Tap and die set recommendation

[Rafiki]

All attempts having failed to remove a bolt sheared at the head I now have a bolt with a (fairly ) neat hole through it and now intend to to make a thread with a tap , or is it die, to take a smaller bolt.

I don't currently have a tap and die set, therefore need to buy one, but research shows a huge price difference. Has anyone got any recommendations for something of reasonable quality - having got thus far through life without havinga set I don't think it is going to get that much use !

Regards

 

[sailorman]

All attempts having failed to remove a bolt sheared at the head I now have a bolt with a (fairly ) neat hole through it and now intend to to make a thread with a tap , or is it die, to take a smaller bolt.

I don't currently have a tap and die set, therefore need to buy one, but research shows a huge price difference. Has anyone got any recommendations for something of reasonable quality - having got thus far through life without havinga set I don't think it is going to get that much use !

Regards

Y a "Set" Y not buy a tap ( internal thread) or a Die (external thread) of the size you req
what size do you req as i have a small assortment of metric & whitworth taps & dies

 

[Heckler]

All attempts having failed to remove a bolt sheared at the head I now have a bolt with a (fairly ) neat hole through it and now intend to to make a thread with a tap , or is it die, to take a smaller bolt.

I don't currently have a tap and die set, therefore need to buy one, but research shows a huge price difference. Has anyone got any recommendations for something of reasonable quality - having got thus far through life without havinga set I don't think it is going to get that much use !

Regards

Dont under stand, have you broken a head stud and are trying to get it out?
Stu

 

[TQA]

Errrgh Is it stainless?

If yes then buy the very best taps and hope that you have not work hardened the stainless when drilling the hole. A set from Aldi is unlikely to cut it.

If it is a blind hole you will need a set of three to stand any chance of success.

Drilling and tapping stainless is a known problem area. I am not saying impossible but definitely difficult.

 

[Brian blue bear]

If you now have a small hole try a stud extractor these tighten anti clockwise hopefully removing the bolt

 

[pagoda]

If you now have a small hole try a stud extractor these tighten anti clockwise hopefully removing the bolt

I think the OP needs to let us know what diameter the offending bolt / stud is - and also what size of hole he's managed to drill through it.
You are REALLY stuffed if you try an "easy-out" - thread extractor which is too light for the job. It may well break off in the hole- leaving you with a seriously hard blockage!!
If you have a really good central drilled hole - I'd work up a few drill sizes - very carefully to about 60-70% of the bolt size at least before trying an extractor.
Don't buy the cheapest set please.
With stainless - I would also suggest you get a set of decent cobalt alloy drill bits- which will give you a fighting chance- and work "light" so you don't over heat and harden the problem area.
If you enlarge the hole somewhat - you might have the chance of cutting a smaller thread inside it - depending on how beefy it needs to be?
And you have made a really well centralised hole - I have occasionally drilled out progressively to release the spiral thread "spring" of the old bolt- which often can be removed by hand with an awl - or something similar- leaving the the old threaded hole in good shape. - or good enough to clean up with a 2nd or a plug tap.

Give us some more info and a better appproach may be worked out?

Graeme

 

[Rafiki]

If you now have a small hole try a stud extractor these tighten anti clockwise hopefully removing the bolt

I tried that today, but without any success, I was fearful of breaking off theextractor within the stud.

Regards

 

[earlybird]

All attempts having failed to remove a bolt sheared at the head I now have a bolt with a (fairly ) neat hole through it and now intend to to make a thread with a tap , or is it die, to take a smaller bolt.

I don't currently have a tap and die set, therefore need to buy one, but research shows a huge price difference. Has anyone got any recommendations for something of reasonable quality - having got thus far through life without havinga set I don't think it is going to get that much use !

Regards

The cheap, carbon steel £12 to £15 sets from DIY outlets are rubbish, their only use, if any, is for cleaning up damaged threads. Rather better carbon steel sets will cost significantly more, and, from what you say, will be little used.
You require just a set of taps, 2 or 3, and a suitable tap wrench. The easiest way would be to go to your local engineers merchant. They normally only sell high speed steel taps, but usually individually. They are expensive and probably overkill, a taper and plug tap plus wrench will set you back about the same as the cheapo set.
If your job is transportable, can you take it to the local workshop?

