Get Material Flat in Vise

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NP317
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Re: Get Material Flat in Vise

Post by NP317 »

Another potential issue that can introduce errors in your mill work:
The rotary base!

I only installed my vice's (pre-Kurt acquisition) rotary base when I needed to perform angled work.
I always directly mount the vice to the cleaned mill table.

Your experiences my be different...
RussN
RONALD
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Re: Get Material Flat in Vise

Post by RONALD »

I recently purchased the smallest Wilton (Asian made) vise.

I have yet to mount it on that Servo for milling small parts.

I suspect I will encounter lots of the problems described above.
DSC_3414.jpg
Richard_W
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Re: Get Material Flat in Vise

Post by Richard_W »

mcman56 wrote: Sat May 14, 2022 8:48 am You are looking for a starrett no. 54 hold down.

Can you explain what these do? They just look like parallels.
I don't have one here to show you. They are not like a parallel. It has an angle ground on both long sides, so when you tighten down the vise jaw it forces the part down. Used on the moveable jaw. At least that is how I used them. They are sold in pairs, so I would think in some instances you would use both. They work well. You need to see an end view to better understand how it works.

Richard W.

I actually found a picture on ebay of the end view.

https://www.ebay.com/itm/185424241961?h ... Sw-qlfhMQK
Last edited by Richard_W on Sat May 14, 2022 1:03 pm, edited 1 time in total.
Richard_W
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Re: Get Material Flat in Vise

Post by Richard_W »

mcman56 wrote: Fri May 13, 2022 12:34 pm I have an old mill vise and frequently struggle to get material to sit flat. I use parallels, tighten and then tap on material so that parallels will not slide. Sometimes or frequently, I can not get this to work and the parallel on the movable side of the vise continues to slide. The attached picture shows the result when I rotated material 5 degrees in the vice and took a cut. You can see the material is higher on the movable side of the vise. (It was originally cut holding the long sides but I needed to switch to holding the short sides for this 5 degree operation..)

I don't know the brand of the vise but it does not have a dovetail.
When you put the material in the vise like you did in the first picture. When you tighten the vise on thinner material will have a tendency to bow up in the middle. I would have turned the material 90 degrees and clamped it. Because it would be less likely to bow up in the center. As well as reduce the chance of chatter on thinner material. Especially if you are using a 4 or 5 tooth face mill. Looks like you got a good finish the way you did it.

Actually when you learn to use the older non-kurt style vises you should still be able to do good work. I did anyway 50 years ago.

Richard W.
SteveM
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Re: Get Material Flat in Vise

Post by SteveM »

I have four used Kurt vises. One I paid $150 for, and the rest I paid about $50 each.

If you can install a 6" Kurt on your mill, they are typically the cheapest, as they are like Toyota Corollas - millions of them out there.

If not, look for a 4", but prices have gone up since they stopped making the D-40.

You can still get rebuild kits for the 6" and 4", but not the 3" and 5" (guess which sizes I have?).

Also, replacement jaws for the 6" vise are a dime a dozen, but pretty much nobody sells jaws for the 5". There are some available for the 4".

You can find 6" kurts for $150-$200 on ebay.

If a vise doesn't have the jaws, figure in what they will cost.

Most people recommend against the swivel base, but in your case, you may need to get one so that you can put the jaws perpendicular to the table, as the spacing on the bolt holes may be too far apart for a kurt to bolt directly down.

Steve
earlgo
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Re: Get Material Flat in Vise

Post by earlgo »

And speaking of the swivel base, the one that came with the vise I bought had the degree scale on it and the vise only had a pointer on one side. Because I was using it for angle cuts, I very carefully put a second pointer on the vise diametrically opposite the original one using the base scale as the reference. Surprise when I turned the vise 180° the second pointer didn't line up with the 0° mark by a couple of degrees. I took the vise off the base and haven't used it very often since. You might want to check the accuracy of the scale on your vise base.
Good luck.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
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rmac
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Re: Get Material Flat in Vise

Post by rmac »

mcman56 wrote: Kurt vises look quite pricey. Are there some decent clones?
I have a 4" Glacern vise. It was pricey, too, but not Kurt-level pricey. I'm perfectly happy with it. I've never seen a Kurt in person, though, so I don't know what (if anything) I'm missing. I can say from experience that the Glacern folks give excellent customer service.

-- Russell Mac
SteveM
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Re: Get Material Flat in Vise

Post by SteveM »

rmac wrote: Sat May 14, 2022 3:03 pm I have a 4" Glacern vise. It was pricey, too, but not Kurt-level pricey.
Glacern is pretty much the only other vise maker that people rave about.

The downside to them is you can't find much on the used market.

Steve
mcman56
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Re: Get Material Flat in Vise

Post by mcman56 »

"First, are you sure the side against the fixed jaw is true 90 deg to the bottom of the part being held (or for that matter sure the fixed jaw is perpendicular to the base ie. the table)".

