[SanDiegoCNC]

You boys play nice now!

While I don't know what "most" programmers do, "many" programmers do in fact work this way and this is not the first time I've heard that thought.

In fact, I know shops that make the lower left corner of the fixed jaw (nearly the same thing) that work datum. The vise stays put on the machine and it makes it easy to load almost any program, slap a part down relative to that corner, and go.

Cheers,

BW

Part of the reason why its better to work from the front left corner is because it keeps all of your X and Y values positive. Another is that materials are not always cut to the same relative size. That means you have to either find the smallest sized part and use that for your setup or adjust the datum further into the part to compensate for the occasional undersized block. That's something you learn from experience, not by taking a course or two in programming and calling yourself a machinist. :cheers:

[JRoque]

work from the front left corner is because it keeps all of your X and Y values positive

ah, I get what you're saying now. I'm no machinist but do that all the time too. In fact, I don't have a "home" 0, 0, 0 position on my machine. It all depends on what I load on there. Even Z is reset depending on the material I'm working so I know that Z- is cutting and Z+ is not.

Separately, I wish Kurt made a very low-profile vise since I don't have a lot of clearance under Z. The one's I've seems are something like 4" high. This is fine for column/knee type mills but for lowly homemade like mine, it's limiting.

JR

[SanDiegoCNC]

1. ah, I get what you're saying now. I'm no machinist but do that all the time too. In fact, I don't have a "home" 0, 0, 0 position on my machine. It all depends on what I load on there. Even Z is reset depending on the material I'm working so I know that Z- is cutting and Z+ is not.

2. Separately, I wish Kurt made a very low-profile vise since I don't have a lot of clearance under Z. The one's I've seems are something like 4" high. This is fine for column/knee type mills but for lowly homemade like mine, it's limiting.

JR

1. That's a good practice. Its always good to have a standard way of setting up a machine tool. That way, the next shift machinist can step into a job and know certain things have already been done. Saves on having to redo something that was already set.

2. I'm primarily a lathe guy. But I've got to believe there are smaller vises out there that are just as well made as a Kurt. I hate to bring Quad-I back up but they do make at least 3 sizes of the same type vise. One is 4.0 wide and may be lower than a Kurt. (http://www.quad-i.com/products-vises.html)

[Geof]

Part of the reason why its better to work from the front left corner is because it keeps all of your X and Y values positive.....

And part of the reason (maybe the whole reason) it is sometimes better to work from a center point is that it can be easier to mentally calculate perimeter coordinates and hole locations. Being dogmatic and insisting there is one correct way can be unhelpful.

[Shotout]

Part of the reason why its better to work from the front left corner is because it keeps all of your X and Y values positive. Another is that materials are not always cut to the same relative size. That means you have to either find the smallest sized part and use that for your setup or adjust the datum further into the part to compensate for the occasional undersized block. That's something you learn from experience, not by taking a course or two in programming and calling yourself a machinist. :cheers:

The front left corner on a Kurt vise is the movable jaw, so if the stock varies my program origin could be inside or outside of the stock. The Left rear being stationary will keep my program origin at the corner of the stock at all times no matter the stock variation. So how would it be better to use a floating point for an origin rather than a fixed one? I'm not following that at all. If they set a work offset to an over sized blank then when using a smaller blank the toolpath could easily be off the stock, when using the fixed jaw the toolpath will always be on the stock providing the stock is large enough to contain the part.

The only reason I can think of to keep the coordinates all in a positive quadrant would be to help the operators to edit a program at the machine. Why would I want under qualified persons editing my program? I've spent time engineering a process, creating SPC data sheets, creating work instructions, established minimal and maximum conditions for the stock, programmed the part, designed secondary operation fixtures, quality assurance instructions and a setup package to document it all that supplies all the pertinent data to the setup person, operator and QC tech. I just don't see the benefit. Granted the majority of my programs originate from the center of rotation but even then I need a known position of the corner of the stock so it is always going to be a fixed position of my work holding device otherwise mismatch would be a problem when I rotate the work.

