This morning I managed to make a couple of gear studs for the Myford ML7 I have just refurbished. If you want to see more then visit my Myford specific site. I managed to turn a couple of gear studs which have replaced the old style that came with the lathe. With the newly made studs I do not have to dismantle as much when gear changing.

My next project will be to resume the camshaft for the Seal engine and make inline boring bar and a tool setting device for the boring bar so watch thiis space. I will be producing drawings for both the inline boring bar and the tool adjustment fixture as part of my learning to use 3D cad software.

On Tuesday the 3^rd February I had something of a mixed morning in the workshop. The anticipation of work that could be finished was far in excess of what was finished!

Not feeling my best, I thought I would test out how machine able the leadscrew was and what damage, if any the leadscrew would sustain in the chuck. First action though was to test it in by putting it through the half nuts on the saddle. Whist the Myford thread is perhaps a little more square at the top than the replacement It seemed to work fine and the half nuts closed with little problem.

 Happy that it would fit I placed the threaded leadscrew in the chuck, and with very little showing, faced it off. I am pleased to say it cut very well and no impression could be seen on the screw from the chuck jaws. However, because the area tested would be turned down later it didn’t matter if any damage was sustained I will still protect the shaft by either shim stock or make a thin brass collet.

The next task was to have a cup of tea and make drawings up with dimensions, for the jobs I had to do. This involved four drawings in all. Sounds grand, but just pencil on a ring bound note pad. Nevertheless by drawing up the job to do allowed me to check if I had all the required tools and stock material. Because this is such an important part of the lathe (and I didn’t want to buy another length of leadscrew) I wanted everything in place.

Just then our post lady arrived with the bronze material for the bearings, so one step forward. Looking to see what reamers I required I found that I didn’t have two of them, and since I only need two, that was a step backwards. I also searched out for a couple of split pins to suit and again I had none. So it started to look like it would not be full steam ahead quite yet. Not deterred too much I looked to see what I could actually make and the only item I found was the joining piece between the leadscrew and the gear change end of the lathe.

This was a relatively easy task, and after getting the nearest size stock I could, turned and parted off to dimensions. I didn’t bore out either of the two holes as I had not yet changed the 3 jaw for the 4 jaw chuck and those pesky reamers needed to be sourced. So after measuring the angle of the chamfer on the existing part I cut the chamfer on the new joining piece and since I wasn’t at my best, decided to call it a day and go in and order all the parts required and chase up the revolving live centre still outstanding from RDG Tools.

Wednesday wasn’t much better for me health wise and since parts were outstanding and I couldn’t do any more on the MGA wing mirrors, I had a day of rest.

As soon as I feel up to it and hopefully this corresponds with a couple of deliveries, I will concentrate on the leadscrew. This is the only outstanding issue for the Myford ML7 rebuild ass all other parts are to complete the build. The digital readouts will be delayed for a little while as funds need to be restored…..Luckily the chess set I made as a retirement present for my brother Stephen, has been accepted for an article to be published in the next couple of Model Engineer magazines starting with the issue on sale from the 13^th February. This will bring in some monies to go toward the DRO’s (after I have kept a bit back for the tax man!)

Whilst the rest of the country is buried under a lot of snow here in Brixham, sunny Devon we have just had a little flurry on one day but the rest of the time it has been raining. So Thursday we are attempting to go fishing for the first time in over 3 weeks (our longest spell other that holidays). If you want to follow our fishing exploits have a look at http://www.dartmouthfishing.co.uk

Well the Myford refurbishment made a leap forward today with the motor driving the new countershaft for the first time! If you want to read more about it visit my Myford website. It was nice to see this move forward and the oilite bushes were slowly run in at varying speeds and directions.

Didn't really feel well enough to do very much today so I just fiddles with assembling the lathe and then some time on the phone sourcing materials.

I use an excellent model engineering forum HMEM and one of the replies to my post on the Myford refurbishment is shown below (copied courtesy of Peter):-

"Mike, I had to do this a few years ago when I completely rebuilt my ML7, including making a new leadscrew.
The front drive shaft for the leadscrew was unhardened EN8 as supplied from Myford. The easiest replacement - with a ground finish - is a piece of 5/8" silver steel, and will probably last another lifetime.
You do need a woodruff key cutter though, to fit the drive gear on the end.
The original bearings in that end (there are 2, with an oil gap in the middle) are Oilite. I ordered a pair from Myfords and found they were around 2mm too small on diameter, but they insisted that these were the correct part number, and were all they would supply. Boring and reaming can 'smear' and block the pores on Oilites, so I turned up a pair of bushes from LB4 leaded bronze instead. Don't be tempted to use Phosphor Bronze with an unhardened shaft though. Also turned up another leaded bronze bush for the other end of the leadscrew.http://www.kingston-engineering.co.uk/ and make a new one.
Much cheaper than Myfords too.

