How to hold work-pieces at strange angles for drilling. A special Vice ???

[harryb94]

What's the head made of? I was impressed by this the other day:

 

[dobbslc]

Keep your dick in a vice!

 

[Gareth J]

Tried it. The studs are so corroded they won't budge. The nuts just keep snapping off. I've tried heating the head etc. I've tried everything.

They will do if you just try to weld a nut on. Try just blobbing weld onto the sheared face, plenty of amps, building it up blob by blob.

Most important is to blob on enough to grab with small grips and and when it moves, stop turning and screw it back in again or it'll shear again. Work it out like that, back and forth, back and forth with fluid.

Got a rusted m6 out of ali the other day, sheared below the surface.

Fair enough if you've tried the above but I've not had much luck just welding a nut on unless it's a pretty big bolt - the nut fills with weld before you can get enough heat into the sheared bit.

 

[Kent]

Tried it. The studs are so corroded they won't budge. The nuts just keep snapping off. I've tried heating the head etc. I've tried everything.

I think you miss read what he suggested and its exactly what I should do before reaching for a drill. this is way more effective than extractors. You see your not adding a nut just weld bit by bit all the time your getting the heat right were it wants to be without hitting the big heat sink that surrounds them. Once your clear you grab it (the weld blob) with mole grips and twist mostly its like it was never even stiff let alone stuck

 

[MrFluffy]

Adjustable angle plate, bolt it to the machine bed and set it 20deg off vertical so the stud is presented vertical. I have a homemade rotating fixture I can set to any angle that I can bolt a 4 cylinder head into my mill for porting and chamber work (I build dragbike stuff occasionally for fun).
The easiest way rather than faffing round trying to get a grip on a head with milling clampdowns is to make a fixture plate that bolts the table through the standard holes already in your angle plate into tee nuts or holes if it doesnt have slots, and drill into the plate and tap it and bolt the head to that. Bonus is you can reuse the plate with clever use for different bolt patterns until it starts looking like swiss cheese, and you can mark the bolt pattern so the next head you get through from the same bike can be bolted on the same way.

Something like this I just found on tinterweb is what I mean for the angle plate, it just needs to be two big solid pieces with a hinge and a way to lock it to angle.


As cautioned a drill press might wander because drills are a bit flexible, so if you dont get the angles perfect, the end of the stud ground flat first and get the guide centre dot on centre you can end up with it wandering off into the softer alloy material around and then you are into welding up the repair and retapping it. If its new to you, best have a practice go on that old engine lying round the back you dont care about first. Honda's are great for this

 

[Screwdriver]

CRIKEY !! That things huge hahah. Out of interest, how much are you selling it for ?? If you are that is.

Couple a hundred quid I guess but I too restore old motorcycles and I wouldn't use it for that job.

Weld and unscrew and if you can't do that, take it somewhere that can, presumably, as has been said, with a spark eroder.

What bike is it by the way?

S.

 

[tedmagnum]

I've tried all sorts of welding methods. The studs are M6 and they are so corroded they crumble. I guess its worth another go using the blob method.

The studs did have thread protruding when I got it. I put as much heat into the head as I dared without warping it. They still wouldn't budge and would crumble. Once the 'crust' fell off them they were more like M4's..

It's a Yamaha XT600. They're well known for this problem. I've done a few of them in the past. This one is the worst I've ever seen. Off-roaded in a salt marsh by the looks of it.

I've drilled and tapped plenty of heads in the past. I'm comfortable with the job. Just not at angles.

Correct, a pillar drill does have more drift than a mill. My pillar drill is an old Startrite. It's pretty solid and 'wander' is rare. I keep the drill bits short and use a lathe centering tool to start the hole off. I've been 95% successful on drill the centres out and then tapping out the very thin sleeve of what's left.

I'm always open to new ideas and suggestions though. Keep them coming. I will try them.

