I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass. I
can go with a really small WOC, but then the surfacing of the bar starts to
take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?

On Saturday, May 26, 2018 at 11:26:36 AM UTC-4, Bob La Londe wrote:

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?

Try hanging a good sized C clamp on the aluminum. It will reduce the chatter.

Dan

On Sat, 26 May 2018 08:26:31 -0700, "Bob La Londe"
wrote:

I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass. I
can go with a really small WOC, but then the surfacing of the bar starts to
take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?

Add mass/restrict chatter. If not a vise, how about a 3rd hand? (No,
not the type used for soldering, but larger)

A pair of vise grips on a stick might be the ticket for you. I saw one
years ago but didn't save the URL. This is similar:
http://weldingweb.com/showthread.php...rticulated-jig

Maybe easier yet would be to weld up a piece of bar in a U shape with
a vise grip on one end. Chuck it in the vise along with the bar to be
cut while the vise grip holds the floppy end. I think I'll do this
with one of the cheaparse Chiwanese vise grips I have which aren't
good for anything else. I have that problem all the time and, like
you, have never spent the time to solve it ahead of time.


--
If we can ever make red tape nutritional, we can feed the world.
--Robert Schaeberle

Bob La Londe wrote:

I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass.
I can go with a really small WOC, but then the surfacing of the bar starts
to take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I
just start working on setting up a second vise aligned with the first on
those machines?
You can also put some strips of scrap on either side of the workpiece, and
clamp the 3 together with C-clamps. 3 pieces with clamps are WAY stiffer
than one single piece. I have some parts I make that are wider than the
vise jaws, but I usually do 8 at a time. Works great with the clamps.

I have also made a custom holder for some other long parts. It is made from
3/4" aluminum, and has a step on one long corner. There are 5 tapped holes
so a clamp bar can be pulled down over the step. It is a foot long.
So, you put this in the vise with the edge with the step facing up, and can
indicate off the step. Then, put the parts in it and clamp with the 5
screws (vertically). So, this thing is kind of a custom vise that I use for
machining 3/8" square and 3/8 x 1/2" bars for a particular job.

For some other long parts, I have made up some fixture plates. One is 12 x
12", the other 12 x 24". Both have a 1" grid of 10-32 tapped holes. I made
a bunch of steel clamps with 1" long slots. So, you put some bolts in
strategic spots to locate the parts, and then a row of the clamps to hold it
down. You can put bits of scrap aluminum under the actual part, so you
don't dig into the fixture plate when machining. If you need to machine all
around the part, you can move the clamps several times, as each edge is
machined, always keeping a couple clamps tight so it doesn't move.
The holes in the plate allow coolant to flow down to the slots and galleys
in the table.

I hope all of this makes sense without pictures.

Jon

On Sat, 26 May 2018 08:26:31 -0700, "Bob La Londe"
wrote:

I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass. I
can go with a really small WOC, but then the surfacing of the bar starts to
take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?


The jacks won't help much unless they apply pressure against the work
or are somehow affixed to the work. With a typical cutter that has a
helix that pulls the work up a thin part will be pulled away from the
jack and you will still get chatter. If you can apply pressure to the
work, say with a finger or a wooden stick, to hold the work against
the jacks then the jacks will help. You can use double sided tape to
hold the part to the jack, I have done this more than once and it can
work very well. The jack of course must be fixed to the table for
this method to work. Have you thought about vacuum? You could make up
little vacuum jacks that would hold themselves to the work and the
table. I seem to recall you saying you have a vacuum pump. Maybe that
was someone else.
Eric

On Sat, 26 May 2018 08:26:31 -0700, "Bob La Londe"
wrote:

I often find myself cutting aluminum flat bar that extends beyond the jaws
of the vise. When that happens it can result in chatter or harmonics that
affect surface finish. Particularly in the actual first surfacing pass. I
can go with a really small WOC, but then the surfacing of the bar starts to
take up a significant amount of time.

Do you think jacks under the part are enough to reduce that or should I just
start working on setting up a second vise aligned with the first on those
machines?


Jacks are VERY useful for this. So is a second vise.


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Upon Some reflection, how about a thick bar suspended between two or more
jacks?

Hmmmm... I think I am getting into the area where I am just going to have
to try it and see.

First I guess I need to make some jacks with different heads. Flat head,
flat flanged stud head, etc.

Ultimately I am thinking I'll have to go back to the idea of shoehorning two
vises on the machines. Maybe a pair of 4 inch screwless machined out to
hold six inch stock to keep the weight down, and have the compact length.

4 inch mill vise or lockdown vise will not fit inside enclosure without
hitting the doors. Just a hair too long. However my 6 inch screwless
machined out fit just fine. I actually bought a couple 4 inch lockdowns for
those machines. Oops. On the other hand they make great drill press vises.
LOL.

Maybe it would be better to just sacrifice some of my tooling and make some
fixtures with edge clamps.

I definitely do not need another cup of coffee this morning. LOL.

"Bob La Londe" wrote in message
news
Upon Some reflection, how about a thick bar suspended between two or
more jacks?

Hmmmm... I think I am getting into the area where I am just going
to have to try it and see.

First I guess I need to make some jacks with different heads. Flat
head, flat flanged stud head, etc.

Ultimately I am thinking I'll have to go back to the idea of
shoehorning two vises on the machines. Maybe a pair of 4 inch
screwless machined out to hold six inch stock to keep the weight
down, and have the compact length.

4 inch mill vise or lockdown vise will not fit inside enclosure
without hitting the doors. Just a hair too long. However my 6 inch
screwless machined out fit just fine. I actually bought a couple 4
inch lockdowns for those machines. Oops. On the other hand they
make great drill press vises. LOL.

