Some time back I started working on a DRO scheme for my lathe cross slide.  There's not a lot of room on top so many of the approaches I saw had one disadvantage or another.  As a result I came up with a scheme to put the DRO underneath the lathe and used a "C" shaped piece to transfer the cross slide motion beneath the lathe.  I had an iGaging DRO for the purpose because I bought two when I was working on my Z axis DRO setup, so I already had what I needed.  Or so I thought.

Unfortunately, the iGaging design uses a sliding contact with a fairly strong spring, which required a fair amount of force to overcome.  DRO mounting schemes that put the mounting system inline with the sensor aren't affected by this, but my C shaped piece would deflect under the force enough to cause about a .005" error.  I tried several ways to stiffen up the system but that was about the best I could manage.

So I decided to modify my DRO to reduce the amount of force needed to move the rule through the sensor.  This involved making a replacement base out of aluminum and replacing the sliding contact with bearings.  I used aluminum because the rule MUST be connected to the sensor's internal ground in order to work correctly.

My first iteration used flanged bearings because the rule needed to be constrained on two of its axes, but the flanges rubbed on the rule too much, which caused erratic variations in the force needed to slide the rule back and forth.  So I replaced the flanged bearings with conventional ones -- but then had to add bearings to the bottom and top assemblies to constrain the rule on its vertical axis.

At this point I debated on whether it really was worthwhile to continue my attempt to use an iGaging DRO, but since I already had a fair amount of time invested in this thing I forged on.  This is known as the "sunk cost" syndrome, and I admit to falling victim to it.

So after buying more bearings and  spending more machining time on the base (and 3D printing a cover, also with bearing pockets) I got this:

The top photo shows the scale, sensor, aluminum base and printed cover.  The side bearings are 3x10mm and the top/bottom are 3x6.

And here are photos of the mounting scheme:

I used a "T" extrusion in an attempt to stiffen up my "C" assembly but it didn't improve things much.  The 3D printed stuff was done with an older Ender 3 I bought from a friend.  This is the first project I've used it for.  The pieces were designed using openSCAD.  Not shown:  all the pieces that had something wrong with them :).

The scale passes through a slot I milled in the vertical piece.

At first the (re) assembled DRO had a terrible EMI problem.  I added some shielding on the back of the sensor board, which helped a teensy bit.  It turns out that the main problem was the spacing between the bottom of the sensor board and scale.  I had used some 3mm brass washers to make sure the board didn't rub against the scale, but that turned out to be a mistake.  I removed them and suddenly the noise problem disappeared.  The board still isn't rubbing so that was a solution without a problem.  I was sure that the DRO would misbehave once it was installed and the motor controller was turned on, but so far so good.

I checked the DRO vs the dial and they are very close.  That was a big unknown, since I wasn't sure if the spacing between the scale and sensor board would affect the readings.

Lipstick on a pig?  Well, probably.  If I had known what I was going to encounter along the way I think I would have just bit the bullet and found myself a DRO that would work right out of the box....

Attachments:
Base cover sensor.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/0
Scale.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/1
Mounting assembly front.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/2
Mounting assembly rear view.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/3

That's how I did it:
https://www.ajawamnet.com/ajawam3/swarf/DSCN2848.JPG
https://www.ajawamnet.com/ajawam3/swarf/lathetopassylg.gif


On 5/4/2024 4:30 PM, Mark Kimball via groups.io wrote:

Some time back I started working on a DRO scheme for my lathe cross slide.  There's not a lot of room on top so many of the approaches I saw had one disadvantage or another.  As a result I came up with a scheme to put the DRO underneath the lathe and used a "C" shaped piece to transfer the cross slide motion beneath the lathe.  I had an iGaging DRO for the purpose because I bought two when I was working on my Z axis DRO setup, so I already had what I needed.  Or so I thought.

Unfortunately, the iGaging design uses a sliding contact with a fairly strong spring, which required a fair amount of force to overcome.  DRO mounting schemes that put the mounting system inline with the sensor aren't affected by this, but my C shaped piece would deflect under the force enough to cause about a .005" error.  I tried several ways to stiffen up the system but that was about the best I could manage.

So I decided to modify my DRO to reduce the amount of force needed to move the rule through the sensor.  This involved making a replacement base out of aluminum and replacing the sliding contact with bearings.  I used aluminum because the rule MUST be connected to the sensor's internal ground in order to work correctly.

My first iteration used flanged bearings because the rule needed to be constrained on two of its axes, but the flanges rubbed on the rule too much, which caused erratic variations in the force needed to slide the rule back and forth.  So I replaced the flanged bearings with conventional ones -- but then had to add bearings to the bottom and top assemblies to constrain the rule on its vertical axis.

At this point I debated on whether it really was worthwhile to continue my attempt to use an iGaging DRO, but since I already had a fair amount of time invested in this thing I forged on.  This is known as the "sunk cost" syndrome, and I admit to falling victim to it.

So after buying more bearings and  spending more machining time on the base (and 3D printing a cover, also with bearing pockets) I got this:

The top photo shows the scale, sensor, aluminum base and printed cover.  The side bearings are 3x10mm and the top/bottom are 3x6.

