OzVMX Forum
Clubroom => Tech Talk => Topic started by: FAT-TOY on November 04, 2012, 08:49:09 PM
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We all know about and have probably used a helicoil. What I want is a tap size chart for them. By that I mean if I want to use a (8 x 1.25) helicoil what size tap do I use for it to screw into, is it a (10 x 1.25) or some mongrel size made specially for the helicoil.
I have a selection of helicoils plus the home made tools to insert them a break off the tang I just need the correct sizes for the taps without having to go to the expense of purchasing the full kits.
Zane
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As far as I know the taps are to suit the helicoils.
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Many a knackered thread I have drilled out to the next size and made a 'plug' with the inner tapped back to the orginal bolt size. If you are tapping aluminium the proper tap to use is a forging tap, like a spoke threader it cold forms the thread. Lots of threads can be reclaimed using these.
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Thanks Lossa, Wasp I have seen the Wurth product and it looks good. I have been making my own inserts like Lossa uses but I picked up a good selection of Helicoils at an auction a while back and they cover most of the smaller sizes up to M12 in metric and 1/2" unc in the imp sizes. So if I can pick up the correct taps then I can use them. I did borrow a tap from a mate to do a small job but it had no size stamped on it. From memory it was slightly under the 10mm but had the same pitch as the helicoil. I dont want to borrow again I think if I have to borrow twice then I should own one.
Pity my family members didnt think the same.
Zane
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I bought a Recoil brand kit for the common M6x1 that is used in crankcase screw threads. The tap with the kit only has the helicoil size marked on it - not the tap size. I would think you could order the taps from any engineering supplier using the helicoil size as the basis for ordering them. You shouldn't need to know the tap size.
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there is a much better solution . That is the Wuerth time serts
I can recommend the Wurth sleeves too. Back when I was in the trade we used them instead of helicoils on stripped threads that were to take a lot of load. I can't recall one failing either.
http://www.wurth.co.uk/products/600601 (http://www.wurth.co.uk/products/600601)
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As Pezberg says you should be able to buy the taps as a spare part separate from the kit
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I have purchased special taps to install inserts and just helicoil taps before from Carmet I believe, I think you can use a 7 x 1.00 to put 6mm coils in but you cant use a 10x 1.25 to put in a 8mm. The helicoil taps are the same pitch. I like the worth inserts but they do need more material OD than coils for example Honda 4V heads you can not use them.
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I can measure up a few different sizes of taps for the kits at work but won't be til wednesday unless it's raining tomorrow.
My gut feeling is that the taps are pitch size bigger than nominal ie M6x1 uses 7x1 tap, M8x1.25 uses M9.25x1
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Recently bought these to repair head stud threads on an IT barrel. http://www.ebay.com.au/itm/Helicoil-Thread-Repair-M8-x-1-25-Drill-and-Tap-12-Inserts-/280832843830?pt=LH_DefaultDomain_15&hash=item4162f12036