DROs etc

All my equipment and designs have been made without DRO's. I have worked for nearly 40+ years as a toolmaker using countless types of DRO. They are not a panacea to more accurate work. One Boss thought fitting a DRO to a clapped out Mill was a means of giving that machine a new life. Unfortunately the geometry of the slideways were not up to the accuracy that the DRO could obtain on a more serviceable machine.

I am not anti-DRO, but I do find it easier and quicker to obtain a position using a dial rather than a DRO, which flickers between one digit and another. Resolution of the DRO is a big factor to accuracy. The better the resolution the dearer will be the DRO package.

While it would be handy having one on my current mill due to the 1.5 mm pitch feedscrews. The diminuitive size of the Proxxon mill makes it hard to find a system which does not look like the mill is the add-on, and not the DRO.

Regards

Gray,

I would have thought a stick on magnetic strip would not overpower the Proxxon and the read heads are quite small at 10 x 15 x 35mm. A cunning engineer like yourself could probably hide the scale within the dovetails rather than mount it externally which will be what I will do on teh Lateh cross slide if I ever decide to fit a DRO to that.

As pointed out by others a DRO cannot perform miracles, but it comes close.

I fitted my well abused 1947 Tom Senior out 15 years ago with a Chinese glass scale 3 axis job. The reason - I had a crankcase casting to machine which cost well over 2 DROs. One slip up with counting turns, scribbling on dials, going past and coming back for the backlash etc would be expensive. I was taught that way, but I wouldn't go back.

I can now delight in picking off pitch circles, cutting radii by numbers, making parts years apart and knowing that all the bolt holes will line up. It saves a lot of time and faffing about.

Martin

Edited By Martin Johnson 1 on 24/09/2023 16:29:11

Hi Jason,

I have been pursuing this avenue but have struggled to find a small reading head. I have seen one in a YouTube video which is about 10 mm square. I have had no luck with a reply from the poster of the video.

I would be grateful for information, if you know of any such reader. Also the readout to go with such a system.

Regards

Gray,

Gray

The smallest read head (really small!) is to use a bare sensor and put it your own housing. Some time ago a poster here showed how he enclosed and terminated these tiny modules.

I have tried searching this site but cannot find the relevant thread, the poster gave part numbers, wiring diagrams etc. I think the sensors are made and supplied by a European (Swiss?) company.

I'm not sure if the one is this picture is the same but this poster 'Jed Martens' has not posted recently (if this link works!)

https://www.model-engineer.co.uk/sites/7/images/member_albums/181671/846798.jpg

Ian P

This Thread

Brilliant Jason, was that from memory or searching?

Ian P

I did search for it yesterday and found it fairly quickly.

Thanks Ian P & Jason,

I recall seeing this post some time back. Unfortunately it is beyond me as regards the electronics. Plus the read head will still be too large. I have found an M-DRO Mini Head. which has a 10 x 12 mm section, but the cost of these will make the project impossible.

Thanks for taking the time out to look,

Regards

Gray,

Anything electrical is just about beyond my knowledge as well Graham. And I don't know if the idea may or may not interest you. But one thing I have learned is most dros today use a fairly narrow range of signal types they operate with. There were a number of others used on the much older dro systems, but a lot of those now seem to have been abandoned. If my information isn't faulty, most of today's dros will use one of about 4 - 6 different signal types. As long as those are the same for both the reader head and the display, plus the number of wires used are the same. Then the plug end can be easily changed over to suit the connection type on the rear of the dro display. For your purposes, then finding something to fit a small mill like that as a complete off the shelf system could be difficult, expensive or impossible as you've found. A display using different scales and reader heads and some well thought out machining on the table or slides to gain some clearance might be the only possible way to do so in a cost effective way. For that machining and knowledge about how and where it could be done without any adverse effects, then imo few would understand that better than yourself.

Yes it was on a Bridgeport with standard sized scales and reader heads. But the ROBRENZE channel on Youtube had a video a few years ago where he mentioned he mounted his X axis scale and head inside the table to eliminate mounting it on the front of rear and have much better protection. Unfortunately he didn't actually detail or show exactly how that was done.

Hi Pete,

Thanks for taking time out to post your reply. I was un-aware that the systems now use a fairly common number of signal types.

Unfortunately there is no room inside the slides for the reader even at 10 x 12 m section. Space is that tight that it needs the backlash adjusting screw on the Y-Axis feedscrew to be backed off, in order to remove the cross slide assembly. The feednut of which completely fills the cast in cavity.

Thus any DRO will have to be mounted externally and the smaller it is the better. The only other alternative is to fit two waterproof Digital Scales. Although this will not be small by comparison. This was done by the original designers of the Proxxon Mill, the Sakai Special Camera company. I have seen a picture of this set-up some years ago, but have been unable to locate that on the web recently. It was at the time sold as a kit.

Thus at the moment I am undecided as to which way to go.

Once again thanks for your input, it is much appreciated.

Regards

Gray,

Looking at the mods you have done the magnetic tapes could simply be stuck over the engraved scales you already have. You then only need to make provision for the mini encoders. The X encoder could be mounted to the left of your stop and the Y take the place of the pointer and it's rod that you have. The stop clamps could just be modified to clear the tape if you still wanted to be able to us ethem.

Edited By JasonB on 29/09/2023 10:57:34

Hi Jason,

The mill above is used mainly for milling while the one below is intended for co-ordinate work and it is this machine that I was intending to fit the DRO to.

I was going to add this picture today on the Proxxon post, as I have just finished the new table feed attachment.

Regards

Gray,