Parlec Vise Hopeless?

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SteveHGraham
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Parlec Vise Hopeless?

Post by SteveHGraham » Thu Aug 13, 2009 7:08 pm

Every time I put a part on parallels and crank up my Parlec vise, the part rises enough for the parallels to slip. Beating the part with a hammer doesnt' help.

Is this vise a piece of junk, or is there some way to adjust it? There is no manual.
Every hard-fried egg began life sunny-side up.

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GlennW
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Post by GlennW » Thu Aug 13, 2009 7:13 pm

You are hitting it too hard..
Glenn

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SteveHGraham
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Post by SteveHGraham » Thu Aug 13, 2009 7:15 pm

I think I've hit it about a thousand different ways. How hard is right?
Every hard-fried egg began life sunny-side up.

lakeside53
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Post by lakeside53 » Thu Aug 13, 2009 7:41 pm

Happens often on my brand new Kurt 688 also.... A lot depends on "how" you tap down the part, and the shape of the part. If the part isn't parallel to the vice jaws, something wants to move. Without the use of cylinders, ball etc, you can only stop that within certain limits and "hammering" may not help.

A slightly loose parallel doesn't always mean "bad". If it's loose by a few 10ths, it will slide out...

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SteveHGraham
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Post by SteveHGraham » Thu Aug 13, 2009 7:42 pm

This is pretty amusing. In order to find out how to adjust my Parlec vise, I am downloading a pdf of a Kurt manual. Evidently, there is a set screw to adjust. I got a couple of sheets of paper with the Parlec, but I'm pretty sure there is no manual.

Looks like I was stupid to mount things off-center. The Kurt manual also says not to mount them too high, but that seems hard to avoid with small parts.
Every hard-fried egg began life sunny-side up.

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Mid Day Machining
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Parlec Vise

Post by Mid Day Machining » Thu Aug 13, 2009 8:32 pm

If a Parlec vise is made like a Kurt vise, there is a adjustment screw in the center of the moveable jaw. If this screw is not adjusted properly, the front jaw will lift your part off the parallels.

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seal killer
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Post by seal killer » Thu Aug 13, 2009 9:11 pm

SteveHGraham--

I do not know anything about Parlec vises, but what I have heard and read is positive.

When I use parallels on my Kurt D675--and even when I do not--I put paper, strips of the phone book, between the parallel and the workpiece. Then I hold the workpiece down by hand and put the barest amount of force on the jaws . . . just enough so the workpiece will stay in place.

Then I see if the paper remains tight between the parallels and the workpiece. If it does, I tighten the vise a little bit more and re-test, as previously. As long as the paper is tight, I am good to go.

But, if one of the pieces of paper loosens, I start tapping that side or corner (depending on the workpiece) until the paper becomes tight. It must be tight on both sides or all four corners. Then, I give the vise another crank.

I repeat this process until the vise is tight enough to hold the workpiece for my machining operation. If a piece of paper simply will not stay tight, then I make a decision: Does what I am going to do require the workpiece to be THAT level or not? The answer is usually yes.

If the answer is yes, then I resort to other techniques, such as placing a drill rod between the workpiece and the moveable jaw. (Of course, you have to hold the drill rod up with skinny parallels so that it is somewhere at the center of the workpiece or a little above. (Even vise setup take time, especially good ones.)

Between these two methods I have always been able to achieve "tight paper" in my vise.

Others doubtless know more and better.

--Bill
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mechanicalmagic
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Post by mechanicalmagic » Thu Aug 13, 2009 11:03 pm

Steve,
I would suggest you measure the rise on the movable jaw.
Put a part up high on parallels, then tighten the screw by hand (no handle). Now put a Dial Test Indicator on the top of the movable jaw. Tighten the jaw. If you measure a significant rise, you have a problem. Some vises have an o-ring under the movable jaw, it crushes during tightening, causing the jaw to drop.
If the jaw rises, take the vise apart, it probably needs some attention.

If it rises .0001", and you think it's excessive, I'll pay the shipping to scrap that anchor, here on the West Coast.
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Dave_C
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Set Screw

Post by Dave_C » Fri Aug 14, 2009 7:23 am

Steve,

On my vise there is a screw dead center in the rear jaw that adjust the slack between the jackscrew and the vice jaw. Mine had a set screw behind the inside set screw so I was confused at first as turning the screw made no differance. Then I figured out what was going on. I took out the first set screw and adjusted the inside setscrew. Everything works fine now.

Dave C.
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GlennW
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Post by GlennW » Fri Aug 14, 2009 7:46 am

SteveHGraham wrote:How hard is right?
Not as hard as you've been hitting it :D

Over tightening is sometimes an issue too. There is a chart on the Kurt site that converts handle torque to jaw force. It's quite an impressive ratio and easy to deform parts too!

People tend to exert tons of jaw force on a part when it's for sure not necessary just to drill a few holes. You'll develop a feel for it after a while.
Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

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SteveHGraham
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Post by SteveHGraham » Fri Aug 14, 2009 8:56 am

I'm going to work on it today. It was nice of the Kurt people to write such a useful manual.
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lakeside53
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Post by lakeside53 » Fri Aug 14, 2009 9:33 am

Try clamping something you know to be true, like a 1-2-3 block.

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