Tip & How-To about Hand Tools

Need to tap a hole and no tapping chart?

If you need to tap a hole and do not have a drill tap chart and it is not absolutely critical that the threads are perfect, this is a quick way to determine what size hole to drill. Take a nut of the same size and thread pitch you want to tap. A drill bit that fits through the nut with just a bit of play will give you a close enough hole to tap. If the thread is metric an easy rule of thumb is to take the bolt size, deduct the thread pitch and another 0.1%, and that is your tapping drill size. eg. M 10 pitch is 1.5 mm, deduct this gives 8.5 mm, less another 0.1% gives 8.4mm, the closest tapping size for M 10 threads.

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Is there a way to replace a broken eye bolt on a 1992 Dixon ztr? The threads are broken in the cradle


If its a case of the threaded part of the eye bolt sheared off and inside the cradle. you may be able to unscrew it by drilling a hole through the centre and screwing in an eaxi-out which is a tapered tool with a left hand thread. So as you srew in the eazi-out it gets tighter until hopefully the broken thread comes out.
Failing that.
Buy a new eye bolt
Take it to an engineering supplier so they can identify the thread size and thread form
Buy a tapping drill and a set of taps to suit the eye bolt
Carefully drill a pilot hole through the centre of the broken stud in the cradle
use the tapping drill to enlarge the hole
Starting with the taper tap, run the tap down and progress with the second tap and then the final one - use lubricant when cutting the thread.

Jun 07, 2016 | Cars & Trucks

2 Answers

What is the proper size drill bit to use for a 3/8 tap?


Thread size makes a difference:
3/8 x 16 NC is 5/16 drill

3/8 x 24 NF is Q size bit

May 24, 2015 | Drills

1 Answer

ir tourch has brocken off the unit


That's OK. When IR broke off did it leave any hole into the cavity of the scope? If it did, use some black anodized aluminum (or black plastic) plate 1/16 or smaller and mold it and fit to where it broke off only if there are holes.

Once the plate been fitted tightly. Now you drill some holes. The number of drill holes is up to you. Go down to your local fastener business, the carry all kinds of screws, machine screw, bolts, nuts, everything that you might need. Get the machine screws that are the self threading. They will look like a little machine screw with SAE threads but it will be tapered on end with a small notch cut in the end. This way you will not have to use a tap to thread the holes.-----One more thing here, pre-tap the drill with self tapping machine screws. This way you can clean out the scope cavity Then apply a thing layer of black rubber cement to the cover plate and then screw the machine screws. The length of the machine screw are critical. You don't want the to long where the reach far into the scope cavity. It could disrupted the flow of light to the NV scope.

Now, for a IR lumination. Get head light with one high luminating bulb. Get an IR lens and have it fitted to the head light, now you have IR lumination. Simple, hey. stewbison

Feb 06, 2011 | Yukon (744105200223) Weapon Sight

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