Repair a broken vise

[Screwdriver]

Would I still need to grind out a deep V for the braze? How would I braze it at the back?

Oh, I pinged Swindens with a cheeky question about the step on the jaw mountings.

 

[Screwdriver]

With the brazing, I'm less worried about it giving way in shear and more concerned about it bending or lifting off at the join. Ideally I'd like to keep as much of the original casting as possible, it's broken basically half way up the jaw so most of the strength is still there at the middle which is ok especially for a pipe clamp type jaw. I think it must have broken because someone used too much clamping force at the very top of the jaw, rather than the middle...

S.

 

[Wendelspanswick]

Tensile strength for a M6 grade 12.9 bolt is 24550 N, or 2.5 tons.

http://www.tech.plymouth.ac.uk/sme/desnotes/boltb.htm

 

[Screwdriver]

Set up the vice on a flat plate to square everything up. Have to say I was surprised and somewhat dismayed to discover the top and bottom jaw mountings are nowhere near parallel! I would expect the setup as shown to give me two perfectly parallel bars. It's easily one or two degrees off, enough to spot by eye. (I did have the parallels against the machined edges when I measured it)

This is what I am aiming for. It's got plenty of meat on it, most of the tangs will get ground off though it occurs to me I could leave a bit more on rather than go for symmetry.

Devil of a job getting it jigged up but I wanted the front plate flush and square, tacked with a TIG.

It's really nice to be working with chunky stock rather than thin panels. I whacked the amps up to 120 and got that sucker welded alright!

All done bar the blending. I'll probably tidy it up a bit before brazing and finish it once it's all done.

So next job is to chamfer all the buttresses then bolt it onto the jaw.

After that, I'll be doing my first ever braze! Have to say, it's all looking very doable at the moment.

Screwd.

 

[Screwdriver]

Trimmed off the edges with a disk cutter and tidied up on Bertie the Linisher.

Marked up and drilled out the three bolt holes at 4.0mm to use as a guide for drilling into the body.

Getting it clamped up in a jig was a bit of a chore but got there eventually. An extra arm or two would have helped.

Cast iron is lovely stuff to drill - dry of course.

Used the repair piece as a guide for the drill.

Then counterbore for clearance and to countersink the cap heads. The angled hole was a right pig because the drill just wanted to wander off the slope. Just did it slowly and surely with everything clamped solid.

Done.

Had to fettle the cap head bolts a bit for depth and put a radius on the angled head to match the angle at the bottom of the hole. I don't have any bottoming bits, or bottoming taps come to think of it.

I'm relatively happy with the result. Now just have to decide whether or not to chamfer the edges now or bolt it up and grind out a groove prior to brazing.

Screwd.

 

[Pete.]

Can't deny that it's looking damn good so far.

 

[roofman]

Why do my eyes keep getting drawn to that surface table with all the marked out clamping holes We dont have drooling smilies so these will have to mirror my feelings on that table. That vice repair is a work of art so far too..

 

[Screwdriver]

Thanks, yes, rescued from the scrappie would you believe. It's an 18 inch square jig plate, not perfect but good enough to be very useful. Looked like a chunk of rust covered with oil when I nabbed it. Took forever to clean out all those holes and I did a fair few before I even spotted the threads!

 

[MattF]

Nice work on the vice Screw'. With regards the stepped machined surfaces, not exactly unexpected with a Swindens, IMHO. I'm of the opinion that finesse has never been their strong point.

 

[Screwdriver]

So to the most dangerous aspect of this thread and perhaps the most risky venture in my shed. Brazing!

I got an old oxyacetylene kit knocked up out of some free bottles and some secondhand bits gathered from eBay. It has issues! Anyhow, the flame comes on and without any better info to hand I loaded a number 3 nozzle, set the gas to 4lpm (?) for each cylinder and away we go.

First I tidied up the face of the vice with a fresh grind.

Then put a chamfer on the repair piece so the braze has somewhere to go. Looks dirty but thats because it is shiny clean!

And...

Sorry, once I got going I just got on with the job. No pics from the braze. I sat there for 10-15 minutes heating the casting gently, then got on with it. Lots of flux then allow the braze to flow when the area gets hot enough. The casting is sitting on a large firebrick and that is a real welding blanket!

It definitely got hot enough because I did overdo it a couple of times, melting away the repair piece edges and burning the casting.

As you can see I filled in the allen key holes (it is NOT coming off again!) and after brazing the main body at the back, ran an extra bead around all the joins.

I just grabbed a bunch of photos as quick as possible because I wanted to get it under a blanket asap.

