Precision Vise Problems Again

[Mosey]

I too have one of those inexpensive 2" precision vises. The problem I am having is that the vise doesn't tighten up, while it appears to be tight. The work slips out when a drill is applied. The bolt under the vise doesn't turn sideways as some have reported, In my case the bolt hangs up between the grooves and while the tightening screw gets tight, the jaw of the chuck does not move forward to take up the space between the jaws, so it never actually gets tight against the work. What can be done to assure that it is tight enough to hold the work? All ideas are welcome.

 

[ksouers]

Mosey,
I've had one of these vises for a number of years, and it is probably my favorite.
I've encountered the same problem and it's really a user issue. The bolt can be tightened up at an angle, pulling the jaw down and forward at the same time. The problem arises when the bolt is almost vertical, pulling downward more than pulling forward. This allows some horizontal movement of the jaw in some instances.

I've also had instances where the cross pin catches between slots and acts like it's tightening up, then slips into the rearward slot.

It's something you have to feel for. Move the bolt around, pushing it down to make sure the pin disengages from the slot. Also tilt the bolt downward and back to make sure the pin is in the most forward slot you can reach. The pin has to be towards the front of the jaw so it can pull it forward.

Hope this helps.

 

[doc1955]

I agree with Kevin for I had the same thing happen a couple times when the screw was turned to far into the receiver nut and was too vertical with no forward pull but once you get the hang of it the problem will go away.

 

[Mosey]

I have tried to do exactly as you suggest, several times resulting in parts pulling out of the vise and ruining them! I have tried more carefully than you might imagine to get the pin into the first slot when working with very thin pieces, and that is when it is worst. I now think the way is to make fairly precise replacement parts for the cross-pin, screw, etc., everything below the moveable jaw, out of good quality steel.
I got it for working on these tiny pieces, and if it isn't reliable, then it goes. I wonder if some of the domestic, high-quality/price vises have this problem
Thanks for your helpful suggestions.
Mosey

 

[hobby]

The problem with mine was similir, I would tighten the bolt until it wouldn't turn anymore, the jaw would be tight, but if I put a little force behind it it would move forward again and be loose.

First I replaced the small pin with a larger pin that went all the way across both sides, but still the same problem, I noticed that it seemed like the bolt was bottoming out, tried adjusting the slots ect... but what was happening was the nut underneath was a little stripped so far down, and it would start turning with the bolt, thereby cinching the pin asgainst its hole, but not tightening itr down completely, so I was able to restore the thread on the bolt and the nut, and it worked smoothly after that.

It now tightens properly, because the nut stays in its position, and doesn't turn with the bolt.

While were on the subject of these kind of vises, if you are using the 6" long parrallels from ENCO, these parrallels are thin enough that with the bigger screwless vices, the "V" groove on the base against the back jaw, is wide enough to allow these kind of parrallels to seat down inside, enough to cause an uneven clamping with the other parrallel against the movable jaw.

 

[Omnimill]

I've also got a 2" version that does the same thing sometimes and I remade* the cross nut or whatever you want to call it and it's still a risk. The only way to be really sure is to remove the cross pin and replace it by sliding a much longer one all the way through each time - but that would be a real PITA! If anyones come up with a failsafe solution I'd sure like to see it.

*The original "nut" and bolt were M6 but I've made the new versions M8.

Vic.

 

[Mosey]

When I can get to it, I will work through making replacements for all of the parts below the moving jaw, with the idea that better quality/precision bolt, nut, pin, etc., may be the answer. The bolt is already worn out at several threads after about 10 uses. I call this grade of material "c" grade for crap. And I am going to call the LittleMachineShop to see what they think, since it's theirs. Maybe I can make it a posting here for all to see.

 

[Omnimill]

The through slot on the base of my vice has a pretty rough surface as well which I'm sure doesn't help. It's quite hard though so all I did was take off some of the high points with a stone. Running a carbide mill down it may improve things.

Given the number of folks that have had problems with these I do wonder if it's operator error or the basic design is flawed, or maybe they're just not made as well as they should be?

 

[narrowgauger]

Hi Guys,

the issue is operator error since the problem is intrinsic in the design. Yes, there is some tweaking that can be done to assist in minimising the problem but in the end it is a visible check in location of the pin that is vital.

couple of improvements that will assist:

- paint the ends of the pin white so that they are more visible when viewing from the sides;
- reduce the lock pin diameter by approximately 0.5mm
- hold the allan key by putting pressure rearwards whilst tightning the bolt to ensure that the lock pin does not drop down.

with these very minor adjustment this is a very efficient vice that will give trouble free service over a long time

have fun
Bernard

 

[dgjessing]

- hold the allan key by putting pressure rearwards whilst tightning the bolt to ensure that the lock pin does not drop down.

That was going to be my bit of advice... Also, you can tell (roughly) how far in/out the screw is by observing the angle at which the rocking washer is in the movable jaw.

 

[Omnimill]

- reduce the lock pin diameter by approximately 0.5mm

That sounds like a good idea, I'll try that on mine.

 

[Mosey]

Vice Problems Solved!!
OK, the problem has been identified and solved. The issue is the semi-circular groove under the moving jaw is not deep or wide enough for the rounded bolt to lay down in. As a result, the rounded bolt hangs up, moving the pin out of the slot it is supposed to fit into, and the bolt jumps out of the slot, releasing the jaw.
The fix took 2 minutes with a Dremel grinder and a round stone to open up the slot. The vise now works without problem. Make sure that the bolt lies down fully in it's groove. Tighten her up!
Here are the pics I forgot to show you of the area you need to open up.