- The rule of thumb for vacuum workholding
is if you can hold it in a vise, do it.
But when it comes to large or thin parts
that absolutely can't be held in a vise,
then vacuum is a fantastic alternative.
But in this Fixture Friday,
I'm gonna show you why I broke my own rule
and use vacuum to hold a vise part.
♪ I was made for this ♪
In this Fixture Friday, we are making this part right here.
Now, this is one of our simple products
known as the SmartPlate.
The SmartPlate allows you mount a rotary unit on your table
and gives you the option of two positions,
both outboard to maximize X travel,
or you can use the inboard position
to maximize your swing clearance.
It also, depending on your hos machine,
can mount your rotary unit outside of the machine's envelope
so that the body of the rotary unit doesn't take up
any valuable machining space.
We'll add a link to the product below.
But in this Fixture Friday, I'm gonna show you
why this part, which typically could be made in a vise,
was perfect for vacuum workholding.
A quick overview.
Now, I say that if you can hold a part in a vise
or a fixture, do it.
But if it's impossible to hold it in a vise
like thin or flat work pieces, or if you have a part
that needs a consistent floor thickness,
if you're trying to hold a critical Z dimension,
that's why you would want to go to a vacuum fixture,
which applies equal holding pressure
on the entire bottom surface area of the part.
Now looking at this material, it starts out
at about an inch and a half thick
and is roughly 10 by 12 inches.
And that's robust enough to hold in a vise, but kind of.
Now, the first thing we do with this material
is we have it Blanchard ground to a very close flatness
and consistent thickness.
Now once we've done that, we can't quite hold it in a vise
because we wouldn't be able to machine the perimeter
of the part, so vacuum actually is a natural fit.
So looking at this top plate, we use this
for both the first and second operation.
For the first operation, we take this part,
place it on the top plate, and all the features
that break through break into these gasketed areas
that are either isolated off or on the outside
of the vacuum area.
Now we eyeball this into place,
but we don't take a cut around the perimeter.
For the second operation, we add pins.
And on the backside of our work piece,
we have some tooling holes
that have no effect on the part performance,
but only allow us to locate it on the top plate itself.
Now I've talked in other videos
about using the sandpaper technique, just because we can,
which would've added traction.
But instead, we've shifted our strategy
so that all the heavy cuts are taken
on this second operation because the pins
holding the part in place adds lateral stability.
Remember, it's not likely
that you are ever going to lift apart on a vacuum chuck.
Typically, the side forces
from a cut is what shifts apart sideways off the gasket,
and there's your point of failure.
Now in a future Fixture Friday,
I'm gonna show you how you can locate your part
in a pocket to keep the lateral forces high,
but the pin method is completely legitimate
and serves the same purpose.
If you're a machinist looking to brush up
on your fixturing skills, this is the series for you.
So if you haven't yet done so,
consider subscribing and hit that notification bell
so you don't miss the next Fixture Friday.
Now until next time, go innovate your production.