And here are photos of the mounting scheme:

I used a "T" extrusion in an attempt to stiffen up my "C" assembly but it didn't improve things much.  The 3D printed stuff was done with an older Ender 3 I bought from a friend.  This is the first project I've used it for.  The pieces were designed using openSCAD.  Not shown:  all the pieces that had something wrong with them :).

The scale passes through a slot I milled in the vertical piece.

At first the (re) assembled DRO had a terrible EMI problem.  I added some shielding on the back of the sensor board, which helped a teensy bit.  It turns out that the main problem was the spacing between the bottom of the sensor board and scale.  I had used some 3mm brass washers to make sure the board didn't rub against the scale, but that turned out to be a mistake.  I removed them and suddenly the noise problem disappeared.  The board still isn't rubbing so that was a solution without a problem.  I was sure that the DRO would misbehave once it was installed and the motor controller was turned on, but so far so good.

I checked the DRO vs the dial and they are very close.  That was a big unknown, since I wasn't sure if the spacing between the scale and sensor board would affect the readings.

Lipstick on a pig?  Well, probably.  If I had known what I was going to encounter along the way I think I would have just bit the bullet and found myself a DRO that would work right out of the box....

Attachments:
Base cover sensor.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/0
Scale.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/1
Mounting assembly front.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/2
Mounting assembly rear view.JPG: https://groups.io/g/7x12MiniLathe/attachment/119497/3

On Sat, May 4, 2024 at 05:44 PM, WAM wrote:

That's how I did it:
https://www.ajawamnet.com/ajawam3/swarf/DSCN2848.JPG
https://www.ajawamnet.com/ajawam3/swarf/lathetopassylg.gif
toggle quoted message Show quoted text ( #quoted-237560421 )

Aha!  I thought I had seen something similar but couldn't remember where.

I like your swarf shield, that's something that still needs to be done.  The portion behind my bracket is easy but the front part is a different story.  I want something like a shield rather than a brush or felt pad since I went to a lot of trouble to reduce the friction as much as possible.

What type/brand of DRO did you use?  I'm assuming its frictional drag is low enough to not cause a problem like mine.

On May 25, 2024, at 8:00 AM, Ralph Hulslander via groups.io <rhulslander@...> wrote:

I have the iGaging dros on my Clausing 8520.

One thing I learned in installing them is that only one end needs to be fixed, the other end can float.

I installed a long DRO with both ends fixed and had erroneous errors. I Googling the problem I learned that I could let one end float relieving the tension

that was causing the error.

Of course a "professional" installer freaks out when they hear this but they get paid to install them without the tension, fixed on both ends.

I have one that has was installed ten years ago with a floating end and still working fine.

Ralph

On Sat, May 25, 2024 at 9:37 AM OldToolmaker via groups.io <old_toolmaker=yahoo.com@groups.io> wrote:

Mark,
I am in the process of using an iGaging DRO on one of my Unimats. I am also experiencing some issues with mounting the system in a neat fashion.  

Yes, it should be clear that you can’t mount the DRO at three locations and have them slide accurately unless you drill the mounting points with 0.0001 level precision.   The “roller” was to be EXACLY parallel in both directions the what is moving and that is impossibly hard to do.   The solution is two-point mouting.  Fix one end of the rule and the slider.  Let the other end of the rule float.

It’s not tension on the rule, it is that you can’t expect to mount the rule parallel to the motion.   

I think people try to hard to make the mounting strong.  You can use 3D-printed plastic and magnets.  Magnetic mounts if well-designed work well, Everyone use then on their dial indicators.

Rare Earth magnets are now really inexpensive and you cn buy them on Amazon.  These things are powerful enough to be dangerous if mishandled.

On May 25, 2024, at 8:00 AM, Ralph Hulslander via groups.io <rhulslander@...> wrote:

I have the iGaging dros on my Clausing 8520.

One thing I learned in installing them is that only one end needs to be fixed, the other end can float.

I installed a long DRO with both ends fixed and had erroneous errors. I Googling the problem I learned that I could let one end float relieving the tension

that was causing the error.

Of course a "professional" installer freaks out when they hear this but they get paid to install them without the tension, fixed on both ends.

I have one that has was installed ten years ago with a floating end and still working fine.

Ralph

On Sat, May 25, 2024 at 9:37 AM OldToolmaker via groups.io <old_toolmaker=yahoo.com@groups.io> wrote:

Mark,
I am in the process of using an iGaging DRO on one of my Unimats. I am also experiencing some issues with mounting the system in a neat fashion.  

    Cow magnets are extremely strong too .

animal

On 5/25/24 10:41 AM, Chris Albertson wrote:

Yes, it should be clear that you can’t mount the DRO at three locations and have them slide accurately unless you drill the mounting points with 0.0001 level precision.   The “roller” was to be EXACLY parallel in both directions the what is moving and that is impossibly hard to do.   The solution is two-point mouting.  Fix one end of the rule and the slider.  Let the other end of the rule float.

