As a rule of thumb, the pilot hole diameter needs to be half the diameter of the coach screw when using softwood and three quarters when using hardwood. Nice one Robin, I’ll add it to the article when I get a mo. Someone suggested that I cut the head of a M4 40mm and then use an electrical ferrule and connect the headless M4 40mm to a M4 100mm by crimping the two screws together inside a ferrule. Many Thanks! Don’t worry too much about hitting mortar, obviously if it’s three out of four holes maybe! Cheers Most coach screws are made from steel and are offered in a number of different finishes: The most common type of fastener, a hex head bolt is designed to be tightened with a standard spanner or ratchet and socket. because each type of wood and each type of screw behaves differently. And What drill bit size? You mention the wall is concrete, just concrete? or +47 91754808, Made with the ever marvellous WordPress running the X theme, tweaked by Ian. Hi Alex, - ASME B18.5-1990 does not specify dimensions for the #8 or #12 diameters. Popularly used in all assemblies, a standard hex bolt is a staple across the world. Well, I had an apprentice once who was a bit of an ‘eejit’ and used to drop screw boxes on a regular basis! Hey Ken, Metric Stud Bolt To Nut Size Chart. Thanks for getting in touch. Thanks, Chris. Metric screws are simply measured and the thickness is given in millimeters. click… Metric wood screws explained Metric screw sizes provide a diameter and length in mm. Depends on so many things! It shouldn’t be too tight a fit at the neck of the plug, as it will get tight once you get further in. What is the job and your thinking behind drilling a 5mm hole (instead of a 6mm)? A Number 10 Screw seems to have a 5.0mm thread but a 3.5mm shank? Take the bolts with you to the store and check the diameter of the bolt’s shaft to the inside diameter of the plug. This will also make it easier to remove the screw at any point. Don’t worry about the length of the brown plugs, just tap them deep into the hole until there is only 40mm (or equal to the length of the plug) of the screw/ bolt sticking out. Then the holding point is down at the bottom of the hole. I agree that metal expanding bolts could be too much for the brickwork in this case. if you’ve got a 50mm long plugs and 75mm long screws you want to push the plug into the wall 20mm or so. Is there a tip on drilling into plaster walls? Drill holes very slowly and carefully (SDS etc)and blow out the dust (seems worse on vertical holes as the bit doesn’t clear as well as horizontal holes). . Hi Bernard, If the screw starts to get too tight, then it’s advisable to back out and re-drill a larger pilot hole rather than risk breaking a screw (you’ll be having a very bad day if you snap a screw…..). a 4mm head is approximately a 4g screw though…. Been without internet in Croatia for ages and have been travelling back. To ensure that any heavy object that will be fixed to the wall is secure, it is essential to use a wall plug with the coach screw. You’re going to struggle to get a red rawlpug into a 5mm hole, although we used to get them into 5,5mm holes when using small gauge screws. This means that should you ask for a 1/2-inch x 12 x 4-inch Grade 2 Hex Bolt Head with a 1-inch thread, the request is universally understood by bolt manufacturers. To be sure, put one over a tape measure and take a pic and send it to me and I’ll know for sure. Ian. Read up a little more here…, Re the star drive, I’m not sure what you’re asking! Imperial screw sizes provide a gauge size and a length in inches. They could only tell me that the head diameter is 4mm and the length is 20mm. Am I right that if I drill a 6mm hole into a brick wall, use a red plug and then an 8g screw 2 and a half inches long I have got the right idea? Blue wall plugs are another example, they can be either 8mm or 10mm, go figure! Credit subject to status, UK residents only, Toolstation Ltd, acts as a broker and offers finance from a restricted range of finance providers, PayPal Credit is a trading name of PayPal (Europe) S.