# DRO -- Educate Me Please



## Rick_B

I am leaning strongly towards a DRO purchase for a Bridgeport mill.  The mill is a Series 1 J head with a 9 X 32 table and X axis power feed.  With the power feed the table movement is 16-1/2" in the X direction and 12" in the Y.  I know VERY little about DRO's so I thought I'd start a discussion relating to some high level questions and working down into the details.  Please don't consider any of the following as factual statements - they simply represent what I think I know today.  At a 50,000 foot level:

What a DRO isn't - it is not a CNC type of functionality.  It cannot be programmed to perform a series of steps that can be executed by the push of a button.

What a DRO is - in simple terms it  is a tool to measure and monitor table movement but the movement is executed by either manually using the the lead screw or a power feeder in one or more axis.  In other words a DRO replaces the standard lead screw dials as a means of measuring how far the table has moved in any of one, two or three directions (depending on what you buy).  As a result, any lead screw backlash is no longer significant because the DRO is measuring only actual table movement  where as the dials are factoring in any backlash in the lead screw/nut configuration as well as table movement.

If the above is correct then let's drop down to 5,000 feet
the DRO uses a scale on each axis to measure movement and reports that back to a display - *Question - how does the scale actually measure the movement?*

When using a DRO I believe you can set a zero point and then measure from that zero point and return back to the zero point.  *question - does the zero point represent the tool center - in other words can the tool diameter be reported to the DRO and then it compensates for that diameter or is that an operator calculation?* 

What can I do with a DRO beyond the elimination of backlash issues.  Some examples - touch off the end of a work piece and measure the distance a slot has been cut, touch off the work piece and find its center, touch off a work piece with a hole and find the hole center.  Are these typical DRO features?  What else can be done with a DRO before you need to consider full blown CNC functionality?

That's probably enough for now - thanks for any thoughts/comments you may have.

Rick


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## Cobra

Try looking at DROPros.com for a good introduction into the differences between glass and magnetic.
They are very helpful in selecting the DRO that best suits your needs and equipment.


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## cathead

Well, for starters, it is more accurate than the mechanical scales.  I know there are two basic types, the magnetic and the glass
scale type.  Supposedly the glass scale is slightly more accurate.  You can set your zero point anywhere you want to to establish
edge surfaces or hole centers.  Most will do bolt circles which gives you numerical coordinates of each bolt hole center.  I often use
an edge finder to set my DRO.  You find the edge of the enge finder tool and then move the table half the diameter of the edge finder and
you are at the edge of the part.  Then you can reset the DRO to zero.  You can also edge find both ends of a part and determine the
center.  I do that a lot and work from the center for easy symmetry.   I'm not an expert on this subject, just having learned from doing.


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## RJSakowski

The DRO scale is typically optical, magnetic, or capacitive.  It consists of a repetitive pattern on a linear scale and sensor which can detect that pattern.  The frequency of the repetition determines the resolution of the DRO scale.  Generally , the DRO uses a detection scheme which can determine the direction of movement.

The DRO simply determines the position relative to a reference position.  It doesn't compensate for tool diameter.  On a mill, the table moves underneath the spindle.  Setting a zero reference position can be any point.  Typically, one would refer to the spindle axis but you could just as easily bring a tool up to the edge of the work and set a zero there.  Substituent milling into the work on that axis with that tool would be relative to the edge.


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## Bob Korves

Many better DRO's have functions for bolt circles and step measurements.  After the first position you push a button, and the next position will then become zero, zero. Go there.  Repeat until done.


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## brino

Rick, you seem to have a good handle on the use and benefits of DROs.

Personally I have not made the jump to DROs yet.

Many people like the little igaging LCD units, and the price is certainly right.....
12 inch: http://www.busybeetools.com/products/digital-remote-readout-0-12in-in-metric.html
24 inch: http://www.busybeetools.com/products/digital-remote-readout-0-24in-in-metric.html
36 inch: http://www.busybeetools.com/products/digital-remote-readout-0-36in-in-metric.html

However I have two things I do not like about those:
1) the small size of the LCD, and
2) the lack of bolt circle and other functions because the axes are independent. 

Sure you can work-around those issues by mounting them on a swivel arm with a light and you can work out the coordinates of each manually or with the help of your Machinery Handbook, but if(when?) I pay for a DRO unit I want to realize the biggest benefit!

-brino


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## Rick_B

Thanks for the info guys - this may be a short lived discussion.  I just took a look at pricing and now have sticker shock.  If I can't get into the DRO game in the $300 range I will likely seriously reconsider the jump to DRO's.

