Hole taps

[Napster]

Hi

I need to drill some box section with a 6 to 8mm hole and tap it so I can put a bolt in, now my daft question is do I drill 6mm and tap with 6mm tapbit or do I drill smaller and if so how much smaller.

Some help would be really handy so I dont get wrong size taps etc etc

Cheers for any advise

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[Spectre]

Slightly smaller @Napster but the tap manufacturer usually recommend a drill size. Also, if you drill by hand then the hole may be slightly distorted or larger then if done in a press.

How thick are the box section walls? There aren't going to be many threads.

I think it was Lidl had sets of cheap tap and dies, they would be ideal for occasional use. Use some oil when you're cutting.

 

[Napster]

Cheers m8 thats given me something to work with will look into this more

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[Spectre]

Might be better off with nuts and washers @Napster., depends what you're doing of course.

 

[Napster]

I think it will be easier just to drill all way through and use bolts as you say its only a metal fence panel that needs refixing the weld has broken over the years.

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[ekwat]

Tapping size for M6 is 5mm. It's a 1mm pitch so you'll not have much strength in box section as Spectre's post.

 

[trevortron]

Good advice re. bolts & nuts. And washers of course! If I were in the drill/tap quandry, I'd probably try first on a piece of scrap, but matching the drill size-down with the thread pitch makes a lot of sense

 

[Him Her]

A pic might help decide which option is best, but one way to get around the hole size issue is to use a taper tap for the first cut and finish with a plug tap. That way the hole can be smaller to start off with.

Oh, if you decide to tap, as well as using oil back off regularly to let the oil in to avoid tearing!

 

[miggy]

You could try this option Mr Napster
SEALEY THREADED NUT RIVETER AK393: Amazon.co.uk: DIY & Tools

 

[Napster]

You could try this option Mr Napster
SEALEY THREADED NUT RIVETER AK393: Amazon.co.uk: DIY & Tools

I like the look of that m8 thanks for posting it.

 

[Napster]

its fence posts around front garden posts are 2" square so I woulds say thickness will be 3mm panels are only low so no weight there just a matter of holding it up 4 bolts 2 per side should be enough panel is 6ft by 2ft its like the stuff you see on top of walls black with gold tops .


like ones in picture

 

[miggy]

I like the look of that m8 thanks for posting it.

These work great for me when on site fabrication was needed Napster. They are a lot stronger than cutting 3 maybe 4 threads in a thin wall box section. Good luck with what you choose though and keep us posted.

 

[Spectre]

Are you sure they aren't solid wrought iron @Napster?

 

[Napster]

Don't, think so m8 as each post has a cap welded on, but I will drill small hole before I buy anything just to make sure.

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