If your leadscrew is badly worn, as mine was, the tailstock end will give you a problem as the shaft will have worn undersize, but the thread on the end (7/16"?) is the same size as the shaft, so you cant really turn the shaft down and use a smaller bush, unless you downsize the threaded part at the same time.

For me, the easiest solution was to buy a bit of leadscrew stock from Kingston Engineering 

Good luck with the rebuild and keep us posted.

Peter"

Armed with Peters suggestion in response to a problem raised with regards to the tailstock end of my existing leadscrew, I contacted Kingston engineering and purchased a half length. This of course was after measuring the existing leadscrew and comparing it with their data sheet. I must admit they were very helpful. The only problem being the cost of shipping and packaging (to protect the screw) was nearly as much as the leadscrew!

The staff were extremely helpful so watch the postings for how I manufacture a brand new leadscrew and bushings at a fraction of the price from Myford! I may be a little nervous of the manufacture but how else do you expand you technical levels?

Watch this space as they say......

The Myford refurbishment has come on a little with the backplate and sideplates of the bench done as well as the raised blocks. Work has started on reassembly on the lathe starting with the motor bracket, after making a new pin.

The oilite bushes for one side (I didn't order enough....) were drifted out and new ones pressed in. Then because of the missing two bushes, the making of the new countershaft has to be put on one side.

So after a phone call to the suppliers of the inverter/motor package (who have been very helpful) a start has been made on the wiring. There is more on the main website if you are interested.

Welding alumium has always been a specialised task so I thought. However I have read a few articles in the past about a system of welding aluminium that is supposed to be as easy as 1,2,3! Life never seems so easy in reality and it would be interesting to see if the claims were true. At the moment I am in the middle of refurbishing a Myford ML7 and one of the castings had a crack in it that ran through both sides. So it seemed a good time to try out the claims that Durafix make for their product.

The process involves cleaning up the part to be welded with the supplied stainless steel wire brush. Then the parts need to be brought to the temperature at which the welding rods will melt when in contact with the metal, and not the flame of the propane.

Here is where I learnt an important (and obvious now) fact that there is a considerable amount of heat required to get the metal to the 700 °plus needed. The great amount of heat is made worse by holding the parts to be welded together in the vice. As we know aluminum is a great conductor of heat so you end up heating the parts plus the iron vice!

Well when the heat was eventually reached the welding rod was rigorously rubbed in the indented V between the two parts and the rod flowed easily enough into the space. After letting the whole area (!) cool down the two pieces were inspected and there seemed to be a good weld considering the small run or weld.

Armed with this experience I moved out into the garage and decided to hold the casting to be welded in my ‘old’ B&D work bench. At least the heat transfer problem from the trial wouldn’t occur although the piece to be heated up was much bigger than the practice piece. At least I knew it would take some heating up and I was now prepared for that.

After grinding out a V shape in each side of the crack the casting was held in the workmate bench and heating started. When I thought it was getting close to temperature the flames fierceness was dropping off…..yes the gas was running out. Quickly I got my spare cylinder out only to find it also was empty. How I don’t know but it was. So I had to go and find a supplier, needless to say the first one only had empties himself! Eventually I returned home with a full cylinder but a cold casting! SO the process started again with cleaning the area to be welded being brushed hard with the supplied stainless steel brush, the heating supplied and after several minutes the rod was applied away form the flame and it ran into the V nicely. It was here that I learnt my second and important lesson, if I turned the casting over, would the weld already made drop through? Well it was too late to worry about that now and heat was again applied to get the casting up to temperature and the weld done as for the first one. When looking, the work done before was undone.

I decided that the crack, which opened slightly when heated the first time, allowed the welding rod to flow through so that was a positive but I would redo the outside edge and accept that the inside joint would have to be held the best I could. When allowed to cool the outside weld was done and the inside had also a good depth of weld but it had been about to drip. So the next time I try a repair similar to this one I will place some material over the first repair so it has no where to go, before doing the second side. I am sure that will make a neater and therefore stronger weld.

So what were my overall impressions?

1.      You need a significant source of heating if you are repairing a large part.

2.      The three steps are easy enough to remember and the kit does come with everything you need.

3.      I was considering ordering a larger amount of rods (I got 20) but they should last for a long time, as there didn’t seem to be a lot of wastage.

4.      I am happy that the casting repair was done to the instructions i.e. the rod being melted by the casting and not the flame. Therefore it should be a strong weld, as they say it is stronger than the surrounding metal.

5.      It takes longer than you think to heat the material.

Will I use it again? You bet. I think this is a serious solution to welding aluminum and I will experiment with other repairs to learn better techniques. So I think it was a success. Makes a change to find something that in the end does what it says!