Setting a Machine Vice Parallel on the Mill

In another thread I promised to show my method for setting a machine vice parallel to the table movement on a milling machine. Rather than clutter up that thread I've started a new one.

First I check the table and bottom of the vice for swarf or nicks. Then I place the vice on the table and align it roughly using the as cast clamp cutouts against the edge of the T-slots:

Then I fit the clamps:

My clamps are from a standard 5/8" milling clamp set. The left side clamp is done up until it bites, and then a bit more. The right hand clamp until it isn't loose. Then I use a DTI against the back of the fixed jaw to fine tune the position:

I start with the DTI at lefthand side of the jaw and move the cross feed until I get a reading; doesn't matter about the actual number, but note it. I then move the vice a bit to the left and see what the DTI reading is. If it's changed I tap the vice at the handle end to return the DTI to it's starting number. The theory is that the vice pivots around the tighter clamp. Depending on how far out the vice is I might make several adjustments across the width of the jaw, or just one. I then tighten both clamps rather more and run the DTI back to the start. If there's no change fine, if there is another light tap. Then the clamps are finally tightened and a check pass made. Generally doesn't take very long, a few minutes at most.

Some other points; I indicate on the rear of the jaw because the DTI won't reach the front. I checked the jaw width with a tenth micrometer this afternoon. I can't really see any difference in readings; possibly half a tenth? So it's essentially the same as checking the front. Total time to set the vice up and take the pictures was less than 5 minutes. Now the embarrassing bit. It was quick because I was less than 0.02mm out over the jaw width straight from setting by eye.

Special note for SillyOldDuffer: Feel free to curse me as some smug barsteward who sets his vice right from the word go rather than suffering like everyone else.

Andrew

I always do mine much the same except it's a cheapo vice and somehow the fixed jaw has a marginal bow in it's grind so I pop a parallel in and just finger tight the jaws, indicate off the far face of the parallel and accept the equal micron change from centre to each end. It should have been returned when bought but back then as a total newbie I foolishly thought 'twas me.

I once did a bricklaying course and the instructor said anyone can lay a brick, he placed the brick on the mortar bed and checked it for level, you couldn’t have got the bubble nearer centre, he claimed he was lucky but he did it two or three times, experience certainly counts.

Mike

I use a straight, flat rule held in the vice and sight it against the edge of the table (ground on both sides).

This seems to give me an alignment within a few thou over a foot.

If I need better, which is not often, I do more or less what Andrew does. The loose and tight clamp idea is a good one.

Neil

Edited By Neil Wyatt on 22/08/2018 20:17:53

Same here DTI off rear jaw only, trial and error tapping until correct. Hate having to remove.
Even a quality vices front jaws will have some amount of play.

Previous vices i have been able to machine three working edges, flip job over 180 degrees and machine the top to within 1/8" at 100 yards. Flipping over will double any runout.
Just need ground up jaws and a bit of time setting.

As I often have to remove the vice to make room for other fixtures I have fitted a tenon to the underside of the vice, this saves clocking the vice every time it is used, if the job requires the utmost accuracy I check the fixed jaw with a clock before use but find it is always within a few tenths of a thou.

I'm pretty sure it has been shown on this forum how to accurately fit a tenon for such use.

Emgee

One of my vices has a tenon, but for a quick cheap and cheerful, an angle plate held in the vice and indexed against the column of the mill, then tighten the bolts.

Bill

Of course that presupposes that the edge of the table is ground dead parallel with the dovetail slides. Using the DTI ensures you are measuring directly against the dovetails.

My vice has slots for tenons underneath. But I don't use them. For one thing my machine vice gets moved between three milling machines. And while the T-slots are all nominally 5/8" they vary in width by a few thou from machine to machine. That's not really good enough for me to be happy. And I don't know that my T-slots are perfecly aligned with the table dovetails. Another issue with not setting the vice accurately every time is that at some point you nip out to do a rush job, forget that you didn't set the vice properly; and fudge the work. Same thing when you tilt the milling machine head or swivel the table. Either reset it properly or at least leave it so far out it's obvious.

Andrew

Andrew, I have 1 vice that overhangs the front of the mill table, similar to the way your Kurt does.

This vice it fitted with a tenon that is only used on the edge in contact with the front of the table, it was clamped and drilled in situ after checking on the back jaw for truth of movement in the X axis.

I understand the problems stated ref slight differences in widths of Tee slots, the above method is not effected by Tee slot width.

Emgee

Similar to the previous posts. I have a tenon fitted to the underside of the vice but I always push it against the side of one of the keyslots when I tighten the bolts. Therefore does not matter if the width of the key slot is wider than the tenon key. This method is accurate enough for most of the machining jobs and fast to set-up. For precision jobs, I check with an indicator.

Paul.

My machine has got a mounting point for a TDI-on-a-stick on the side of the head. I just stick the tenth's indicator in and zero up the fixed jaw when I re-mount the vice/s. It takes a little longer than using a tennon but it's like centring a four jaw chuck, it gets pretty fast with practice. Definitely use the 'nip one side down and pivot around it' technique when only using the one vice.

My initial setting is by bumping the back of the vise to the mill column. Closer than I need it for most of my work. The rough finish on the vise did need milling flat originally.

Does anyone try to align their vise with both holding bolts loose?

