Workholding...or too big for the vise

[trlvn]

So, I have a chuck of 1/4" aluminum plate that I'm reusing for a project. I've made the long edges parallel by claming in the vise and end milling the edges. That's all well and good but what is a simple way to make a short edge square to the long edges? The stock is roughly 5" X 11" and my vise won't open wide enough to hold it. My vise is not one of those new fangled ones where you can move a jaw to the back edge.



Is there some simple technique to clamp the part to the table while registering the already milled edge against the edge of the table so that I can use Y travel to mill square? <Run on sentence? You betcha! Just read it 4-5 times and you'll get the gist.)

To be clear, my goal is "pretty square". This isn't aerospace work so I won't fret about a few tenths of an arc minute! But this seems like reasonably common problem so I suspect that there is likely more than one way to get close enough.

To tell the truth, if it wasn't the end of the day, I would probably have used the mitre gauge on my table saw. I've got an old 9" blade, carbide tipped, that I use pretty much just for cutting aluminum. Lots of shrapnel but it cuts like buttah.

Craig
(The objective is to end up with an "L" shaped part--ideally with rounded corners. I may come back with more questions before I'm done!)

 

[Brent H]

Fastest way - if your set up for it - clamp two stops in the slot on the front of your table to use as a fence. Make sure they are tall enough and spaced well. Butt your part’s (set on some 123 blocks and clamped) edge up to those stops. Mill your y edge. Does that make sense?

 

[Tom Kitta]

Part feels too flexible to easily use the vise.

Just place your part flat on some 1-2-3 blocks and use these two holes I see in the part to clamp it to the table. You will have to also have something on top of the part - maybe something like 4" long to make sure it is all held well - also underneath maybe use like 4 1-2-3 blocks.

use one of the edges of the table to align your part with for square. This is rough but you said rough will do.

Then mill your part to a rectangle you want. if it vibrates take lighter cuts. Remember go 3x as fast as in steel. Use 2 flute EM.

 

[YYCHM]

How did you manage to mill the two long edges parallel?

 

[trlvn]

How did you manage to mill the two long edges parallel?

Like this:



The piece wanted to vibrate but I gripped it with one hand (well away from the cutter) and it worked out OK.

Craig

 

[Former Member]

Like this:

View attachment 24907

The piece wanted to vibrate but I gripped it with one hand (well away from the cutter) and it worked out OK.

Craig

Also go to a 3 or 4 flute cutter increase your rpm, decrease your feed and reduce your depth of cut can greatly reduce or eliminate your chatter.

This is great for the long edge, short edge could be dangerous but doable (maybe if your medical and life insurance is paid up, oh and don't forget to video it it makes for a great high count YouTube video should it go wrong). A better method is to remove the jaw faces check the fixed side is true and use without the faces. Not ideal but sometimes you gotta improvise.

Think outside the box.

 

[trlvn]

This is great for the long edge, short edge could be dangerous but doable (maybe if your medical and life insurance is paid up, oh and don't forget to video it it makes for a great high count YouTube video should it go wrong). A better method is to remove the jaw faces check the fixed side is true and use without the faces. Not ideal but sometimes you gotta improvise.

I can't mill the short edge with it standing up in the vise because I don't have enough Z height. Even if I had enough height, I think the vibration would be pretty extreme. It is only 1/4 inch aluminum plate.

But, my jaw liners are about 0.400" thick each. If I remove both, I have _just_ enough capacity to hold the workpiece! Whodathunk! Thank you! I'll give that a go later.

Craig

 

[Pinzgauer]

I can't mill the short edge with it standing up in the vise because I don't have enough Z height. Even if I had enough height, I think the vibration would be pretty extreme. It is only 1/4 inch aluminum plate.

But, my jaw liners are about 0.400" thick each. If I remove both, I have _just_ enough capacity to hold the workpiece! Whodathunk! Thank you! I'll give that a go later.

Craig

There is a very simple way by using a table saw. Aluminum cuts like wood on a table saw. The cut will be tougher than when milled but a bit of sandpaper on a board will clean this up. You can also use the holes you have in your plate to tie the sheet onto a scrap pice of plywood may be with plywood on top then you can cut the whole L in one go. I worked on aircraft modifications all my life so what is good for aircraft is good for me

 

[trlvn]

As @Degen hinted, removing the jaw liners gave me just enough room to hold the workpiece in my vise. It also turned out that I was just inside another limit:



The vise has mounting brackets fore and aft as well as on the sides. Just as the front bracket hit the column, I was finished the width of the cut. Whew!

Craig
(You guys with the monster Bridgeports can stop chuckling now.)

 

[Former Member]

Who is chuckling I only have BB CT054 and just under 6" with way covers in place.

Mind you if you see it it doesn't look like a CT054 any more, with flood cooling, column extension, splash shields and catch tray to go with the CNC upgrade .

But I am very aware of how to get around limitations of size.

 

[LenVW]

Sandwich the plate between a couple of bigger, thicker, steel plates.
Acts like oversized vise jaws.

 

[Janger]

I’m Lurking at lunch time here. Another idea to increase vise capacity. Make a tall back jaw and make a second jaw out of L angle shaped material. Bolt the L to the top of the movable vise well back from the movable jaw. Ie Drill and tap into the movable vise body. Sort of a substitute for moving the jaws to the back of the vise. Is that a good idea? I’m not sure. It seems there is enough body there to put in some bolt holes. Has anyone done this?

 

[thestelster]

I made up a couple of plates which get bolted onto the outside section of the vise jaws. Drilled a couple holes to accommodate the tall jaws (.5" x 10" x 5") for tall work. For wide work, the rear plate is higher than the vise jaws, and on the front I bolt on a couple of table clamps.

 

[LenVW]

Make a simple vector diagram of the force loading on the vise.
If the moments are too great you may be prying your vise apart.
Remember the lever created by the large plates.

 

[Susquatch]

I made up a couple of plates which get bolted onto the outside section of the vise jaws. Drilled a couple holes to accommodate the tall jaws (.5" x 10" x 5") for tall work. For wide work, the rear plate is higher than the vise jaws, and on the front I bolt on a couple of table clamps.

I love this! But damn you! Now I have yet another project!

And ya, @LenVW is right, gotta manage the leverage forces. But a vise is for holding things while you machine them. A little bending is ok as long as you know it's under the yield point and stuff isn't popping out of the Jaws or moving.