Rick


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## ch2co

You might take a look at Yuriystoys.com  He has a do it yourself system that comes as a parts only system or he also provides fully built modules 
for reading out DRO's on  large (inexpensive) tablet screen. His site talks about the differences and accuracies of the various sale types.


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## mksj

There are many 2 axis Sino DROs in the $200-300 range, a 3 axis is not much more.  You could get by with a 2 axis with a a separate spindle DRO (about $50). I consider the Igaging Absolute scales much less affordable these days and there accuracy is not up there with comparable glass scales. Glass scales work just fine, I do recommend a scale cover for longevity of the scale. Glass and newer magnetic scales have comparable accuracy, the magnetic scales are less prone to fouling and a bit easier to install, but much more expensive. 
http://www.ebay.com/itm/2-Axis-digi...ne-with-precision-linear-scale-A/291767846797
http://www.ebay.com/itm/2-Axis-digi...ne-with-precision-linear-scale-m/331859638720


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## Bob Korves

For the best prices, go to Aliexpress.  There are the same three axis DRO's there for less than $250, shipped.


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## Holescreek

Rick_B said:


> Thanks for the info guys - this may be a short lived discussion.  I just took a look at pricing and now have sticker shock.  If I can't get into the DRO game in the $300 range I will likely seriously reconsider the jump to DRO's.
> 
> Rick



I took delivery this morning of my third DRO from a seller in China (Enpod), this one is a 3 axis with glass scales.  $313 delivered, received it in 5 days.   My other two are two axis units that are on lathes.
http://www.ebay.com/itm/182295304583?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

The seller is very communicative, meaning they are very interested in making me happy. We exchanged 4 emails before they shipped this one.  I've tried to help them understand some of the confusing parts of their ads relative to scale lengths but to be honest they are just selling the same thing as everyone else - but much cheaper.  It's important to let them know you want the "english" model when you give them the sizes, my first unit was a chinese model and it was a PITA to get set up, but the seller worked hard as a go-between with the factory to get me what I needed.  When I bought the second unit (english) I was able to get the first one straightened out quickly.

I have a thread or two here on installing the units on my Cinci Traytop lathe and Clausing lathe.  The new setup is going on a 9x42" Bridgeport.


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## Bob Korves

Holescreek said:


> I took delivery this morning of my third DRO from a seller in China (Enpod), this one is a 3 axis with glass scales.  $313 delivered, received it in 5 days.   My other two are two axis units that are on lathes.
> http://www.ebay.com/itm/182295304583?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
> 
> The seller is very communicative, meaning they are very interested in making me happy. We exchanged 4 emails before they shipped this one.  I've tried to help them understand some of the confusing parts of their ads relative to scale lengths but to be honest they are just selling the same thing as everyone else - but much cheaper.  It's important to let them know you want the "english" model when you give them the sizes, my first unit was a chinese model and it was a PITA to get set up, but the seller worked hard as a go-between with the factory to get me what I needed.  When I bought the second unit (english) I was able to get the first one straightened out quickly.
> 
> I have a thread or two here on installing the units on my Cinci Traytop lathe and Clausing lathe.  The new setup is going on a 9x42" Bridgeport.


What are the differences between the English and Chinese models?


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## Holescreek

The words on the readout when you are in setup mode are in chinese.  Other than that, nothing.  It is rather hard to set the unit up for a lathe (changing scale resolution to go from radius to diameter readout for example) when you don't know what it says, and the manual is hard enough to understand without that little speed bump.


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## coffmajt

I installed a DRO Pro 3 axis system on my mill two years ago and love the way it works.  You can input your tool diameters and it will compensate from an edge if that's what you want.  Makes centering easy and checking angles even easier, but as some have reported with the magnetic scales, not cheap.  I did not want the glass scales due to concerns with coolant and chip fouling, which have not been any problem with the magnetics,  == Jack


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## Rick_B

Holescreek said:


> I took delivery this morning of my third DRO from a seller in China (Enpod), this one is a 3 axis with glass scales.  $313 delivered, received it in 5 days.   My other two are two axis units that are on lathes.
> http://www.ebay.com/itm/182295304583?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
> 
> The seller is very communicative, meaning they are very interested in making me happy. We exchanged 4 emails before they shipped this one.  I've tried to help them understand some of the confusing parts of their ads relative to scale lengths but to be honest they are just selling the same thing as everyone else - but much cheaper.  It's important to let them know you want the "english" model when you give them the sizes, my first unit was a chinese model and it was a PITA to get set up, but the seller worked hard as a go-between with the factory to get me what I needed.  When I bought the second unit (english) I was able to get the first one straightened out quickly.
> 
> I have a thread or two here on installing the units on my Cinci Traytop lathe and Clausing lathe.  The new setup is going on a 9x42" Bridgeport.




