Fitting a DRO to a Myford Super 7B.

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Tony Bird

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Hi,

For some years I have been considering fitting a DRO to my 40 year old Myford Super 7B. As well as the cost of buying a DRO the prospect of having to move the lathe to fit the saddles linear scale and encoder was a little daunting (001).



At the Bristol Exhibition held in August this year a more reasonably priced DRO was on offer a EMS–I system that was suitable to fit to a Myford. Its price reduced one of the problems so it was decided to buy the DRO kit and try to fit it without having to move the lathe (002).



I had previously fitted an inexpensive DRO to a much modified equal inexpensive Chinese Seig C-O mini lathe where it has been very useful (003).



The EMS–I DRO units came very well packed and contained a digital display with a mount, 2 magnetic encoders, a 300 mm and 900 mm long linear scale and a fitting kit (004).



The first and easy job was to fit the digital display to the workshop wall above the lathe (005).



Before starting on the assembly some research was done; a friend who had fitted a DRO to his Myford sent me some photographs of his installation (006 & 007).





At a engineering show I took a photograph of a DRO system that didn’t require holes to be drilled in the lathe to fit it (008).



Neither of these products are the same as the DRO purchased

Not having to drill holes sounded attractive! It was obvious how the linear scale was fitted to the cross slide using modified ‘T’ bolts. Looking at the back of the bed the linear scale used the screw holes that were intended for a taper turning attachment. The mount for the encoders was held by using the bolts that secured the rear saddle strip to the saddle (009).



This system looked like the way to go, so two modified ‘T’ bolts were made (010).



Clearance slots were made for the cross slide adjustment screws in the 300 mm linear scale (011).



A test assembly of the linear scale to the cross slide was tried (012).



The disadvantage with fitting the linear scale this way was that cross slide ‘T’ slots were shortened and could only be accessed from one side. So it was decided to lower the linear scale on the side of the cross slide to the bottom of the ‘T’ slots. This required sawing off a 6mm length from the securing side of the aluminium angle for the linear scale (013).



The angle was then filled to size (014).



The Cross slide was removed from the saddle (015).



The aluminium angle had holes drilled in it to give access the adjusting screws on the side of the cross slide. The angle was clamped to the side of the cross slide using some HSS tool bits in the bottom of the ‘T’ slots to position it (016 & 017).





The cross slide was drilled for tapping (018).



The aluminium angle screwed to the cross slide (019).



Checking the level of the angle with a DTI (020).



Checking the clearance for a spanner on the locking bolt of the saddle (021).

Happy with progress so far the next job tackled was fitting the 900 mm long linear scale the back of the lathe bed. As the Super 7B is a long bed all of the 900 would be needed. First because it was thought it might cause a problem the protruding lip of the saddle rear strip was filled away, in the event it wasn’t found necessary to do this (022).

To secure the linear scale to the lathe bed some hexagonal spacers were made which were threaded ¼” BSF to screw into the lathe bed and threaded M3 for screws to hold the linear scale to them (023 & 24).


One end of the linear scale was drilled and screwed to one of the spacers fitted to the lathe bed. The other spacer fitted in the lathe bed had a threaded scriber fitted in it and was used to mark the position of the other hole in the linear scale (025 & 26).


Photograph (027) shows the linear scale fitted to the back of the lathe bed.

The parallelism of the scale was check with a DTI and adjusted by reducing the height of a spacer for one plane and elongating one of the linear scales screw holes for the other. It was found smoother to use the power feed of the lathe to move the DTI along the bed rather than by hand (028).

I had looked at the method of holding the encoder bracket to the lathe by using the bolts that held the rear saddle strip to the saddle. The system looked a little messy regarding access to the bolts when the bracket was fitted and I think it might also have been difficult to adjust the saddle encoder. So it was decided to attach the encoder bracket directly to the end of the saddle. So a drilling jig was made from aluminium angle and was held to the saddle by the saddle locking bolt and a blacked off screw hole which I believe was something to do with fitting a coolant system (029).

After fitting the jig holes were drilled and tapped in the end of the saddle (030).

