Bicycle Mechanics - metric Helicoil tap sizes?

If anyone has a reference for metric Helicoil tap sizes - at least the major diameter - please let me know where. I've checked two machinists references, and googled. No find.

If you have such a tap, maybe it's marked on the tool?

What are you trying to ask? There are over 250 different metric tap sizes not including custom built ones for custom jobs.

Is this what you wanted: http://www.ebair.com/downloads/mtb/mtb.pdf

Perhaps this is what your looking for: http://stripe.colorado.edu/~genovaj/Mech_Designers_Bkmrk.htm

Are you familiar with the term "Helicoil®"? It rather narrows down the request.

I have the Machinists' Toolbox. Note that in the Reference section it lists the inch-sized Helicoil tap and drill sizes. Not the metric. Likewise the Colorado site.

Are you familiar with the term "Helicoil®"? It rather narrows down the request.

I have the Machinists' Toolbox. Note that in the Reference section it lists the inch-sized Helicoil tap and drill sizes. Not the metric. Likewise the Colorado site.

I don't appreciate the smartashe comment about: "Are you familiar with the term "Helicoil®"? It rather narrows down the request" Actually it doesn't when you word it like this: "If anyone has a reference for metric Helicoil tap sizes?"

Since you think that I don't have any idea what a the term helicoil is, and you act like you seem to know what your talking about; and since your so smart in the area of machining then you can figure it out on you own.

In my experience (limited) with inch-size Helicoils, I found that the taps were non-standard. For instance, the tap for a 1/4-20 Helicoil will have 20 threads per inch, but its outside diameter will approximate that of a 5/16-18 screw. So while a 5/16-18 tap would have about the right diameter to accept a 1/4-20 Helicoil, the thread pitch would be wrong. I'm guessing the same problem would exist with metric ones. That's probably why Helicoils are packaged with a bespoke tap drill and a tap.

Regards,
Bob P.

Time serts are similar and here is a table of some of the
information desired by the OP>
http://www.timesert.com/html/engineeringdataM.html
The site lists the desirable 10x1 in several lengths as
well as a kit of needed parts. Other sizes are listed
as well for metric and US standard inch sizes.
As Bob P notes, the taps are almost certainly proprietary
sizes as the external thread on the insert would match the
internal TPI/pitch and only occasionally would this match up
with a standard screw size.

I don't appreciate the smartashe comment about: "Are you familiar with the term "Helicoil®"? It rather narrows down the request" Actually it doesn't when you word it like this: "If anyone has a reference for metric Helicoil tap sizes?"

Exactly how is the phrase "metric Helicoil taps" ambiguous?

As Bob P notes, the taps are almost certainly proprietary
sizes as the external thread on the insert would match the
internal TPI/pitch and only occasionally would this match up
with a standard screw size.
Thanks for the pointer to Time-Sert.

I'm aware of the non-standard sizing for insert cutters. And I suspect that different brands use different sizes.

I also suspect that the thread profile itself is different too. For instance, you want to bolt to move in the insert, but not the insert in the repair threads. The tap likely uses an interference profile. But that's another issue... :)

Hello, I work as a machinist and drill and tap STI threads pretty much on a daily basis. Tomorrow I will bring home a chart for Metric STI (Steel Thread Inserts aka heli coils). It has drill sizes for STI taps up to about 1/2 diameter or there abouts. I will list the tap and drill size recommended for the minor diameter of each. Always use some kind of lubricant when tapping.
See ya, I'm about to mount my bike and get,
in difficulty

Exactly how is the phrase "metric Helicoil taps" ambiguous?

Your sentence you quoted here is a partial sentence of what you quoted in your original post, and in the partial sense you would be right, but in the original context you would be taken wrong as I did. Here it is again to jog your fading memory: "If anyone has a reference for metric Helicoil tap sizes". Note the missing word? "SIZES"? Therein lies my over 250 sizes comment. If your brainy enough to be using the Machinists' Toolbox software and understand it, then I would have thought that you were brainy enough to come up with the answer yourself; but instead someone else came up with the http://www.timesert.com/html/engineeringdataM.html site, which I also knew about but thought you were looking for something else because of the way you worded your question, and because you came across as someone not knowing a lot about machining since a machinist would have known the answer you were seeking...assuming you asked it correctly.

