Joel OF Posted December 5, 2015 Share Posted December 5, 2015 Can anyone link me to a site that lists (in millimeters) bolt diameters according to the allen keys that do them up? I've Googled in vein. I.e a Number 3 allen key is for a .... diameter bolt. I need to replace a tiny bolt that does up with a Number 3 allen key, I can't measure the bolt diameter though as it's got mangled. Cheers me dears. Quote Link to comment Share on other sites More sharing options...
yesteryearforge Posted December 5, 2015 Share Posted December 5, 2015 just Google ( what size bolt for a 3mm hex key ) A chart should come up but it is usually one size difference ( 4 mm bolt takes a 3mm allen wrench Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted December 5, 2015 Share Posted December 5, 2015 It depends what kind of bolt head. For M6 - upwards at least, the standard cheese or round head has a larger size key relative to the thread diameter than either a button/snap or countersunk head for instance. What bolt type have you got? I can't remember off hand what either of them are for a 3mm key but there will be two possibilities I hazard. P.S. According to this roymech table countersunk M5 use a 3mm key was do cap/round/cheese head M4. http://www.roymech.co.uk/Useful_Tables/Screws/cap_screws.htm Alan Quote Link to comment Share on other sites More sharing options...
Frozenforge Posted December 5, 2015 Share Posted December 5, 2015 McMaster Carr has cad drawings linked to their hex cap screws. The drawing shows the hex wrench size. Do you know what the thread pitch it is? Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 5, 2015 Share Posted December 5, 2015 Alan , that's a good chart, however when I look at my metric taps I seem to have for example.... M8x 1.0....m8x 1.25 and M8x 1.5 and if you look at metric taping charts its scary as to just how many options there are! Joel, when I first saw your thread I did not reply as I didn't have the foggiest on a "number 3 " Allen key! like wotszat? Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted December 5, 2015 Share Posted December 5, 2015 7 minutes ago, ianinsa said: Alan , that's a good chart, however when I look at my metric taps I seem to have for example.... M8x 1.0....m8x 1.25 and M8x 1.5 and if you look at metric taping charts its scary as to just how many options there are! Joel, when I first saw your thread I did not reply as I didn't have the foggiest on a "number 3 " Allen key! like wotszat? The two possibilities I was referring to were the head types which for any diameter thread give two sizes of Allen key. I think the coarse/ medium/ fine/ pitch thread form does not affect the key size...it is just the form of the head that influences that. Well spotted! I had not noticed Joel referring to number three...I just read it that it was a 3mm AF key. duh! (AF = Across Flats in this instance...before some smart-Alec comes up with American Fine) Alan Quote Link to comment Share on other sites More sharing options...
the iron dwarf Posted December 5, 2015 Share Posted December 5, 2015 most metric thread sizes have common pitches, then you get the more specialized ones and then it gets weirder. M6 and M8 are common M6 and M8 fine are not so common M7 fine left handed is rare but I may have a tap for it Quote Link to comment Share on other sites More sharing options...
Smoggy Posted December 5, 2015 Share Posted December 5, 2015 If you've mangled the original bolt, I suggest your best option is to find any type of bolt with a known thread that fits......from their it should be relatively straight forward to determine what bolt you need......which will have a 3mm hex recess head of the appropriate type. You do have a selection of odd threads don't you.....or tap sets?,,,no! DUH!!!!! This is what happens when someone has a good idea......and everyone else jumps on the band wagon and chuffs it up....Whitworth sorted it out and the rest of the world scuppered the plan! Quote Link to comment Share on other sites More sharing options...
yahoo2 Posted December 5, 2015 Share Posted December 5, 2015 Im with Alan and smoggy. try a M4 first to check the size, to see if it fits and screws in, the standard thread pitch on them is 0.7mm Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 6, 2015 Share Posted December 6, 2015 Joel, for the sake of solving 'your' issue as I think we are presuming that #3 =3mm it would be simple to go to your version of "speedy nut'n bolt" and buy one of each of the close sizes ask the to stick them in separate zip lock bags and label them. Around here some of the owner operated/present places would give them to you if you told they why you needed them! @ Smoggy, as I avidly buy taps and drill bits up when I see them cheap I've ended up with heaps of Whitworth taps.... and never found a use for one Quote Link to comment Share on other sites More sharing options...
