PDB Posted August 22, 2023 Share Posted August 22, 2023 Lost the nut from the rear of the silencer yesterday, my fault having had the silencer apart then not securing the nut back on properly. 😬 Nothing I've got fits, the thread diameter is 3.2 mm and I don't have a pitch gauge so was hoping someone might have an idea of what nut is needed? Quote Link to comment Share on other sites More sharing options...
kc Posted August 22, 2023 Share Posted August 22, 2023 3.2mm might well be 5 BA BA threads are often used only in even numbers, so 5 BA is just not so common but should be available. Might be quicker to go over the workshop floor with a hatch magnet ( very powerful - if its steel it would be found but if it's somewhere out on the flying field -no hope! ) but in the pits possibly but you will find everyones else's first! It will be quicker to find a secondhand nut somewhere amongst discarded equip- if you are not a hoarder no doubt a clubmate will be......... 1 Quote Link to comment Share on other sites More sharing options...
PDB Posted August 22, 2023 Author Share Posted August 22, 2023 Thank you very much @kc, I shall obtain some 5BA nuts and give those a go. Finding the original won't be possible, it came off in flight so is somewhere in a field.🙄 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted August 22, 2023 Share Posted August 22, 2023 11 minutes ago, PDB said: Finding the original won't be possible, it came off in flight so is somewhere in a field.🙄 A magnet hanging under a drone ?.😄 Quote Link to comment Share on other sites More sharing options...
kc Posted August 22, 2023 Share Posted August 22, 2023 I have just tried a 5BA tap and it just slides right through an M3.5 nut ( very common size ) and won't go anywhere near into an M3 nut. To give you an idea of the fit. Actually I couldn't find any 5BA amongst my collection of odd nuts & bolts - it's rare. But EKP Supplies make BA nuts- or used to. Postage might be high so it might be best to buy a selection of similar nuts just in case it's not BA..... 1 Quote Link to comment Share on other sites More sharing options...
John Wagg Posted August 22, 2023 Share Posted August 22, 2023 (edited) Something in the the little grey cells think Irvine used AF threads. 🙄 Possibly depends when nad who it was made by. (OS) ? So a #5 - 44UNF - major dia' = 3.175 mm. https://www.gewinde-normen.de/en/unified-fine-thread.html Again the grey cells think original Irvines were based on an USA engine (K&B) ????? Possibly complete B.S. 🥴 Edited August 22, 2023 by John Wagg 1 Quote Link to comment Share on other sites More sharing options...
PDB Posted August 22, 2023 Author Share Posted August 22, 2023 Hello @John Wagg this engine is an OS manufactured MK4. Quote Link to comment Share on other sites More sharing options...
kc Posted August 22, 2023 Share Posted August 22, 2023 John W might be right -it is just as likely it could be UNF. It might be easier to ask a clubmate for a spare nut or to rob some piece of equipment - I found that my old SLEC stripcutter has No 5UNF thumbscrew nuts holding the blade. 1 Quote Link to comment Share on other sites More sharing options...
alan p Posted August 22, 2023 Share Posted August 22, 2023 Set of thread gauges check thread pitch, mic or vernier the o/d, a Zeus reference book or internet to look up thread with the information aquired. Simples!!!!! 1 Quote Link to comment Share on other sites More sharing options...
PDB Posted September 2, 2023 Author Share Posted September 2, 2023 (edited) Mystery solved, turns out it’s an M3.5. 👍 My cheapo callipers are not very accurate 😊 Edited September 2, 2023 by PDB 2 Quote Link to comment Share on other sites More sharing options...
Outrunner Posted September 3, 2023 Share Posted September 3, 2023 16 hours ago, PDB said: Mystery solved, turns out it’s an M3.5. 👍 My cheapo callipers are not very accurate 😊 Probably not your calipers, bolt threads are usually made a little under the nominal size to ensure the nut will go on easily. 1 Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted September 3, 2023 Share Posted September 3, 2023 18 hours ago, PDB said: Mystery solved, turns out it’s an M3.5. 👍 My cheapo callipers are not very accurate 😊 That's 'Rossi' territory,,, Quote Link to comment Share on other sites More sharing options...
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