I never thought to check but just did and the quill is not square the the fixed jaw of the vise so I have an issue. The quill must have been knocked out of square or maybe the vise is not flat. I'll do some investigation. This would mean that my squared up part was not really squared up so would make it more difficult to get flat in the vise.

I'll look on ebay for a used Kurt but would it be fair to say that a China copy would still be a big step up from what I have?

I see there is a step on the starrett no. 54 hold downs. Does this step go on top of the material such that you could not fly-cut the entire top surface?
Richard_W
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Re: Get Material Flat in Vise

Post by Richard_W »

mcman56 wrote: Sat May 14, 2022 5:42 pm
I'll look on ebay for a used Kurt but would it be fair to say that a China copy would still be a big step up from what I have?

I see there is a step on the starrett no. 54 hold downs. Does this step go on top of the material such that you could not fly-cut the entire top surface?
Actually some China imports need to be taken apart and ground true. I have had to do it.

Actually there is a taper on the no.54 that allows you to fly cut. Maybe not as thin as you would like, but again you have to see and use one to fully understand how they work.

I am not a fan of the swivel base for the Kurt type vise's. The add weight and reduce the area of the underside of the vise to the table. I prefer as much contact with the mill table as possible. Most swivel bases sit on the shelf and collect dust. You can usually use one stud in the vise hold down slot and a toe clamp anywhere else on the vice drip tray and not hurt a thing. My preferred way to do it. The degrees on the Kurt vise isn't very accurate, so I usually set the vise angle with a sine bar. That way it is right the first time.

Richard W.
Richard_W
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Re: Get Material Flat in Vise

Post by Richard_W »

On another note I answered an add for a bunch of kurt style vises. The guy had a pallet full of them he bought from an auction. I went to see them and there were not marking on any of the vises. I asked him if he had a 1/4" Allen wrench which he did. the 1/4" inch Allen wrench fit snug into the screw holding the top of the vise on. So I knew it had to be a Kurt vise. If the 1/4" Allen wrench didn't fit, then the vise was imported and used a 6 MM Allen wrench.

When I got home with the vise and cleaned it up the Letters showed faintly saying Kurt.

Richard W.
Rich_Carlstedt
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Re: Get Material Flat in Vise

Post by Rich_Carlstedt »

mcman56 wrote: Fri May 13, 2022 3:46 pm I was not planning on a new vise. How did machinists deal with this in the "good old" days. Kurt vises look quite pricey. Are there some decent clones?
Excellent Question , and the Old timers had several ways to handle the problem that most home shop machinists have never heard of so i will try.

A Kurt, Hands Down , will give you a much better grip . I also have two.

I am a Manufacturing Engineer by trade and I gave seminars to Machinists on Work Holding , so let me share
some of those to explain how to improve your work - two general comments before my explanation :
First thing I would do is get rid of the swivel base. Only use it when you when need angular work
Second thing is understand the "Six Degrees of Freedom" for total control of objects -look it up and know that law of Physics

Now, What you really need to know is called 3,2,1 and how it works - VERY IMPORTANT !
So here are some slides on the program I give ( Hope there is enough room, I may go to a second post )
Chaski 1.JPG
Chaski 2.JPG
so a Plane is easy to understand, as they are all around us. Any 3 points determine a Plane
A surface table is a plane , your milling table is a plane The Jaws on your vise are a plane ( 2 really ! )
Now lets look at the other 2 factors.
Any 2 points is a line ( connecting the two points ) and a Single point is a Point !
Chaski 3.JPG
Now you are armed ! THIS is what old timers knew !
To control the Position took 3,2,1 !
Note , we are talking about "position" , not about clamping..you need to understand that
so lets look at hold a block and where 3,2,1 are used
Chaski  4.JPG
So in the above picture , the plane on the bottom supports the block, the line gives "alignment" and the point gives "location" or 3,2,1
Using this will always give you accurate location and are 3 of the 6 Degrees of freedom
( Which means any object can move in 6 directions and to control it requires all must be controlled)
Now to control the block in the picture you only need 3 single points opposite the 3,2,1 restraints
- To control the plane, one vertical downward point is used
- to control the line add a single point pushing towards the line ( Like from the observers view point )
- to control the point on the left, One is used on the right

Now when you use a vise, the problem arises because you are not following the above Law
Yes, you have vise ways , a Plane, But you have a solid jaw which is a plane AND a moving Jaw Which is a Plane AND they may not be perpendicular to each other AND your workpiece may not be perpendicular it self to ad to the problem ... Now you know why you have trouble !
Now the problem arises when you try to change the relationships !

There was a comment made about Toe Clamps earlier . These are tilting bars that have Obtuse angles ( ~ 93 degrees) that when clamped on the work piece, produce a downward force , maybe you can see it here in this photo
Rich
Chaski 5.JPG
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