Ok i think i need to learn how to correctly do this before i break something.. brought a tap\die set from autozone. ok so maybe its not the best quality. but i was desperate and it was only like $20.. so i try to drill\tap a stripped bleeder screw hole on my rear caliper. and i can't get it to work!!! drilled a 3\8" hole for a 7\16" tap. and the tap won't go in. it just spins and spins and i think im doing more damage to my tap bit then i am my hole..

so what is the correct way to tap a hole? like how fast are u supposed to go and should u use a drill or what? and how much pressure should u apply? there were no instructions with the kit, and i looked online and couldn't find anything.. and i wanna learn how to do this properly...

thanks

 

well, first thing i'd do is buy a good quality tap (its just so much easier then trying to dig out a broken tap..), next, if your not used to using taps i wouldn't suggest using a drill, to easy to brake is off. you should use a T handle and once you've got the tap started, turn the tap in 1/2 a turn then out a 1/4 turn, repeat untill finished. as for geting the tap started, you'll probibly need quite a bit of pressure to get the tap to catch. and make sure you have the right size hole drilled for the tap your using. Good luck and hope all goes well!

 

didn't your parents have "the talk" with you.

sorry, just a funny title for the topic.

 

trash the auto zone tap set and buy a good one, or at least the tap you need. use a tapered tap to start a hole and a bottom tap to finish it. use a chamfer tool to finish the top of the hole after you drill it to make it easier to start the tap. if you can set it up i a drill press and the tap has a center hole you can use the chamfer tool or a tap wrench for a drill to start it straight and apply preasure. make sure you use the right tap drill and lube if it's required, some metals and plastics tap better dry. when you get the tap started go 1/2 turn or so and the back a little to break the chip.

 

Yeah, I'm gonna have to agree with Rage and Ede on this one, that you probably need a better tap. Also, you should start out tapping by hand, it gives you a better idea of what the tap is doing.

Here's the breakdown on how to tap a hole (any of you master machinists out there feel free to add comments / corrections)

1. Drill the hole. A decent quality tap should have the reccomended drill size marked on the shank somewhere. it's probably going to be a wierd size like, 27/64, but you can probably round it off to the nearest 1/32 inch. Try to drill the hole as true as possible.

2. Start the tap. Easier said than done, especially on steel. You need to rotate the tap as smoothly as possible, while keeping it straight up and down, and applying a whole lot of pressure to it.
You will feel the tap starting to bite, and see a small shaving or two. When it starts to feel like you're threading a bolt in to a nut with a damaged thread, or something like a Nylock nut, you are starting to cut threads. A good way to check this is to back the tap out a little way, and see if it spins easily back down.

*I don't know how to utilize a drill for tapping holes, so I can't reccomend it. I think you will be better served by doing your first few by hand so you know what the tap has to do.

3. Tap, tap, tap. Once the tap is started, it's time to cut some threads. Usually the rule is to turn the tap about 3/4 of a turn, unitl it gets tight, and then back it out 1/4 turn, then turn it in again. Backing the tap out will break loose the chips and shavings that are coming off of the freshly cut threads and keep them from jamming up the tap. On most metals, and I'm pretty sure steel is one, use of a 'cutting fluid' or similar oil will help the tap cut eaisier.

 

I can vouch for the guys saying buy a good tap set or the tap you need. I spent 6 hours under a truck drilling out a reverse threaded bit after it broke off inside a transmission casing. I ended up buying a really good set of drill bits to drill through the damn tool metal. It was more like shave through the tool metal.

 

Breathment:

My local "RECOIL" dealer RENT the tap and the tool for tap a hole. It's very cheaper. I only needs buy the coil.

If the information is O.K. the USA dealer is located at 1051 Third Avenue SW. Carmel, IN 46032.

Tel (317) 846 8830 or (800) 826 2884.

Recoil is an Australian company (I think) like "HELI-COIL" for thread insert systems.

Good luck

 

Firstly the late model (after 78) caliper bleed screws are metric.

You might b better off at this stage with a rebuilt caliper.

I would suggest the following.....

A thread pitch guage....both a metric and sae one. Good ones (Starret etc) are expensive.....you can cut corners with a Harbor Freight piece from India on this however.

A good basic tap and die set....metric and SAE./..prefferably US made but Japanese or European mfgr is satisfactory. Yes they are not cheap...but a GOOD set will last you a LIFETIME. This will come with a die stock (handle for dies) and a Tap wrench.

And cheap but necessary is a tap drill chart...shows you the drill size to use for all the tap sizes. These are usually free at your local industrial hardware store.

Call Emco or MSC Industrial Supply and see if you can wangle a catalog.....a huge amount of info can be gained by reading these.