Spiral Flute Taps

[Tony Wells]

Bob, the "driven end" that John referred to is the "outside" of the part. And you're right, spiral points do tend to push the chips forward, so can pack the hole up at the bottom. Spiral flutes do the opposite, towards the driven or machine end.

 

[Bob Korves]

Bob, the "driven end" that John referred to is the "outside" of the part. And you're right, spiral points do tend to push the chips forward, so can pack the hole up at the bottom. Spiral flutes do the opposite, towards the driven or machine end.

Thanks for the correction, Tony. Yes, John had it correct (as usual!) I also mostly use hand taps for just about everything, simply because I have so many of them, good brands in nice condition, bought for pennies on the dollar. Many machinists do not seem to want to clean up and sort drills and taps...

 

[Robert LaLonde]

Any disadvantage to spiral flute taps vs standard plug taps?
They seem to be enough of an advantage to not bother with regular taps any longer.

I thought a plug tap was a sort of in between taper version of a hand tap. Sort of a universal application. Not a taper or starter tap and not a bottoming tap but part way in between.

Spiral flute and spiral point (machine taps) also can have different starting tapers. I've found for machine tapping through holes that spiral point taps work better for me than just about anything else. I also sometimes use them for hand tapping. If you are tapping a blind whole a spiral flute tap draws "most" of the chips out of the hole the same way a drill bit does. However I find there are always some fine chips that can back up in the hole anyway. Its always a good idea to stop short and blow out the hole before finishing to the bottom.

I've been using an old set of Harbor Freight taps and dies for probably close to 20 years. They are all plug profile hand taps (well except the dies. LOL) On tough tapping I prefer not to use them at all. I am in the middle of a project tapping a bunch of holes in 4140HT (not as bad as stainless) and I have been starting them with a taper hand tap and finishing with a bottoming tap. Since I knew it would be tough I went over to Copperstate Bolt and bought some brand new taper and bottoming hand taps for the job. I am amazed at how much better they work than the cheap HF taps. Even the HF taps that have not seen much use and are still pretty sharp. I would note that the taps I got from Copperstate ARE sharp.

Getting back on topic. I have a number of different types of taps, anbd I have found spiral point go through the easiest followed by long taper starting hand taps. (Sometimes labeled as taper taps) Spiral flute are only third and if they do not have a starting taper they can be nearly as hard to drive as a bottoming hand tap.

Less and less often do I use a plug tap from that old HF set, and more and more I buy quality taps 1-3 at a time for specific applications. I just wish Copperstate stocked machine taps in the local store. I would note the taps from Copperstate were not all that expensive. Less than $6 each. I bought spares of each. I know that's a lot if you want to buy a whole set, but its not much to get through today's job.

 

[19E60]

I tried spiral flute taps (Korean YG1) for the first time tapping cast iron blind holes on the mill for DRO install. I have since used them to tap both aluminum and mild steel by hand and machine. I will likely never go back to standard taps unless I have no other option.

 

[T Bredehoft]

Spiral flute taps are the ones I choose first. When tapping by hand they seem to want to go straight, without leading off. When machine tapping the chips coming out behind the tap encourage me, knowing that they are not inside, getting ready to jam the tap. I do use bottoming (regular) taps when a hole isn't tapped quite deep enough.

 

[Robert LaLonde]

Bob, the "driven end" that John referred to is the "outside" of the part. And you're right, spiral points do tend to push the chips forward, so can pack the hole up at the bottom. Spiral flutes do the opposite, towards the driven or machine end.

You must be talking to the other Bob. However, I want to make it clear that based on direct experience spiral flute taps clear out "most" but not all of the chips. Its always best to remove the tap and blow the hole out before bottoming.

 

[GoceKU]

Only reasons i can think of is higher price and strength, they are easy to break off, for a home shop they are awesome.

 

[cmantunes]

I tried spiral flute taps (Korean YG1) [...] I will likely never go back to standard taps unless I have no other option.

Same here, also using YG1, both on milling machine or manually. These YG1 spiral flutes are just a delight to use and they are not, IMO, all that expensive.

 

[neshkoro]

About the only reason to use them is for blind holes, because they eject the chips at the driven end; I don't thin that I have any of them, I use ordinary hand taps for most everything.

John, spiral POINT taps push the chips ahead, spiral FLUTE taps pull the chips out. It is often said that spiral point taps are for through holes, and spiral flute taps are for blind holes, but it is not that simple and there is some crossover.

I like spiral point taps as they require much less force to cut. Only problem is that they push chips forward. Not ideal for blind holes. Makes for a lot of work to clean out the hole after.


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[JPMacG]

I broke a spiral tap and haven't used one since. It seemed like it broke way too easily compared to a conventional tap. Maybe I should give them a second try. I have a bunch that I got at an estate sale.