 

It’s not tension on the rule, it is that you can’t expect to mount the rule parallel to the motion.   

 

I think people try to hard to make the mounting strong.  You can use 3D-printed plastic and magnets.  Magnetic mounts if well-designed work well, Everyone use then on their dial indicators.

 

Rare Earth magnets are now really inexpensive and you cn buy them on Amazon.  These things are powerful enough to be dangerous if mishandled.

 

 

 

 

On May 25, 2024, at 8:00 AM, Ralph Hulslander via groups.io <rhulslander@...> wrote:

I have the iGaging dros on my Clausing 8520.

 

One thing I learned in installing them is that only one end needs to be fixed, the other end can float.

I installed a long DRO with both ends fixed and had erroneous errors. I Googling the problem I learned that I could let one end float relieving the tension

that was causing the error.

 

Of course a "professional" installer freaks out when they hear this but they get paid to install them without the tension, fixed on both ends.

I have one that has was installed ten years ago with a floating end and still working fine.

 

Ralph

On Sat, May 25, 2024 at 9:37 AM OldToolmaker via groups.io <old_toolmaker=yahoo.com@groups.io> wrote:

Mark,
I am in the process of using an iGaging DRO on one of my Unimats. I am also experiencing some issues with mounting the system in a neat fashion.  

 

 

I usevcow magnets for test for 400 series stainless steel and picking steel items that drop hard to get places. 

 

I have no idea where get cow magnets. 

 

Dave 

 

On Fri, Nov 8, 2024 at 10:39 AM, mike allen wrote:

    Cow magnets are extremely strong too .

animal

On 5/25/24 10:41 AM, Chris Albertson wrote:

Yes, it should be clear that you can’t mount the DRO at three locations and have them slide accurately unless you drill the mounting points with 0.0001 level precision.   The “roller” was to be EXACLY parallel in both directions the what is moving and that is impossibly hard to do.   The solution is two-point mouting.  Fix one end of the rule and the slider.  Let the other end of the rule float.

 

It’s not tension on the rule, it is that you can’t expect to mount the rule parallel to the motion.   

 

I think people try to hard to make the mounting strong.  You can use 3D-printed plastic and magnets.  Magnetic mounts if well-designed work well, Everyone use then on their dial indicators.

 

Rare Earth magnets are now really inexpensive and you cn buy them on Amazon.  These things are powerful enough to be dangerous if mishandled.

 

 

 

 

On May 25, 2024, at 8:00 AM, Ralph Hulslander via groups.io <rhulslander@...> wrote:

I have the iGaging dros on my Clausing 8520.

 

One thing I learned in installing them is that only one end needs to be fixed, the other end can float.

I installed a long DRO with both ends fixed and had erroneous errors. I Googling the problem I learned that I could let one end float relieving the tension

that was causing the error.

 

Of course a "professional" installer freaks out when they hear this but they get paid to install them without the tension, fixed on both ends.

I have one that has was installed ten years ago with a floating end and still working fine.

 

Ralph

On Sat, May 25, 2024 at 9:37 AM OldToolmaker via groups.io <old_toolmaker=yahoo.com@groups.io> wrote:

Mark,
I am in the process of using an iGaging DRO on one of my Unimats. I am also experiencing some issues with mounting the system in a neat fashion.  

 

 

    Cow magnets are extremely strong too .

animal

On 5/25/24 10:41 AM, Chris Albertson wrote:

Yes, it should be clear that you can’t mount the DRO at three locations and have them slide accurately unless you drill the mounting points with 0.0001 level precision.   The “roller” was to be EXACLY parallel in both directions the what is moving and that is impossibly hard to do.   The solution is two-point mouting.  Fix one end of the rule and the slider.  Let the other end of the rule float.

 

It’s not tension on the rule, it is that you can’t expect to mount the rule parallel to the motion.   

 

I think people try to hard to make the mounting strong.  You can use 3D-printed plastic and magnets.  Magnetic mounts if well-designed work well, Everyone use then on their dial indicators.

 

Rare Earth magnets are now really inexpensive and you cn buy them on Amazon.  These things are powerful enough to be dangerous if mishandled.

 

 

 

 

On May 25, 2024, at 8:00 AM, Ralph Hulslander via groups.io <rhulslander@...> wrote:

I have the iGaging dros on my Clausing 8520.

 

One thing I learned in installing them is that only one end needs to be fixed, the other end can float.

I installed a long DRO with both ends fixed and had erroneous errors. I Googling the problem I learned that I could let one end float relieving the tension

that was causing the error.

 

Of course a "professional" installer freaks out when they hear this but they get paid to install them without the tension, fixed on both ends.

I have one that has was installed ten years ago with a floating end and still working fine.

 

Ralph

On Sat, May 25, 2024 at 9:37 AM OldToolmaker via groups.io <old_toolmaker=yahoo.com@groups.io> wrote:

Mark,
I am in the process of using an iGaging DRO on one of my Unimats. I am also experiencing some issues with mounting the system in a neat fashion.