Thanks again. Great forum

 

[penfold]

As cautioned a drill press might wander because drills are a bit flexible, so if you dont get the angles perfect, the end of the stud ground flat first and get the guide centre dot on centre you can end up with it wandering off into the softer alloy material around and then you are into welding up the repair and retapping it. If its new to you, best have a practice go on that old engine lying round the back you dont care about first. Honda's are great for this

This is where centre drills come into their own; start the hole off using them as they are far stiffer then swap to a jobber to drill through.

 

[addjunkie]

Ive done a few jobs of this nature.....the tilting mill tables are great, but when you plonk the head on it and need space for the clamps, the seem to shrink imeasyrable. Is that a word....anyway if buying you need to buy big to allow for the clamps.

I to would use a center drill to start it, but then id run in with a much smaller drill, and gradually increase, you may be lucky and trim so the bolt splits and you get the remains out with out helicoils and retapping.

 

[ukracer]

Hey all.

As a motorcycle restorer I often have to drill out broken studs, bolts etc.

I have a particularly tricky job on. I have to drill out some severely corroded exhaust studs from a motorcycle head.

The problem is, the studs are all at a 20 degree angle so I can't get a straight run on my pillar drill. I don't want to use a hand drill in this case as the margin for error is MINUTE..

So, are there any tricks, tips, tools or clamps that I can use to hold a fairly large work-piece and rotate and angle it etc ??

I've seen tilting vices but they're all very small. Seems they have a 100mm jaw. I need something with wide jaws. 200mm really

Thanks in advance.

Ted

291657077756

 

[Maker]

Use a big sine plate.

 

[MattF]

If it's an alloy head(?), dropping some vinegar on the studs or in the holes can sometimes be effective. It's not fast, (can take a couple of days), but I've used the method in the past for helping remove corroded in and snapped studs/bolts. It eats the steel & corrosion but leaves the alloy alone.

 

[tinman123]

agree with the lads,
under certain circumstances blobbing on the weld carefully to build up the head so as you can get grips on it or times id blob on enough and weld on the head of a nut can work very well but there are variables in it too.
worst case scenario as long as your neat with the weld even if it dosent work your no worse off at least, and you will know just how tight it is by then.
if its a 6mm stud?, it makes it trickier.

if it didnt come out, then id be inclined to drill it then, but as said, you'd want to be bang on the money when you'd make the first hole.
harryb94's post above with the you tube video is quite interesting i must say.

your probably going to drill it out to the point hopefully you would be fit to pull out a coil spring at the end, but alas thats a rare enough site to see unless you had a lot of thing going for you when you started out, one can only aim for it.
i have a few of these type of extractors here, they arent infallible but id find they will work 6 or 7 times out of ten which isnt bad for extractors but maybe you have other plans.

 

[Gareth J]

I've tried all sorts of welding methods. The studs are M6 and they are so corroded they crumble. I guess its worth another go using the blob method.

The studs did have thread protruding when I got it. I put as much heat into the head as I dared without warping it. They still wouldn't budge and would crumble. Once the 'crust' fell off them they were more like M4's..

Worth one last go! It's not about heating the head to get it to expand away from the stud, it's inituative to imagine that's what needs to happen but in reality ali is so conductive, it'll never get hotter than the stud sitting in it. What welding into the stud does is gets it red hot in a relatively cool block of ali, this temp differential is what releases the threads and then by the time you've cooled the stub with some penetrating fluid, it shrinks back to the same or a smaller size. Or at least I think that's what happens.

I was recently beaten for the first time with the blob method - an outboard motor, some imperial 1/4" thread, sheared below the surface with over a full inch of thread in the casting. It'd been sat in the sea for so long it was really corroded and with the depth of thread, it just wouldn't budge.

Good luck either way!

 

[Pete.]

I always hand-drill cylinder head exhaust studs. I wouldn't call the tolerance minute in fact I think it's reasonably wide but then that depends what you're comparing it to. Having made a couple of turbo flanges for bikes I have found that I had to open up the holes precisely cut because the studs were variable distances apart.

Easiest way is to make a drilling guide. Take a block of steel and drill a pair of holes in it at the right pitch. Looking at pics it seems the port face is flat enough to use a squaring guide so long as you relieve the corners to clear the stubs in the casting so centre-punch the easiest stud dead centre, spot it with a drill then place the guide over it and locate the drill in the divot through the guide. If you hold the guide against the port you'll get your angle bang-on. drill one, tap, install a bolt and then drill the other.