Joel OF Posted December 6, 2015 Author Share Posted December 6, 2015 Yikes, I've inadvertently opened the door to 'thread pitch Hades'. Far too much for me to comprehend a.t.m through this fog of hangover & cold. I'm going to my workshop later, I shall bust out my trusty vernier and try to at least crack the case of what diameter a Number 3 allen key is, because from memory it doesn't look like 3mm. Thanks for the help folks. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted December 6, 2015 Share Posted December 6, 2015 When I was first setting up my forge in the seventies, a chap came up to my table at my first craft fair and asked if I would be interested in some of his late father's tools. It was the last day of the craft show and at midday it was a bit quiet so I went with him to have a look...thinking it was just going to be some stuff in the garden shed. Turned out it was the repair workshop behind a hardware shop. An Aladdin's cave of kit from leg vices through to boxes of files, old lathe chucks, lead and pipe working tools, leather punches, a veritable cornucopia... He wanted £300 for the lot. Bargain of a lifetime! In the five days previously I had sold enough at the show for only half of it. So with tears in my eyes and a heavy heart I sorted out the bits I could not "not-have", ready for collection the next day. I went back to the show and in the last two hours just could not stop selling! I sold another £150 worth so rushed back to the hardware shop the next day and bought the lot. The reason for my ramble, is that amongst the wooden champagne boxes that now filled my little workshop, there were boxes and boxes of taps and dies. So whenever I have been repairing any old cars or old British power hammers and presses, American lend-lease lathes and etc. I have managed to match the threads of... Whitworth, BSF/BSC British Standard Fine and Coarse, BA British Association, UNC and UNF, let alone a host of gas and water pipe fittings. There was even a Coventry die chuck for a lathe, though I have never used it...maybe it will come in one day still! There was even a box of the antique forged die plates with the hand made thread cutters. I will post of photo of one of those one day. They are made by drilling and tapping a bit of tool steel plate with the thread you need, then drilling two smaller holes on either side which intersect with the tapped hole. The intersecting arcs form the cutting edges. Alan 41 minutes ago, Joel OF said: Yikes, I've inadvertently opened the door to 'thread pitch Hades'. Far too much for me to comprehend a.t.m through this fog of hangover & cold. I'm going to my workshop later, I shall bust out my trusty vernier and try to at least crack the case of what diameter a Number 3 allen key is, because from memory it doesn't look like 3mm. Thanks for the help folks. Just to be cruel to your hangover....do you mean the included or the enclosing diameter?.... A/F is what mine are measured by, whether Metric or Imperial. Alan Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 6, 2015 Share Posted December 6, 2015 15 minutes ago, Alan Evans said: There was even a box of the antique forged die plates with the hand made thread cutters. I will post of photo of one of those one day. They are made by drilling and tapping a bit of tool steel plate with the thread you need, then drilling two smaller holes on either side which intersect with the tapped hole. The intersecting arcs form the cutting edges. Alan That first bit made heaps of sense and was obviously an absolute bargain then alas for this last bit you inadvertently lapsed into 'Klingon' please post a picture or two. Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted December 6, 2015 Share Posted December 6, 2015 Grall-op tare! (translated from the original = will do! ) Alan Quote Link to comment Share on other sites More sharing options...
Joel OF Posted December 6, 2015 Author Share Posted December 6, 2015 46 minutes ago, Alan Evans said: Just to be cruel to your hangover.... Don't. I stayed at my folks' house last night as they live near to the Christmas market I had a pitch at yesterday. Sometime ago I forged a replacement strap hinge for their wonky garage door, and for some reason I decided at 8am that taking off the existing distorted strap hinge (complete with rusted nuts/bolts) and putting mine on would only take about half an hour and help my hangover. About 15 minutes in to the 2 hour job, as the drizzle was going down my back, I realized how swollen my glands are, how sore my head is and how my Dad didn't really have any of the right tools. At least the door opens now. Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 6, 2015 Share Posted December 6, 2015 1 hour ago, Alan Evans said: A/F is what mine are measured by, whether Metric or Imperial. Alan A/F........ Aft. To Front? Er. Is that length? Joel, it's a bonus if it closes too! Quote Link to comment Share on other sites More sharing options...
Alan Evans Posted December 6, 2015 Share Posted December 6, 2015 3 minutes ago, ianinsa said: A/F........ Aft. To Front? Er. Is that length? You 'affing a laff? Alan Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 6, 2015 Share Posted December 6, 2015 Quote Link to comment Share on other sites More sharing options...
Smoggy Posted December 6, 2015 Share Posted December 6, 2015 2 hours ago, ianinsa said: That first bit made heaps of sense and was obviously an absolute bargain then alas for this last bit you inadvertently lapsed into 'Klingon' please post a picture or two. Ian if you google image for "watchmakers thread plate" all should become clear...... Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 6, 2015 Share Posted December 6, 2015 6 minutes ago, Smoggy said: Ian if you google image for "watchmakers thread plate" all should become clear...... Gotcha , thanks! P.s. To those who do not fall in the 'old farts' generation the A/F Alan was referring to was meant in "engineering speak" not texting! Quote Link to comment Share on other sites More sharing options...
Crazy Ivan Posted December 6, 2015 Share Posted December 6, 2015 Do you absolutely need the exact bolt, or can you just drill it out and tap it to the next size up? That's a common method for quick repairs if finding the hardware becomes a problem. Quote Link to comment Share on other sites More sharing options...
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