[JMFabrications]

I just bought a used 3 axis CNC vertical mill that is being delivered sometime next week. I wanted to order a few things ahead of time so I can be ready to cut when this thing gets here. This will be my first CNC mill so Im anxious to use it. From what I read the Kurt vises are the best. Enco says the 3600V is recommended for CNC machining, but the opening is only 6". I was looking at the D688 which has an 8" opening, but Im not sure if its the best choice for CNC, Id like to have at least an 8" opening without spending $1k on a vice. I see alot of setups that run 2 vises to hold longer material, at what lenght do you recommend using a 2nd vise? Any input on this would be greatly appreciated.

Thanks,
Jim

[mxtras]

Kurt may be the best, but some of the knock offs are very suitable and cost less than 30% of the Kurt. A 6" Kurt is - what - $600? A 6" Enco is $150ish? I don't know - but I think I would consider it - if you don't like it for some reason, sell it and get a Kurt but to get going, you are going to need lots of tooling and lots of other things - maybe research the knock-offs and save yourself some $$ now. You can get the Kurt when you complete your purchasing binge....unless you have ample cash. I don't know your situation.

I have been using an Enco for quite a while and I have used countless Kurts in the past. There is a difference but the Enco is suitable in my opinion. Some may argue that - so lets hear it....

Scott

[DareBee]

I have used a few Kurt knock-offs, the differences are very subtle, but for longevity and satisfaction nothing beats the Kurt (that I have seen). It is all I will buy anymore, period.
I use a D688 on my VMC and am happy, the vise you chose needs to suit YOUR requirements. For my job shop I need nothing special. For production or super high precision a 688 shouldn't be your first choice.

[WayneHill]

The jaws can be placed on the outside of the slide and the stationary for a larger holding area.

A Kurt vice will last the life of the machine and more.

Don't scrimp on the vice. Buy a Kurt or Chick. Leave the
cheap vices on the store shelfs.

[ViperTX]

Besides when you buy a Kurt the $90 or so to ship it doesn't sound bad....when I buy my cheap vise (Phase II or Enco).....the shipping is as much as the vise and that feels bad....

Also the CNC vises have features which allow you to stack them, accurately place and remove them....etc.

[kmbx]

as far as holding longer work pieces you can just make your own jaws at any length
used both kurt and knock-offs for 15 yrs. yes the kurt holds up better but its like buying a caddy or a geo metro they both get you from point a to z.

[One of Many]

A few comments on the larger opening vises and multiples.

It is not that all of the imports are weak or wear faster, but whether they are precision as far as square and parallel that counts. That can be a crap shoot and a questionable gamble at best. Even more so if you intend on buying more than one.

The Kurts are work horse, that is for sure. If you plan on using more than one, you might consider a matched pair(or match them yourself). Otherwise, I have seen them differeing in base height. Then there is the fixed jaw and jaw thickness, that can have some tolerance issues that may offset them IF you intend to use the T slot keys.

The larger opening vises do have the screw casting protruding out the back below the fixed jaw until it is open a couple inches. On narrower tables this forces them to be mounted toward the front of the table so there is no interference with the Z axis ways or column dovetails. I've seen operators run a program and wipe out the ways behind the table and believe me it can do serious costly damage to the rails, way covers, vises, table or anything else in the mix.

Distance between 2 vises is normally as needed for the present operation. Not as hard on mills with bearing rail ways, but the added weight over the long term on sliding member machines will induce additional wear on constant extreme travels. After a while, the wear from the over hung weight can make machining flat surfaces impossible. Primarily the reason most mills are only given a tolerance spec over the saddle anyway, but you get the idea of what is at stake for the convenience of multiple vises.

DC

[JMFabrications]

Thanks guys for all your help... I ended up getting the Kurt D688 to start, if I dont like it, I can always upgrade. My CNC machine is scheduled to arrive Monday, cant wait to use it.

Thanks again,
Jim

[jed102]

Hello Jim,

I just bought a d675 and noticed that there is a lot of side to side movment on the movable jaw, in fact 0.024 inch. Could you please let me know how much you have in your vise as I would like to see if this is normal for Kurt. I spent the big bucks to get precision, so I am not too impressed.

Frank

[Gads]

Hi I notice you purchased already I was going to recommend looking into a kurt DL double lock vise or clone. I have a small Dl and it allows you to have
a large choice of setups and or multiple work locations as well as being able to be set on side or end etc. with great accuracy.

