Milling vise mounting

[DPittman]

I've read that most people don't use the swivel base on their milling vice very often and feel they reduce rigidity so they remove them altogether.
I bought myself a new milling vise that came with a swivel base and the way I am mounting my vise I don't see how it would reduce rigidity on my setup. Take a look and tell me what you think. There would actually be me iron under the vise itself with the swivel base then without.

 

[Brent H]

I think in most cases it is personal preference and also how much height you have from spindle to the vice. Smaller mills do not have the clearance for many projects and the swivel eats up valuable height.

Mine is still on the vice and I have used it to tune some very precise angles that would have taken a while to set up on the vice just mounted to the table. I also have it on a full size mill so space is not an issue for many functions. You can true it up quite quickly by using the swivel as well.

It is all up to you if you use it or not.

 

[YYCHM]

If you have the head space to spare use it. It is faster to true that's for sure. I'd use mine but I lack the head space to drill with it.

 

[Tom Kitta]

Yeah I have my Kurt setup same way as well as all my other vises on K&T mill and radial drill press. Some people will buy off you the swivel - I got like $20 for one and there were many takers.

 

[CalgaryPT]

I only have a mini mill and a tiny vise, so I'll let others with bigger machines speak more from experience.

I do know that what you say is true WRT to cross slide vises on drill presses. Granted, these are far less rigid and far more prone to wobble though. I finally bolted my drill press to the floor and should brace the column with a split flange/bearing because the issue is still there big time. In fact, the wobble and lack of rigidity are why I hate drilling so much and punch on the ironworker now whenever I can. My cross slide is almost 7" above the table and the vise has far less mass to it than your vise, so you may be OK. Obviously the wobble is a function of the vise's height from the table, but there are also tool forces at play here as well. I routinely remove my cross slide vise when the hole is critical as I know categorically I get a better result.

I'm now a big fan of the post in @YYCHobbyMachinist 's RF30 thread that said, "How precise does the machine need to be?" But your whole question speaks to the issue of mass and rigidity on mills. I recall a thread somewhere about mid-sized mills for sale somewhere that were almost the same price. The consensus was, everything else being equal, the more mass the better. I'm sure the same holds true for vises. So a heavy vice that is higher than a shorter one could in fact have less wobble.

 

[DPittman]

Well I don't have much room from spindle to vice but the swivel only adds less than an inch I believe. And even with the swivel base on it I still gain room over my other vise.

BTW. This new vice is a KBC branded made in Taiwan (vertex) vice and although i haven't done any measurements on it it appears to be a well made and finished hunk of cast iron.

 

[Johnwa]

On a column mill I think the column is the weak point. The higher the head is the more flex you get in the column.

 

[DPittman]

On a column mill I think the column is the weak point. The higher the head is the more flex you get in the column.

Isn't the flex/ leverage the same all the way up?

 

[YYCHM]

Isn't the flex/ leverage the same all the way up?

No, you always mill with the head as close to the table or work piece as you can get.

 

[DPittman]

No, you always mill with the head as close to the table or work piece as you can get.

Yes certainly to reduce quil extension that makes sense but I would think the forces and geometry are the same all along the column. Now move out on the y axis and that's another kettle of fish.

 

[Johnwa]

the upward force on the quill will bend the column backwards. Sideways force will twist the column. The column is effectively a spring. Lowering the head shortens the amount of column involved resulting in a stiffer ”spring”.

 

[RobinHood]

Isn't the flex/ leverage the same all the way up?

The flex per unit of length is the same along the column.

Machining a part generates certain forces. Yes, these forces would not change if you applied it at the base of the column or the very top.

What changes is the lever arm length. So if the column deflects, say 1 thou per inch under a certain load, at the base (one inch up) you would have a 1 thou error. 6” up the column, that would be 6 thou. And so on.

So exactly as @Johnwa said: the column is a “spring”.

Same principle applies to your vise. The farther the part you are machining is from the anchor point (where the vise is bolted to the table), the larger the deflection of your set-up. That’s why a lot of people remove the swivel base, even if it adds just an inch or so in height and they have lots of headroom. You can always install the swivel base if you need it for an angle set-up.

 

[Tom Kitta]

On a shaper the spring thing can be observed in real time - you can see the vise flex and you can see it flex at where the swivel is. Certainly for heavier cuts. Even the whole saddle flexes visibly despite it having a front support.

The swivel is yet another attachment - i.e. more bolts - not just a static extension, but a flexible extension. Thus say a vice that is 2" of the table and one that is 4" of the table may not be a huge difference if both are solid, but with a 2" vice connected to a 2" swivel it now is quite a difference.

You can , as someone else mentioned, put a swivel under your vice when you want to use it - you have to re-align your vise anyways if you use the swivel.

Maybe I even make a video illustrating shaper and the flex present when taking heavy cut. It is quite visible.