3600V Kurts. Love them. They are ground in which makes them nice. I have 4 per pallet on our HMC and they locate on keys mounted to the pallet. The greatest deviation from one vise to another is .0003. I also like the fact they are less susceptible to lift and can be mounted vertically as well. As a lower cost option, we bought 8 at once, they are nice. I know there are better ones on the market, but like I said we had to buy 8 of them when we tooled up the horizontal so we went with the Kurts rather than another brand.

[SanDiegoCNC]

The front left corner on a Kurt vise is the movable jaw, so if the stock varies my program origin could be inside or outside of the stock. The Left rear being stationary will keep my program origin at the corner of the stock at all times no matter the stock variation. So how would it be better to use a floating point for an origin rather than a fixed one? I'm not following that at all. If they set a work offset to an over sized blank then when using a smaller blank the toolpath could easily be off the stock, when using the fixed jaw the toolpath will always be on the stock providing the stock is large enough to contain the part.

Well, Shotout, you're correct if I were talking about a Kurt vise. My comments dealt directly with a Quad-I vise. On the Quad-I, the front jaw is fixed, hence the name Quad-I.

[Shotout]

Well, Shotout, you're correct if I were talking about a Kurt vise. My comments dealt directly with a Quad-I vise. On the Quad-I, the front jaw is fixed, hence the name Quad-I.

My mistake. I lost track of the thread after all the fracas.

The only real issue I can see with switching to those vises from one where the fixed jaw is in the back would be for repeat setups. Then the points I raised in my last post would manifest providing that the program origin was from the rear, fixed jaw of the vise. Engineering reviews and releases about 20 job folders a week at our shop on repeat work and most of the programs utilizing vises are from the fixed jaw.

[SanDiegoCNC]

My mistake. I lost track of the thread after all the fracas.

The only real issue I can see with switching to those vises from one where the fixed jaw is in the back would be for repeat setups. Then the points I raised in my last post would manifest providing that the program origin was from the rear, fixed jaw of the vise. Engineering reviews and releases about 20 job folders a week at our shop on repeat work and most of the programs utilizing vises are from the fixed jaw.

I have no idea what kind of CAM software your company uses. But with MasterCam (ver 9.0), all you have to do is to go into the Toolpaths and then Job Setup. From there, you can select where you want your origin. After selecting the new origin, just regenerate the toolpaths and post.

[converterk]

Has anyone used the Glacern reversed premium vise? They are reasonably priced, But I am concerned how well they would hold up in use.

[BobWarfield]

Part of the reason why its better to work from the front left corner is because it keeps all of your X and Y values positive. Another is that materials are not always cut to the same relative size. That means you have to either find the smallest sized part and use that for your setup or adjust the datum further into the part to compensate for the occasional undersized block. That's something you learn from experience, not by taking a course or two in programming and calling yourself a machinist. :cheers:

If you've got the lower left corner of the fixed (rear) jaw as the datum, you will have negative Y's and positive X's. There's no worry with that I can see. If it bothers you, I suppose you can use a reverse vise so the fixed jaw is at the bottom instead of the top.

As for different sizes of workpiece, they don't matter either, as long as they're all bigger than the part. If the left and top edges of the workpiece are not squared, you simply leave a little allowance for the part so it isn't aligned on X, Y = 0 and let the profile operation do its thing.

That's the whole point of the approach, is you can bandsaw a close enough workpiece, pop it on the vise and go without changing the program, touching off, or anything. Just push the green button.

The system works well for the shops I've talked to, and I like it myself. Some of them are using fixture plates set up the same way. They'll even start their cad with the fixture plate or vise jaw on the drawing so they can line up the part. It's not perfect for everything, but it gits 'er done a lot of the time.

Cheers,

BW

[SanDiegoCNC]

If you've got the lower left corner of the fixed (rear) jaw as the datum, you will have negative Y's and positive X's.

Bob, on a Quad-I vise, the front jaw is fixed. Therefore, both X and Y are in the first quadrant. The name Quad-I says it all.