I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?
In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

On Fri, 19 Aug 2011 05:17:55 -0400, Tom Gardner mars@tacks wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?
In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.


I've been wondering the same thing, but with 5. I think I may be
better off not having interchangeable parts. Sure would be nice to
have one of those CNC machines, so one could machine them and it
wouldn't matter if they got mixed up or flipped over.


SW

Tom Gardner wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?


In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

You can do that easily if the mill head is true. Not sure why you would
spot the holes with
combination drill countersink. or do you mean center drill?

On Aug 19, 4:17*am, Tom Gardner mars@tacks wrote:
I have to make four identical 1/4" plates that have 15 holes. *11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. *These fixtures will hold wood blocks in a
machine. *I need .005" difference between hole placement in the plates..
* The plates are 8" x 6"

My question is: *Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?
* In other words, will the drill wander more than .005"? *I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

Since you have to counterbore 11 of the 15 holes, it would seem that
you might save more time using counterbores with built-in pilots (type
of drill bits) and do each plate individually. With the counterbores
done on the mill, the pilot holds could be finished off on a drill
press (if necessary)
http://www.mcmaster.com/#=dos3is

On 8/19/2011 9:25 AM, jim wrote:


Tom Gardner wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need.005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?


In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

You can do that easily if the mill head is true. Not sure why you would
spot the holes with
combination drill countersink. or do you mean center drill?

The Bridgeport is as perfect as any can be with very low hours, trammed
to perfection. I guess it's worth some test holes.

Yes, a "Center Drill"! Us old people have had many arguments over the
years about the official name of the tool. Had I typed "center drill" I
certainly would have gotten flack from other old people.

Tom Gardner wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?
In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

I'd ream them; it shouldn't be necessary to tack them together if you have
a decent set of clamps for your mill. Put them on top of a couple of cutoffs
so that the drills and then the reamer can go all the way through. (or
on top of a sacrificial piece of something softer than the parts.)

Have Fun!
Rich

On Fri, 19 Aug 2011 16:31:03 -0700, Rich Grise
wrote:

Tom Gardner wrote:

I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together
and drill all four plates at once in the mill using the DRO to position
the plates and have the top plate and the bottom plate be within .005"?
In other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

I'd ream them; it shouldn't be necessary to tack them together if you have
a decent set of clamps for your mill. Put them on top of a couple of cutoffs
so that the drills and then the reamer can go all the way through. (or
on top of a sacrificial piece of something softer than the parts.)

Have Fun!
Rich
For only 5 plates, with a DRO, I'd just do them one at a time and
eliminate the possibility of screwing up all 4 at once. Likely be just
about as fast too.

If it was 40 or more it would be a good excuse to put an NC conversion
on the mill.

On 8/19/2011 2:17 AM, Tom Gardner wrote:
I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together and
drill all four plates at once in the mill using the DRO to position the
plates and have the top plate and the bottom plate be within .005"? In
other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

Back up just a minute, Tom.

You wrote the plates are 8" x 6". that tells me right away they are not
all the same size, but may be varying by 1/16 to 1/8 inch each way. Are
they perfectly square?

If I was going to do what you are attempting, I would stack them and
clamp them on the mill table and sacrifice two of the 15 holes for roll
pins that are smaller than what you will eventually drill those holes
out to.

Then drill your holes and mill the stack to the ultimate size needed.

Paul

Paul Drahn wrote:

On 8/19/2011 2:17 AM, Tom Gardner wrote:
I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together and
drill all four plates at once in the mill using the DRO to position the
plates and have the top plate and the bottom plate be within .005"? In
other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

Back up just a minute, Tom.

You wrote the plates are 8" x 6". that tells me right away they are not
all the same size, but may be varying by 1/16 to 1/8 inch each way. Are
they perfectly square?

If I was going to do what you are attempting, I would stack them and
clamp them on the mill table and sacrifice two of the 15 holes for roll
pins that are smaller than what you will eventually drill those holes
out to.

Then drill your holes and mill the stack to the ultimate size needed.

For what he is doing it doesn't sound like it matters whether the edges
are straight or square. It might look nicer if they were but it wouldn't
add anything useful.

-jim


Paul

On 8/19/2011 11:34 PM, Paul Drahn wrote:
On 8/19/2011 2:17 AM, Tom Gardner wrote:
I have to make four identical 1/4" plates that have 15 holes. 11 of the
holes be countersunk for 1/4" socket-head countersunk screws that will
be used to mount fixture parts, 4 of the holes are for #10 SHCS for
mounting to the machine. These fixtures will hold wood blocks in a
machine. I need .005" difference between hole placement in the plates.
The plates are 8" x 6"

My question is: Can I stack all four plates, tack weld them together and
drill all four plates at once in the mill using the DRO to position the
plates and have the top plate and the bottom plate be within .005"? In
other words, will the drill wander more than .005"? I will use a
combined drill countersink to spot the holes then drill undersized, then
drill the 1/4" hole using all new drills.

Back up just a minute, Tom.

You wrote the plates are 8" x 6". that tells me right away they are not
all the same size, but may be varying by 1/16 to 1/8 inch each way. Are
they perfectly square?

If I was going to do what you are attempting, I would stack them and
clamp them on the mill table and sacrifice two of the 15 holes for roll
pins that are smaller than what you will eventually drill those holes
out to.

Then drill your holes and mill the stack to the ultimate size needed.

Paul

The only thing that matters is the relationship of the mounting holes to
the holes that fixture parts mount to. The outside dimensions don't
matter as long as I have a (x=0, y=0) point on which to base all the
holes coordinates.