Tightening up a screwless vise

[Frank O]

I have one of these LMS 3" screwless vises I bought about 12 years ago:

Vise, 3" Screwless 1590

Screwless Vises 1590 Hardened and Precision Ground; Square and Parallel within 0.0005"; Ground "V" Way; This high precision toolmakers screwless vise ...

littlemachineshop.com

It worked out okay over the years on a mini-mill, but after getting a larger 5550/Siegx2.7 mill recently I've noticed it's harder and harder to get a good grip on the workpiece with it.

Today for example I had a rectangular piece of 1/8"-thick aluminum to make some holes in. I put a couple of parallels against each jaw of the vise, put the workpiece in on top of them, then push the jaws together as forcefully as possible as I tighten the hex bolt on top of the vise. No matter how much I pushed, the workpiece ended up just sliding back and forth.

I thought maybe there was some grit inside the vise, so I disassembled, cleaned and reassembled it, but this didn't cure the problem.

Is there some issue with my technique, or should I be thinking about a new vise? (A larger one having been on my wanted list for a while anyway.)

 

[francist]

I have one very similar and I really like it. One thing that gets me every now and then is if I’m right at the transition limit between notches, as it were. If the bolt runs out of thread in its receiver before the jaws tighten against the work it can still “feel” tight but the jaws aren’t. Try putting in a spacer (doesn’t matter what thickness, 1/4” say) with the same 1/8” thick piece you’re trying to clamp. If it tightens fine that could be the reason, if you still can’t get it tight then there’s something else going on.

-frank

 

[benmychree]

Maybe you need to back off the allen bolt further before sliding the jaw up, then do the tightening?

 

[Mini Cooper S]

Sometimes those vises will not tighten because it runs out of travel for the hole that the cross pin is in, could that be what is happening? I have one of those from Suburban Tool. It is VERY accurate and I use it for grinding only. As for a new vise, I have one word for you....Kurt! I do realize that we must live within budget constraints

 

[higgite]

Maybe you need to back off the allen bolt further before sliding the jaw up, then do the tightening?

This ^^^^. Ben and Coop both nailed it.
I have a similar vise by Tormach and it does the same. Drove me crazy until I figured it out. (I know, I know, crazy isn't a drive for me, it's just a short walk.)

Tom

 

[T Bredehoft]

I bought one (screwless vice) 6 months ago, to keep from wearing out the screw type one I made in 1973. I've only tried to use it twice, couldn't get it to tighten. My inexperience, I guess. I'll try again next year.

 

[brino]

I'll try again next year.

Wouldn't want to rush into anything.......

 

[petertha]

I have a few of these. The price is right, the basic grinding is good. But the pin & bolt assembly on mine were all crap.

- if you increase the OD of the larger diameter body, it will give more screw length, which gives more jaw movement for any notch. It will also help with the annoying issue when it drops out of the notch & gets cockeyed, necessitating much fiddle farting. The larger diameter just drops down a bit (the underlying surface typically).

- make the width of the large body closer to the rail sides and the pin diameter a closer fit to notches. It slides much better & you can hear/feel each detente position. Mine were just plain badly executed.

- clean the grinder mung while you're in there

 

[Frank O]

As for a new vise, I have one word for you....Kurt!

Speaking of vise upgrades ...

I see Amazon has a 6" genuine Kurt for $587:

Amazon.com: Kurt DX6 Vise with 9" Opening, 6" Size, 4.360" Height, 7.391" Width, 16.810" Length, Blue : Sports & Outdoors

Buy Kurt DX6 Vise with 9" Opening, 6" Size, 4.360" Height, 7.391" Width, 16.810" Length, Blue: Fly Tying Equipment - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

smile.amazon.com

While LMS has a 5" "pro" Kurt-style on a swivel base for $309.95:

Vise, 5" Precision Milling, Professional Grade 3951

Milling Vises 3951 Precision 5" Kurt-style milling machine vise with swivel base; Top, bottom of vise bed, gib, jaws, swivel base, and all plate mount...

littlemachineshop.com

Which brings two questions to mind:

First, is there any potential issue with either or both of these being the appropriate size for an LMS 5550/Siegx2.7 mill?

Second, apart from the fact that the Kurt is U.S.-made and the other is almost certainly not, is there a strong case to be made for spending almost twice as much for the Kurt?

 

[mikey]

The LMS 5550 has a table a little over 6" wide so yeah, there is going to mean overhang on your side. I'm not even sure you could bolt a 6" vise in the forward T-slot without some of the vise hanging over the back end of the table; this is going to compromise your space in Y and that's a big deal. I think a 4" vise might work and one could argue that a 3" might be just right. My table is 8" wide and a Kurt 4" is the perfect fit for it.

Well, with Kurt you have a precision vise with a known reputation for quality and accuracy and a lifetime warranty. A Kurt vise will work right out of the box without requiring any mods to work correctly. The same cannot be said for many import vises. Given that the vise is the most important work holding tool on the mill, yeah, a case can be made for a Kurt.