"Refining" an Import Milling Vise

[HMF]

You need a milling vise for your heavy mill, but you cannot afford a Kurt, so you buy an import.
It's not bad, but the jaws are a bit warped and uneven. They don't close smoothly. The operation of the closing mechanism is rough. What do you do, or did you do if you have already fixed one of these, to improve the situation?

 

[OldMachinist]

You need to check if its the jaws or the surface they bolt to thats causing the problem. If its the jaws they would need to be reground. First you would have to shim for the warpage and grind one side flat, then flip them over and grind the other side parallel.
The block the stationary jaw bolts to could also need to be reground or the keyway that aligns it could be off.

The roughness of the screw is likely just a poorly machine thread.

Did you take it all apart when you got it and clean all the packing grease and chips out of it?

 

[Pitchfire]

I went with new South Bend instead of GMT (Glacern) and while it's not bad, it's not perfect either. Glacern would be my nod to those who haven't purchased a vice but may be reading. I got lazy and just consolidated all of my ordering that I could to Grizzly. I wound up getting a Glacern face mill anyways so if their is egg on the screen it dripped from my face.

 

[DMS]

Pull the jaws off, replace them with aluminum or mild steel soft jaws. Rejoice, because you would have been better off doing that in the first place

Seriously, I used my original little 4 inch vice with the stock, hardened jaws for the longest time. Then I heard about soft jaws, and replaced those with some stepped aluminum jaws. Huzzah! The aluminum is soft sticky. It grabs parts much better than the hardened steel (those jaws tend to be polished, and therefore slick). You don't have to tighten as hard to get a good hold, and they don't mar your parts like the stock jaws will. I highly recommend you try them for yourself.

I have heard of people souping up their vices by installing thrust bearings. I also found a very good writeup from someone who seems to have had the same issue as you. he did a complete teardown and overhall.

http://www.docsmachine.com/projects/4vise/4vise-01.html

As an aside, I also have an import 5". Mainly got it because the Kurt 5" was expensive, more expensive than the 6", and I can actually move a 5" vice without a crane...