Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately the
same as the bolt spread on the column/base attachment . I'm thinking I need
to shim .004 at the left front and right rear bolts , .008 at the right
front .
Am I headed the right direction , or am I about to make the error double ?
--
Snag
Hot , sweaty , and happy as a murff

On Jun 28, 11:14 pm, "Terry Coombs" wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
Normally the tramming sets the spindle perpendicular to the table,
done by slight rotations of the head about its 2 axes that are
parallel to the table.
The shimming you describe might be necessary if as you raise the head
(or raise the spindle) up the column (if it's that type of mill),
indicating on the two vertical sides of a square standing long leg up
on the table, you see a tilt of the column from perpendicular to the
table - again check 2 axes of tilt. Do this before trying to tram the
spindle or head.... Joel in Florida (aka Critter 67 FLH)
==========
mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately the
same as the bolt spread on the column/base attachment . I'm thinking I need
to shim .004 at the left front and right rear bolts , .008 at the right
front .
Am I headed the right direction , or am I about to make the error double ?
--
Snag
Hot , sweaty , and happy as a murff

Terry Coombs wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately the
same as the bolt spread on the column/base attachment . I'm thinking I need
to shim .004 at the left front and right rear bolts , .008 at the right
front .
Am I headed the right direction , or am I about to make the error double ?

I presume you are referring to a mill/drill type machine. Someone posted
on RCM about a similar problem and it turned out the problem wasn't
inaccurate machining but burrs around the holes where the column mounted
IIRC. Cleaning up the machining and reassembly sorted the problem.

David Billington wrote:
Terry Coombs wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial
indicator mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the
right and at the front . The sweep diameter of the indicator is
approximately the same as the bolt spread on the column/base
attachment . I'm thinking I need to shim .004 at the left front and
right rear bolts , .008 at the right front .
Am I headed the right direction , or am I about to make the error
double ?
I presume you are referring to a mill/drill type machine. Someone
posted on RCM about a similar problem and it turned out the problem
wasn't inaccurate machining but burrs around the holes where the
column mounted IIRC. Cleaning up the machining and reassembly sorted
the problem.

You're the second person to point me towards cleaning ... thanks ! Guess
it's a good thing I still have my lifting apparatus in place , that column
and head prolly weigh nearly 500 pounds .

--
Snag
wannabe machinist

On Jun 28, 11:14*pm, "Terry Coombs" wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...
* It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately the
same as the bolt spread on the column/base attachment . I'm thinking I need
to shim .004 at the left front and right rear bolts , .008 at the right
front .
*Am I headed the right direction , or am I about to make the error double ?
--
Snag
Hot , sweaty , and happy as a murff

I would use it for a while first, to wear in the table ways. I bought
a mill-drill that was off by 0.009" IIRC and never noticed a problem
in the parts we made with it.

The table slots weren't quite parallel to the X axis either. I made
the vise base key a very snug fit in the tee slot and then milled a
step in its upper sides to make them parallel to the table travel.

Jim Wilkins

Terry Coombs wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately the
same as the bolt spread on the column/base attachment . I'm thinking I need
to shim .004 at the left front and right rear bolts , .008 at the right
front .
Am I headed the right direction , or am I about to make the error double ?

I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Terry,
Use a true collet, not a chuck. Clean the base and column and torque the
bolts with a torque wrench. Measure at least 3 times. Dissassemble and check
again. You are looking for consistancy before you make any changes. Lastly
you want the front of the table up about .001 to .002". Even new mills
measure that way on purpose. This compensates for post deflection when under
load
Steve

"Terry Coombs" wrote in message
...
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the right
and at the front . The sweep diameter of the indicator is approximately
the same as the bolt spread on the column/base attachment . I'm thinking I
need to shim .004 at the left front and right rear bolts , .008 at the
right front .
Am I headed the right direction , or am I about to make the error double ?
--
Snag
Hot , sweaty , and happy as a murff

On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:

Terry Coombs wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...


I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.