Helicoil and other similar type of thread inserts use a non standard tap size. The tap used is compatible between the several brands of inserts we use in the shop. Our smallest insert is 3mm and the largest is 12mm.

I will list the tap size first. Followed by two drill sizes. The first drill size is for cut taps, the second is for roll taps. Both are for the "nominal" hole diameter required, nominal being midway between the upper and lower tolerance limits for the minor diameter. The taps are STI taps and should have STI printed on them. STI means Steel Thread Insert.
Here goes,
Tap Size_______ Cut tap_________ Roll tap
M2.5 - .45 _____#37 drill________ _#33 drill.
M3 - .5 ________1/8 drill_________ #29 drill.
M4 - .7 _______#19 drill__________ #15 drill
M5 - .8 ________#5 drill__________ 5.7mm drill
M6 - 1 _______6.3mm drill _________6.8mm drill
M8 - 1.25 _____8.4mm drill ________9.0mm drill
M10 - 1.5 _______Z drill ___________7/16 drill
M12 - 1.75 ____12.5mm drill________ 17/32 drill
M16 - 2 _______16.5mm drill ________45/64 drill

Use some type of cutting fluid. Also you can go up a couple thousandths on the diameter if tapping steel or other hard materials.
Be careful,
in difficulty

Helicoil and other similar type of thread inserts use a non standard tap size. The tap used is compatible between the several brands of inserts we use in the shop. Our smallest insert is 3mm and the largest is 12mm.
You use different brand taps and inserts together? That's interesting. So you think that Helicoil and e.g. Timesert taps would be the same size for a given repair?

in_difficulty, thanks for the chart. Is the thread spec in the left column that of the original or the repair threads?

What do you have for M10-1.0, the common dérailleur hanger threading?

in_difficulty, thanks for the chart. Is the thread spec in the left column that of the original or the repair threads?

What do you have for M10-1.0, the common dérailleur hanger threading?

OK the chart's cool but start with a smaller drill than the chart shows,you can expand a hole,not reduce onced you've drilled.Get a high quality drill bit in the smaller sizes,worth the 2-3 bucks extra.I worked as a machinest,it's quite tricky to center a hole,drills can "dance" off-center.

Yes, you may want to start small if your useing say, a hand drill because it will tend to wobble and drill over size. If your mounting a bike part I would not worry about it too much. Heli coils in a loose hole can still have threads that are "in print" so to speak. If your original threads were 10 - 1. metric then just run the right size drill through the existing hole. It should follow right on through. Then counter sink the hole and tap with an M10 - 1. STI tap. Piece of cake. My reference chart only shows M10 - 1.5. Tomorrow I will check my heli coil spec. book and search for M10-1. By the way, people seem to have a bit of an attitude here. Whats up with that? I am just trying to be helpful not Mr. Know it all. later, in difficulty

You use different brand taps and inserts together? That's interesting. So you think that Helicoil and e.g. Timesert taps would be the same size for a given repair?


No! Timeserts are a different animal. We get our "Helicoil" inserts from more than one manufacturer not just the Helicoil brand name.

The brand of tap does not matter. A 1/4-20 joe blow tap still cuts 1/4-20 threads. STI taps cut threads for heli coils. Simple as that.

No! Timeserts are a different animal. We get our "Helicoil" inserts from more than one manufacturer not just the Helicoil brand name.

I thought they were different. This is the statement that's confusing me:


The tap used is compatible between the several brands of inserts we use in the shop.

What do you mean?

Edit: Oh, I think I get it. The other "brand" inserts are made to Helicoil dimensions so the same tap works with them.

The brand of tap does not matter. A 1/4-20 joe blow tap still cuts 1/4-20 threads. STI taps cut threads for heli coils. Simple as that.
And here, I think, we run into a problem with industry jargon. Please correct me if I'm wrong. "Steel Thread Insert" to me is a generic term. There are many different kinds of STIs. You seem to be using it specifically for Helicoil® brand inserts (or those that use the Helicoil dimensions).

But if "STI" is generic, then the brand of tap *does* matter since we're not specifying the tap by the dimensions of the thread it cuts (as you do above), but by those of the threads we're trying to repair. For instance, I don't say I want a M10.95-1.0 (specifying the repair thread dimensions) STI tap. If I did, any brand that cuts M10.95-1.0 would do*. Instead I say I want a M10-1.5 Helicoil® (you would say "STI") tap (to repair M10-1.5 threads). Or I could ask for a M10-1.5 Time-Sert® tap (and counterbore) knowing that the result is the same, even though it cuts M12.04-1.0 threads for its insert.