à.r.l … I am not really sure if the wall is pure solid concrete, most probably bricks under and cement plaster on the surface. The diameter refers to the major diameter, or outside edge, of the threads. Helen. To stop the coach screw from becoming stuck in wood, rub the threaded shaft with hand soap. I have 10mm lag screws that I need to fit into a 15mm render and 100mm concrete block wall. Manufactured to ISO 4014 or DIN 931, and therefore includes an unthreaded section of the shaft. The holes for the drill bits are all labelled (metric: mm). Wanting to try drilling into masonry (indoors) & bit wary but willing to give it a try. I talked about this a lot on another post, here’s the link: How to Properly Use Wall Plugs. Unless you buy them as a ‘kit’ (like a basin hanging set) I think you’re going to struggle to find a wall plug big enough to use on a M10 bolt. Also known as lag bolts or lag screws, they have a square or hexagonal head engineered to be used with a wrench, spanner, or pliers. Hils fra Snarøya, That’s why the millions are rolling in lol! That was a quick reply. I wrote this post yesterday actually! Aw, don't go. Our metric stud bolt to nut table is meant to help determine the correct size bolt or nut for your purpose. Hi, I am about to install a sky dish for my son? What length are the screws/plugs? Good luck with your jobs! I can’t equate this to your table above. Am i meant to measuring the threaded part of the screw or the non threaded (shank only) of the screw? Supplements: Metric hex nut dimensions calculator By coincidence, the size of an imperial screw head also roughly equates to the gauge. I have a slotted square 80mm hook which I want to use for hanging a large mirror on a masonry wall. Bolts are tightened usually by using a socket, wrench or screwdriver, so have a variation of head types. Over 19 years of experience in the stainless steel industry has lead us to form partnerships with leading UK suppliers in the stainless steel fixings industry. Finance provided by PayPal Credit. Let me know if you get stuck! Ian, I think the chap talking about STAR screws needs to have the difference between Phillips head and Posidrive heads, how to recognise them and which screwdriver to use. Just that sometimes it’s best to sink the plugs into the wall a little (if the screws are long enough). Are they all the same type of screw Helen? Also, there is only a few main ones. Thanks for the kind words, Cheers Thanks, Thanks Grant, glad it helped. I definitely agree with you re the larger screws, I’ve got nothing over a 10g x 100mm in my box for sure. Let me help you improve your 'handy' skills with a free, easy to follow, mini DIY course. Cuts through all the ‘blah’ on other sites. I would like to know what wall plug size (blue or brown) should I use for a 8mm hole? Many Thanks! The higher the ISO numbers are, the stronger the bolt. Don’t forget that the weight is mostly in ‘shear’ too; i.e. This is the picture of the screw I bought. Do you think this “cowboy” type plan might work? Little concerned about the gap Geoff. Ian, Hi Ian The most common type of fastener, a hex head bolt is designed to be tightened with a standard spanner or ratchet and socket. I’d check the store first for an 8mm plug though, try here….. 8mm plugs from Fischer Nuts and bolts come in many different types and sizes and some are shown below. The size of a metric screw or bolt is specified as diameter, pitch and length, in millimeters (millimeters is abbreviated "mm"). Then the screw shank will obviously be much smaller. A brown 7mm plug needs a 7mm hole for example. Thanks, Andy. I’m one of those people who have to have every single thing explained (!) Thanks for stopping by Dave. Hi Brian, What would be the smallest you could create? p.s. I explained how using a substantial fixing on flimsy twin slot uprights will not work as the countersink is not deep enough but on genuine Spur which we make in Devon England will take the larger screw size and still allow the bracket to fit. Otherwise it’s best to head into the store and find the biggest plug that will take the screw shank diameter (the threaded part but minus the actual threads). p.p.s. Let me know if I can help. What’re you making? Usually I would use a heavy gauge regular (12g/14g x 75mm etc) screws with a large ‘penny washer’. Let me have more details or a even a pic two two, and I’ll take a look for you Let me know what you’re fixing up and clarify the shank diameter of the screw and I’ll be much more specific, I promise! (That’s also good advice to stop and re-drill if you think it’s too tight.). Hi Rob, This site uses Akismet to reduce spam. Its on their website. You might get them in a 7mm plug but 8mm would be better (if you can find them). Our website uses cookies and similar technologies to provide you with a better service while searching or placing an order, for analytical purposes and to personalise our advertising to you. from ebay… Ta muchly! Although, it would be closely followed by a T20 star these days. (He didn’t use the through bolts either but that’s another story) The result is the diameter of the head is slightly too wide for the countersink in the handle and the covering rose plate doesn’t screw fully home. Ian. Use the dimensions of your bolt to determine the appropriate size nut. An ISO Class 10.9 bolt roughly corresponds to