Maybe it would be better to just sacrifice some of my tooling and
make some fixtures with edge clamps.

I definitely do not need another cup of coffee this morning. LOL.

If you don't mind modifying vises you could cut shallow work locating
and clamping steps at the tops of the jaws and make support blocks the
same height.

"Jim Wilkins" wrote in message news
"Bob La Londe" wrote in message
news
Upon Some reflection, how about a thick bar suspended between two or more
jacks?

Hmmmm... I think I am getting into the area where I am just going to have
to try it and see.

First I guess I need to make some jacks with different heads. Flat head,
flat flanged stud head, etc.

Ultimately I am thinking I'll have to go back to the idea of shoehorning
two vises on the machines. Maybe a pair of 4 inch screwless machined out
to hold six inch stock to keep the weight down, and have the compact
length.

4 inch mill vise or lockdown vise will not fit inside enclosure without
hitting the doors. Just a hair too long. However my 6 inch screwless
machined out fit just fine. I actually bought a couple 4 inch lockdowns
for those machines. Oops. On the other hand they make great drill press
vises. LOL.

Maybe it would be better to just sacrifice some of my tooling and make
some fixtures with edge clamps.

I definitely do not need another cup of coffee this morning. LOL.

If you don't mind modifying vises you could cut shallow work locating
and clamping steps at the tops of the jaws and make support blocks the
same height.

************

I definitely do not mind modifying vises. I have a bunch of screwless and
except for my 1 inch insert vises which already have a stepped jaw I think I
have machined at a minimum a stepped jaw in all of them. I've also machined
stepped jaw or soft step jaws for most of my mill and lockdown vises. I
think only the 2 4 inch lockdown vises and a 4 inch Enco swivel base mill
vise I bought with some other stuff from a shop going out of business have
original jaws in them. I lost count of how many vises I have a long time
ago. Well over 20. Maybe over 30. I guess vises are one of my vices.

Anyway, mounting support blocks on the table and milling them to match the
height of the jaw steps is a good idea. I can use 1" by X" aluminum flat
bar to try it out, and then if it works upgrade to some more permanent
pieces from 4140 or whatever I have on the bits and pieces shelf.

On Mon, 28 May 2018 09:22:35 -0700, "Bob La Londe"
wrote:

Maybe it would be better to just sacrifice some of my tooling and make some
fixtures with edge clamps.

Why not simply buy some edge clamps and cut some riser blocks?

I definitely do not need another cup of coffee this morning. LOL.

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"Bob La Londe" wrote in message
news
"Jim Wilkins" wrote in message news
"Bob La Londe" wrote in message
news
Upon Some reflection, how about a thick bar suspended between two
or more jacks?

Hmmmm... I think I am getting into the area where I am just going
to have to try it and see.

First I guess I need to make some jacks with different heads. Flat
head, flat flanged stud head, etc.

Ultimately I am thinking I'll have to go back to the idea of
shoehorning two vises on the machines. Maybe a pair of 4 inch
screwless machined out to hold six inch stock to keep the weight
down, and have the compact length.

4 inch mill vise or lockdown vise will not fit inside enclosure
without hitting the doors. Just a hair too long. However my 6
inch screwless machined out fit just fine. I actually bought a
couple 4 inch lockdowns for those machines. Oops. On the other
hand they make great drill press vises. LOL.

Maybe it would be better to just sacrifice some of my tooling and
make some fixtures with edge clamps.

I definitely do not need another cup of coffee this morning. LOL.

If you don't mind modifying vises you could cut shallow work
locating
and clamping steps at the tops of the jaws and make support blocks
the
same height.

************

I definitely do not mind modifying vises. I have a bunch of
screwless and except for my 1 inch insert vises which already have a
stepped jaw I think I have machined at a minimum a stepped jaw in
all of them. I've also machined stepped jaw or soft step jaws for
most of my mill and lockdown vises. I think only the 2 4 inch
lockdown vises and a 4 inch Enco swivel base mill vise I bought
with some other stuff from a shop going out of business have
original jaws in them. I lost count of how many vises I have a long
time ago. Well over 20. Maybe over 30. I guess vises are one of
my vices.

Anyway, mounting support blocks on the table and milling them to
match the height of the jaw steps is a good idea. I can use 1" by
X" aluminum flat bar to try it out, and then if it works upgrade to
some more permanent pieces from 4140 or whatever I have on the bits
and pieces shelf.


My support block is a scrapped part from a prototype Segway.

On Mon, 28 May 2018 12:32:08 -0400, "Jim Wilkins"
wrote:

"Bob La Londe" wrote in message
news
Upon Some reflection, how about a thick bar suspended between two or
more jacks?

Hmmmm... I think I am getting into the area where I am just going
to have to try it and see.

First I guess I need to make some jacks with different heads. Flat
head, flat flanged stud head, etc.

Ultimately I am thinking I'll have to go back to the idea of
shoehorning two vises on the machines. Maybe a pair of 4 inch
screwless machined out to hold six inch stock to keep the weight
down, and have the compact length.

4 inch mill vise or lockdown vise will not fit inside enclosure
without hitting the doors. Just a hair too long. However my 6 inch
screwless machined out fit just fine. I actually bought a couple 4
inch lockdowns for those machines. Oops. On the other hand they
make great drill press vises. LOL.

Maybe it would be better to just sacrifice some of my tooling and
make some fixtures with edge clamps.

I definitely do not need another cup of coffee this morning. LOL.

If you don't mind modifying vises you could cut shallow work locating
and clamping steps at the tops of the jaws and make support blocks the
same height.

Or machine replaceable jaws in those shapes.

--
If we can ever make red tape nutritional, we can feed the world.
--Robert Schaeberle