The jig was then used to drill the fabricated encoder bracket (031).

Photograph (032) the encoder bracket fitted to the end of the saddle, the bracket was made too long so that the saddle encoder could be offered to it to gauge its position, this done the bracket would be suitably shortened.

First the cross slide encoder was attached to the bracket using some aluminium angle (033 & 034).


The saddle encoder was then fitted to the bracket (035).

Which was then fitted to the lathe (036).


Clips for the encoder cables were fitted into existing holes in the back of the lathe (037).

Now it was time to fit the magnetic strip and its protective cover to the groove in the aluminium angle. It is very important that the orientation of the magnetic strip and its encode is correct there are marks on both components that allow this (038).

When fitted the magnetic strip and its cover are about level with edges of the groove in the aluminium angle (039 & 40)


That finished the installation on the lathe (041 & 042) so the encoders could now be connect to the DRO and you can start to play.



There are light indicators on the encoders that are green if they are correctly positioned red if they are not (043 & 044).


Photographs of the DRO in use (045 & 046).


Notes.
The kit comes with instructions with the tolerances allowed when fitting and positioning the encoders. Given that the kit is intended for different lathes there is not much in the way of instructions regards fitting of the components. Except for the aluminium angle that the encoders are fitted to I didn’t use any of the fitting kit as it was supplied. It was cut up to supply some parts and I added some aluminium angle of my own. The linear scales can be cut to any length but on my lathe they were used at their full length.
I cannot comment on this brand or type of DRO kit compared with other manufactures as I don’t have the electronic knowledge or enough practice in using DROs. Once I had got my head around it, it was fairly straight forward to fit even without moving the lathe. Though I have to say it was a bit of an effort having to lean over the lathe bed and set up some of the parts using a Mirror!

Regards Tony.
 
Tony,
That's an excellent article on Super 7 DRO fitting!
The magnetic scales weren't available when I fitted my DRO and thus to minimise obstruction I went down "the path less trodden", constructing an independent parallel slide/scale unit that could hang fully outboard to the rear,
Regards,
Nick

Very neatly done, Tony. Now we wait for you to install the electronic bits in the topslide!

Dave
The Emerald Isle

Dave,
I fixed it for you ;-)

- Nick
 
Congratulations but the only thing is 'combien de?'

Your S7B is actually younger than mine- mine has a sight glass! However, I'm rebuilding as mine was slideways ground but the roof came off the workshop and I'm still recovering. I bought the ML10 as sort of cheap repair kit.

I don't want to put anything on the back of the lathe as eventually, I want to fit the fabricated 10" round sine bar version of the taper turning attachment that was written up for me by 'Slangbela' or my old sailing and white water kayaking 'oppo' of yonks ago.

I think that phone calls and wallet spanners are needed. The 6 station turret has arrived but I wonder whether it will 'get in the way'

Thanks for excellent detail

Norman
 
Just like Nick above, mag scales just weren't available when I did mine.

I did look at them when going to buy the ones destined for my surface grinder, but found that they were not accurate enough without spending lots of extra pennies to get the higher resolution ones which are a required fitting on a surface grinder.

But from what I have seen on your fitting, they are much less susceptible to being out of wack than the glass scales. They are more tolerant to misalignment.

Very well shown and described

John
 
Hi,

As there has been some interest at my model club of my fitting of the DRO to my lathe so I have decided to include its construction in my annual club talk which is in a couple of weeks time. To this end I have made a Mk.2 encoder bracket fitted with some dummy encoders to show what the parts look like in the flesh. The bracket is a little smaller and a bit easier to make than the Mk.1 was though I suspect it will not replace it on the lathe.





Regards Tony.
 
Hi Norman,

As a follow up, I phoned and E-mailed Tony's supplier- without success.

That's unfortunate, other than the company has recently come into the hobby market after supplying industry with DROs for some years I know nothing of them. I believe they supplied Myford with the DROs that they are fitting into their machines, I saw some at a show very impressive you wouldn't have known that the lathe had DROs, even the top slide!

I have to say that the two email enquires I made about fitting their equipment were replied to in a couple of days. The last from Friday last week was replied to yesterday. Might be worth trying again?