--
Ned Simmons

On Mon, 30 Jun 2008 15:45:26 -0400, Ned Simmons
wrote:

On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:

Terry Coombs wrote:
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial indicator
mounted on it in the drill chuck , just to see ...


I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.


assuming the chuck as no pitch and yawl......

gunner


"The American people will never knowingly adopt socialism, but under the
name of liberalism they will adopt every fragment of the socialist program
until one day America will be a socialist nation without ever knowing how it
happened." -- Norman Thomas, American socialist

On Jun 30, 5:00*pm, Gunner Asch wrote:
On Mon, 30 Jun 2008 15:45:26 -0400, Ned Simmons
On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:
Terry Coombs wrote:
I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.
assuming the chuck as no pitch and yawl......
gunner

I have to agree with Ned. If the chuck is crooked the bottom end of
the rod will rotate in a circle but that circle will be centered on
and perpendicular to the spindle rotation. Try it with a piece of bent
gas welding rod (my favorite steel wire / rod up to 1/4").

BTW, if you don't have a good dial indicator you can tram the mill
square with just a bent rod and feeler gauges. It's easier if you
check height to the top of a parallel so the rod won't catch in a
table slot.

Steve Lusardi wrote:
Terry,
Use a true collet, not a chuck. Clean the base and column and torque
the bolts with a torque wrench. Measure at least 3 times.
Dissassemble and check again. You are looking for consistancy before
you make any changes. Lastly you want the front of the table up about
.001 to .002". Even new mills measure that way on purpose. This
compensates for post deflection when under load
Steve

"Terry Coombs" wrote in message
...
Got the new machine set up on it's base today , and checking it out ,
cleaning , getting it ready to use . I chucked a rod with a dial
indicator mounted on it in the drill chuck , just to see ...
It's reading zero at the rear and straight left , plus .004 on the
right and at the front . The sweep diameter of the indicator is
approximately the same as the bolt spread on the column/base
attachment . I'm thinking I need to shim .004 at the left front and
right rear bolts , .008 at the right front .
Am I headed the right direction , or am I about to make the error
double ? --
Snag
Hot , sweaty , and happy as a murff

So much advice and discussion is a good thing ! Many thanks to all who have
contributed to this thread . I have learned several things , not the least
of which is to have the table a thou or so high in the front .
I think I'm going to run it as-is for a couple of weeks , let all the
parts get to know each other . I'm just kinda learning how it all works
together right now , precision can come as my skill develops . Whoever it
was that said there is no such thing as clamping too well is right . The
first thing to be replaced is going to be that POS "vise" that came with the
machine .
--
Snag
Goin' out to the shed as soon as the A/C cools it off a bit .

On Mon, 30 Jun 2008 14:16:23 -0700 (PDT), Jim Wilkins
wrote:

On Jun 30, 5:00*pm, Gunner Asch wrote:
On Mon, 30 Jun 2008 15:45:26 -0400, Ned Simmons
On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:
Terry Coombs wrote:
I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.
assuming the chuck as no pitch and yawl......
gunner

I have to agree with Ned. If the chuck is crooked the bottom end of
the rod will rotate in a circle but that circle will be centered on
and perpendicular to the spindle rotation. Try it with a piece of bent
gas welding rod (my favorite steel wire / rod up to 1/4").

Or think about where the indicator is attached: to the end of an
assortment of rods and joints whose entire purpose is to swing the
indicator in as large a circle as is practical. A little wobble in the
chuck only serves to make the circle a bit larger.

--
Ned Simmons

On Mon, 30 Jun 2008 14:16:23 -0700 (PDT), Jim Wilkins
wrote:

On Jun 30, 5:00*pm, Gunner Asch wrote:
On Mon, 30 Jun 2008 15:45:26 -0400, Ned Simmons
On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:
Terry Coombs wrote:
I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error

Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.
assuming the chuck as no pitch and yawl......
gunner

I have to agree with Ned. If the chuck is crooked the bottom end of
the rod will rotate in a circle but that circle will be centered on
and perpendicular to the spindle rotation. Try it with a piece of bent
gas welding rod (my favorite steel wire / rod up to 1/4").

that works great unless you change to another tool holder.

yes..the chuck spins in a circle, but it will be in a plane at an
angle to the table..which means you have just introduced two seperate
planes of movement..the one involving the head..and the one involving
the chuck.