 

[Rafiki]

I think the OP needs to let us know what diameter the offending bolt / stud is - and also what size of hole he's managed to drill through it.
You are REALLY stuffed if you try an "easy-out" - thread extractor which is too light for the job. It may well break off in the hole- leaving you with a seriously hard blockage!!
If you have a really good central drilled hole - I'd work up a few drill sizes - very carefully to about 60-70% of the bolt size at least before trying an extractor.
Don't buy the cheapest set please.
With stainless - I would also suggest you get a set of decent cobalt alloy drill bits- which will give you a fighting chance- and work "light" so you don't over heat and harden the problem area.
If you enlarge the hole somewhat - you might have the chance of cutting a smaller thread inside it - depending on how beefy it needs to be?
And you have made a really well centralised hole - I have occasionally drilled out progressively to release the spiral thread "spring" of the old bolt- which often can be removed by hand with an awl - or something similar- leaving the the old threaded hole in good shape. - or good enough to clean up with a 2nd or a plug tap.

Give us some more info and a better appproach may be worked out?

Graeme

It is an 8mm stud and I have drilled a 4mm hole right through it (but I can't get to the underside of the stud. I have also drilled 5mm part way through. My intention is to tap it such as to use a 6mm bolt. It isn't stainless just normal steel.

I have a decent set of drill bits as you describe and didnt break any of them, but it's taken me two hours to get this far ( plus travel time so that's 6 hours!)

To explain further it was a stud holding one of the rubber engine mounts in place, it therefore bolts into the engine bearers (into a threaded insert).

Today I was attempting to get the stud out with one of those LH thread inserts, my next attaempt will be to thread the inside of the bolt to take a 5 or 6mm stud. If all else fails I will make an even larger hole and epoxy in place some sort of insert, but from my drilling today I have ascertained that there is some sport of hollow underneath the bolt so simply making a larger hole and filling with epoxy which I was thinking of doing may not be feasible.

Regards

and thanks for any suggestions as to the quality of dies I need.

 

[srp]

Try Dormer or Roebuck. As someone above mentioned, a local engineering suppliers will be better than messing around with rubbish from B and Q, or you could try Buck and Hickman ( www.buckandhickman.com ). An M5 or M6 tap will cost around a fiver, and you need a set of 3 (taper, second and plug tap). Also a tap wrench. For confined spaces one like this (this is a fancy ratchet version, but a standard type is fine):

I think I'd be tempted to try drilling out a bit more to resurrect the original thread - if it is 8mm then a 5mm replacement is hardly likely to be up to the job. Try and work up to a 6.5mm drill if you can, and then expose the first few threads by working the waste out with a pointed tool like a scriber. Clear enough to locate an M8 tap, and if you're careful you should be able to restore the original. Use grease as a lubricant, or better still a cutting compound like Trefolex. (The correct drill for tapping M8 is actually 6.75mm I think, but not many people have one in their toolbox).

 

[Avocet]

As has been said, you need to go for "HSS" taps (High Speed Steel). Forget about the cheap ones - they're worse than useless. "Goliath" and "Dormer" are both well-respected brands. Be very wary of taps that claim to be "Hardened" or "Cobalt" or "Titanium coated".

As for trying to put an M5 bolt in to do the job of an M8, I'm not sure I'd risk it (although it depends on the sort of load that will be on it). Generally, most designs won't have such a big safety factor that you can almost halve the size of the fastener and still have it work.

Generally, IF (and it's a big "if"!) your hole is central, you can go down there at almost the tapping drill size and then run a tap down it again. Usually, with an M8 bolt, if you can get a 6mm (or better, a 6.5mm) down the middle, you might well find that the remains of the bolt will relatively easily collapse in on themselves with a bit of help from a centre punch or and M8 tap.

Another point. Taps tend to come in threes. For 8mm you'll have a "taper", "second" and "plug" or "finishing" tap. The taper is just that. It is tapered and gives a gentle lead-in. Probably the best for starting to tap a new thread. The middle one is the one that everyone uses when they're too tight to buy the set of three. The plug tap has no taper and is supposed to get as close as possible to the bottom of a blind hole.

One last thought: Make sure the original fastener was the same pitch as the tap that you buy! M8 x 1.25mm is the most common metric "coarse" thread, but you can get finer ones.

