I was made aware of a Myford ML7 for sale. The price was good, so I decided to check it out. I have been looking for a good used lathe of this size with the aim of converting it to CNC. My TOS FN20 mill already go that treatment, and the result is very satisfying, so I want a lathe with the same capabilities. But I still want to retain the fully manual operation. In my opinion that cannot be done on a CNC lathe without severe compromises, so I'll keep the Emco as is, and make this one controlled exclusively by computer.

I have the necessary ball screws, servo motors drives and the other stuff. But I don't have the time to build the rest from scratch. And with the reputation of Myford, how much better basis can you have in this size?

This is what I found when I arrived at the previous owner. Old, but not too bad?

Well they say a picture never lie. This is a proof of the opposite. It does not show the completely worn out screws, the completely destroyed MK2 spindle bore or the worn down cross slide and topslide guides.

Anyway, I offered him what I felt was a suitable price. This lathe would have been a total disappointment for any beginner in the hobby, as just the cost of new feedscrews and nuts plus a spindle and bearings would bring it close to the market price for a good example of this type. To me it means little, as the leadscrew and the cross slide feedscrew will be thrown away and replaced by ballscrews anyway. And the topslide will not be used at all.

Every useable part will be saved though, as I may be able to get another ML7 that I would keep completely original and unchanged. This is for personal reasons, and I might come back to that another time.

Oohh Kaay... So I got the old corpse for my suggested price. Now let's see if it can be brought back to life. Here's the last of the "before" pictures.

The slides was re-ground according to the previous owner. That's not really describing the procedure used very well. It was actually face milled, with the milling marks still showing. Not too bad in my opinion, as it could be seen all over the slides. This means it was not much worn after the machining. If much worn, the machining marks would be uneven, or even disappearing. So if it was set up properly, it just needs to be scraped in to be in perfect shape. Now that is done, and the apron runs as smooth as it ever did. Now that's good, as it means I have what I was looking for: a sound basis for a conversion. If there are any nasty surprises from here on, I can make new parts with little trouble.

I will show some pictures of the scraping. Notice that this is not for visual pleasure but for achieving a high accuracy of slide movement. So scraping is not in a fixed pattern, but at all times just where it is needed to get a straight surface. The sliding surface on this part is not fully covered by the mating surface at all times, so I aim for straightness and a very smooth surface. The same goes for the bedways of the lathe.

Here are some of the aids I use. A surface plate, a glass plate that is straight to a very high accuracy (a mirror from a big optical machine) and some blue engineer's dye. In the upper left you can see a couple of glass rods. They are mirrors from an old laser printer. They are also very straight and flat, and can be used as reference surfaces in narrow places.

The dye is smeared on the reference plane, in this case the surface plate. A bit of scraping have already been done here, and it's now being checked. The slide is put down on the surface plate and slid along the area smeared with dye. As you can see, some of it have transferred to the slide, thus highlighting the high areas. The next operation is to use the scraper and shave down the marked area a tiny amount. After that the process is repeated as many times as necessary. When the whole area of the slide is marked when slid over the surface plate, it's finished.

And then it's on to the cross slide surface of the apron. This surface is at all times fully covered by it's mating slide, so I aim for a surface that is straight, but not perfectly smooth. The reason is that the slight scalloped surface will retain the oil better and thus give less friction than if it were smooth. Maybe it does not make sense to you, but I've found it to work very well. The same applies to the other side of the apron facing the bedways.

Here I used the glass mirror shown a couple of pictures back as a reference surface. It was smeared with dye and slid over the part to scrape. In this case I first had to scrape the part that is not part of the sliding surface so it gets down level with the worn part. On this picture that is mostly done, and the slide face can be included in the process. It's quite evident also in this picture where it needs to be scraped.

The apron is fixed to the slideways using a tool clamp as quite a bit of force is used in the first stages of the scraping when several micrometers are to be removed. Actually the lathe itself needed frequent tugs to get it back where I wanted it.

And here is just another view like the previous one. I'll take a pic' of the scraping tools and replace this one, as I realize these important tools did not make it into any of the pictures.

Now I'm painting the base. Very boring, so I'll add more pages when there is more interesting things to report.