Tap and Die

[adi1974]

Hi there. I'd like to clean up the threads on my engine before I rebuild it. So I'm looking to get a tap and die set. I wondered what I should look for in a kit. What are the essential items I'll be needing? Also I've seen alot of cheap sets but I'm guessing they're a risk (particularly the taps). Is it the kinda tool you really do need to buy quality?

If anyone can recommend a kit that'd be great. I see Mikes has one but I'm in the UK.

Cheers
adi

 

[racerdave]

There is a difference between cleaning threads and making threads. Look into thread chasers

 

[adi1974]

I'm going by what I've ready here by Hugh... http://www.bikermetric.com/p/techtips_10.html

 

[jd750ace]

A tap cuts sharper profiles than the preferred rolled profile. To maximize the benefits of the factory profile, a chaser is the way to go on threads that are not otherwise damaged.

 

[5twins]

For cleaning up bolt threads, you can't beat an old fashioned thread file. They do a wonderful job and don't cost much. I've had one for years but just recently started using it and I'm impressed.

 

[racerdave]

5twins, agreed. Been using them for years on both metric and American threads. The damn things are so hard to fit into bolt holes though

 

[SE Road King]

Also note that there are significant differences between thread forms on tapered pipe threads and their unions, eg: NTP and NTPF.
IMO they each have a place.
Where pressures are low (<45 psi) and tempretures are low(<280*) where fluids are concerened I would promote the use of NPT pipe taps and dies along with the use of teflon tape or liquid teflon sealants. (Slightly hotter up to 400* with proper sealants.) Above that and where heated vapors are included with fluids above 60psi I would elect to go with NPTF taps and the dryseal type of fittings. Special care must be used with NPTF taps and finess assembly techniques used for dry seal fittings. (1 application only) When properly applied this thread form will provide superior sealing.
It is a matter of opinion where the fluid and vapor pressure break points are for the thread form use, Vickers says this, Kawasaki heavy says that, Sunstrand, Catapillar, Hitachi all say something different and I've seen a lot of teflon tape on 1,200 psi systems. I don't like it but I've seen it.
Just be aware.
I will be cutting dryseal (NPTF) threads for my oil feed lines but not so on static drains and plugs. There I will be cutting NPT and using #565 Teflon Thread Sealant.
My favorite motorcycle manufacturer knows this now and engineers appropriately. Until reletivly recently ('83) AMF had ignored this. 7 of the 8 pre '84 american v-twins I have owned never leaked a drop after my machine work, except the '49 EL which is supposed to expell oil in two places by design. The other 7 shovelheads did so from the factory but I know how to seal them up, I am sure many others do as well. I picked on Harley because of the stigma they carry, I've owned countless metric bikes that rarely leaked as well. I despise oil and vapor leaks, it's just not acceptable. LOL.

 

[SE Road King]

For cleaning up bolt threads, you can't beat an old fashioned thread file. They do a wonderful job and don't cost much. I've had one for years but just recently started using it and I'm impressed.

Blue point (snap-on) makes SAE and ISO(metric) thread files in both fine and coarse thread. With just a little practice you will be able to repair most bolts and screws very well and quickly. With little chance of failure or scraping your project. A must have in any wrench's tool box

 

[Cafe-Dave]

M6x1.00 tap, M8x1.25 tap and die, M10x1.25 tap and die

That will take care of your case studs + acorn nuts (M8x1.25), cylinder studs + acorn nuts (M10x1.25), and sump plate + starter gear door (M6x1.00)

 

[willyguzzi53]

If you do buy some taps and dies don't buy cheap ones. Even a cheap tap is harder than a drill bit when you break it off in a hole.

 

[SE Road King]

A tap cuts sharper profiles than the preferred rolled profile. To maximize the benefits of the factory profile, a chaser is the way to go on threads that are not otherwise damaged.