Clock reading at both ends of the jaw and halve that reading at the centre point, or one chosen as preferred. Cannot possibly take more than ten adjustments if carried out properly - think here of trying to fold a sheet of paper, in half, ten times! Or ten times the radioactive half-life will result in very little residual activity.

Mathematically, divide 1 by 2^10 and note the reduction. Final error should be 1/1000 of original, which should be good enough for most of us! Invariably fewer adjustments are necessary for most of us!

If a wide enough parallel were to be used such that its face was exactly in line with the fulcrum point, the adjustment could be done in one, theoretically - but tightening that other holding bolt might create an error...

I have a wide piece of ground flat stock that I put between the knee dovetail and the back of the fixed jaw. I push the vice back snug against the plate,use the X and Y screws to position the table under the vice and tighten the bolts. Few things need better accuracy than that but if they do I use a mag mount and DTI on the front face of the fixed jaw.

Inspired by an article in MEW, a long time ago, I made up a vice alignment fixture, looking like a set of goal posts.

It was made from 1 inch round bar (25mm for those who are Metric).

The foot of each upright is turned to be a tight fit in the Tee slots of the table.

Each upright is drilled through to take a long bolt (more convenient than a stud) that picks up on the Tee nut in the slot.

The "crossbar" is secured to the uprights, by socket head screws, at a height that matches the vice jaws, and located to the uprights by a vee in one or the other.

The fixture is clamped to the milling table and a light cut taken along both sides, to produce a flat about 3.8" (10mm) wide.

You then have faces that are on the travel line of the cutter, even if the tee slots are not.

The vice is placed on the table, in the required position, but not clamped down, yet. The "goal post" fixture is placed within the opened jaws of the vice, and clamped down to the table. The vice jaws are then closed, firmly upon the fixture, before being clamped to the table. The vice can then be released, and the "goalpost" fixture removed and stored for the next time that it is needed. My checks usually show the vice jaws to be aligned within 0.001inch, (0.0025mm).

H T H

Howard

I though this was just S.O.P?

I bought a relatively inexpensive Soba (Shoba) vice from Chronos. When I got round to checking it I was pleased to note that the nicely machined mounting holes were parallel to the jaws. I simply turned a pair of press in sleeves to fit the slots in my mill. Simply placed on the mill and bolted down it’s within one thou parallel. Not sure why I bother but I normally “fuss” it until it’s spot on.

I have to wonder if a budget manufacturer can make a vice with accurately machined mounting holes why can’t some “premium” vice manufacturers do it instead of nasty as cast slots.

There's a lot in that Mike. I got into trouble using exactly the same method as Andrew. Be nice to blame my Chinese made mill and vice, but it's not true. Most of my disasters are down to me!

In the other thread I reported taking about 40 minutes to set my DH-1 vice and theorised the problem was due to the washer. Michael Gilligan suggested burring, but that's the photo exaggerating loose paint. This is the suspect washer, it is tall and narrow. I suspected it was rocking and causing the vice to jam rather than swivel when tapped.

I replaced the washer with an ordinary one and took 6 minutes to align the vice including time wasted swapping the washers on both sides. The new washer hasn't eliminated the problem but I found that alternating taps between front and back doesn't cause sticking.

Andrew advised "The left side clamp is done up until it bites, and then a bit more. The right hand clamp until it isn't loose." This is exactly what I do, but I'm wondering if the bite part is critical. When the vice is tapped, I want it to swivel, not slide. I'm wondering if tapping causes the vice to slide as well as turn because left clamp isn't tight enough. Possibly setting the optimum torque comes with practice

Never had a problem aligning my other vice, maybe because being heavier it has more inertia.

Dave

Hmmm...just had a thought (rare)..I wonder if a bearing on a rod in the quill could be used to line a vice quickly..

pgk

Well that was a waste of internet bandwidth; copying the whole of the original post just to make a zero content comment. It's the electrons who whizzed around the world to no avail I feel sorry for.

Andrew

Vic

I like that idea. Been meaning to do something similar for "not telling you how many" years. But I find simply pulling the vice hard back so studs are tight against both lathe Tee slot and vice mount slot always gets me to a thou or so in four inches error. So hardly seems worth the bovver.

Of course I left the swivel base on so getting the basic adjustment right was easy. As is tweaking when it has to be dead nuts right. But I have a Bridgeport so loosing an inch of vertical clearance matters not at all.

This ease of tweaking is the only real justification I can see for the conventional swivel base. Theoretically it can be used as a sort of poor mans rotary table I suppose. But who does that? I might have done it once in 30 years.

Wonder how well re-working one vice slot to carry a fixed pivot would work. If the opposite slot were also machined to have smooth sides and faces an eccentric, hex headed, T shaped spacer bored a nice fit on the stud would make accurate, controlled, angle adjustment easy. I guess ± 20 thou / 0.5 mm adjustment range would be more than enough.

Big question is if a simple drop over ordinary studs set up would work or whether you'd need to arrange for the studs to be fixed down rigidly before dropping the vice on. Rigid studs or posts should theoretically be better but whether the better adds up to anything you'd see in practice is a different matter. Not in principle difficult but, as ever, the devil is in the details.

Hate monkeying around tapping stuff into place.

Clive.

Edited By Clive Foster on 23/08/2018 11:43:27