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newbie DRO question

Jason H

Stainless
Joined
Mar 29, 2006
Location
Los Angeles, CA.
Please excuse my ignorance when it comes to DRO’s. Will any brand fit to any mill? Is there any modification that has to be done to the mill to accept the DRO? To be specific I have a Tree 2uvrc that needs a DRO. I know this is basic, but I have never installed one.
 
Not any DRO will work with any mill. You'll need to know the table size and travel. Give this info to the company you order from and you should be set.
 
Thanks all for the response. Troll if you have a free moment I would appreciate if you could post the pics. Since my machine was purchased used from a dealer, there might have been one mounted to it and I just didn't know. There are some unused threaded holes around the machine. I will post some photos in a bit.

Thanks again!

Jason
 
Looks like a Bridgeport clone. An Acu-Rite 200M would be a nice addition. There is a choice regarding DRO using the knee vs using the vertical z axis quill. I couldn't see the quill well enough to see if it is a match to the Bridgeport, but the other two axes looked awfully close. If a close Bridgeport clone, there will be lots of brand choices.
 
A DRO is a system comprised of several components. The items which must "fit" the machine are the scales, one for each axis of measurement. A mill DRO usually has three scales, X, Y, and Z. The X axis is the side-to-side travel of the table. The Y axis is table front-to-back, and the Z axis is the table height, controlled by the handle to raise or lower the knee.

It's possible to install a Z-axis scale on the machine quill. The readout for this scale is usually not coupled with the knee Z-axis scale. You position the knee as desired and lock it in place. Then you use the Z-axis readout on the quill to determine the vertical position of the tool.

I have a four-axis system on my Bridgeport, with three scales on the knee and one on the quill, as shown below. The top readout is the quill. I believe this is the most versatile and accurate system you can put on a mill.

SonyDROq.jpg


The other system component is the display and control box. This has a keypad for control and numeric entry, so you have to mount it somewhere within arm's reach. A complete system will include a mounting bracket with a long arm to support the box. This allows you to move the display to a convenient position.

On a Bridgeport machine the arm mounts to the top of the ram with a single large bolt. The arm swings around, pivoting on that bolt. The arm is large, about 1.5" square steel tubing.
 
I have an Acu-Rite 300M DRO on my Enco 9x42 Bridgeport clone. I've been very pleased with it. Absolutely love the bolt circles / arrays feature. This unit is capable of 4 axis operation, but I believe the current models are capable of 6 axis operation with support for both straight line and rotory encoders on any axis. I currently use 3 axis, x,y,z, z being on the quill. I've been watching Ebay for a scale for the knee. One neat feature is the ability to add or subtract 2 axis and display the result as a single axis. Perfect for combining the quill and knee.

Here's a couple of pictures of the scales on my mill so you can get an idea of they're installed.

DRO.jpg


DROSCALE.jpg



The mounting of the X is pretty straightforward. The scale is mounted to the back of the table and the reading head is mounted to the saddle. Some people put them on the front of the table because you loose a bit of Y travel on the rear. For the Y, the scale is mounted to the knee and the head attaches to the side of the saddle with a bracket. Installing a scale on the knee for Z (or W) would be similar. The quill gets a little more complicated. On a 1J/2J Bridgeport it's pretty straightforward. I'm a Home Shop Hack so I'm not familiar with many other machines, but looking at the photo of your Tree mill it appears the quill stop mechanism is internal so I'm not sure how you'd attach the scale. Maybe someone else can provide some insight there.

Happy Chips!

Marc -
 








 
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