Saftey first , saftey glasses always!
If a fellow is handy with a dremmel and/or die grinder one can fashon a nice chaser from a high grade bolt of the given size. Just vice up the bolt to expose say 5-10 threads, and using a slitting wheel (or a round stone of a diameter equal to about 1/2 or no greater than the diameter than the bolt) cut out a fluted area on your chaser bolt to provide a near perpendicular, faux cutting face about twice the dept of the thread (up to 1/2 the diameter) and across 5-8 threads making a cavity for trash to collect in. You will need to wrap your head around the screw and visualize which is the face that will be faux cutting face. Using care youll be able to clean up tapped holes cheaply and not buy a bunch of taps that you will never use. They are hearty and tough to break off into a hole. Now this kind of chaser will not last long, but in some cases, could be reground.
WARNING. do not force these types of chaser, or any tap or chaser for that matter and remove your debris very frequently. You will want to use hand-driven tools only to drive this chaser, as you'll be able to tell at once when your torque is getting too high.
Butter bolts are not a good choice for this type of tool. And never chase a interference fit tapped hole, like for studs that should not turn. These threads are of a special form and a common tap is likely to ruin your job HAPPY WRENCHING!

 

[Cafe-Dave]

I would advocate not using a tap handle to drive the taps. An adjustable wrench keeps the misalignment problems to a minimum. Guide the body of the tap with your fingers.

 

[SE Road King]

M6x1.00 tap, M8x1.25 tap and die, M10x1.25 tap and die

That will take care of your case studs + acorn nuts (M8x1.25), cylinder studs + acorn nuts (M10x1.25), and sump plate + starter gear door (M6x1.00)

On acorn nuts, chances are that you'll need a bottoming tap. Look for my cheap chaser instructions in this thread, it may help you.. However, acorn nuts rarely get trash in them (cannot while installed anyway) but can become dammaged if cross threaded or over torqued. In this case a tap or a chaser is of little value. Replace them.

Also remember if your case studs are by design, not ment to rotate DO NOT use the common tap on this hole. Interference thread holes require a special therad form, and therefore will require taps with smaller pitch diameters. (and my instructions for chasers do not work here either)

 

[SE Road King]

I would advocate not using a tap handle to drive the taps. An adjustable wrench keeps the misalignment problems to a minimum. Guide the body of the tap with your fingers.

Caution y'all=== With all due respect
IMO a tap handle or tap wrench is the proper way to drive a tap. Using a cresent style wrench can easily load one flute ascew and unnessasarily cut your hole oversize . it is very easy to riun a tapped hole using a one sided driver.
For a safe way to use a tap handle or tap wrench, always start your tap alone by hand and after it positivly started then apply your tap handle, using equal pressure with both hands , one on each side, to drive the tap centrally about the axis of the hole.
Always use care when using a HSS(tool steel) tap for chasing purposes. By allowing the tap to run out of the intended axis of the hole it dosent take much to cut the pitch diameter oversize. Which may not seem to be a problem to many, it actually is a problem. when torqued the bolt threads are now loaded out side of the engineered pitch diameter and is therefore weaker (by a longshot) and subject to failure easily. A small piece of bar stock equal to 3-4 or more threads can be used as a perpendicular guide when drilled the same size as the tap O/D

 

[3Deuces]

This is what you want:
http://www.sears.com/shc/s/p_10153_...01&srccode=cii_17588969&cpncode=31-44346233-2

You want to clean/restore the threads, not cut new ones.

 

[racerdave]

Thats a great little kit 3deuces.

 

[jd750ace]

That's the kit I've had for fifteen years. Great set.

 

[3Deuces]

I get to use the thread files from that kit quite a bit at work. Guys like to put threaded adapters or bushings in the vise when they are trying to seperate them

 

[Purplezinger]

I have to jump in here, a crescent wrench on a tap is absolutely wrong. Used this way guarantees incorrect threading or a broken tap or both. Buy a proper tap handle and use it.

 

[SE Road King]

Respect to the gent from Kentucky who applies SPC principals to life. Love the quwip.
Good machining/manufacturing practices are all about maximizing quality and negating falure. AKA " Robust Processes". They are not wrapped by magic or mistery, but logic and technology. Happy wrenching!