That's the main reason I want the actual dimensions of the repair threads. With those I can tell which taps are interchangeable.

For instance, Cyclus sells a repair tap for M10-1.0 that cuts to M12-1.0. The Helicoil tap in the "M10-1.0" repair kit presumably cuts somewhat smaller since the drill size (which they do tell you) is nearly .030" smaller. But just what size does the tap cut? It seems to be a giant mystery.


*Ignoring profile for now.

Sorry, but I have never heard of timeserts, and yes we only use heli-coils, not for repairing threads but for making stronger threads in aluminum parts. As for the M10 - 1. (this is a fine tooth thread) the correct drill is a 10.25mm . Run the heli coil one turn below the surface. If your heli coil is longer than your part is thick just clip a coil or two off the top. I am not sure of the actual thread specs that the STI tap cuts, but who cares if it works, right? Try not to over think it. Make it simple, in difficulty

Correction:

STI stands for Spiral Threaded Insert, not "steel threaded insert"

There are other manufacturers of spiral threaded inserts, Recoil is one I've seen, other than Helicoil. Spiral threaded insert is the generic term for Helicoils. There are other thread repair methods, some of which have a larger insert that matches the next larger standard size thread, these use standard taps. A spiral threaded insert is able to repair threads with the least amount of material removed, therefore special STI taps are necessary. To get the correct STI tap, you need to match it to the proper STI. Size is dependent on the thread you're repairing. Metric or otherwise.

Edit: I've also seen STI as Screw Thread Insert, but I've heard them called spiral thread inserts, which is what I usually call them. Either way, they can be made from other materials than steel, bronze being one.

A little more:

http://www.katonet.com/techinfo/specs.html

Note that this is a reference for the various specifications on this type of insert (helical wire inserts, like heli-coils).

Time-serts and Keenserts are different animals, and require different taps. The STI is a standardized thread repair standard and thus the inserts and taps should all be interchangeable between brands, provided that they are made to spec.

The thread data you are asking for is hard to come by, it may be spelled out in the specs I linked to above, but I don't actually have the specs, so I don't know. What I do know is that standard screw thread taps do not fall into the proper range for a STI. Some of the Mil specs are available on line, but I don't have the link in front of me right now. As someone who has done many thread repairs, I just buy the proper STI tap and be done with it.

Like I said before, there are several thread repair systems out there, many are proprietary, some, like heli-coils, are standardized.

If anyone has a reference for metric Helicoil tap sizes - at least the major diameter - please let me know where. I've checked two machinists references, and googled. No find.

If you have such a tap, maybe it's marked on the tool?

I guess I'm not seeing in this thread the reason for your request. I've installed hundreds of Helicoil inserts and each kit I owned had it's own tap for sizing the hole. Have you lost the tap that came with a kit, or are you trying to chase the threads on a hole with an insert, or something else?

Lots of wrangling just to answer a simple question:


http://www.helicoil.in/pdf/HeliCoil%20Catalogue.pdf

Quite a bit tangent to the original topic, but are you trying to repair a stripped rear derailleur hanger?

If so, there are specific bushing kits available to repair these threads that do not require threading the repair hole. You drill the damaged threads out oversize and slip a flanged bushing in. The rear derailleur bolt then threads into the bushing. Here is the complete Var kit but the bushings are available individually for about $8 each and Wheels repair bushings are about $10 each.

http://www.biketoolsetc.com/index.cgi?id=92531081272&d=single&c=Shop-Aids&sc=Thread-Repair&tc=Complete-Kits&item_id=VR-130

Incidentally, Bike Tools Etc. offers complete metric thread repair kits (drill, tap and inserts) for a wide variety of thread diameters. Do a search on their web site for "thread repair".

Wow! Sometimes it pays to re-animate moribund threads! Much more info than the first time around.

Dave, it appears that most of the info I wanted is indeed in the catalog, and I'm more than a little surprised that I couldn't find it online the first time around.

On first look they don't mention outer thread profile but the way they describe the positive fit in the repair seems to imply that they don't need an interference profile. I'll spend some more time with the document later.


HillRider (et al.), I frankly don't remember what caused this thread. After a while it turned into a question to be answered for its own sake. ;)