I'll have to nip back out there every so often to make sure it's not on fire. Don't know how I am going to resist taking a quick peek but I guess I ought to leave it overnight at least.

S.

 

[Welderpaul]

Placing it in a bag of cement is a very effective way of slowing down the cooling rate. Make sure it is well packed.

 

[Screwdriver]

Well its under a couple of blankets and that will do for me.

 

[Richard.]

Look forward to seeing that all linished up and in full working op. Cracking repair job screw and nice to see you took the time and thought to do it all properly. Don't be tempted to peek. Let her rest till the morning.

 

[Screwdriver]

Thanks Richard. I think I can afford to start thinking about jaws now. Not the big fishy one but the replacement concave type. I am thinking I might try and cast some in HDPE. I have one good jaw to make a mould, not quite sure how but I have a pile of old milk bottles I was going to melt into a machinable block. Must be some way of casting it in a mould?

Or I could go for a soft aluminium alloy or maybe even solid copper and use it as the welding vice. I'm beginning to think this might actually work and I may even end up with a really nice vice!

S.

 

[Screwdriver]

Bit of a tidy up with various grinders, dremels etc.

Naturally my main concern was to keep the new face flat, parallel and square.

Overall I am pretty happy with the result. I did have an issue when after welding, the main 12mm face actually distorted, bulging in the middle to about 0.1 - 0.2mm at the ends. I tried flame straightening but the part was too complex to get any discernible result. This is after a quick grind then a lot of cross filing and finally using emery.

Tidied up the rear so I could refit the jaw bolts and for cosmetic effect! it needs a bit more work but when painted, should look OEM and I'm assuming the braze was successful so it should also be dead strong.

At least the new face seems to line up perfectly with my parallels. A bit of play in the vice will take care of any slight misalignment, after all, it came out of the factory with a 0.2mm step!

Now I just have to make up some jaws. Swindens never answered my query about getting hold of a replacement.

S.

 

[Richard.]

Bit of a tidy up with various grinders, dremels etc.

Naturally my main concern was to keep the new face flat, parallel and square.

Overall I am pretty happy with the result. I did have an issue when after welding, the main 12mm face actually distorted, bulging in the middle to about 0.1 - 0.2mm at the ends. I tried flame straightening but the part was too complex to get any discernible result. This is after a quick grind then a lot of cross filing and finally using emery.

Tidied up the rear so I could refit the jaw bolts and for cosmetic effect! it needs a bit more work but when painted, should look OEM and I'm assuming the braze was successful so it should also be dead strong.

At least the new face seems to line up perfectly with my parallels. A bit of play in the vice will take care of any slight misalignment, after all, it came out of the factory with a 0.2mm step!

Now I just have to make up some jaws. Swindens never answered my query about getting hold of a replacement.

S.

Quality!!!!!!!

 

[eSCHEn]

Brilliant job ^_^

 

[slim_boy_fat]

Overall I am pretty happy with the result.

Justifiably so.

 

[mr migwire]

that is looking fantastic mate, top job....

 

[Screwdriver]

Thanks guys. Another update.

I drilled out the holes after carefully lining up with the existing holes and using the hardened jaw as a guide.

Imagine my surprise when it was a mile out! The jaw only fits one way up or it hangs over the edge. WTF? So I double checked the OEM jaw:

OMG! I can hardly believe it. Thats almost a whole millimetre out in just 14mm. What on earth is going on. I'd expect an expensive hardened steel jaw to test the accuracy of my measurements. This throws some of the other stuff into harsh light. The machined step in the jaw faces, the fact that the opposing jaws are nowhere near 180 degrees apart, the anvil not being parallel to the base etc. etc. I had wanted to defend this amazing vice as being the best of British but this particular one is surprisingly crude.

I started to linish the anvil flat but I didn't want to take too much material off. It was about 1-2mm off being parallel with the base so I did most of it and just left it at a slight angle to parallel. I may revisit that.

Still, it's a tool and I can't wait to try it. I'll probably make some HDPE jaws up out of an old chopping board or maybe mahogany. I can't see myself throwing any more money at this though, will be interesting to see how much the new jaws cost.

But hey, it's starting to look nice!

Now I just need to decide if I want to risk another braze to fill up the cracked off back cap retaining screw. I say risk because I don't want to heat up the whole thing just for that small braze right on the end. On the other hand, I do know it's possible to distort and crack castings if you're not careful, plus I'd have to machine off any excess. Maybe I could TIG it using those brass rods??

S.