Got the same problem, bought a secondhand rectangular topslide assembly for my super 7 and it is about 3 degrees out. I can only assume that Myford scribed the fiducial on assembly and topslide are unique to each machine. Would have thought that it would be easy to engrave a scale at right angles to the dovetails, only need a simple location fixture.

I do know the Fiducial line was engraved on final assembly of the topslide to the cross slide. From a tour of the factory on a visit to Myford’s back in the 1980’s.

I also recall the topslide base has a hole in it to register the part when the base had the the graduations rolled on. Similar to the knurling action of a knurling wheel. Clearly the initial set up of the “Knurling Wheel” to the part has gone awry.

I worked a brand new Hardinge which had a similar problem. Unfortunately it proved to be expensive for Hardinge as the graduations where in the cross slide. This only showed up when the topslide was swung around to 90 degrees and it was not square with the bedway. Our firm was the first to report the problem and a new cross slide was scraped in on site. Apparently a new operator had been put in charge of the engraving process and there was a batch of cross slides all the same. The batch size was never stated but if the man-hours taken to scrape each cross slide in. On both the defective part and the replacement then it was expensive. It took the Fitter a whole day to do the firms machine.

Regards

Gray,

I too have a similar problem on my S7, I won’t bother with the story as to why but I did see a solution on a machine at an ME show, I think it was the one at Ascot racecourse.

Anyway on that machine the owner had machined a small shallow pocket in the top slide and inserted in his case a brass plate held by two small screws thus enabling a new fiducial mark to be engraved.

On my To do list !!!

John

here we are – problem solved https://www.model-engineer.co.uk/forums/topic/emco-compact-5-modifications/page/4/ see post of 14 Aug.

Nick – start tonight, one clear photo of result, clear concise explanation and you have a nice half page article for the new ME&W which will not be padding it with waffle and big blank margins 🙂

Since you have two bases you could machine one for the insert mentioned by John above. Or if you follow the link I gave above you can see GM’s removable vernier plate.

Simple work around when you want to angle the topslide is to stick a bit of masking tape on it. Mark a line against the zero on the scale and then just rotate to your required angle. When job is done peel off the tape and he o Myfords will have been harmed.

I do it quite often with the rotary table particularly when using it vertically as the mark is hard to see when it is in that [position. Similar with the quill scale on the mill, a sharpie mark where it is in my line of site has worked for years rather than the factory one which needs me to bend down to see.

Prompted by this discussion I have decided to turn down the diameter where the engraving is and to fit an engraved steel ring. Hopefully the zero will then be in the correct orientation and the engraved lines should be finer than Myfords rolled effort and look more like the engraved scale on ML7 machines.

It has been an insight for me to hear the graduations were rolled. I would never have thought of such a process as being even roughly accurate enough. Production engineers live in a different environment.