Regards Tony.
 
Thanks Tony but two attempts should really be 'two' many.
I always remember the stricture that one out of two businesses fail after the second year of trading.

Currently, there are more things to fill life and empty my pocket than attempting to deal with reticent company.

I'll let economic circumstances dictate their eventual outcome.

Meantime, I send my kindest regards whilst concentrating on more important problems.

Norman
 
I used Machine DRO over a period of 10 years+ for 4 full DRO systems, they are part of Allendale Electronics and their service and support has always been exemplary,

- Nick
 
Tony,
Fascinating and helpful as usual. My first attempt to install a DRO was on my mill. Which is a Chinese model from the Little Machine Shop. The DRO was a magnetic type. Not a very successful venture. Ultimately I removed it and replaced it with a mechanical setup which is much better. But I see that I need to put more time and effort into the mounting of the encoders to remove a small error in readings. If only I had your experience and skills!:(
As yet I do not have the nerve to try and put a DRO on my Chinese lathe - perhaps one day I will get braver.
 
Tony,

Very good write-up. I am just about to fit DRO's to a recently obtained Super 7 and have a few more ideas now having seen how you have installed yours. In my case I am using those from Machine-DRO. I already have them fitted to a ML7, Colchester Student, Cowells lathe and Cowells Mill. No connection just a satisfied customer. I intend to fit the carriage scale using the existing taper turning attachment holes. I have a taper turning attachment but intend to fit it on the lower set of holes and extend the adaptor stud up to the cross-slide. I had already bought the bits from Machine-DRO but did see the solution you have used at the Midland Show. I did like how they had fitted the magnetic scale into the aluminium angle and this is a possibility for the cross-slide on my lathe.

Colin
 
Hi Colin,

Very good write-up. I am just about to fit DRO's to a recently obtained Super 7 and have a few more ideas now having seen how you have installed yours. In my case I am using those from Machine-DRO. I already have them fitted to a ML7, Colchester Student, Cowells lathe and Cowells Mill. No connection just a satisfied customer. I intend to fit the carriage scale using the existing taper turning attachment holes. I have a taper turning attachment but intend to fit it on the lower set of holes and extend the adaptor stud up to the cross-slide. I had already bought the bits from Machine-DRO but did see the solution you have used at the Midland Show. I did like how they had fitted the magnetic scale into the aluminium angle and this is a possibility for the cross-slide on my lathe.

I also saw the installation at the midland show, a good idea not having to drill any holes in the cross slide or anywhere else I suppose.




Inspired by this I came up with a similar version for a friend who didn't want to drill holes in his lathe.







It works OK and gives access to both ends of two of the 'T' slots and leaves a flat top to the cross slide. However it is more work than my original idea which allows access from both ends to all the 'T' slots. The bracket to hold the encoders uses the rear saddle strip bolts to hold it in place. It cannot be fitted to the lathe in one piece as the bolts under the saddle have to be accessed so the angle that holds the saddle encoder in place has to be removed along with the linear scale. After the bracket is fitted the scale followed by the angle can be replaced. This system doesn't require any holes to be drilled in the lathe however it isn't as easy to fit as my original idea which does require two holes drilled in the cross slide and saddle.

Regards Tony.
 
Hi Dave,

Very neatly done, Tony. Now we wait for you to install the electronic bits on the top slide!

The friend who wanted the DRO fixing to the lathe without having to drill and tap holes asked if it was possible to fix a linear scale and encoder to the top slide. This is the result alas not without drilling and tapping four holes.






It is the prototype, it works OK but needs a little tweaking, so I am waiting for some more parts to make another.

I have also streamlined the encoder bracket I designed for him so it uses just one size of angle and more of the parts that come with the DRO kit.




Regards Tony.
 
Hi,

A small modification has been made to the top slide linear scale and encoder which is to lower them, this allows my tangential tool to be swung out of the way when necessary.

Regards Tony.

IMG_8346 LR.jpg


IMG_8347 LR.jpg


IMG_8345 LR.jpg
 

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