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Can anyone direct me to a supplier of drilled M5 cap head bolts?


SLR No.77

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I specifically need M5 cap head bolts drilled to take lockwire but can't find anyone supplying them, can anyone help? I'd prefer them to be stainless but might accept titanium. Parallel or taper head is fine.

These are for the trumpets & backplate on roller barrel throttle bodies, ProBolt make a hex head version but there's not enough space for the flange or to use a socket to tighten them.

Anyone? I'm getting desperate!

Stu.

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Have you tried Spalding Fasteners?  Ive just ordered a new bits and bobs online from them, but for your specific needs probably best to call.  What about Titan, they made the RBTB and might be able to help. 

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Can you put them in a vice and try and drill them yourself? You can get some tiny drill bits both in the big DIY sheds and specialist modelling suppliers. Dremel probably do them for their multitools.  How many do you need?    

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Stu,

Was the pro-bolt comment in your original post or did you add it - just wondering if I'm going mad or need to read things more thoroughly!?

What do they screw into? Ally casting or is there a nut at the back. Just wondering...If just a nut and bolt maybe easier putting the lockwire at the back and drilling the threaded portion of the bolt?

May need to get a jig!

Alternate - flanged bolt in a spinning cordless drill and dremmel the flange off then use an open ended spanner.

Ian

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Roger, I've looked at the jigs but unsure how easily I'm going to be able to drill stainless bolts, I think the lockwire hole size is usually 1mm - 1.6mm which is pretty small for drilling into stainless.

Ian, I edited my post for spelling, the ProBolt comment was there originally! Unfortunately although some of the holes do break through the TB casting slightly there's even less space at the back, plus the rest of the holes are blind. Cap heads really are the only option.

Stu.

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You'll have get a pair of wire locking pliers.  Will you drill a hole in the back on the trumpet base to put the wire in? 

What about just using small nord-lock locking washers? Apparently these are more reliable than traditional spring washers, or do you want to physically retain the bolt to stop it falling out?  

https://www.nord-lock.com/shop/buy-here/?gclid=EAIaIQobChMIwfekg9L34QIV7bDtCh1MrQQtEAAYASAAEgIO3PD_BwE

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Have you got a friendly machine shop close by?  They may be able to drill two diametrically opposed holes in whatever bolts you supply.  Motorsport lockwire is typically 0.8mm, so 1mm holes should do the trick.  Then you could run the wire in a closed loop round the trumpet.

I'm not sure why you would need six holes per bolt head, unless it's to provide better wire alignment?

JV

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I was thinking 6 holes per bolt purely due to alignment.

I've borrowed the lockwire "pliers" from another club member and I have someone on hand who's been trained to lockwire components on aircraft wings so should be able to have a pukka job done, I've just been struggling to get the correct bolts. I've been in contact with ProBolt but they can't supply anything outside their range as listed on their website.

Thanks for the offer Regin, I'll let you know if I don't get anywhere.

Stu.

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6 holes aren't necessary. You only need one. Even if it doesn't line up nicely for the lock wire and can turn, it will only turn a very small amount and will not come undone. In your application that's all that's needed ....



If you're really stuck for time, and Regin's kind offer doesn't work out, Locktite them and add a blob of silicone over the heads. This should suffice for one event


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I might also consider using alloy cap heads for holding the trumpets on. There's no real stress here and alloy will be a lot easier to drill. If its holding a relatively heavy backplate etc, maybe not .....


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