an SAE Grade 8 bolt. Ian, Tried to find some info about screws, read a bit and then your picture jumps up on my screen – glad you got top spot on google, and thanks for the info. However, when I look at the table, an 8-guage screw is ~4mm in diameter. I’ve spoken to several screw suppliers and they all want to sell me what they have in store but no-one has yet convinced me that what I’ll get will have a 4mm diameter head! Image credit: UC Davis Engineering Pitch is the measurement between the apex of adjacent threads on the bolt's shank. Ian Oh, and some free stuff mixed in with regular posts :-). Any advice or input will be highly appreciated. My question is what is the best fixing option? An extensive range for any job large or small, on site or at home. Or you can use a hook of some kind… http://www.screwfix.com/p/smith-locke-long-robe-hook-brushed-stainless-steel-64mm/8364p or similar. Difficult without knowing the weight of the mirror, but I’d have through that an 80mm slotted, square hook would be fine with a regular brown 7mm plug, making sure that you push the plug into the masonry itself and through the plasterworks. . This handy chart below hi-lights a few differences between the two. Thanks for making the time to say thanks, appreciate that Ian, You’re most welcome Mr Morad, hope your project went well? See what they have at the store screw/length wise, stainless steel is best of course. Hi Ian, A Coach Screw is a heavy duty screw which has a square or hexagonal head and an externally threaded cylindrical shaft that tapers to a point at the tip. TIMco have produced this great video ‘What’s the difference between coach screws and general purpose screws?’ where they also demonstrate how to use coach screws here. The diameter of a bolt is the Shank diameter, expressed in millimetres for Metric bolts. Manufactured to ASME B18. I am lost on what size plugs to buy. If the screw is a bit fat, i.e. then you’ll need some special drywall fixings which spread out behind the drywall (let me know). Righty-ho, lets jump right in…. It’s difficult to be exact as it really does depend on the plug and the cleanness of the hole drilled etc. The Fastener Dimension Guide is a web application that allows you to find bolt dimensions directly from your mobile device. Judith. These screws come in a wide range of sizes, from the very small ones packed with furniture designed to be assembled by the consumer to extremely big ones … Sizes. Put it this way, I only have space for one permanent screwdriver in my pocket and that’s always going to be a PZ2. Especially if someone falls or pulls on it etc. Thanks for the comment. Post was not sent - check your email addresses! Hope that helps you sort out your screw dilemmas. Cheers Definitions of terms are located below the chart. Hey Mairin, 995979268 and registered for VAT. Where I live in Indochina we can only get hardwood chopsticks. A heavy mirror really needs to go into the studs of the wall. Contact: ian@handycrowd.com Hi Ian We’ve just fitted new doors and lever on rose handles. Then you could use a longer screw (cut short) into VERY carefully drilled pilot holes to fill in the hinge holes and look ‘proper’. Ideally you want the bottom of the screw and the bottom of the plug in the same place. To be fair, the manufacturers don’t know what you’re fixing into and they seem to assume solid concrete! When tightening or loosening a coach screw it is important to use the correct size spanner, wrench or impacts socket to avoid damaging the head of the screw. Usually most bolts are too big for the ‘standard’ or common brown 7mm plugs. You could try a specialist machine screw place but it’s likely the threads will be too small to hold in MDF. Ian. Ian. I guess I could (resin) glue in steel threaded rod and fix down with nuts? I’m 99.9% sure it will be a 10mm hole. Let me know how you get on. Terms and conditions apply. A washer is normally placed before the nut to stop it sinking into the wood as it is turned. It might leave the drive a little small for the screwdriver though… Alternatively, can you increase the countersink a little (without going all the way through!)? .tg td{font-family:Arial, sans-serif;font-size:14px;padding:10px 20px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} But I’m pretty cool about this, so for any enquiries regarding use, head up to the contact page and we can talk turkey…, A little more about me and some stuff I've done over the years... Click the orange bit... 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Hiya, then go up to a brown 7mm plug. Course, then you’ve got to sort the drill bits to put them back in the box . Just how big is that mirror lol! Can I first ask what you are fastening to the wall? Maybe in the States but I’ve never seen anything that small in local stores/merchants in the UK/etc. There is an exception though—if pitch isn't specified, the fastener is coarse threaded. 