# A DRO system for my King PDM 30 (RF 31 style) round column bench mill



## Canuck75 (Jan 23, 2014)

[h=2]A DRO system for my King PDM 30 (RF 31 style) round column bench mill[/h]As most reader will know, counting hand wheel turns is a necessary evil when moving around a work piece to make sure you are in the right .100" bracket. Accurate and visible layout can also help in ensuring the drill or end mill is in the right place, but if you have ever had to go back and start counting turns over again, it doesn't take long to wish for a better system. A DRO is the only solution I know of. I had already installed a 6" digital caliper on the Z but wanted a 3 axis "system". I looked at Shooting Star, Schumatech and others but money or wait times kept me looking. I found a company called "Hobbymetrix" on line. The all in cost for 6", 8", 20" scales, their YADRO (YetAnotherDRO) interface, and connecting cables worked for me so I took the plunge. At the time they had some serious electronic supplier issues which resulted in me getting one of their "lab" boards, so that saved me all the angst of soldering in all of the components, I just had to finish out the case and the plug in wires. The YADRO actually has a 4 axis capability if you have a knee mill. There is a pile of detailed information on this product at "Hobbymetrix.com".




 


The finished YADRO interface box is 1-1/2"x3-1/2"x7". A small capacitor needs to replace the battery in each scale as they now get their power through the interface (as I understand it, a capacitor helps to smooth out any voltage variations). I made a simple brass ring the size of a battery with a plastic shell pressed in from the back which accommodates the capacitor, pinches the positive wire to the rim and feeds the negative wire out the bottom to make contact on installation as a normal battery would.




 




Several operating conditions dictated how I would mount the scales. The kind and amount of machining I do doesn't warrant the cost of a X servo, so displacing the possibility of travel stops on the front area of the table is not a biggy, and, a front mount doesn't cause me to loose any Y travel which a rear mount would. For the Y, the back face of the saddle was machined making it easy to make a bracket and have the Y scale stick out the back and also staying out of the way of the Y gib locks. The Z is mounted centre front after taking out everything associated with the old quill depth stop and putting in a flat AL plate. I made custom AL mounts for the ends of all the scales and and a new bottom quill bracket which accommodates the Z scale on the front, and my quill return cable attached to the rear. AL angle protects the X and Y scales. (just a note - the X and Y reader mounts in these pictures are first try rigid types, later replaced as shown below).




 




Anchoring the reader heads caused me some concern. The X scale had a slight bow in it (front to back) over its 26" length, and, while somewhat flexible, I didn't want to put any stress on the readers as they travel along. Similarly, on the Y and Z, it is difficult to ensure that the scales are perfectly true to the line of movement. Also, on the Y, the only place to attach the reader bracket was to the cast surface of the mill base. For all three axis I therefore used a "plate and insert" anchoring system. Each reader has a plate attached to it with a milled slot with an associated very close fitting plug. The plug (which I keep oiled) allows for motion on two axis to relieve any alignment stress as the reader moves along. Also, at each reader, cable clamps were installed to ensure cable plug-in continuity is maintained.




 


Finally, I needed somewhere to hang an old Toshiba laptop which is used for the display. This is part of the YADRO approach to keeping costs down and gives a nice big readout. The solution I used was to make a mount on the back of the column base and make up an articulated arm using pipe and pipe fittings. Not very elegant but it works a treat. The display can be moved around at will. A plywood platform supports the laptop and the interface is mounted on the underside to keep it out of the way. 

Hobbymetrix was very helpful with explicit instructions. The system cranked up on the first try and has been very reliable ever since. There is no noticeable "lag" to the readout and the system has all the capabilities that I need.


Critique and suggestions always welcome.​


----------



## rdean (Feb 3, 2014)

I also have a YARDO system on my RF31 mill.  I see they are still using the DOS interface for the readout.  Almost 10 years back I wrote a Windows based display that has many of the same features but looks much nicer.  If you would like to try it just let me know.