 

[Pete.]

Another trick I use, if you have a thread or two showing is this method of using a drill bushing to drill right down the middle of the bolt/stud. I documented this a couple of years ago on another forum:

I went to remove the headers on my 1996 Bandit yesterday, and all eight of the bolts sheared off at or just below the head. This is my third Bandit and I have removed the exhaust off all three for the same reason - rotted collector. Here is how I went about tackling those 8 broken studs. Forget easy-outs and stud extractors for frozen-in bolts, you will very likely only make things much worse.

There are a couple of tried and trusted ways to remove a stud that has some thread showing.

One way is to put a nut over the stud and weld the end with a mig welder getting it nice and hot, then un-doing the nut which should bring the stud with it. I don't have a mig welder - I have an arc welder but they are much harder to get good results with since the rod is fatter and for small diameter studs it's likely the arc will wander when you try to weld in the well of the nut.

The other way is to drill out the stud. This is no easy task, starting off on the end of a sheared stud is tricky and you must be dead centre to avoid having the drill wander off the bolt into the softer ally threads. This is how I have done it - by making a drill bushing.

First, take an old 12.5mm drill and chuck it up in the lathe backwards. Drill bits are not hardened at the shank so you can drill, file and cut them but they are made from hardenable steel which is what we want. Drill the tail-end 6.8-7mm which is tapping size for a M8 bolt.

Then drill it deeper with a 4mm drill, which will be the pilot for drilling out the stud.

Now I set up a M8 taper tap in the lathe using the centre to keep it perfectly in line.

And follow it with a 2nd tap and plug tap to get the thread right to the bottom of the hole.

After that I part it off.

Now I need to be avble to tighten this bushing, so I file two flats in it for a 10mm spanner.

Broken studs.

Bushing fitted

I used the drill rod so I could harden the bushing for use. This involves heating it up to cherry red and quenching. Here is what I did, but unfortunately I could not get it hot enough on my gas ring to lose it's magnetism (which is when it becomes hardenable) so it remained soft - so I used it anyway. Tomorrow I will take it to work and heat it with oxy-acetylene then it will be glass-hard.

As you see, the drill now takes a straight path directly dwn the middle of the stud.

Drill extension for those hard-to-reach ones. Just a bit of mild steel rod, grind four small flats on the drill you use to drill the rod with then poke it in and give it a little squeeze in the vice.

Holes drilled, spot on centre and right through each bolt - only 6 more to go.

Once all eight are drilled I will follow the pilot with a 1/4" or 6.5mm drill to allow me to pick out the remaining threads.

 

[Pete.]

Did some more tonight. 6.5mm drill down the middle:

Too small as it leaves the thread intact, though it looks pretty cool. Tapping size is 6.8 but I wanted to allow a bit of extra clearance so I went for a 7mm drill. Tapped using a 1/4" socket extension backwards in the tap wrench to reach past the frame. You need a GOOD tap to do these:

Both done and bolts fitted:

Middle ones will have to wait until I get some more 4mm drills

 

[Shox Dr]

What's the head made of? I was impressed by this the other day:

I wont touch exhaust bolts anymore, more hassle than the jobs worth.

If this works as good as that video, then its worth a try, heads already off, make a solution and dunk it in. Happy days

 

[ukracer]

What's the head made of? I was impressed by this the other day:

I'll have some what he is on...lol

 

[harryb94]

I wont touch exhaust bolts anymore, more hassle than the jobs worth.

If this works as good as that video, then its worth a try, heads already off, make a solution and dunk it in. Happy days

It almost seemed too simple when I watched the video so I had a Google and there were quite a few references to using it for removing broken taps and such, I think the main problem is you need to make sure the solution can't touch anything else iron based or it'll corrode that out too!
Also saw mention of using vinegar for the same thing too although I don't think it's quite as effective but ties up with what was mentioned earlier about using it as a penetrating fluid