[Project 8] Fix (quick) fix location bar for the K4 Vice

Following on from the discussion in Vice Upgrade I've decided to take John and Jason's advice and install a bar into the bottom of my K4 Vice. The K4 already has a mounting slot for such a thing, so in theory at least, we're already half way there (removes tongue from cheek)! Fortunately, the slot is exactly the same width as the slots on my Super Major Milling Machine (13.8mm).

Squaring up a piece of 20mm x 20mm square bar I found in the shed:

Slicing off 5mm in the bandsaw (massive time saver):

After milling to size and chamfering, the bar fits perfectly into both slots:

Counter-bored holes for the M5 fixings:

So far, so good:

The bar fits very snugly into both the vice and table t-slot with no movement.

However, once fitted tightly to the table, a quick run up and down with a DTI showed 0.2mm run-out over the width of the jaws.

The next step is to clamp a parallel into the vice and turn it over. Taking care to slide the parallel into the t-slot. Biasing it to line-up with the front of the fixed jaw. Once home, the plan was to clamp the vice down mill out any discrepancy:

However, there is a problem. The jaws aren't parallel to each other:

So for now, I've strapped it down biasing on the fixed jaw:

This is it's the position she currently lay.

I figured it best to wait for feedback before taking the next step, in case there was something fundamental I was missing.

I'd be inclined to sort out the jaws first if they will machine. Then clamp a parallel (or perpendicular) to the table and fix the vice upside down on it. I'm amazed that the jaws aren't parallel TBH, I'd have thought that would show up almost immediately you got it?

It's strange. It's not something that looks obvious during use.

Perhaps it's a strange manifestation relating to jaw lift?

I have terrible trouble getting parts to lie hard against the parallels (even after a whack).

It all seems to have squared up by the clamping (seen in the final image).

TBH this is the sort of thing I see regularly in budget equipment, you get a lot for the money but the 'quality' isn't quite there, not really complaining as I don't expect perfection at the prices paid.

Tony

I'd be hesitant to blame the tools just yet - this could just as easily be my ineptitude.

Although it was disappointing that the homing slot wasn't exactly parallel to the jaws.

Might be worth slackening and "fiddling" the jaw plates, even if you have to remount it on the table and clock it in - it's worth taking a little trouble now to establish a known "good" datum for the future, surely? ..not sure what kind of wiggle room there is, if you slacken them off, you'll be able to see if it looks possible, or is a complete non-starter, before committing, I guess..

Okay, so I pulled down the set-up and had a good play around.

It looks like the apparent disparity is caused by jaw lift.

When closed normally, the jaws look fine:

Even though there are clear gaps/misalignment (this could just as easily be the table):

So new method.

This time I'll remove the non-fixed jaw completely and drop the fixed jaw into the t-slot.

This worked beautifully. This sorted out the misalignment to ~0.005mm, which I was happy with.

However (why is there always a "however"? *sigh), the t-nuts no longer fit under the vice.

So I had to mill down the ends of the Vice Bar to make room for the t-nuts:

And now there isn't enough bar to hold firmly against the t-slot without disparity/wobble.

So I need to have another go at this.

Plan is to start by milling the vice slot true this time. Then maybe make-up some bespoke t-nuts.

If at first you don't success, give up! No wait, the other one ... try, try again!

Although my machine vice has slots on the underside for tenons I think I'll stick to indicating the vice each time I move it. The vice can be mounted on three milling machines and while all the slots are nominally 5/8" they are not consistent, even on one mill. So I prefer to indicate and be assured that I'm within 0.01mm over the 6" wide jaws.

Andrew

That's all well and good, but then I don't get to publicly highlight what a terrible machinist I am! 

Edited By Lee Jones 6 on 17/11/2020 10:08:21

Have you thought about using buttons to locate the vice? As my mills have 10mm table tenon slots I am usually in the position of having to 'step down' from fixture slots (things like 5C spin indexers) to meet the table slots. A dual diameter button does this simply and easily. As Andrew says though I only ever use these buttons as a guide and always tram up the squareness of the fixture.

I have to say I am amazed that such products as this K4 vice, with so much inaccuracy, is peddled on the market with no outcry from disappointed customers. I see it has a nice 'crackle black' paint finish and nice shiny ground bits but is otherwise fit for the scrap bin.

Recently I purchased an Edgwick 4" machine vice that was in a 'Antiques Centre' sitting aside boxes of 10 brand new grease wrapped BSF taps in 1/4, 5/16, 3/8 and 7/16. Bought the lot for £45! At some point the jaws of the Edgwick had been changed for some 'specials' (had a clearance hole in the fixed jaw for a casting protrusion I would imagine and a step in the moving jaw) I replaced these jaws with a suitable piece of Ground Stock Plate, cleaned it up and gave it a lick of paint, adjusted the gib strip, filled in the couple of inevitable drill tip marks in the base (used JB Weld) and checked it out for truth. Parallelism and truth between jaws and table base was 0.0002" maximum. Jaw lift when tightening is negligible, a light tap with a copper hammer of lead head will seat components easily. The moral of this is that 'quality' can still be found at an affordable price - you just have to hunt it down.

I made an alignment fixture for my K4. The idea was a variation on someone else's scheme, published in MEW some time ago.

My device is essentially a goal post arrangement.

The bottom of each pillar is turned to be a snug fit in the T slot, and drilled right through. The cross bar has two Vees milled into it, with a hole drilled through the bottom of the Vee. The pillars are drilled and tapped, so that the cross bar can be bolted to it, and solidly located.

The pillars are secured by studs running from Tee nuts through the pillar to a clamp nut on the top surface

The "goal post" is secured in place, and a light cut taken along each side, with an end mill. This ensures that the surface to which the vice will be clamped is in the plane in which the cutter moves.

When the vice is to be aligned, the vice is placed on the table of the mill, and the "goal post" placed over it, and clamped down, so that the vice can be clamped to it. For some machine / vice combinations, it may be that spacers will be required to ensure that the "goal post" and the Tee nuts under the vice line up satisfactorily.

The vice is clamped to the cross bar of the "goal post" and the fixings into the Tee nuts tightened. Once the vice is clamped in place, the "goal,post" can be removed.

Clocking the vice jaws usually shows that it is aligned within a thou.

Howard

Do you guys have pictures of the two methods please? The buttons and goal posts.

Hi Lee!

Have finally managed to upload a photo into my album, of the Alignment Fixture for my Vertex K4

Howard

Ha ha! Yes, it's not he easiest thing in the world to work with. Well done and thanks for doing that.

Oh, I see. Wow, that is some piece of kit. That is not what I imagined at all.