What is your impression of the accuracy and repeatability of the DRO's you are using?  Also - they see to have all of the features of the more expensive models - would you agree with that or are there things/features that you don't get?

Thanks
Rick


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## Bob Korves

Rick_B said:


> What is your impression of the accuracy and repeatability of the DRO's you are using?  Also - they see to have all of the features of the more expensive models - would you agree with that or are there things/features that you don't get?
> 
> Thanks
> Rick


Rick, the technology used for glass scales should give the same accuracy regardless of brand, if built to the same nominal accuracy.  The issues with the imported stuff is the quality of the mounting and supporting equipment, which are often not made to the same robustness as the best made ones.  Repeatability can be impacted by loose mounting hardware and less rigid construction over the longer term.  Then again, hobby machinists are not usually as rough on equipment as commercial shops are.  You pay your money and take your chances.


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## Rick_B

Thanks bob - that brings up a good question - how do the 3 scales mount to a Bridgeport - is hardware generally included?  I suspect that it depends on where you get it - like you said the more you spend the closer it will be to plug and play I'm thinking?

Rick


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## Bob Korves

Rick_B said:


> Thanks bob - that brings up a good question - how do the 3 scales mount to a Bridgeport - is hardware generally included?  I suspect that it depends on where you get it - like you said the more you spend the closer it will be to plug and play I'm thinking?
> 
> Rick


I am the wrong person to answer that question.  I don't have a BP, and I have not looked critically at many installations.  A careful installation of any DRO, with additional protection added where needed, pays dividends long term.  It is really important to keep the oil and swarf out of glass scales, and to not let them get bent or otherwise physically damaged.  Hardware is usually included, but quite often it must be modified or new parts made to achieve an accurate, protective, and robust mounting.


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## mmprestine

I purchased one for my mill and one for my lathe from aliexpress, very nice units and the price was unbelievable for what you get.  Plus it was free shipping and came in 5 days to my door.

https://www.aliexpress.com/snapshot/8098317053.html?orderId=78278135569879&productId=1708239801

https://www.aliexpress.com/snapshot/8098317054.html?orderId=78278135579879&productId=32698054362


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## mksj

Rick_B said:


> that brings up a good question - how do the 3 scales mount to a Bridgeport - is hardware generally included? I suspect that it depends on where you get it - like you said the more you spend the closer it will be to plug and play I'm thinking?



When it comes down to it there are many different variations on mounting, I purchased the DRO Pro EL700 with 4 axis, and used only one bracket for the X-Axis mount. If you need to modify or fabricate the brackets it is easy to do with some aluminum stock. The alignment of glass scales is more critical then the magnetic so you need to spend the time to make sure they are aligned properly. The cheaper glass scales may not be as coolant proof as better ones, but in the hobby environment this should not be an issue if they are properly installed.  There are lots of references online as to mounting DROs on knee mills. I assume your Z-axis would be the knee, which is easier to mount than the spindle scale. As I mentioned you can get an inexpensive battery operated spindle DRO, which comes with brackets and are easy to mount for around $50. 
http://www.hobby-machinist.com/threads/dro-educate-me-please.56139/reply?quote=462897


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## British Steel

Bob Korves said:


> I am the wrong person to answer that question.  I don't have a BP, and I have not looked critically at many installations.  A careful installation of any DRO, with additional protection added where needed, pays dividends long term.  It is really important to keep the oil and swarf out of glass scales, and to not let them get bent or otherwise physically damaged.  Hardware is usually included, but quite often it must be modified or new parts made to achieve an accurate, protective, and robust mounting.



I've fitted a few to Blidgepolts  (Chinese ones), not that difficult but most of the supplied hardware went in the scrap for melting... it's important to ensure the scales are EXACTLY parallel to the movement, I run a dti gauge along the scale to check horizontally and vertically, aiming for zero to a few thou" divergence, with the dti mounted where the read head is going.
You will probably need to make adjustments so mounting on pads with grubscrews at their corners will give fine adjustment on castings with draft and allow fitting the scales more neatly than the supplied hardware (clunky cast ally angle brackets).
Leave the plastic shipping shim between scale and reader in place until you get to mounting and shimming the reader to ensure the right alignment and spacing. If you can, make removing the shim the last step (you may need to remove its retaining screws while you can get to them though, and tape it in place - bloody awkward!)