20mm+ in thickness. We used to do the same in the UK with metal ‘knob and tube’ up until the 1950’s or thereabouts. They are also known as lag screws or lag bolts but should not be confused with coach bolts or carriage bolts. TYPICAL COACH BOLT The coach bolt has a square collar under the domed head and this locks into the wood when the nut is tightened. Thanks for your input, always good to hear others experiences as it adds to my own! Like this… Consider this size… M8-1.0 x 20. Do you think a hole drilled with a 5mm bit would be too tight for a 4x40mm screw in a red rawlplug? Thanks Ian. Insist on the best it will be branded Spur UK. Buy Coach Bolts & Screws at Screwfix.com. The length of any non-countersunk bolt/screw is always measured from beneath the head and countersunk bolts/screws are measured from the top of the head Thread lengths vary over the size ranges but are generally 3/4" to 1". You say at the end of the article: “By coincidence, the size of an imperial screw head also roughly equates to the gauge. Metric Size mm Approx. Finance provided by PayPal Credit. Working directly with two factories, We supply some of the largest outlets in the UK and Europe with high quality, BA, BSF, BSW, UNF, UNC and Metric threaded hardware. Thanks so much Ian. Longer plugs are available but these are ‘frame fixings’ and not designed to be used outdoors. I understand there’s a ‘range’ but why not give us the ‘ideal’ measurement, because mostly we have a choice? Because this is approximately the same as the Major or Thread diameter the thread diameter measurement can be used for fully threaded bolts. 6mm – I’d go for a 10mm plug (near enough as above for a No14); I’ve just used 8mm coach screws in preference to a 10mm self-tapping brick screw for a gate-post on a wall. You can actually buy ‘socket box extensions’, but my experience finds that not many places keep them in stock. I would like a plastic gauge so I can simply poke the screws through the holes to determine their size. you might find this useful….. handycrowd.com/quick-tip-using-wall-plugs-rawlplugs-in-a-plastered-wall. Longer plugs are available but these are ‘frame fixings’ and not designed to be used outdoors. Thanks for looking in Bob, Click the book to grab your copy via amazon). then I’d use multiple hanging points, they hang better and move less too. As mentioned, a set screw is fully threaed along the length of the body, therefore the length is stated by the measurement from under the head to the end. Imperial Nuts and Bolts specialise in the manufacture and distribution of imperial hardware. Ian. Screw sizes as marked on the lable of most products. Then the holding point is down at the bottom of the hole. I don’t have too much problem getting the bigger gauges in, as I use a pretty powerful drill driver, but yes, you can’t stop and they need lots of ‘feed’ or you’ll get into trouble. Hmm, you say you just need to get the cover plate back? Dishes we’ve done in the past used a blue plug in a 10mm hole (if it’s the 50mm or so, bolts I have in mind). Another topic I guess…….. Hey Mike, Assuming the wall is masonry (brick, block etc. Ian. Around 6mm? 10g or 5mm etc. Hiya, Is there a discussion on the types of ‘star’ screwdriver and matching them with the correct screw. Ian. Plus, – how is a screw size, say, 8mm, what is that? You could even consider structural timber screws, if you can get a wall plug big enough for them. I have a good quality stud detector and have established that there are no frame struts suitable to accommodate the requirement. Cheers I saw a guy do one once by drilling a few 25mm (1″) holes through the plasterboard, packing in some fibreglass (at the bottom, to stop the adhesive falling down) and then pushing lots of drywall adhesive into the large holes until the area around the holes filled up with adhesive. Great table, but an additional column listing appropriate masonary bit size would be good. Coach screws are heavy duty screws designed for metal to timber connections, or to join heavy timbers. Ian, Dear Ian, your site is brilliant! Use one designed for double boards, i.e. You could go even bigger and go for 7mm brown plugs and a 10g screw of the same length. However the size or gauge of screw the plug takes is flexible, according to the manufacturers. Metric. Learn how your comment data is processed. Or do you perhaps have any other suggestions? What exactly is the gap? Hope that gives you an alternative and I really must write up this tip into an article (so thanks