As for the slop in the movable jaw you want slop if you look at how a kurt vise works they have a wedge between the jaw and the screw that pulls the jaw down as you tighten the part and the slop allows for some squareness variation. most kurts have an allen adjustment on the back side of the movable jaw section that allows you to adjust just how much slop is in the jaw.
my experience with kurt vises has proven they are well worth the money..
Gads

[jed102]

Yes Gads, you are right about the allen key adjustment for the up and down aspec, but it doesn't help the situation in regards to grabbing certain small parts that are easier to work with on one side of the vise.

I may end up making some modifications to allow for adjusting the amount of side to side slop for different situations. It does seem that it isn't a real big concern to some, and thanks for your thoughts.

Frank

[dertsap]

Yes Gads, you are right about the allen key adjustment for the up and down aspec, but it doesn't help the situation in regards to grabbing certain small parts that are easier to work with on one side of the vise.


Frank

put a dummy part on the othe side of the vise

[jed102]

It seems a shame to have to do that. I could understand having to do that on a cheap drill press vise. In fact right now on my old non kurt vise I don't have to do that. Some machinists expect too much I guess.

Frank

[WhiteTiger]

It seems a shame to have to do that. I could understand having to do that on a cheap drill press vise. In fact right now on my old non kurt vise I don't have to do that. Some machinists expect too much I guess.

Frank

Never had to play games with my jet vise either, until I'd used it about a decade and a half. I guess by that time it had worn enough to become a kurt?

(couldn't resist that one)

Tiger

[jed102]

Thats funny Tiger! But I hope we haven't opened up a can of worms here

Frank

[dertsap]

It seems a shame to have to do that. I could understand having to do that on a cheap drill press vise. In fact right now on my old non kurt vise I don't have to do that. Some machinists expect too much I guess.

Frank

kurt vises force is consentrated to the center of the vise if parts are loaded off center then you will not have even force across the edge of your part ,because the moving jaw kicks to the side not a big deal when running small parts , but when you get into heavy hogging , you need the most even force across the part , or face the lesser pressure end pulling out of the vise ( done that), but even with small parts when i need to work from one side of the vise i almost always put a block at the other end on the curt vises , there are other good brands that do allow you to work off center , but i don t find kurt to be too forgiving on this and ive worked with many different kurts
but kurts bullet proof
and ya dude we do expect too much ,but its the best way to get the job done right

[jed102]

Ya, I can relate to the part lifting when taking a big cut too! One other issue with clamping parts off to the side, is loss of parallelness to the non movable jaw, which is important when machined details must relate to the surface against that jaw. One side of the part will be grabbed tight while the other may even have an air gap (especially with this kurt vise, but I believe they are bullet proof).

One big problem for me is that I can never seem to find something the perfect size to stick in the other side of a vise. So, for someone like me who does a lot of work off to the side, I would rather have very little side to side play in the movable jaw and then if I need to clamp a large uneven piece across the full width of the vise, put a small piece of flat bar in the middle of the movable jaw to equalize the pressure.

I like that, "expecting too much is the best way to get the job done right"

[fpworks]

The "rotational play" in the movable jaw is intentional by the manufacturer and desireable (of course, too much is bad).

You DO NOT want this type of play in centric (or centering) type vises where both jaws move. (then you will have terrible repeatability)

Back to intentional and desireable:
You want the movable jaw to conform to the workpiece, otherwise the movable jaw will be fighting the rigid jaw to locate and clamp the workpiece. (I'm talking about conforming to anything less than PERFECT, so even if your part has very precise ground surfaces, you still want the movable jaw to conform, it just has to conform less.)

Additionally, this play allows you to accurately and robustly clamp two parts in one vice station.

As measured with an indicator on the corner of the movable vice jaw, my 3600V has 0.007" of play, and my Chick vices have ~0.005" of play.

By clamping one part off center, you are causing the following problems:
1. Available clamping force is reduced, because the movable jaw is binding as it is clamped.
2. Reducing repeatability because clamping forces are not parallel. (an small angle is induced because of the "play")
3. Additional distortion of the base can occur because of the binding, which can further reduce repeatability.

Not saying it shouldn't be done, but just avoided if possible...and I know it isn't always possible.

Justin

[jed102]

Thanks for the measurements that you provided. I would be extremely happy if the side to side play in my kurt D675 was only .005 or .007, however it is .024 and that is not exceptable to me as a machinist, especially for the type of work that I do, and can imagine that many others do.

In fact if I had the amount of play that you have there wouldn't even be an issue for me. I'd be very happy!

Any of the obvious advantages of a "small" amount of side to side play on the movable jaw are understandable to a point. But, once that point is crossed other issues which to me are at minimum very inconvenient and annoying come up.

[WhiteTiger]

Heh... is it just me or does this thread sorta resemble apologetics to anyone else?


Tiger