Dave H. (the other one)


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## Holescreek

Rick_B said:


> What is your impression of the accuracy and repeatability of the DRO's you are using?  Also - they see to have all of the features of the more expensive models - would you agree with that or are there things/features that you don't get?
> 
> Thanks
> Rick



Long story short, my first DRO was bought from a fellow in Hong Kong maybe 13 years ago for about $480 shipped.  It's a Meister Top 10 3 axis unit.  In all the years since I've barely dipped a toe into the included features the unit has built in.  I've never even tried the calculator function since there's a stack of them on top the tool box.  I have used the bolt circle and straight line hole layout and chop milled a large radius in using the programmable function.  Mostly I set zero and watch the numbers.  

The first unit I bought from the current seller went on my Traytop which also had a Trav-a-dial on it and they jive perfectly for accuracy.  I checked the second one on the Clausing with gauge blocks and it matches as well.

The unit comes with a small bag of screws, a mount for the DRO , 3 angle brackets and scale covers for each one.  I'll get something posted on the installation in a few days, The X and Y are done and I'm finishing up the Z axis tomorrow.


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## bruedney

mmprestine said:


> I purchased one for my mill and one for my lathe from aliexpress, very nice units and the price was unbelievable for what you get.  Plus it was free shipping and came in 5 days to my door.


Those links don't work

I would be intersted in knowing the actual units please.

Cheers
Bruce


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## Rick_B

So here's a high level question - I have a line on several acu-rite DRO's - both are two axis units.  One is an ACU-RITE III and one is an ACU-RITE D200.  Both include scales and cables as well as the read out units.  I don't believe either of these are currently offered and may not be supported - I'm going to check that out.  Cost is sub $400 range.

I can get a 3 axis import unit for a little less money that seems comparable in terms of published specifications.

So the question - is an older used ACU-RITE  2 axis unit a significantly better buy than a 3 axis import - assuming the same price range?

Thanks
Rick


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## Happycamper

Rick, there are several different brands/names and I'd venture to say the chineses ones are all very similar if not the same. Whatever you get you will be happy with. These are all elctronics and usually if they work when you get them, they'll work for a good period of time. I know that you will find (after  installing and using a DRO) that it makes machining a LOT easier and you will wonder why you didn't install them years ago!

Hawk


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## mksj

Given that an older used DRO unit is as is and lacks some of the newer functions of DROs. I would opt for a new DRO. I have also seen issues with older DRO head units with regard to the resolution of the scales they support. I did have an Acurite View DRO on my last mill and it was great, they offer very good quality DROs, but the two models you are looking at are quite old.  Personally at the price range you are looking at, for about $100 more I would seriously look at the Easson ES-12B. This would be a step up on the generic Chinese DROs, a number of us have the ES-12 series and they work great..
https://www.aliexpress.com/store/pr...xis-DRO-system-and-3/1021179_32789719488.html


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## Rick_B

mksj said:


> Given that an older used DRO unit is as is and lacks some of the newer functions of DROs. I would opt for a new DRO. I have also seen issues with older DRO head units with regard to the resolution of the scales they support. I did have an Acurite View DRO on my last mill and it was great, they offer very good quality DROs, but the two models you are looking at are quite old.  Personally at the price range you are looking at, for about $100 more I would seriously look at the Easson ES-12B. This would be a step up on the generic Chinese DROs, a number of us have the ES-12 series and they work great..
> https://www.aliexpress.com/store/pr...xis-DRO-system-and-3/1021179_32789719488.html



I did/do have a  concern with used, older prducts that may no longer be suported.  I'm curious about your recommendati regarding why you consider it a step above other imports? Is it functionality, build quality/robustness, customer service?

How is the customer support fromthe imprt dealers?

Thanks
Rick


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## Bob Korves

DRO Pros are known for providing good service after the sale and for standing behind their products and honoring their warranty.  That comes as a cost.  Much of their product is Chinese import equipment, and is sold at much higher prices than the cheapest priced stuff from eBay or Ali Express.  If you want somebody to hold your hand, they are a good choice.  If you want to save considerable money at the cost of manuals that are at times indecipherable and maybe looking for help on the web and here on H-M, then go with the bargain price stuff.  Lots of the cheap stuff has been installed quite successfully and is in regular use with good results.


