Installing a DRO

First, let me say that I am a totally self-trained, rank amateur machinist-gun butcher. I have never even seen a mill or lathe with a DRO installed on it. I live in a very small, isolated town in far West Texas so there are no examples to see.

I have a Smithy BX-288 mill (you’d think that even a non-mechanically inclined, economist would know better than that, wouldn’t you?).

I have just bought a Shooting Star BT-3 DRO that I need to install on the Smithy. (Incidentally, as was pointed out on another similar thread, Shooting Star’s customer service seems to be first class and they assure me that the unit is compatible with my machine.)

The instructions are OK but, obviously by necessity, very general. In fact and frankly, so general I really don’t know where to start. My particular problem is exactly where to mount the rack and head assemblies on all three axes.

The difficulty is likely because (having never seen one) I do not understand how the thing is supposed to work—e.g. is the readout head mounted to the moving part of the axis (table, cross feed, quill) and the rack supports attached to something stationary? Or is that vice versa? Or am I totally out in left field?

Good close up pictures of all three axes would surely help. Could anybody lead me to such?

BTW, this particular machine does not have a “knee” per se. Instead, the gear box-spindle housing is mounted on a support column that is cranked up and down. (I can send a diagram if that would help).

Thanks in advance for any and all help offered.

Not sure if this helps. When I mounted my Newall readout on my Bridgeport mill, I mounted the scale, thats the long part to the table. I mounted the scale to the front of the table, because in my situation if I mounted the scale to the back of the table, I would have lost some travel of the table in and out.

Since you are reading relative motion, it would not matter where the rack and reader are mounted, but it would seem that it makes more sense to mount the rack to the table and the reader to the support.

I have not been overwhelmed by the consept of the plastic rack and the rotary encoder, but they seem to function.

The instalation varies a bit with each machines. Most times custom brakets to fit the castings and other things in the way have to be made.

Things to consider. You want to mount it where its least likely to get hit/damaged.

It doesn't really matter if its the head of the scale that moves. Here is a pic from when I was instaling the DRO on my mill/drill. http://i5.photobucket.com/albums/y183/snd_machining/DSCF00028.jpg

As you can see, the X axis scale moves and the head stays fixed to the casting. The Y axis scale is fixed and the head moves. ALso the cable don't actualy run as shown in that pic.

You have to watch for where cables are going to run so that they don't get caught and pulled out.

The scale has to have as parallel/square to the axis as possible. So your brakets need some adjusment and you want some space to be able to shim. You can actualy seem some of the shims in my picture. Some of which are tapered to match the casting. I think some brands require to be within .010" over the whole lenght of the scale. So aim for less then .005".

Take your time. It doesn't get done in 1 hour. Often doesn't get done in a day if you're as picky as I can be.

When everything is in place, make some covers for them. Here's a picture of the one I made. http://i5.photobucket.com/albums/y183/snd_machining/DSCF0010.jpg

We can't really see the cover for the Y axis very much in the picture but its sheet metal with a type of long brush on one side to keep the chips from falling inside.

You may also need to make an arm to support the screen.

Good luck.

Gunny,
I recently went through the same thing mounting one on my lathe, not a Shooting star but I did go to Shooting Star's web site and there are some pretty good photo's of dro's mounted on customers
machines.
Also you might want to go to Grizzly's web site and download there instruction books
Hope this helps.
Dee

When I mounted my Shooting Star unit to my lathe,I had trouble getting the scale mounted on an even plane end to end, so I mounted it on a piece of angle iron and then mounted the angle iron straight and level. That made mounting the head much easier. I have had my unit for about five years and am completely satisfied with it.

Without getting into specifics...there are a couple of generalities to follow.

- run the machine's axes to the very ends of their travels...and "mock up" the scale and reader positions carefully...see below on overtravels.

- scales must be very parallel to the axis of travel...which includes the reader head's alignment. The best design would have a linkage that's kinematically rigid in one direction and compliant in the other two because it would help protect the device from misalignments, but that's somewhat of a difficult proposition to implement.

- think of how the wires will be routed to the display...long loops are preferred as this puts less stress into the cable over the long haul, and those wires ain't going away.

- vertical chip guarding an excellent idea...very thin wall aluminum angle (like 1/16" wall) is nice if the kit doesn't come with it.

- "smash protection"...this is the overtravel protection. When you mount the scale on the back side of the table, install a hard stop which prevents you from concentrating on the workpiece while crunching the scale into the column before you break out of the trance and realize what's going on. It is a small detail and takes a little bit of doing but is very cheap insurance.

- carefully plan hole locations...don't want to be drilling a bunch of extra holes into your machine. Transfer, drill and tap with care and precision.

Gunny, I have mounted a CBX and an Accurite on different Smithy Granite machines. I know yours is a stand alone, but I can provide photos of the 3-in-1 mounting if it would be helpful...

All you guys have been very helpful. Thanks a bunch and I will keep you posted.

DanR, yes, if it wouldn't be too much trouble, the pics certainly couldn't hurt anything. If it is not too much trouble, please send to [email protected].

Thanks again to all.

Gunny,

When you're finished, I'll bet you have the only DRO equipped Smithy in Alpine!

Bluegrass
(studied K-rats many years ago...)

I have pulled the "before" pictures, but can't seem to locate the after pictures. Not a problem, though, because the after is sitting in the garage and I will take the shots tomorrow with my digital & send them tomorrow.

I was incorrect in my terminology in the first message. I had looked very carefully at the Escala II and the CBX when I did the first one, and the deciding factor then was the ability of the Escala II to be corrected in software for linear error.

I mistakenly remembered the Escala II to be "CBX" but now seem to remember that to be the Shooting Star... It doesn't matter much though, since they are very similar.

I bought the 100S Acu-Rite for the same reason that I had gotten the Escala though. It can take error correction if necessary. The Shooting Star guy told me there was no correction in their unit, nor was one planned at the time (Mar 06).

The Shooting Star has always gotten good reviews though, and the Escala is no longer made. I will try to send them by noon, since by your email address you may have to wait until Monday if I am too late... Dan.

DanR, that reminds me of an e-mail exchange I had with an old (high-school) friend a while back. He grew up to be Dean of the School of Business at Oregon State U.

One Friday afternoon I e-mailed him someghing. He came back and said, what are you doing in the office? Don't you know tenured faculty do not work on Friday afternoons?

I fired right back, Are you trying to tell me that tenured faculty WORK? lol

Hey, thanks for all your trouble.

thegunny, 419

I got the original pictures out in an email at about 1600 ?? --- but saw after supper that the email was too big for your ISP to handle. It was kicked back... so then I sent about eight messages with a couple of pics each... Hope you can make some sense out of it. When I get back from on the 21st I will try to be a little clearer with the description.

DanR, got 'em. Absolutely fantastic!!! Hope you have a good trip and thanks again.