wanted to start. I measured the pitch with an old inch gauge and got around 20 tpi which is a bit finer than the 18 tpi of 5/16 nc, and pretty well matched the 8 mm thread. Then I looked at the heads of several 8 mm bolts and they all said 8.8. I thought it must mean 8 mm and .8 mm pitch – about 20 tpi. Good thing I came here to understand what it really means.

]]> By: Joe Pinchback /understanding-metric-bolt-and-screw-grades-head-markings/#comment-453 Fri, 01 Oct 2021 18:02:59 +0000 /?p=348#comment-453 In reply to Alexander Iliev.

Sorry, can you clarify what you mean by Load Weight?

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