BTW, if you don't have a good dial indicator you can tram the mill
square with just a bent rod and feeler gauges. It's easier if you
check height to the top of a parallel so the rod won't catch in a
table slot.


"The American people will never knowingly adopt socialism, but under the
name of liberalism they will adopt every fragment of the socialist program
until one day America will be a socialist nation without ever knowing how it
happened." -- Norman Thomas, American socialist

Gunner Asch wrote:
yes..the chuck spins in a circle, but it will be in a plane at an
angle to the table..which means you have just introduced two seperate
planes of movement..the one involving the head..and the one involving
the chuck.


Try this : chuck an indicator on a rod into the drill chuck , sweep the
table . Now , add a bend to the rod just below the chuck , and sweep again .
Bet ya a bottle of Dickel White Label you get the exact same *runout* .
The assembly is going to rotate around the centerline of the spindle
bearings , even if the rod (or offcenter chuck , whatever) is bent into a
pretzel (rigidity issues aside) .
One of the suggestions was to lay out the bolt pattern on the table , set
the length of the horizontal so that the indicator swept the centerline of
the bolt pattern circle . Then find the highest corner , add the exact
reading you get at each of the other three bolts .
Torquing the bolts all to 70 ft/lbs changed the error ... which tells me
that I need to clean those mating surfaces before I can expect to get
anywhere with getting it trued up .
--
Snag
'90 Ultra "Strider"
'39 WLDD "Popcycle"
Buncha cars and a truck

Terry Coombs wrote:
Gunner Asch wrote:
yes..the chuck spins in a circle, but it will be in a plane at an
angle to the table..which means you have just introduced two seperate
planes of movement..the one involving the head..and the one involving
the chuck.


Try this : chuck an indicator on a rod into the drill chuck , sweep
the table . Now , add a bend to the rod just below the chuck , and
sweep again . Bet ya a bottle of Dickel White Label you get the
exact same *runout* . The assembly is going to rotate around the
centerline of the spindle bearings , even if the rod (or offcenter
chuck , whatever) is bent into a pretzel (rigidity issues aside) .
One of the suggestions was to lay out the bolt pattern on the table
, set the length of the horizontal so that the indicator swept the
centerline of the bolt pattern circle . Then find the highest corner
, add the exact reading you get at each of the other three bolts .
Torquing the bolts all to 70 ft/lbs changed the error ... which
tells me that I need to clean those mating surfaces before I can
expect to get anywhere with getting it trued up .

And cleaning the mating surfaces brought the front-rear difference to less
than a thousandth . Side error is about .005 difference on a 15" circle
(7.5" arm length) which I can adjust out by rotating the head (Of course I
really should set up a 1 2 3 block and an indicator , crank the head up n
down the column to be certain it's perpendicular ... but I got no blocks yet
..). I'm not sure the error is material at this point , using a maximum
diameter of 3/4" end mill that's less than .00025" ... I know damn well
that's more accuracy than *I'm* capable of !
--
Snag
I'm havin' a blast !

Jim Wilkins wrote:
On Jun 30, 5:00 pm, Gunner Asch wrote:
On Mon, 30 Jun 2008 15:45:26 -0400, Ned Simmons
On Mon, 30 Jun 2008 13:17:41 -0500, RB wrote:
Terry Coombs wrote:
I'd suggest you use a collet to hold the DI rod.
drill chucks can impart error
Not if he's sweeping the table with the indicator. The indicator point
will follow the spindle's center of rotation regardless of how bad the
runout of the rod is.
assuming the chuck as no pitch and yawl......
gunner

I have to agree with Ned. If the chuck is crooked the bottom end of
the rod will rotate in a circle but that circle will be centered on
and perpendicular to the spindle rotation. Try it with a piece of bent
gas welding rod (my favorite steel wire / rod up to 1/4").

