ARC Versatile 100mm Milling Vice question?

[Bo’sunParticipant @bosun58570]

Good afternoon,

During a recent check, I noticed the tops of the jaws were sloping (less than 1 deg.) from the clamping face downwards.  I guess it’s deliberate, but does anyone know for what purpose?

[Tony Pratt 1Participant @tonypratt1]

I can’t think of any reason for the slope apart from careless grinding? I’m sure others will come up with reasons for the 1 deg. slope.

Tony

[Clive FosterParticipant @clivefoster55965]

Generally considered bad practice to have gripping faces angling outwards so whatever is being gripped has tendency to squeeze out. Perfect is dead square but (inevitable) errors should be angling inwards to pull the part in.

Similarly on the top surface of the jaw, where parts may need to seat down on, dead flat is the ideal. But errors making the part furthest from the gripping face higher give a more stable seat than when the highest point is nearest the gripping face.

It would seem prudent for a decent maker to set up so the errors from ideal dead flat go the safe way.

Clive

[Clive Foster]

On Clive Foster Said:

Generally considered bad practice to have gripping faces angling outwards so whatever is being gripped has tendency to squeeze out. Perfect is dead square but (inevitable) errors should be angling inwards to pull the part in.

Similarly on the top surface of the jaw, where parts may need to seat down on, dead flat is the ideal. But errors making the part furthest from the gripping face higher give a more stable seat than when the highest point is nearest the gripping face.

It would seem prudent for a decent maker to set up so the errors from ideal dead flat go the safe way.

Clive

On Tony Pratt 1 Said:

I can’t think of any reason for the slope apart from careless grinding? I’m sure others will come up with reasons for the 1 deg. slope.

Tony

Hello Tony, The fact that both surfaces are sloped the same amount, and in opposite directions, makes me think it’s deliberate.

[Dave HalfordParticipant @davehalford22513]

Anti lift, saves all that knocking down.

[Tony Pratt 1Participant @tonypratt1]

The thought that the manufacturers are diligently grinding say a 1 degree angle on every vice jaw top face and then fitting them the ‘correct’ way round is stretching credibility.

The basic reference faces on a milling vice bolted to the machine table are the fixed jaw and the bottom face where the work or parallels sit, the jaw top faces are in my opinion and experience never used as location faces, I have never checked my Arc vice jaws for squareness but I did pay for both jaws to be surface ground as they were out of parallel by over .1 mm if memory serves?

Tony

[JasonBModerator @jasonb]

If the 80mm is anything to go by then you could flatten them with a Carbide cutter as the cutters have won when I have driven them into a jaw on the CNC.

I can’t see it has anything to do with anti lift as the top surfaces don’t come into contact with anything when tightening the vice

[BazyleParticipant @bazyle]

Isn’t it more likely it is the faces the jaws are bolted to that are ever so slightly not vertical.

[Bo’sun]

On Bo’sun Said:

Hello Tony, The fact that both surfaces are sloped the same amount, and in opposite directions, makes me think it’s deliberate.

I presume that this is the vice in question:

https://www.arceurotrade.co.uk/Catalogue/Workholding/Machine-Vices/ARC-Versatile-SG-Iron-Milling-Vices

… in which case, it seems eminently reasonable that a batch of jaw-facings would have been ground in a single production-run, and any two from the lot would have been used on each vice: If so, using the same component on each jaw will automatically mirror the geometry.

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

I wondered if the vice was one of these?

 

 

Adam Savage mis-adjusted one whilst demonstrating his new PM728V mill, so it clamped with the moving face tilted and came loose.  I think it’s in this Youtube Video.

The PM728V is an interesting machine.  Although it’s much the same design as that family of small mills of which my WM18 is a member, the PM728V is made to a notch above usual standard  and costs significantly more.  Adam claims his has a 0.0002″ run-out.  Made in Taiwan, and doesn’t appear to be available in the UK.

Adam Savage’s workshop videos are informative, but don’t expect to see best practice!  Although he has good tools and a rock-solid track record making models and much larger film-props, Adam shows many signs of being self-taught, albeit in a professional environment.   Pleased to say his production values are honest – he leaves mistakes in, and often discusses them.

Dave

 

[JasonBModerator @jasonb]

No, it’s the one called a Versatile Vice Dave, as per thread title. Probably this type rather than the SG that Michael linked to

[SillyOldDuffer]

On SillyOldDuffer Said:

I wondered if the vice was one of these?

[…]

 

I wouldn’t know, Dave !

All I did was to put the words from the title of this topic into Google … which directed  me to a specific page on Arc’s website.

MichaelG.

.

Edit: __ Having just seen Jason’s reply, I concede that Google might have misled me slightly … but the gist of my first comment remains valid.

[Bo’sunParticipant @bosun58570]

Yes Jason, that’s correct.

Bazyle, It’s definitely the jaw facings and not the jaws themselves.

It’s just curiosity that made me ask.  The vice functions perfectly well (for me at least).  Maybe I’ll drop a note to Ketan and ask the question.

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