Tapping size

Gentlemen,

Can anyone tell me the tapping size of a 11/16ths UNF tap, I know its a bastard size, I have bought a tap but none of my books give a drill size for it. Its for Landrover track rod ends.

Martin P

Reply to
campingstoveman
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Can't precisely help you Martin, but thereis a calculator you can use here:

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Peter

Reply to
Peter Neill

MH gives, for 1-1/2D to 3D depth of engagement as between 0.651-0.655" so 21/32" drill is pretty close @ 0.65625"

Tom

Reply to
Tom

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Depends really on what sort of thread engagement you need for the thread. If it is 11/16 X 16UNF the tapping drill is listed as 5/8" here:

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That would give a 77% thread engagement using the calculator that Peter pointed to.

A 15.5mm drill would give 95% thread and ensure a broken tap I feel

The 21/32" that Tom recommends would give a 40% thread and could be a bit loose for your needs.

I think I might go with the 5/8" listed on the chart but I know nothing about track rod ends and the required thread engagement. it is also a bit early so I should check my calculations yourself before drilling.

Keith

Reply to
jontom_1uk

What is the pitch? 5/8" is 18 tpi, 3/4 is 16.

I've got an 11/16" UNS tap, 16 tpi, in my hand which is marked 'use

5/8" drill'.

Tip

Reply to
Tim Leech

Gentlemen,

Thank you, my brother and I used a 5/8 drill on a test piece and it works very well, we had calculated 15.5 but couldn't even get the taper tap to start. Now we will tap the required part. Thanks all for help.

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Reply to
campingstoveman

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It`s 5/8".We manufacture Land Rover track rods,hope your not going into competition.:-)

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Mark.

Reply to
mark

Mark,

No chance :-) my brother builds and races Safari and off road trialers for a hobby, he likes to try different things and quiet often makes his own parts. this time he is modifying the steering by making larger dia steering arms, idea being they wont bend so easily when racing.

Reply to
campingstoveman

Martin,that`s good news.These ones are guaranteed against bending.Made from high strength hollow bar.I believe it`s in the RAC regs that solid bar is not allowed which is a pity as it`s infinitely cheaper.We manufacture for the owner of the brand, who reckons he`s only had to replace two that bent.Not bad as we supply him with thousands of them a year.I suspect that a lot of them are never fitted,the buyers being content with having the Sumo sticker on their windscreen. Mark.

Reply to
mark

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Another useful rule-of-thumb formula is to divide 1 by the TPI and then subtract this number from the O/D to get an approximate tapping drill size. So for example if this was 11/16" x 18 TPI then 1/18 = 0. 0556, then

11/16" (0.6875) - 0.0556 = 0.6319, which is just 0.007" above the 5/8" drill size recommended by others.

The formula also works for metric as well, but these are so simple anyway (O/D - pitch) that it shouldn't really be needed there:)

Peter

Reply to
Peter Neill

My MH gives 11/16" UNF as 24 tpi. As the pitch wasn't quoted...

Tom

Reply to
Tom

TomHi, yes that one confused me a bit although on my lists it is quoted as 11/16" UNEF (Extra Fine??). Not having a track rod to look at I couldn't confirm but from memory I thought they were fairly fine but perhaps not quite that fine? I still haven't found a finite spec but at least the practical approach seems to have worked for Martin.

Regards

Keith

Reply to
jontom_1uk

Missed the UNS, not UNF is it? :-)

Tom

Reply to
Tom

That's why I asked the pitch. So far as I can see, there is no 11/16" UNF defined, but if there were to be one it would be either 16 or 18 tpi.

11/16" UNS is probably the best offer ;-)

Tim

Reply to
Tim Leech

Tom

Yes, I think it should be UNS at 16TPI, at least that is what the LR4X4 forum thinks it is. I suspect the chart I quoted was actually a missprint and called it UNF instead of UNS. It is also a fairly common size used on some plumbing fittings so I suppose it could be called "special". As UNS it is listed fairly often with the tapping drill at

5/8", as of course is 11/16UNEF at 24TPI with a tapping drill of 16.6mm.

Regards

Keith

Reply to
jontom_1uk

UNS stands for Unified Special.

Tom

Reply to
Tom

Well everyone is in on the act. I made some shackle pins the other day for the roller I'm playing with and just to be different they had a 5/8"

16 tpi thread, instead of 14 tpi which is the standard for 5/8" BSF.

Tom

Reply to
Tom

Gentlemen,

Just to put you out of your ag>

Reply to
campingstoveman

I was very well aware of that.

Tim

Reply to
Tim Leech

I'm terribly sorry, I won't mention it ever again! :-( BTW, list, is there a cure for frostbite?

Tom

Reply to
Tom

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