BTW, if you don't have a good dial indicator you can tram the mill
square with just a bent rod and feeler gauges. It's easier if you
check height to the top of a parallel so the rod won't catch in a
table slot.

I use a brake rotor that has been finely surfaced, and the flange cut off.

On Jun 30, 9:15*pm, "Terry Coombs" wrote:

* And cleaning the mating surfaces brought the front-rear difference to less
than a thousandth . Side error is about .005 difference on a 15" circle
(7.5" arm length) which I can adjust out by rotating the head (Of course I
really should set up a 1 2 3 block and an indicator , crank the head up n
down the column to be certain it's perpendicular ... but I got no blocks yet
.). I'm not sure the error is material at this point , using a maximum
diameter of 3/4" end mill that's less than .00025" *... I know damn well
that's more accuracy than *I'm* capable of !

I think my heart nearly stopped when I read RB's suggestion to use a
collet instead of a drill chuck. As an apprentice, I got yelled at for
asking the wrong questions - questions which reveal a lack of
understanding of the overall idea. Suggesting a collet as opposed to a
drill chuck reveals a lack of understanding of what you're trying to
accomplish while squaring a mill.

As long as the indicator is securely fastened to the spindle (the part
that actually turns), you're doing the right thing.

In regards to cleaning up the mounting surfaces, this is most
certainly the right direction. A .001" feeler gauge is your best
friend (along with bearing blue) for correctly assembling machines and
tooling with precise mounting surfaces (like the column to base
connection).

Had you used that feeler gauge, you would have been able to tell that
there was a gap. Hopefully you chamfered the bolt holes and the
perimeter (circumference) of the mounting surfaces before reassembly.
One slight bounce to a sharp edge during reassembly will likely raise
a bump on the mounting surface, which will put you in the same
position as before.

Bearing blue can reveal the type of contact you're getting between
those surfaces. You can do this with a good flat bench stone as well,
but it's more obvious with the blue. You'll be able to see where the
surfaces are actually touching, where they're close, and where they're
not close.

I used to have to manually flatten the bottom of insert blocks in
large stamping dies. You want really good contact around your bolt
holes, and ideally under heavily stressed areas (if such areas exist).
In your case, around the holes and directly under the column. I
understand this doesn't matter much now, but if you find you can't get
consistent results while machining, you may want to check that. Under
machining stresses, anywhere a gap exists, your machine parts WILL
flex.

Another poster mentioned his t-slots were not aligned with the x-axis.
I would again disassemble and check for burrs and debris. If the
builder used good technique (ha!), the slots should be aligned and
this misalignment could point to other issues (burrs, debris,
incorrectly adjusted gibs, etc.)

I've never set the front of the table .001" up or down or anywhere
other than perfectly square. This may work in some situations, but
again, it points to other issues within the machine. You can measure
how far the head is flexing during a cut by mounting a dial indicator
to the head, and having the needle contacting the smooth ground table.
You'll need to protect the indicator from chips, but you can see the
head move (and move it will on decent/heavy cuts!)

The amount of flex will increase depending on the load. Facemilling,
fly cutting and heavy drilling will typically be the worst - all three
are operations where you can easily exceed the max horsepower of your
machine if you simply continue to push harder. This is why there are
finishing cuts, and roughing cuts.

If you get consistant movement under different loads, it is likely
that something is not securely connected (loose bolt, burr, debris).
You can use the an indicator and some muscle to find that type of
issue.

Good luck with the new machine. Now that you have evidence of the
builder not finishing the machine correctly (deburring, cleaning),
don't be so quick to jump through hoops to fix errors. Frequently the
simplest answer (disassemble and clean/deburr) is the correct one.