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## mksj

Easson has been around for a long time, and both from a quality and reliability stand point I would consider to be better built units over the generic Sino DRO. The manuals are in comprehensible English. The DRO head unit is very functionally laid out and the graphical display for milling is a bonus . Alliepress is the cheapest, I would also consider Quality Machine Tools or DRO Pros if you want a unit shipped form the US with better support but at additional cost. The ES-12B/C is about 1/2 to 1/3rd the price of an comparable Acu-Rite or Newall DRO. Other than a generic rebranded Sino DRO, Easson DROs are often supplied with machines for both lathe and mill (ES-8, ES-12). 
http://www.hobby-machinist.com/threads/easson-es-12-b-dro-install-on-a-pm-833t-mill.56329/
http://www.hobby-machinist.com/threads/easson-12b-install-details-on-a-pm1340gt-long-post.55949/


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## Bob Korves

https://www.aliexpress.com/item/2-a...lgo_pvid=37739215-47e4-490b-84e0-7e5e2715c9e2 *
$235.60 including shipping.
*
https://www.aliexpress.com/item/Eas...lgo_pvid=dbcd31e2-d839-4a32-8509-cbaf221e3878 *$435.12 including shipping
*
http://www.dropros.com/DRO_PROS_Easson_Milling_Machine_Digital_Readout.htm *$699 plus freight.*

Just a few examples of three axis mill DRO kits...


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## Holescreek

The "free shipping" from China always amazes me.


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## Rick_B

Bob Korves said:


> https://www.aliexpress.com/item/2-a...lgo_pvid=37739215-47e4-490b-84e0-7e5e2715c9e2
> *$235.60 including shipping.
> *
> https://www.aliexpress.com/item/Eas...lgo_pvid=dbcd31e2-d839-4a32-8509-cbaf221e3878 *$435.12 including shipping
> *
> Just a few examples of three axis mill DRO kits...



I've looked at both Ebay and Aliexpress and I must admit its mind boggling.  Prices seem to be all over the place - but the three I have focused on are Bob's recommendations above for $235 and $435 and Holescreek suggestion linked here http://www.ebay.com/itm/182295304583?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

I don't see a lot of difference so I'm wondering if anyone has experience with the specific Aliexpress models and how they might compare to Holescreek suggestion.

Thanks
Rick


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## Holescreek

I think the quality of the manual on the Eason unit has to be better since so many home guys swear by them and the US companies sell them for greatly marked up prices.  I believe I mentioned that the chinglish of the manuals I got was the worst I'd seen.  

I looked at the links above too and the scales appear to be coming from the same factory, or at least the parts are coming from the same suppliers.  The only difference being the color of the wiper seal (yellow vs. black) The readouts themselves are all different, the $235 unit has a layout similar to my Meister Top10 unit.


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## Bob Korves

I have no idea how those units actually compare as delivered.  And, with how quickly that market has been changing, I don't think anyone really knows the current marketplace and how the different units truly compare, especially thinking down the road 5 or 10 years.  And if the sellers do know, they are only telling their own version of the story.  You pay your money and take your chances.  When I am guessing, I guess with the low cost version.  Just me...  Others want someone to hold their hand, and that is understandable.  It is an expensive hand hold, though...  My current mode is to just wait.  Prices have been tanking on DROs, and it doesn't look like that will end anytime soon.  I get by pretty well with just using the dials.


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## Rick_B

As I continue to flip the should I/Shouldn't coin I got to thinking about some of the old school versus DRO advantages and some comments (maybe here maybe somewhere else) relating to horse and buggy versus car.  I was thinking about this as I was doing some yard work - hauling stones, debris around - I thought I really don't need a lawn tractor and cart - I could do the work with a wheelbarrow.  It would be slower and more tiring but the job would get done.  It sure is esier and ,more enjoyble to use the tractor and cart.  I decided to stop flipping the coin and just get the DRO.

It's going to be a 3 axis unit and an import.  I haven't decided which one yet but am leaning towards the lower cost unit  - given no obvious difference.  One open question is how you size the scales.  Is it table length, width or table travel.  I saw somewhere that it was table travel plus 140 mm (I think).

Any advice on scale sizing?


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## Holescreek

It depends on the seller's interpretation from the manufacturer. It took me a while to get it through my sellers head that I didn't care about OAL, just travel length.  He kept wanting to add the 140mm on top of what I asked for.  He finally gave up and gave me what I asked for.


