Fitting DRO to a mini mill

I'm fed up with trying to count the marks on the scales on the wheels of my Sealey 2502 and the temptation to everything 'by eye' is great!!! So I am getting three of the fairly cheap magnetic DRO scales with remote display that Arc Euro sell.

The 2502 is more or less the same as the Seig models and the Arc Euro parts seem to be the right sort of size to nestle in, out of the way. But I have a slight dilemma which anyone who's done the same installation would probably have an answer for.

The short one I have bought fits the X axis with no problem or modifications and a long enough one (Z) will fit the vertical column in a position just behind the operating lever with a bit of a spacer involved. In both those case, the scales will be stationary.

However, the Y scale is the right size to screw onto the Y table and the slider will need to be fixed, somewhere on the left end (away from the wheel end). Afaics, the scale will fit in without limiting the X movement as long as the slider is out of the way. But that only works with the concertina swarf guard removed. That rubber stuff actually gets in the way, even on its own..

So it seems that I need an alternative sort of swarf guard apron thingey. It's all a bit cramped round the back and things should really be kept below the level of the table to clear my milling visa when it's there. What would do the job is a guard that's fixed to the moving table, rather than the present arrangement that's fixed to the column - as normal.

A few photos would help me a lot - plus any comments about how well or badly your various systems behave. It would make me very grateful.

P.S. I should add that there are a number of videos which show people mounting DRO on a minimill but none of them seem to mention the problem of restricting the cross axis movement due to the DRO scale. IT's only 100mm to start with and ten or fifteen mm lost if you want to protect the dry from being squashed, that's a pain in the X axis.

Edited By andrew lyner on 28/07/2021 15:20:08

Neither are mini-mills but both my x axis scales are fitted to the front edge of the table. Some down-sides, but better than reducing the y axis travel - which is considerably reduced if using a vise (fitted in the usual ‘across the T-slots’ direction) for work-holding.

Edited By not done it yet on 28/07/2021 15:47:19

Have a look in my album.. DRO. there are some pics of my dro fitted onto my WM 250 VF

George.

That's an option that was my first choice but I really doubt there's room. I'll have another look tomorrow and see if it will fit.

Thanks.

Andrew

Trouble is the DRO unit is the same and the mill is a mini. Also I'm pushed for space and the front of the mill table is a vulnerable position.

Judging by Sealey's web site your mill is the same model as my Sieg X2 Axminster version. I have a capacitative scale fitted across the front the table, it's never been any trouble. Many years ago I bought some drawings off the Internet to save time designing a mounting arrangement from scratch but I've no idea where they are now unfortunately. If you want some pictures of the installation pm me. Roy

Agreed. I did say there are some down-sides. It just means that protection must be more substantial and secure. The table lock is the other side on the Centec, but on the Raglan the scale needed careful positioning, but still obstructs the gib adjusters.

I would not be surprised if the travel loss is more than 15mm. You might lose 40-50mm to the vise fixed jaw and only be able to reach just 30-40mm across a workpiece fixed between the jaws. 15mm extra, above 30mm would be an extra 50% in reach - not to be sniffed at if it happens to be as bad as that!

I am surprised you only have 100mm of Y travel my Sieg SX2P has 145mm and I would have thought your Sealey 2502 would have been the same or similar. I don't know how it's set up but does the rear swarf guard reduce rearward travel.? My SX2 didn't come with a guard and I have never felt the need for one.

If I found the guard was interfering with fitting the DRO I would lose it but that's your decision you may not want to. You probably know but the DRO scales need protection from swarf, I used 25mm x 1.5mm equal angle sandwhiched between the scale and the table mounting which works well. I fitted the X DRO to the rear of the table which with the angle swarf guard lost me 25mm of travel at the rear of the Y travel but to date it's not caused any issues on the jobs I,ve done.

If you do a search for my thread New Mill - Starter Tooling and go to page 15 you will find some pictures of my DRO installation it maybe of some help maybe not.

