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Current progress of my ML7 refurbishment 9th February 2009

I have worked out why the last few days haven’t gone well ……….

Because I couldn’t progress the Myford refurbishment I thought I would return the Seal engine project. Since I needed to make a new inline boring bar to bore through the cylinder block casting that was the first job started today. I thought it would be nice to use a part from the Myford for the boring bar. So the kn^&ck%d countershaft will be turned into an inline boring bar, so every time I use it I will remember the refurbishment. After turning the shaft down sufficiently to get rid of the wear and scoring, I removed it and took it over to the milling machine. I was about to drill two different diameter holes for tool steel, followed by two 5mm tapped hole for grub screws at 90° to them when SWMBO arrived with a large parcel.

So after unpacking the heavy parcel containing a new 4 jaw chuck for the Myford, and the necessary reamers for the bushes for the leadscrew, I could at last start on the only major part left to make for the Myford ML7, the leadscrew. I put the boring bar idea to one side and removed the two leadscrew bearing castings from the lathe. Then I pressed out the old bushes using the’ old 2 socket method’ (see photo below).

Removing Myford ML7 leadscrew bushes

Both sets of old bearings came out easily, so the Colphos 90 was brought out of the stock room (aka the en-suite) so the 4 bushes required could be made. It became obvious quite early on however that I had made another error when buying the metal. My leaded bronze was big enough for the right hand side bearings, but was too small for the left hand, or gear side! I had assumed (wrongly) that the housings would have the same internal diameter, and of course they didn’t. I then spent a horrendous amount of money ordering just 6” of 1” diameter Colphos, and will now have to wait until it arrives before I can complete the lathe work. Double Doh! It was one step forward and 1 and a ½ steps back! It’s a good job I don’t employ myself, for if I did, I would have sacked myself!

 After muttering under my breath for a while, I decide that I could at least go back to the inline boring bar, but then I thought that because the leadscrew project contains 5 or 6 different tasks, I could at least make a start on the right hand side of the leadscrew. Decision made, the bronze bar was chucked and faced off. The keeping the minimum amount of bar out of the chuck I turned down the outside diameter of the new bushes using the half method and got the finished size to half a thou larger than the existing oilite bushes.

The next task was to drill out and then ream the internal diameter. I used three progressively larger sizes of drills (after the centre drill) giving a hole slightly undersized, before using one of the new reamers to clean up the bush to the finished internal diameter. When checking the dimensions of the old bushes I was surprised that the length of the two removed to find that they were different. So just in case I parted off both new bushes to the same length as the old ones.

Once they were cleaned up I pressed them back into the bracket casting before running the reamer through both just to make sure they went in square( which happily they did).

The bushes went in square - good news

And that was enough for today. Tomorrow I will take my life in my hands and turn down the left hand side of the new leadscrew to match the bearings and threaded end for the handle. After that I will be able to drill through the joining piece and ream to size before turning down the other end of the leadscrew. Hopefully by the time I have finished all the tasks I can still do, the 1” diameter Colphos bronze will have arrived so in the end little time, if any will have been lost.

Perhaps I will take myself back on again………you never know……watch this space.

So the answer to why things haven’t gone well in the past few days is simply really. I must have been frustrated more than I thought by waiting for the parts to arrive.