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Vise Sine Keys on MVN

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SPICEMAN

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#1
Kurt had a great deal on scratch and dent DX6 vises. To line them on the table they use sine keys. In looking at Burke MVN specifications I find the table slots are 11/16" or 0.6875".
Sine keys listed various places spec out at 0.6870 but the one set I bought are closer to the 0.688" side of things.
My table slots measure more to be closer to 0.6873" so the keys do not fit the slots.

My question is has any one else seen this issue. The next smaller keys are 0.6245" so a bit of a drop. Any ideas on fixing? The darn keys are not cheap so buying another set to try is a bit hard on the pocket book.
 

benmychree

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#2
What is a sine key? never heard of such a thing; Google was no help
 

kd4gij

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#3
He is talking about the little blocks the bolt to the bottom of a vise that sit in the T slots. They are supposed to align the vise. Supposed to that is.
 
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benmychree

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#4
They have no resemblance to anything associated with SINE, they are simply fixture keys.
 
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Asm109

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#5
You have a mill. Make them fit. That is what machinists do.
 

SPICEMAN

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#6
Already had that idea but more wondering why no fit in first place. Maybe 11/16 has changed over the years.
 

Ray C

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#7
Already had that idea but more wondering why no fit in first place. Maybe 11/16 has changed over the years.
Many mills now have metric slot sizes. Maybe they're sized somewhere in-between metric and SAE to work in both cases.

In my experience, positioning keys like that can be cumbersome. For quick and dirty positioning they are fine but can get in the way when trying to do precise positioning. I have a 4" vise and when precision is needed, alignment to 0.0003" variance or less is not uncommon. Positioning keys aren't going to help with that level of precision. Also, they are not intended to help secure the vise; the clamping bolts do that job.

As far as the term Sine Key... I've never heard of that. I watched the Kurt video posted above but, there was no audio so maybe I missed-out on an explanation. I don't see how they can be used to form an angle. I wish there was audio on that presentation so I could hear Kurt's explanation.

Ray
 

benmychree

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#8
I have always just made the keys to fit tightly in the vise body and snugly in the tee slots; the vise may not align absolutely truly, but that is seldom needed in normal machine work.
 

Tinkertoy1941

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#9
We have four Kurt vises all with fixture keys that fit snug.
We sometimes set up two or three vises on a Bridgeport and they will indicate within .002 between all of them
Also the height from table surface to the vise bed will have the same dimension
I would check the check the key-ways on your table some where the key-ways have not been abused!!
With normal use the key-ways can have nicks and other problems, you may need to shine the bed key-ways to get the fit you are looking for

1525517429296.png



Sine key are installed in round holes for setting fixtures
this a sine key for different key-way widths
 

benmychree

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#10
A picture is indeed worth a thousand words; I have seen these before, had some, but never used them.
 

aliva

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#11
Don't waste your time on sine keys, once installed on the vise you still have to tram the vise in anyways. So the sine keys are a waste of money and time. All they do is get you close. Close is not really good enough.
 

Cadillac

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#12
Plus you’d have to lift your vise or vises into position and off. No sliding. I have those but are in my misc. drawer. Like said if you want precise you’ll have to indicate either way. You want mine?
 

SPICEMAN

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#13
Thanks all for ideas and input, I ended up with a lower cost universal set from Jergens. They will fit three slot sizes. After using them a while I may just take them off (and no I do not mind lifting the Kurt on and off it is not that heavy).
If I do take them from the vise I will use them for some other table attachments.
I do notice the size I list in original post is not for the 11/16 milrite table size, after getting the Jergens I found that slot size and sine key size has some "slop".
 

Bob Korves

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#14
In looking at Burke MVN specifications I find the table slots are 11/16" or 0.6875".
Sine keys listed various places spec out at 0.6870 but the one set I bought are closer to the 0.688" side of things.
My table slots measure more to be closer to 0.6873" so the keys do not fit the slots.
So the store bought keys are a maximum of .0007" too wide per the numbers you posted. That amount is easily removed by rubbing the sides of the keys on a bench stone. I do not like the fit of factory made keys and also do not like that they are hardened, which can cause damage to the t-slots. So I make my own from mild steel to the fit I think is correct. It is an easy job, and is also an ideal project for a neophyte machinist.
 
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