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## JPigg55

Here's another fairly recently added option:
http://littlemachineshop.com/products/product_view.php?ProductID=5515&category= (scale specs can be seen here)
This system was designed to work with Yuriy's Toys Touch DRO system.
I believe Yuriy's controller will work better with these scales and as such, have ordered his quadrature controller (http://www.yuriystoys.com/p/store.html).
I didn't order the complete kit, just the scales and readheads (sold separately):
Here http://littlemachineshop.com/products/product_view.php?ProductID=5499&category= and here http://littlemachineshop.com/products/product_view.php?ProductID=5498&category=
The cost saving on the components more than pay for the pre-built controller from Yuriy's site or you can make your own for additional savings.
Touch DRO is an App based DRO display, for those who don't know, that requires an Android tablet.
As an 'Open Source' system, it is continually being updated, refined, and added to by an entire community of people that are available online for help/assistance if needed.
The advantages to this type DRO as I see them are:
1. Flexibility, can have 2 or 3 axes. A forth axis (labeled "W") on the system can be used (usually, for a tachometer, but has other uses).
2.Memory, only limited by the amount on your tablet, expandable via micro SD cards.  This also allows for having back-up copies.
3.Instant updates via the internet.
4.Versatility. Since the controllers connect to your tablet via Blue Tooth, you can connect multiple machines.
I plan on doing a pictorial post of the install an operation once the components get here and I have time to install them.


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## Bob Korves

JPigg55 said:


> Here's another fairly recently added option:
> http://littlemachineshop.com/products/product_view.php?ProductID=5515&category= (scale specs can be seen here)
> This system was designed to work with Yuriy's Toys Touch DRO system.
> I believe Yuriy's controller will work better with these scales and as such, have ordered his quadrature controller (http://www.yuriystoys.com/p/store.html).
> I didn't order the complete kit, just the scales and readheads (sold separately):
> Here http://littlemachineshop.com/products/product_view.php?ProductID=5499&category= and here http://littlemachineshop.com/products/product_view.php?ProductID=5498&category=
> The cost saving on the components more than pay for the pre-built controller from Yuriy's site or you can make your own for additional savings.
> Touch DRO is an App based DRO display, for those who don't know, that requires an Android tablet.
> As an 'Open Source' system, it is continually being updated, refined, and added to by an entire community of people that are available online for help/assistance if needed.
> The advantages to this type DRO as I see them are:
> 1. Flexibility, can have 2 or 3 axes. A forth axis (labeled "W") on the system can be used (usually, for a tachometer, but has other uses).
> 2.Memory, only limited by the amount on your tablet, expandable via micro SD cards.  This also allows for having back-up copies.
> 3.Instant updates via the internet.
> 4.Versatility. Since the controllers connect to your tablet via Blue Tooth, you can connect multiple machines.
> I plan on doing a pictorial post of the install an operation once the components get here and I have time to install them.


That is great JPigg55, but it still costs double what an Aliexpress kit with glass scales costs, and only advertises .002" accuracy, though it may actually be better.  It also still takes some user effort to get it all working with the Android tablet.  I am a big supporter of Yuriy and his work, and of the universality of his designs.  The issues are still pricing totals, expected accuracy, and plug and play in my mind...


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## JPigg55

Bob Korves said:


> That is great JPigg55, but it still costs double what an Aliexpress kit with glass scales costs, and only advertises .002" accuracy, though it may actually be better.  It also still takes some user effort to get it all working with the Android tablet.  I am a big supporter of Yuriy and his work, and of the universality of his designs.  The issues are still pricing totals, expected accuracy, and plug and play in my mind...


I totally agree with you Bob.
For me, however, this was a better option as scale size and length are issues for me. Magnetic scales are much smaller and way easier to cut to length.
Had I been able to find glass scales that were the correct length for my machines, I may have gone that way as it is much cheaper with an increase in accuracy.
I just wanted to post another option for those like me where glass scales may not be an option.
I also like the fact that I can easily replace any component that may go bad instead of having to buy a whole new system a year from now because one thing broke and replacement parts are no longer available.


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## Rick_B

I've been pondering this while takingadvantage of good weather to get some yard projects done.  I've decided I am getting a DRO and likely one of the lower cost models we have been discussing.  I'm still struggling with scale sizing.  According to the Bridgeport manual my mchine, with a power feed, has 16-1/2" of X axis travel, 12" of Y axis and 16" ofZ axis.  I need to verify those numbers but assuming they are correct what would the scale lengths be.  It seems most suppliers use a formula relating to travel + 140 mm.  So do I just measure the travel, add 140 mm and order that scale overall length?

