DRO or not?

i4Marc

i4Marc

Registered
Registered
Joined
Mar 9, 2020
Messages
20
I am in the process of trying to decide which home/hobby lathe to get and was wondering if DRO is essential? I figure probably not if the machine I'm getting is a Harbor Freight 7X12. But I'm kinda liking the Precision Matthews 10X30. Will I regret not getting DRO installed with this machine? Is the DRO that comes installed with the machine a high quality DRO? What questions should I be asking that I am not?
 
The PM DROs look like nice units. I went with an import unit. It took a little fiddling to get it installed on my 1127, but it works great.

I wouldn't call it essential, but I much prefer it over counting turns on it dials.
 
With a DRO you don't have to worry about backlash, only actual movement is shown.With my lathe I have I have a hard time feeling the actual crosslide movement at times.

One less thing to worry about for accuracy.

For threading to me it is easier with a DRO.--Make a pass,pull back threading tool, reverse; find previous spot on DRO and advance a thousands, make another pass and so on until final thread depth is attained.
 
You don't need a DRO to use a lathe or mill. I went for almost fifty years without a DRO on the lathe and more than twenty five years without one on the mill. The lathe is better suited to running without a DRO because measurements of progress can easily be made with calipers or a micrometer. It is more difficult for the z axis but with some ingenuity, accurate work can be done. The same for the tailstock.

On a mill, the DRO is more useful. Movement of more than one revolution of the hand crank requires keeping track of how many revolutions have been made and it is easy to lose count. In addition, backlash must always be accounted for when machiniong. A DRO provides direct measurement of position so both of these problems are addressed.

There are other benefits of having a DRO. It simplfies operations like drilling bolt circles or linear arraus. The ability to change the ctive coordinate system is a plus as well.

All that said, I have DRO's on both my lathe and mill and wouldn't give them up.
 
I guess I would say why not, but agree with you on a small lathe it is much less practical. You can purchase a basic DRO for under $200 these days and do the install yourself, a lathe install is fairly simple and a good learning exercise. It helps minimize mistakes and counting errors, and if you are older and can't see that great, a big help. Two things to factor in specific to a lathe, on the cross slide scale you need a slim line scale which is smaller. You also want a 1 micron so when you use diameter mode the digits do not jump in 0.0004" increments. Typically this is a GS-31 scale, but you need to specify this when/if you purchase. The is a small cost difference.

I would say that that accuracy wise most the DRO's are equivalent at a hobbyist level of use. Ther may be some difference in reliability and how they work at extreme temperature difference (i.e. some displays crap out when cold).
 
I put an aftermarket unit on my 10x30, fiddled with it for a couple of months and decided I didn't use it enought to concern myself with it. If it worked perfectly, I still don't think I'd use it.
 
Excellent comments thus far. I just wanted to add that the need for a DRO on the lathe is very much dependent upon how accurate the leadscrews are. I own two lathes, an Emco precision lathe and a Sherline long bed lathe. Between the two, surprisingly, the Sherline has more accurate leadscrews and I can rely on the handwheel readings. If I interpolate and dial in a 0.00025" cut on my Sherline, that is what will come off. I cannot even get close to this level of resolution on my Emco lathe unless I use the compound feed, which is accurate to the tenths.

So, when I can find the time, the Emco will get a DRO but the Sherline doesn't need one.
 
Really, for a hobby none of this stuff is essential. You have to rephrase the question. :)
 
You must log in or register to reply here.
Back
Top