Regards,

Robin

On Jul 2, 4:13*pm, wrote:
...
Another poster mentioned his t-slots were not aligned with the x-axis.
I would again disassemble and check for burrs and debris. If the
builder used good technique (ha!), the slots should be aligned and
this misalignment could point to other issues (burrs, debris,
incorrectly adjusted gibs, etc.)...
Robin

That was an RF-31 mill-drill from MSC that I bought for an electronics
company shop. It was used for drilling and light milling in flat
aluminum control panels, non-critical jobs that didn't justify taking
time from other projects to clean it up much. I brought in some
precision tools from home to check it and found the slots slightly
askew from the sides of the table and the X axis, and the spindle
tilted ~0.009" over its 5" stroke. The sides of the table indicated
true, so I suspect that the sides/dovetails and the tee slots were
machined in separate operations.

It only matters if you install a key in the bottom of the vise to
position it accurately.

On Wed, 2 Jul 2008 13:13:12 -0700 (PDT),
wrote:

On Jun 30, 9:15*pm, "Terry Coombs" wrote:

* And cleaning the mating surfaces brought the front-rear difference to less
than a thousandth . Side error is about .005 difference on a 15" circle
(7.5" arm length) which I can adjust out by rotating the head (Of course I
really should set up a 1 2 3 block and an indicator , crank the head up n
down the column to be certain it's perpendicular ... but I got no blocks yet
.). I'm not sure the error is material at this point , using a maximum
diameter of 3/4" end mill that's less than .00025" *... I know damn well
that's more accuracy than *I'm* capable of !

I think my heart nearly stopped when I read RB's suggestion to use a
collet instead of a drill chuck. As an apprentice, I got yelled at for
asking the wrong questions - questions which reveal a lack of
understanding of the overall idea. Suggesting a collet as opposed to a
drill chuck reveals a lack of understanding of what you're trying to
accomplish while squaring a mill.

As long as the indicator is securely fastened to the spindle (the part
that actually turns), you're doing the right thing.

In regards to cleaning up the mounting surfaces, this is most
certainly the right direction. A .001" feeler gauge is your best
friend (along with bearing blue) for correctly assembling machines and
tooling with precise mounting surfaces (like the column to base
connection).

Had you used that feeler gauge, you would have been able to tell that
there was a gap. Hopefully you chamfered the bolt holes and the
perimeter (circumference) of the mounting surfaces before reassembly.
One slight bounce to a sharp edge during reassembly will likely raise
a bump on the mounting surface, which will put you in the same
position as before.

Bearing blue can reveal the type of contact you're getting between
those surfaces. You can do this with a good flat bench stone as well,
but it's more obvious with the blue. You'll be able to see where the
surfaces are actually touching, where they're close, and where they're
not close.

I used to have to manually flatten the bottom of insert blocks in
large stamping dies. You want really good contact around your bolt
holes, and ideally under heavily stressed areas (if such areas exist).
In your case, around the holes and directly under the column. I
understand this doesn't matter much now, but if you find you can't get
consistent results while machining, you may want to check that. Under
machining stresses, anywhere a gap exists, your machine parts WILL
flex.

Another poster mentioned his t-slots were not aligned with the x-axis.
I would again disassemble and check for burrs and debris. If the
builder used good technique (ha!), the slots should be aligned and
this misalignment could point to other issues (burrs, debris,
incorrectly adjusted gibs, etc.)

I've never set the front of the table .001" up or down or anywhere
other than perfectly square. This may work in some situations, but
again, it points to other issues within the machine.

I've also heard the .001 high at the front of the table number, but in
relation to how the table should be installed, not as a number to
shoot for when tramming a mill. I've got three Bridgeport manuals
here, going back to one that shows only the M head round ram mill.

That oldest manual says,
"When indicating as in figure A, it may be impossible to get a dead
zero in back and front of table as machines are fitted to be slightly
high in front - usually about .001"."

A J head on a dovetail ram has another axis of adjustment, missing
from the M head in the old manual, that allows the .001" difference to
be trammed out. (But, of course, that means the spindle is not
perfectly parallel to the column ways.)

The next newer manual, which covers the J head, indicates that the
front of the table is intentionally high by .0005 to .001, but is
ambiguous on the tramming process.

The newest manual also mentions that the operator should be aware of
the high front, but is clear that the objective in tramming is to get
the spindle perpendicular to the table in both adjustment axes.

--
Ned Simmons