# Positioning keys width underneath a milling vise



## Debovsky (Sep 25, 2021)

I've scavenged this forum hoping to see if someone ran into the same problem as I do. Or perhaps it is just me who worry about something I should not. You tell me.

I just bought a brand new milling machine (a CX611) and my 4in milling vise has positioning keys that are too large to fit the T-slot key ways of my machine. The vise has keys having 14mm in width whilst the key ways are 12mm. I've tried to find a 4in vise that has the correct key size but it is almost impossible to know that just by reading the product description one could find on any vendor's online store.

Do you guys use those positioning keys at all? I feel like they are there for a reason. I think they should help placing your work on the mill table in a consistent manner. I'm planning to machine them down to 12mm so them they would fit. I'm new to machining so be merciful. Thanks


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## gerritv (Sep 25, 2021)

I would just mill them down, you already have the milling machine to do it 

i added the keys to my vise, gets it 'close enough' for most work. If I need to be fussy it is a great starting point for alignment.

Gerrit


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## cuslog (Sep 25, 2021)

I don't use them, they don't get it in perfect alignment so I still have to square up the back jaw with a finger dial. If you remove / replace the vise very often, they're a protrusion that just gets in the way of sliding it on / off the table.


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## Dabbler (Sep 25, 2021)

Let me say at the outset that they keys are in your rotation plate, not your vise proper.  Most experienced machinists store the rotation plate behind the mill, taking it out only once or twice per decade.

@Debovsky I've heard plenty of opinions on both sides of this issue;  I personally am non-partisan.

So advice #1:  remove the rotation plate and use the vise on the table.  This gives you almost 3/4" extra height, which is valuable. (and no fix to the rotation plate!)

Now to directly answer your question.  Fasten your rotation plate to your table and mill off 2mm off one side of the keys.  Do your best to make it a slip fit to your slots:  these keys are there to ensure that your plate doesn't rotate while adjusting the angle.

That said, that annular ring marked in degrees is only a suggestion, and there are way more accurate ways to set your vise jaws on an angle.


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## Mcgyver (Sep 25, 2021)

Dabbler said:


> Most experienced machinists store the rotation plate behind the mill, taking it out only once or twice per decade.



that frequently 

I use the keys, make them the right fit for table and vise and thye wil get you very close to perfect alignment aligned -more than close enought for milling imo.   If there is inaccuracy with the mill - T slots not aligned or worn,  or in vise,  aligning it each time is safer and the right approach.  However imo that's a time consuming pita if you don't have to.  Do an experiment, run an indicator along the T slot - is it parallel?

You've got a mill, so can make whatever you need.  Keys don't have to have a straight side, just make set with a shoulder.   One section fitting the vise, the other the table.


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## Dabbler (Sep 25, 2021)

3 of my vises are keyless, and 2 have keys. Both of the keyed vises have the keys surface ground so they are a 'forced slip fit' - they align the vise within 3 or 4 tenths every time.  

The two main vises I use are keyless, and stay on the mill for years after I align them   The 5" keyed vise is for specific jobs, and lives on the shelf.  Thew other keyed vise is for the horizontal mill.


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## 6.5 Fan (Sep 25, 2021)

I to would take the rotating plate off the vise, mine is on a shelf someplace. No keys on the vise either.


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## Debovsky (Sep 25, 2021)

Thanks guys. I'm gone to take them out. Indeed, even with keys, one need to indicate the vise anyway so never mind the keys. !


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