Thanks
Rick


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## Bob Korves

Rick_B said:


> I've been pondering this while takingadvantage of good weather to get some yard projects done.  I've decided I am getting a DRO and likely one of the lower cost models we have been discussing.  I'm still struggling with scale sizing.  According to the Bridgeport manual my mchine, with a power feed, has 16-1/2" of X axis travel, 12" of Y axis and 16" ofZ axis.  I need to verify those numbers but assuming they are correct what would the scale lengths be.  It seems most suppliers use a formula relating to travel + 140 mm.  So do I just measure the travel, add 140 mm and order that scale overall length?
> 
> Thanks
> Rick


To find the "real" travel, don't read the manual, move what you are trying to measure all the way to one end of it's travel until it stops, put a Sharpie mark across the interface between moving and stationary parts, move it all the way in the other direction until it stops, and then measure between the half Sharpie marks.


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## Rick_B

Thanks Bob - that's what I had in mond for verifying travel spec's from the manual.

Rick


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## Bob Korves

Bob Korves said:


> To find the "real" travel, don't read the manual, move what you are trying to measure all the way to one end of it's travel until it stops, put a Sharpie mark across the interface between moving and stationary parts, move it all the way in the other direction until it stops, and then measure between the half Sharpie marks.


Forgot to mention that you also need to move any stops, dogs, or other adjustable features that can limit the travel of the axis, out of the way or at least loosen them so they can slide.  Make sure you are achieving the full travel possible for each axis.


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## Kroll

Robert I will be following your post here,if you will please let us(me) know what you order from who.There are so many choices out there it can/does give a person headache.Your questions and answers you receive has cleared up alot of ?marks in my head.So now I guess it comes down to who to purchase and what model from.Sounds like your budget and mine are about the same and I'm others as well.So we are not along on these issues,if I may also suggest to do a search on Youtube.There are several that I think is helpful on installing and what works for us guys that don't do this every day.Myself I am going close to pulling the trap off my BP and getting started on setting it up and install a DRO.Thanks for posting and asking some really good questions---kroll
I guess if a person keeps looking and researching you will find something else to ponder over http://www.star-techno.com/


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## Rick_B

I measured the actual travel on my Bridgeport - X = 17-3/4" (32" table with a power feed), Y = 10-1/2" (movement got very tight at back - I think the gib adjustment is too tight at the back side.  I have another 2" or so of space so I'm going to assume Y = Bridgeport spec of 12"), Z = 16".

When I convert that to MM I get X = 451, Y = 305 and Z = 406.  I saw on holescreek thread where he used 800, 350 and 450 for his 42" table machine and he mentioned that the X axis was about 12" longer than needed but it wasn't a problem.  Right now I'm thinking I would order 600, 350 and 450 (X, Y and Z respectively).  The question I have is that when I look at the offerings I typically see

*Scale Length available*

*physical length is differnt from the travel length*

*50,100,150,200,250,300,350,400,450,500 ,550,*

*600,650,700,750,800,850,900,950,1000mm 5um.*

*physical length = 140mm + travel length*

So if I want a 600 mm overall length what do I order - 600 - 140?  Or is the statement above saying 600 mm scale will give you 460 mm of travel?  I think I've got tunnel vision about this 

Thanks
Rick


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## Bob Korves

Is there a good reason for ordering so much oversize?  The main consideration beyond having enough travel is how and where you are going to mount them.  Mock them up if necessary.  You post does not show if the seller wants travel length or physical length to be supplied, or both.  Make sure what they are asking for, and then make it very clear to them what dimension(s) you are supplying, keeping the language barrier in mind...  Best is to use the exact nomenclature and sizing system (mm or inch) that they are asking for.  Don't complicate things or it can and will get confused.


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## Rick_B

Bob - I am assuming when you question why oversize that you are referring to the X axis - the Y and Z are only 2 inches or so longer than travel.

Regarding the X - I was going off of holescreek's comment that a bit longer was not a problem and that it made locating the scale a little easier.  Given that the cost is the same for the scales withing the range offered above - I'm wondering why a bit longer would be an issue for the X axis?

Thanks
Rick


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## Bob Korves

Rick_B said:


> Bob - I am assuming when you question why oversize that you are referring to the X axis - the Y and Z are only 2 inches or so longer than travel.
> 
> Regarding the X - I was going off of holescreek's comment that a bit longer was not a problem and that it made locating the scale a little easier.  Given that the cost is the same for the scales withing the range offered above - I'm wondering why a bit longer would be an issue for the X axis?
> 
> Thanks
> Rick


My comment was more along the lines of "figure out where and how you want to mount the stuff and then order stuff to fit that plan."