Ray


----------



## Canuck75 (Feb 3, 2014)

rdean said:


> I also have a YARDO system on my RF31 mill.  I see they are still using the DOS interface for the readout.  Almost 10 years back I wrote a Windows based display that has many of the same features but looks much nicer.  If you would like to try it just let me know.
> 
> Ray




Hello Ray

Yes, with it's big squarish pixelated numerals and all. Just out of curiosity I sent an email to Nick Muller in Germany to see if he had ever upgraded the display programme but I never got a reply back.

So, having said that, I would be very interested in trying your "Windows" display version.  Could you post up a picture and maybe give a run down of the features that are incorporated? Also, I just checked my old laptop and it has Windows 98 on it, will that be compatible with your software?


Thanks
Canuck75


----------



## rdean (Feb 5, 2014)

I had to go back to my old files to find the information from 2007.  The program has been tested on Windows 95, 98, 2000, and XP.  It does have some latency on the readouts but never looses its place just takes about 1/2 a second to read.  I have never tried it on a newer laptop or desktop computer to see how it responds.  

Here is the ReadMe file on the Mill DRO.

View attachment Operation.pdf


Enjoy Ray


----------



## Canuck75 (Feb 5, 2014)

rdean said:


> I had to go back to my old files to find the information from 2007.  The program has been tested on Windows 95, 98, 2000, and XP.  It does have some latency on the readouts but never looses its place just takes about 1/2 a second to read.  I have never tried it on a newer laptop or desktop computer to see how it responds.
> 
> Here is the ReadMe file on the Mill DRO.
> 
> ...



Ray

Your display looks fantastic, especially the use of colour. I read your PDF a couple of times and certainly appreciate all the work you must have put into this. Certain little features caught my eye, such as being able to highlight which hole you are on in "bolt circle" but I didn't notice whether it has a starting axis option?. In any case all that is moot until one has a chance to play around with it and see if it fits one's needs.

How do we proceed from here?

Canuck75


----------



## rdean (Feb 5, 2014)

I originally wrote this for resale but only sold about 10 copies so it is free to anyone who may want it.  Just let me know how you get along.

The program automatically installs itself on your computer with an uninstaller also.  Since you have already setup the scales all you should have to do is start the program and set the defaults.

I don't think I can attach it here as it is about 15 meg.
Maybe I can email it to you.
Send me your address and I will try.

Ray


----------



## Canuck75 (Feb 5, 2014)

rdean said:


> I originally wrote this for resale but only sold about 10 copies so it is free to anyone who may want it.  Just let me know how you get along.
> 
> The program automatically installs itself on your computer with an uninstaller also.  Since you have already setup the scales all you should have to do is start the program and set the defaults.
> 
> ...




Thanks Ray, we can give that a try. I'll drop my email in "Visitor Messages"  in your "Members List".

Canuck75


----------



## calstar (Feb 6, 2014)

Hi Canuck75, I recently installed x,y Igages   http://www.hobby-machinist.com/show...y-axis-igaging-dro-easy-install-on-mill-drill  on my similar mill/drill and still have the z to install. Your z axis install looks great, my question is why did you decide to eliminate the quill stop?

thanks, Brian


----------



## Canuck75 (Feb 6, 2014)

calstar said:


> Hi Canuck75, I recently installed x,y Igages   http://www.hobby-machinist.com/show...y-axis-igaging-dro-easy-install-on-mill-drill  on my similar mill/drill and still have the z to install. Your z axis install looks great, my question is why did you decide to eliminate the quill stop?
> 
> thanks, Brian



Brian

Thanks for your comment.

Once you have your XYZ  DRO you will find that you rely on it for all axis movement. Setting stops will be counter productive because you will be henceforth milling to the numbers, which includes the Z. If I am really nervous about a Z depth then I engage the manual down feed for better control as I watch the DRO approach the exact number I want. This is also the reason why I changed the quill return to pull up directly on the quill and not on the quill pinion shaft (see my post - "Removing the Z backlash on my King PDM30 (RF 31 style) round column bench mill"), backlash on the Z is not like backlash on the X and Y, the quill always wants to drop the amount of backlash available to it. This can be really evident when doing sensitive depths when boring in soft materials for example.

Regards
Canuck75


----------

