Milling Rite

[Ischgl99]

You don’t need to have slot keys in your vise, it will work just fine without them once you figure out if there are any high spots. I have been machining for 20+ years and still don’t have keys for my vises. The Burke slots are pretty wide, so you can make a stepped key, one side the size of your vise slot, the other side the size of the t-slot.

The bottom of the vise looks good from the picture, nothing obvious causing a problem. You could grind the nub away just in case it is causing a problem. My table has a few shinier spots after running a flat stone over it, but it hasn’t caused issues with my vise, so not sure if that could be your problem. I think it is more likely there is/was a slight dent, scratch, whatever causing a slightly higher spot. You might have removed what was causing it and not even noticed, it doesn’t take much to cause a problem.

 

[Dave Bonzo]

You don’t need to have slot keys in your vise, it will work just fine without them once you figure out if there are any high spots. I have been machining for 20+ years and still don’t have keys for my vises.

You might be slightly better at this than I am.

The Burke slots are pretty wide, so you can make a stepped key, one side the size of your vise slot, the other side the size of the t-slot.

That's what I was thinking I would have to do...but OMG, the slots of this vise are really rough.

The bottom of the vise looks good from the picture, nothing obvious causing a problem. You could grind the nub away just in case it is causing a problem.

I thought it looked pretty good as well. I took a file to the bit of casting, and it's definitely no longer proud of the base surface.

My table has a few shinier spots after running a flat stone over it, but it hasn’t caused issues with my vise, so not sure if that could be your problem. I think it is more likely there is/was a slight dent, scratch, whatever causing a slightly higher spot. You might have removed what was causing it and not even noticed, it doesn’t take much to cause a problem.

Well, there's still something going on... because I'm right back where I started. I didn't really see much improvement from hitting both the table and the vise with the blue and stone; I can still tighten down one mounting bolt, traverse and correct back to zero, snug the second bolt down, and then just keep chasing that back and forth until I finally get pretty close to zero deviation across the vise...and then I can gently bump the vise with the heel of my hand and throw it off by .00025" or so. Like, if I accidentally run into the vise with my hip, it's gonna be way out...and that's even with the mounting bolts tightened as much as I dare. That's also a problem in and of itself; the vise moves around as I'm tightening the bolts. Maybe there's a camming effect taking place on the top of the mounting ears?

 

[Dave Bonzo]

Pictured: Hmmmmmmm.....

 

[Dave Bonzo]

Well, a new set of washers and some cleanup of the paint on the vise got me nowhere: the vise still just slides around like it's on rollers...and I literally can't torque it down without shifting it around somewhat. I'm trying to steady it with one hand applying counter-pressure to the wrench that's in the other hand...and I'm not putting much force into it.

Second issue: there's just no way to hold it steady with the collet-mounted indicator. So, gotta resolve that.

 

[Ischgl99]

I think you need to get the surface plate and check the vise bottom for flatness. It's possible the bottom of the vise is warped and the stone is just following the curve making it appear it is flat. The other thing I would do is see if you can find a straight edge with a clean surface and see if the mill table has bow in it in the Y and X axis.

 

[Dave Bonzo]

I think you need to get the surface plate and check the vise bottom for flatness. It's possible the bottom of the vise is warped and the stone is just following the curve making it appear it is flat. The other thing I would do is see if you can find a straight edge with a clean surface and see if the mill table has bow in it in the Y and X axis.

Yeah, it could easily be that. And I think I have a way to check: I could just mount the rotary base or some other kind of dingus on the table and see how easily that one moves; if it's hand-bumpable, I know I have a vise issue.

Regarding surface plates: eBay looks like the winning contender, price-wise. There are some Shars A and B grades on there for about $190, shipped from the Discount Machine Shop...shop. Other options are available, but that's the only one that looks reasonable. And I'd be fine with spending the extra money to get an A-grade, but I don't really want the ledges...but I guess that's a compromise I'll have to make.

EDIT

...aaaaand nevermind. Looks like the advertised shipping quote doesn't apply, and it's actually a freight shipping quote. But: I found a Grade B from "Southway Group" or whoever the smurf that is, and it's $135 all-in at the time of this writing...which is only $6,389 in six-months-from-now dollars.

 

[Weldingrod1]

Using a decent straight edge you can hunt bumps...

Sorry, I figured the stoning advise was going to fix it!

You might set it on the table, put the indicator on one side. Set for vertical motion. Push on various parts and see HOW it tips/rocks.

It would NOT behave that way I the two surfaces are flat!!

Sent from my SM-S911U using Tapatalk

 

[Dave Bonzo]

That's a good idea. The magnetic base will be here in the morning, so I can tackle it then.

 

[K_Ridley]

I think the vise not flat thing is a red herring. When I look at the close up picture of the vise clamp bolt it looks like you've only got a corner on the square head of the bolt under the T of the table slot. I think that there's not enough friction with just that corner of the bolt and that's why it is able to move on you. I think that if you used proper T nuts it would alleviate your issue.

One other point. From your pictures it looks like you're using the moving jaw of your vise to indicate off of. I was taught that it was proper to use the non moving vise jaw to run the indicator across.

 

[Dave Bonzo]

I think the vise not flat thing is a red herring.

I think it's not a flatness issue, either. I got the new indicator holder this morning and I checked to see if there was any rocking happening in any direction, and... < drumroll > ...there was.

The short version is this: when I mount the vise in the forward-most T-slot in the table, it's so front-heavy that it takes almost no pressure to accidentally tilt the vise towards the front of the mill and almost knock it off the table entirely unless you catch it at the last moment and strain your back...which, uh, totally didn't happen to me. When just sitting flat with no pressure from the mounting bolts, there's about .001" of rockery taking place, front to rear. And it's not that it's really rocking on a high spot; it just kind of feels... unstable.

If I move the vise towards the rear of the table - as if to mount it in the middle T-slot - all of that rocking motion vanishes instantly.

Hmmmm...

I don't think there's a high spot on the table and/or vise; rather, I think that when mounted in the forward-most T-slot, the center of mass of the vise is so far forward that it's really difficult to mount it solidly. Once that mass is sitting more solidly on the table, the instability vanishes.

When I look at the close up picture of the vise clamp bolt it looks like you've only got a corner on the square head of the bolt under the T of the table slot.

You are correct; it's not a great mounting method. I haven't had a correctly-sized set of T-slot bolts and nuts, so I was hoping these would work...and I don't think they're really doing so. As you pointed out, there's only a small amount of the bolt head catching and holding.

I think that there's not enough friction with just that corner of the bolt and that's why it is able to move on you. I think that if you used proper T nuts it would alleviate your issue.

I have a set on order as of this morning, sized 11/16" to fit the table slots, and with 1/2-13" threads. Hopefully they will help to solve the problem, but I also need to figure out how to keep the bolts from skewing sideways when I tighten them. At current, they'll move well over 1/8" when I try to tighten them down. I think the washers have a lot to do with this; the nuts are grabbing the top surface of the washer while the bottom surface is sliding around on the vise, and that just ends up eventually shoving the vise around on the table.

One other point. From your pictures it looks like you're using the moving jaw of your vise to indicate off of. I was taught that it was proper to use the non moving vise jaw to run the indicator across.

I agree. I need to adjust the contact on the indicator to better index the inside surface of the fixed jaw, but I'm not sure exactly how to do that, so I've been looking for a manual... unsuccessfully. So, I think I'm just going to have to figure out that adjustment without the manual, because I can't really get a good measurement this way.