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## JPigg55

Thought I'd post the unboxing photos of The Little Machine Shop DRO I spoke of before in this thread.
Added a couple shots of Yuriy's quadrature adapter too:


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## Rick_B

Bob Korves said:


> My comment was more along the lines of "figure out where and how you want to mount the stuff and then order stuff to fit that plan."


Bob - given that I have never seen a DRO in person (just internet pictures) and that I have no experience with mounting a DRO - its going to be difficult for me to figure out where and how it would be mounted.  I was assuming that with a "standard Bridgeport" there would not be all that many options for mounting.  X on the back of the table, Y on the saddle and Z on the frame next to the knee.  I'm sure within those general parameters there are variations but I'm betting there are not a lot.

Without only limited knowledge of how a DRO actually works, I am assuming the scale attaches to a fixed surface and the reader head attaches to the moveable surface you are attempting to measure.  Again - with a standard Bridgeport, the Y and Z are a given (I think) but the X has some variability related to table length.  However, my thought right now is that as long as the overall length of the scale doesn't exceed the table length and is longer than the table travel then any length will work.  I was hoping that someone who has installed a DRO on a Bridgeport could simply validate the X, Y and Z numbers I proposed above.

Thanks
Rick


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## Holescreek

I measured the scale length on my 32" table BPM and it measured 660mm That length did not include the end caps, just the scale itself.  You'll be fine with a 600. 

Just be sure that your seller understands that you are asking for "travel length" when you order.


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## mksj

There is quite a bit of information and various installs on the DRO Pros website: http://www.dropros.com/Digital_Readout_DRO_Installation.htm

My calculations based on the travel measurements using glass scales would be:
X scale overall length of 600 or 650mm
Y scale overall length of 450 or 500mm
Z scale overall length of 550mm
You need to take a look at the mounting surfaces to make sure nothing is obstructed, I would get the slightly longer scales on the X and Y if you have the space. I would  order the scales as they indicate which is overall length based on their calculations. I find that if you ask for anything else, you might not get what you want, especially when your are ordering from Asian sellers.

The X scale is mounted to the table which is the moving surface. the reader is mounted to the saddle.
The Y scale is mounted to the knee and the reader is mounted to the saddle.
The Z scale is mounted to the column and the reader is mounted to the knee.
Since the surfaces may not be even (with the exception of the X axis on the table), you need the ability to adjust both the reader and the scales so that everything is run parallel and true. This is usually done with a test or dial indicator. I mount my Y and Z scales on aluminum rectangular bar stock usually with 4 jacking screws. Scales also come with jacking screws on either end and the mounting holes are usually slotted to allow some adjustment.


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## AGCB97

I posted this thread  quite some time ago. Then I was very disappointed but now having become used to it, and having used some of the most useful functions, I see nothing wrong with the unit, only bad instructions and paper work. (actually if you know Chinglish, they're not that bad. It just took lots of video watching to figure it out)

I've used the bolt circle function many times and centering is a breeze. The line hole and arc functions are also good to have.

If I had it to do again, I still couldn't resist the low price.

I may not have the best tools but I have lots of them. Besides, I'm not making my living with this stuff. That would entirely change the picture. The tools I MADE MY LIVING WITH (now retired) were only brand name top shelf.

Aaron


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## Rick_B

Thanks Aaron - I've firmly decided to go with oe of the lower cost models - now I just need to get by a dozen other things in front me (unrelated to the shop unfortunately) and get to ordering one of them.

Rick


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## Kroll

Good morning,Rick any updates or pics of what you pickup?Boy I would like to purchase from DRO pros but my pockets just won't allow it.Lots of info on their site and a warranty with support,but I also will have to go with the cheaper so rolling the dice.


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## Rick_B

Kroll said:


> Good morning,Rick any updates or pics of what you pickup?Boy I would like to purchase from DRO pros but my pockets just won't allow it.Lots of info on their site and a warranty with support,but I also will have to go with the cheaper so rolling the dice.




Unfortunately I haven't made any progress with this project - I've been taking advantage of the nice weather.  10 yards of mulch and 8 yards of run a crush.  Hopefully I will be getting to this soon.  My current plan is to get the same unit asd Holescreek referenced up thread - unless I win the loottery 

Rick


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