Mill Vise Hold Downs

Seems simple... How do you think It will work out?
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or here if the picture won't show by itself.
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Obviously adjust the dimensions to match your application. Is there
something better that might make it easier to square and repeat alignment
upon removal and remounting of the vise? The only think I can think of is
to mount an alignment bar on the bottom of the vise that will drop in the
table t-slots.

Reply to
Bob La Londe
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That looks very like what came with my Gerardi modular vice but they don't have the radii your images shows, also the Gerardi ones are thicker in the T slot area and the tip is thinned to fit the slot in the side of the vice. The Gerardi came with a slot in the bottom and keys for the purpose of alignment in the T slots. The vice it replaced had dowel pins in the underside for alignment to the edge of the T slots. I was taught that the T slot can be used for this purpose and on good machines are accurately ground parallel to the movement. Many tools such as the Suburban tool spin indexer have the base ground so that it can be place against a bar set into the T slot for quick alignment, I had to do the base machining myself to allow that on my cheap Chinese knock-off spin indexer.
Reply to
David Billington
Similar clips attach the mag chuck to my surface grinder.
A bar or two keys under the vise works fine, but is difficult to machine accurately, especially if the tee slots aren't exactly parallel to the X axis. I figured out how for an RF-31 mill-drill once and if yours are angled I'll try to remember and post the method.
Reply to
Jim Wilkins
"Bob La Londe" fired this volley in news:iho89b$4c9$
Even that isn't accurate enough for good work. Unless you're profiling the outside of an over-sized piece, you always need to true up the work so it indicates parallel to the X axis. And even if you are profiling a big piece, if you must ever re-vise it to a new face, you won't be accurate unless you've previously got the vise squared to the table.
My 8" mill vise has a bottom Y-axis cross-bar on it, along with a Y-slot in the BP's table. It's within a few thousanths of true end-to-end as soon as it drops into the slot, but still must be trued by hand.
Reply to
Lloyd E. Sponenburgh
Blocks, or a bar that fits in a table slot is good for getting alignment/setup close.. but table slots will wear with repeated (dis)mountings.
Hold-downs should be adequately strong and well tightened to absolutely insure that the workholding device won't move untentionally.. not just held in place from the "that looks secure" perspective.
The clamps shown appear to be fabricated from angle iron, which is generally thin for the overall size of commonly available sizes. Thicker cross sections can be found in angle with large dimensions, not so much with smaller dimensions.
It appears that the items which were referred to could be suitable/reliable for only light duty milling.. anything larger would very likely require much more subtantial thicknesses in material.. and more material relative to the size of the slot.
It's the width of the slot size that makes those suggested clamps (look) weak, IMO.. removing 1/2 of the material seems very counterintuitive to me.
I try to keep the hold-down bolts (with a heavy washer under the nut) close to the side of the workholding device, whether the bar/clamp have a slot, or just a hole.. this is generally easier when blocks are placed on the other/outer side of the bolt.
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