 

[Ubergeekian]

I don't currently have a tap and die set, therefore need to buy one, but research shows a huge price difference. Has anyone got any recommendations for something of reasonable quality - having got thus far through life without havinga set I don't think it is going to get that much use !

Absolutely the best place for taps and dies is the unsurprisingly named "Tap and Die Company", www.tapdie.com. Their range is astonishing (five different pitches of M5 alone, as I recall), the quality is superb and the prices, particularly if you buy a set, are high but reasonable.

I'm just a customer. They are fast and pleasant people to deal with.

 

[Deleted member 36384]

Don't Bodge Your Engine Mounts

I would advise that you have to remove it and fit the original size stud to ensure the engine mounting is in line with the original design. If you have to take the engine out the boat to do this, then it will be worth the effort.

My own experience when one engine mount failed was a sheared gearbox flange on a lee shore with a F7 up my chuff. Luck saved my day - just.

If this stud forms part of the security of the engine (as opposed to maybe just retaining the rubber) then don't do a bodge job on it. Its highly unlikely that a smaller diameter stud can resist the same cyclic loads, for the same length of time as a bigger stud.

I have persisted with small drills, small files, small centre punches, drifts, heat, cursing and skint knuckles to get sheared bolts / studs out. Keep at it if you can. If you can get a drill in then you can snap a small diameter file into short stubs and put it into your drill. Then try and "mill" it to a thin wall such that you can remove the old stud carcass. Good Luck.

Post Posting Note: I have assumed that you are considering using the smaller bolt to mount the engine after successfully fastening it into the old stud.

 

[simonfraser]

if the origional stud has hardened and is now making the job even harder, i assume you have considdered making a new hole in the old block ?
might be easier to do that and reposition the engine support ?

 

[Sans Bateau]

I tried that today, but without any success, I was fearful of breaking off theextractor within the stud.

Regards

The stud extractors that work with a tapered anticlockwise pitch will be unlikely to work, believe me. If you stand any chance of removing the stud at all then you need to get one of these:
http://buy1.snapon.com/catalog/item...d=1254&supersede=&store=snapon-store&tool=all

Sorry it is the USA web site but a quick Google will find UK contact details. You will not need to buy the complete set, just the size you need. They work by drilling a hole, (which you already have) and then a steel shaft with flutes in is tapped into the hole, a nut type device then slips over the shaft and you can then, with a spanner, work away at the stud. You may start to get the stud moving by trying to turn it clockwise then anticlockwise, rock it back and forth.

One word of warning, there is no guarantee that the stud will come out, you need to stop BEFORE you brake the extractor, other wise you do have a problem.

 

[JohnTH]

Is it possible to get at your broken stud to weld? I have had some success with welding a flat washer through the hole on to the stud then weld a nut on to the washer. The heat from welding has played its part in loosening the stud too.

Sometimes drilling hard material is just too difficult. Even my best quality drills struggle with small roll pins so I grind them out with diamond burrs fitted to the dremel.

73s de
Johnth

 

[Rafiki]

if the origional stud has hardened and is now making the job even harder, i assume you have considdered making a new hole in the old block ?
might be easier to do that and reposition the engine support ?

Thanks for your suggestion but the problem is the bolt(one of a pair) attaching the rubber mount to the engine bearer. The attchment to the engine (very heavily load bearing) is OK.

 

[TQA]

I would forget about trying to tap it. If you have already got a centralised hole just keep enlarging it until you can remove the broken off remains. Another poster suggested an awl, that is what I would use once you get close to the edges.

 

[Appleyard]

Another thing to consider is a left handed drill...yes they do exist. Ihave used them on occasion and with some success as the name suggests,they drill in an anti clockwise direction ...same direction as unscrewing the stud,and a combination of the heat from the drilling and the torque is enough to wind the bugger out.
I think FROST the car restoration suppliers do them.

Also,if you can,make a "Dam" round the stud with some putty or similar ,fill it with penetrating fluid (plus gas is best) and leave it till next weekend.Then have a go.

 

[PetiteFleur]

Another possibility is to drill it all out and fit a stainless thread insert(I forget the trade name......). The hole is tapped out with a special tap, the insert screwed in, a tang snapped off and a stud of the original size can then be screwed in. But will only work if you are drilling into solid metal. Most engineers can do it - not worth buying the complate kit as it's expensive.