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View Full Version : Wrong size DRO--Best new DRO for BP Mill?



mikem
07-16-2007, 09:19 AM
My bridgeport 42" mill has an Acu-rite 5 35" scale on the table and Quik-count readout. This must be for a smaller table. Sometimes the table hits the limit switches and I have to remount my workpiece to get a long part where I can mill it.

How long would a scale for a 42" table normally be? Would even the right length scale reduce my table travel?

What DRO is the best? What DRO is the best for the money?

Machining is a hobby for me but if a couple of hundred more would get a lot better DRO, I might be able to scrape it up. Thanks --Mike

SGW
07-16-2007, 09:48 AM
"Best" is a matter of opinion, depending on your particular circumstances. Personally, after extensive research, I settled on an Acu-Rite with 0.0002" resolution scales, but you might decide on something else. The Newall, for instance, is attractive for its durability. I couldn't use the Newall for my particular situation, however, because the overall scale length is 10" longer than the travel distance and it wouldn't fit my mill. That shouldn't be a problem on a Bridgeport though.

Check with Mike at www.candomachinery.com and see what he can do for you. When I bought my DRO a few years ago, he was very good about responding to my questions both before and after the sale, and I thought his price quote for an Acu-RIte "package" was really good. (Usual disclaimers)

I also decided, after looking at all sorts of DROs, that you pretty much get what you pay for.

mikem
07-16-2007, 12:33 PM
Thanks SGW. Does your new acu-rite do bolt circles and things like that? What color is the read out?--Mike.

mikem
07-16-2007, 03:54 PM
Maybe the 35" scale is the correct one, since the table travel is around 30"?

pcarpenter
07-16-2007, 04:08 PM
A couple of hundred more? You mean like you can take the cost of your existing DRO and add some money to it (as in return it)? Or do you have to start over with a complete new one?...which won't be a couple hundred more in any case.

I recently bought one of the Chinese "SINO" branded DRO's from www.cdcotools.com (http://www.cdcotools.com) for my lathe and am very pleased. I have a Newall for my mill (came with it or I could not have afforded it) and its not in this class, but I was very impressed with the neatness of the installation and included stuff for scale mounting and sheilding, for something that was under $500. A shop here at the university has an Accurite on a lathe and while its scales may be better shielded in the first place ???, it did not come with the nice extruded scale shields and mounting track that my cheapy did.

The case for the readout itself appeared in pictures to be plastic. In point of fact, its cast aluminum or zinc or something. I think I got more than I bargained for. On the other hand, the device itself is not all that intuitive and the Chinglish instructions take a lot of head scratching to interpret. Once its function is understood, however, this is not a big deal.

I was going to post some pictures here soon anyway. When I was trying to decide on buying one, I wanted more pictures and information on the DRO but could not find them. I guess its my duty to provide them now ;)

Paul

mikem
07-16-2007, 04:54 PM
Was considering an Acu-Rite at around $1000 but it won't do bolt circles and midpoints. The model that does do these is about $200 more.

Does anyone out there have a 42" table Bridgeport with an Acu-rite scale to check for length?

pcarpenter
07-16-2007, 05:09 PM
That's going to be a difficult request to glean useful information from. Someone could have one with a longer-than-needed scale (won't hurt anything) that could lead you to believe that you needed one that long.

Theoretically, the scale only needs to have as much travel as the table. However, that may be cutting it close and mandates that you *must* have it positioned on the back of the table *very* carefully. More typically they are just a bit longer than needed, but may still not be as long as the table.

I think I would pull the reader head loose from the saddle and move it by hand to determine its actual travel. Then, while its still disconnected so you don't do any damage, remove the stops and check the table for its actual full travel and see if and by how much they are different. If the scale has become a limiting factor because of its length and not because it was not installed in the right position, you could certainly just buy the needed longer scale for the DRO you have (provided its not too old). If the scale was just installed in the wrong physical location to accomodate full travel, then you could fix that without spending a dime.

Paul

SGW
07-16-2007, 05:53 PM
I've got the Acu-Rite 200M, the predecessor to the 200S they're selling now, with ENC-150 scales. Yes, it does bolt circles, centerlines, and tool offsets. The bolt circles and the centerline function are great. I haven't been able to get comfortable using the tool offsets, but maybe the 200S has a better interface. www.acu-rite.com has all the manuals online.

I''d second pccarpenter's suggestion to measure the table travel and make 100% sure of what you need. In theory, you're supposed to install "shipping brackets" on the read head before you dismount it, so it won't flop around and damage the scale or itself, but if you're careful you may be okay.

The overall physical length of the ENC-150 scales is something like 6" greater than nominal scale travel. For example, my 24" travel scale is actually 30 3/8" long. But all that sort of information is on the Acu-RIte website, if you dig a little.

mikem
07-16-2007, 06:52 PM
The Cando Machinery guy (Michael) just emailed me (and he got back to me very quickly) and said the proper scale is about what I have, so maybe I'm just imagining that I am limited by the scale length. When I get home tonight, I'll try out Paul's suggestion about taking them apart to see if that increases travel. My readout unit still locks up sometimes and I have to tap on the top of it to get it to work. THanks to all--Mike.