Appropriate size DRO

wildcatfan

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Been reading the site for a long time however i seldom post.
I have a Bridgeport clone (Summit) , that i purchased to start this machining adventure.
Table is 45inches long x 10in wide and knee appears that it will travel around 15inches.
Looking to purchase a 2 or 3 axis dro. Realisticaly what size scales should i be looking at?
Is it as simple as the full length and width of the table?
Or is there some other basic rule of thumb?
 
Hi, if you call the mfg of the dro you’ve chosen and tell them what size and make your machine it’s, they should be able to set you up with the correct size of the scales and what components you’ll need ! I bought my dro this way from dro pros ( no affiliation) and it went right on !
 
You want your scales to have more length than your travel in X Y Z. I bought mine based on the table size that the seller recommended. Unfortunately after I had them mounted I realized I did not have full travel in the y axis on my mill.
My bad for not researching the travel on the scales and accepting the dro was designed for that size machine as advertised.
I had the same problem with my lathe. I didn't notice it on the mill until I had the dro installed on the lathe and I didn't have full travel on the carriage. Then I checked the mill and I had the same problem with the y. Don't buy based on machine size - 13 x 40 lathe for example. Check the actual travels on the machine and make sure the scales are long enough.
 
If the scales are an inch or more too long, then you will have some wiggle room while installing the scale, and will not have to be so fussy about the exact mounting locations. If there is not enough space to do that easily, think outside the box for a while on mounting options so you can get some extra mounting room if possible. Do not accept an installation that will allow the read head to crash into an end bracket. If it can happen, it eventually will. Buy a different length scale if necessary.
 
On a mill, look to see if you have mounting bosses for the scale and plan accordingly. I didn't plan for that. My scale travel is long enough, but the next step longer scale would have been easier to install. Stuff that's hard to know until you actually have the parts in front of you.
 
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Longer then the axis travel, nothing will make you more angry then reaching the end of the physical machine travel and breaking a dro scale.
If a mill is capable of 60" in x axis travel purchase a 61" scale. Quite simple really, you would not buy a 5 gallon bucket to hold 6 gallons of material would you?
 
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