for that push!) Great tip Jay! Incidentally if you want to help support this site, grab your… screws etc. Hi Ian, Thank you so much for the comprehensive guide. Cheers Instead I use chopsticks! There is something of a divide throughout the UK between those who use the metric system for measurements, and those who prefer to stick with imperial equivalents. My question is what plan can I make to secure a plug cover to a wall electrical plug box on a wall where some plastering work has caused the depth of the plug box to be beyond the standard M4 100mm length? I think I might amend the table and add a couple more lines, but like you said it’s getting dangerously close to bolt territory then! Hi Lal, Been in Sweden all weekend and just got home. But there are lots of other ways…, Let me know the gap and we can talk again (it sounds like there are some timber battens or framing over the bricks to take the plasterboard?). As the name implies, they have a hexagonal head and come with machine threads for a firm and rough handling. .tg td{font-family:Arial, sans-serif;font-size:14px;padding:4px 20px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;} Click the book to improve your handiness today... Go on, make yourself useful! How deep does a wall plug need to be? I’m mounting a TV to my wall and the bracket has come with 10.5mm plugs and the corresponding screws but no note of what size masonry bit I’ll need to make a hole to accommodate. However it’s just occurred to me…. There are two main grades of Stainless Steel: Coach screws come in an array of different sizes and are manufactured to confirm with DIN 571 German national standard dimensions, .tg {border-collapse:collapse;border-spacing:0;} Data listed for these sizes is independent of the ASME specification. Click the book to grab your 424 pages of pure handiness... Go on, be handy! Getting too old for new tricks maybe? Cheers and good luck! How to be Handy [hairy bottom not required], 12 Ways to Fix Lath and Plaster Ceilings: Complete Do-it-Yourself Guide for Homeowners, http://www.screwfix.com/p/smith-locke-long-robe-hook-brushed-stainless-steel-64mm/8364p, handycrowd.com/quick-tip-using-wall-plugs-rawlplugs-in-a-plastered-wall, How to Repair Lath and Plaster Ceilings (10 different ways). I simply bang a chopstick into the drilled hole as far as it will go, then break it off and in with the screw. Ian. To be honest, you might be more familiar with sizes in the US (I’m in Europe…)than me! Makes life so much easier for a DIYer. .tg th{font-family:Arial, sans-serif;font-size:14px;font-weight:normal;padding:4px 20px;border-style:solid;border-width:1px;overflow:hidden;word-break:normal;border-color:black;background-color:#FFFFFF !important;} Let me know. However this method does require that someone knows what size each screw is to start with so that you can make up the guide board! Then what you do is drill two holes in the back of the box corresponding to the holes on the front. (eBook via amazon). Sure you can buy ‘sets’ of big screws that come with a large plastic plug (sink/washbasin screws to name one) but usually if you’re hanging something heavy on a masonry wall you’d use a ‘rawlbolt’ style expanding bolt; either a hex head and washer or a nut and washer. Once it had set, he remarked out the holes and drilled into the brickwork as normal. They are primarily used for holding together heavy timber, fixing metal to timber and in some cases masonry or concrete. Then you’ll need to consider whether to use a smaller gauge screw or drill a larger pilot hole if it’s in wood. I don’t use wall plugs, you never seem to have the right size. by 10mm lag screw, do you mean a screw with a 10mm head? Clearance hole; measure the outer diameter of the threads. They are primarily used for holding together heavy timber, fixing metal to timber and in some cases masonry or concrete. You will need to use a wood drill bit to drill the pilot hole. INC VAT … For sure the fitting supplied go straight into the bin in most cases on my jobs! All rights reserved obviously (duh!). Definitely not a brown plug as they are 7mm and blue plugs are usually 10mm so neither are any use in an 8mm hole. I’ve also done something similar using matchsticks or cocktail sticks, just fill up the hole with them and snap them off flush with the surface. Best of luck with your projects! The dimensions of a bolt can be expressed in metric or imperial units, both of which are better explained in the Bolt Standards section of this selection guide. The staff at ScrewFix cannot give me any suggestions, they only sell products (-; Since the mirror is not really that heavy, will you give me any suggestions on what size and type of screws should I use?