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kolleamm
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I need to know what is the strongest most reliable tap for threading 6-32 into stainless steel. I used like 3 cheap steel taps and they all broke. Any advice is greatly appreciated.
Thank you
Thank you
I will try to mount the tap in the drill press rather than doing it by hand in that case.Baluncore said:Cheap taps are commonly made from Carbon Steel. More reliable, harder taps are made from High Speed Steel.
HS is almost certainly “High Speed”, the steel goes without saying.
G H3 is probably the finish and oversize. H3 may mean 1.0 to 1.5 thou oversize.
Find some way to support the tap in line with the hole. Experiment with cutting fluid, oil or soap. That will almost certainly reduce breakage. Some taps in some materials produce the best finish by cutting continuously. Others require a slight advance, then a reverse to break off the cuttings. You will need to experiment to find the best technique.
Corrosion is usually the most important parameter, but if possible select a grade of stainless that is free machining.
I tried it both ways without the drill press and it broke regardless. Funny thing though I just screwed it in in the drill press and it worked even without turning it back.CWatters said:Sorry if you know this but... Are you just trying to screw the tap in or are you doing the normal half turn in and a quarter turn out?
Could you explain the material hardening? I still don't fully understand it. The stainless type is 420Baluncore said:Different stainless steels work harden differently. If you “work” the tap you may harden the material, then break the tap when it hits the previously hardened wall. If you continuously turn the tap the chips will be hardened but the material being cut will be fresh and normal hardness. The speed of cutting is important because the hardening process is a chemical phase change. In some materials, if you back off torque momentarily you may hit a hardening wall.
Avoid machining old, salvaged or unidentified stainless steel. You will probably need carbide tooling.
There are different flute profile taps, spiral flute taps are designed to cut continuously while straight flute are designed to be reversed to break the chips. Don' be mislead by “spiral point”, in hard materials they are often as bad or worse than straight flute because they clog with chips, especially in blind holes. The spiral path of the flute decides the curl of the chip and the quality of the thread finish.
There are many different stainless steels. What grade material are you threading ?
How long or deep is the thread you are cutting? Blind or through hole?
Is your material new or aged? Has the material been subjected to cold temperatures? for what periods?
kolleamm said:Could you explain the material hardening? I still don't fully understand it. The stainless type is 420
kolleamm said:True, also I found a very easy way to get small broken taps out is by hole punching it about 20 times. It just flies right out.
You are being pessimistic. It is not a black art, it is a science.gjonesy said:I have seen aluminum break taps, its so soft it grips the tap and the metal chips get hung up and the tap just breaks. It happens, you just have to work with it.
Thanks guys I think this sort of knowledge is very good to know, and you will mess up at some point when first learning it. As long as you learn something from it that's what's important.Baluncore said:You are being defeatist. It is not a black art, it is a science.
There is an optimum way to perform any operation. If you are breaking tools then you do not know what you are doing. If you use a spiral flute tap made of the right material, with the correct cutting lubricant and the correct technique, then it will not break the tap.
Brittle materials cannot be tapped but they can be ground. I think any non-brittle metal can be tapped with the correct tool material, profile and process.kolleamm said:On another note, is there any materials out there that you can't tap with anything? I'm thinking Inconel for example.
kolleamm said:I need to know what is the strongest most reliable tap for threading 6-32 into stainless steel. I used like 3 cheap steel taps and they all broke. Any advice is greatly appreciated.
Thank you
I have some really thick stuff which has been good to me so far.Baluncore said:it is essential that you use a cutting fluid.
It's easy to go too far but I 'control myself' to use very small angles. OTOH, for the right material and the right tap (and the right drilling size) 'they' (manufacturers) seem to just tap in one go with continuous rotation. That can avoid the work hardening situation but you need to keep your nerve and have everything just right.OldYat47 said:And never turn the tap more than 1/2 turn without backing off at least 1/4 turn.
A good technique and fine if you can get to the other end of the hole but the really awkward situations are often the ones that you can't get there and the hole is blind and you have to do by hand at a funny angle.kolleamm said:True, also I found a very easy way to get small broken taps out is by hole punching it about 20 times. It just flies right out.
The best tap size for threading stainless steel depends on the specific size and type of stainless steel being threaded. Generally, a smaller tap size is recommended for thinner stainless steel while a larger tap size is needed for thicker stainless steel. It is important to consult a tap and die chart or a machining expert for the best tap size for your specific application.
The most effective type of tap for threading stainless steel is a spiral point tap. This type of tap has a pointed end and flutes that spiral up the tap, which helps to push the chips out of the hole as it cuts. This reduces the risk of chip buildup and breakage, making it ideal for threading stainless steel.
It is not recommended to use a standard tap for threading stainless steel. Stainless steel is a hard and tough material, and a standard tap may not have the necessary cutting edges and design to effectively cut through it. This can result in poor quality threads or damage to the tap.
When tapping stainless steel, it is important to use a lubricant specifically designed for stainless steel. This can include cutting oils, tapping fluids, or even a mix of oil and water. The lubricant helps to reduce friction and heat, which can prolong the life of the tap and produce better quality threads.
To prolong the life of your tap when threading stainless steel, it is important to use the correct tap size and type, as well as a suitable lubricant. Additionally, it is important to use the correct cutting speed and feed rate, as well as periodically stop and clear any chips that may have accumulated in the hole. Proper maintenance and sharpening of the tap can also help to extend its life.