# DRO for my Bridgeport J head



## Mutt (Oct 31, 2017)

The seller of this DRO says that you will need to choose the length of the linear scales when ordering. The table on my Bridgeport is 9" x 42" but the travel is no where near that long. Could someone tell me what length scales I will need? It's a 2 axis dro, X & Y axis

https://www.ebay.com/itm/Digital-Re...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649


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## Bob Korves (Oct 31, 2017)

Move the table to one end of the travel.  Put a vertical Sharpie mark across the interface of saddle and table.  Move the table to the other end of the travel.  Measure between the two halves of the Sharpie marks.  That is your travel.  A simple test is worth 100 expert opinions, and worth 500 H-M opinions.    The length of the scale you need will be longer than the table travel.  The length to choose depends on several things, including read head size, interference with the end caps of the scale, and what sizes the seller offers.  It also matters where you can find places to mount it.  If it is a glass scale, do not attempt to shorten it.  Usually the seller has a good idea of what works and has sold them to Bridgeport owners with 9x42" scales, very common.  Warning, do not compare apples and oranges, only the one you are buying needs to fit...


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## Mutt (Oct 31, 2017)

the x travel is 30" and the Y travel is 12",


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## jmarkwolf (Nov 6, 2017)

Consider the dimensions required for the mounting brackets at the end of the scales, the travel dimension, and that the read head has room before bumping into anything at the ends of your travel, and "then add some". 

There's no problem if your scales are too long (provided they fit on your table), but too short is definately a problem.


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## Mutt (Nov 6, 2017)

I watched a video on Youtube.  He ordered scale sfor a 9x42 and they are 30 and 12" long. Looks like a super easy job, just a bit of time. Thanks y'all


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