Ron

P.S. The DRO set I fitted are the ARC ones the same as yours and they have been 100% reliable and the accuracy is close enough for all that I do. Some say that this type of DRO eat batteries but the set I have from ARC don't they are still on the set they came with. 

Edited By Ron Laden on 29/07/2021 07:32:43

Edited By Ron Laden on 29/07/2021 08:05:20

As Ron Says when I had the cheaper scales on my X3 I fitted a 25 x 25 aluminium angle to the front of the table and the scale to that which keeps the muck off and also offers physical protection.

Hi Andrew, I fitted my Arc one on the front of my mini mill with a guard over it, OK it hides the gib adjusting screws up a bit, but are still able to be adjusted, albeit a bit fiddley and I made an extended locking screw to lock the x axis. Photos of how I done mine DRO for mini mill none of the two Arc ones have given me any trouble.

Regards Nick.

When I fitted my first mill with Capacitance scales from ARC, way back in 2012, I fitted the X-axis scale to the front with no problems with access to the gib screws or interaction with the bellows:

You will note that the scale is mounted upside-down. That was so that the vice didn't get wiped off the second time it passed the read head - yes, that happened the first time! I used the scales with a remote readout, so the whole kit was powered from the mains through a wall wart. No dead batteries! I see that the design is subtly changed in the intervening years and seems better suited to such an installation now. Photos of the other two axes are either side of the photos of the X-axis (above) in my album: X-axis dro installation on Amadeal XJ-12 mini mill.

That mill, by-the-bye, looks to be very similar, dimension-wise to your Sealey 2502.

John

I fitted the cheap ones from ArcEuro. The backlash in the slides makes these pretty invaluable; there’s no way I could do much more than the most basic drilling and milling without them. Lots of drilling and tapping and making brackets, but nothing too difficult:



X:



Y:



Z:



And some aluminium covers and 3D printed end caps:





Readouts were mounted to some MDF, and I used an ancient Eastman Kodak camera ball and socket mount so I can position them for best viewing angle. Glad I kept that mount...





I’ve since tidied the cables up a bit more.

They’ve been on since about last April, and have seen a fair amount of use. Despite frequently getting spattered with oil and swarf, they’ve been absolutely fine.

… And some aluminium covers and 3D printed end caps …

How much y axis travel did you lose?

Can’t remember - I guess the width of the aluminium angle, 20 mm or so maybe.

Can’t remember - I guess the width of the aluminium angle, 20 mm or so maybe.

I lost 25mm in Y on my SX2P with fitting the DRO to the rear of the table using 25mm angle for the swarf guard. It's not been an issue I have had a couple of larger jobs which where tight for travel but got over it with repositioning the workpiece.

Yep, mines lost 25 mm too. Never missed it for the work I’m doing, but ran out of x-travel on a job recently. I 3D printed some fixtures that allowed me to move the work along while maintaining alignment.

IMO any loss of travel is more than made up for by the benefits of the DROs.

Those of you who have used the remote readout version of ARC's scales must be aware that their quoted accuracy is much worse than for the more expensive scales with integral displays that can be connected to the one-, two- or three-axis display units. How have you found the accuracy in practice?

I queried this as a possible misprint with ARC a couple of years ago because this addition is on my 'to do' list. No, the specs are correctly quoted.

Alan

Mine are actually those scales, (but they are all read out on a single display). Any two decimal place metric scales will have a greater possible error than a scale resolving to 3 decimal places. I have both Arc and Warco versions.

You pays your money and takes your choice. I have not yet found it a real problem for the work I do - I don’t work for NASA🙂 .

Everything has a tolerance and mass produced items often have to fit together, just as spares would if required later. Most things I make are one-offs and the parts only need to fit the rest of that one thing. If a really close tolerance of fit is required, surfaces can be lapped together, or whatever it might take to achieve the required outcome.

I have also found the ARC DRO,s to be accurate enough on all I have done to date. It would be nice to have all the features on a display with all the bells and whistles. PCD,s for instance but a minute spent with a calculator is hardly a drama so I haven't bothered to upgrade, when I change over to a larger mill I will.

Edited By Ron Laden on 06/08/2021 07:17:38