Myford QC Gearbox Project.

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Pete W.:
Hi there, Don, and thank you for your encouragement.

--- Quote from: Pete W. on March 05, 2014, 03:58:56 PM ---SNIP
The securing nut, item #6, is a 7/16" BSF Simmonds nut. The original had a locking ring of red fibre but age has taken its toll of that and I can tighten or loosen it by hand.
About twelve months ago, I had bought a couple of 7/16" BSF Nyloc nuts but the shed gremlins have run off with those too! :ddb: :ddb: :ddb:
So I adjourned to the 'Bay and ordered a few more, with washers. They're promised for Friday delivery - I bet the original ones will turn up tomorrow (Thursday)! :D :D :D

--- End quote ---

It was worse than that! As my head hit the pillow last night I had a flash of inspiration - I'm currently holding in my hand the two 7/16" BSF Nyloc nuts! :clap: :clap: :clap:
They'd never got out to the workshop but were in my 'study' all along.

Pete W.:
Hi there, all,

Well, I fitted a 7/16" washer and a 7/16" BSF Nyloc nut to the RH end of the lead-screw and adjusted the nut to take up the slack without being too tight. Then, just to be sure, I checked the 15 thou clearance between the face of the gearbox and the back of the lead-screw gear (see earlier post) - all was OK.

According to the Beeston Myford fitting instructions, the next stage is to align the top of the gear-box casting relative to the upper surface of the lathe bed. They recommend using a mag-base on the lathe carriage with a clock gauge on the bar and touching the top surface of the gear-box casting (with the gear-box lid removed). Then, with the gearbox fixing screws finger-tight, to rock the gear-box until both ends give the same clock reading. They suggest using either wooden wedges or screw jacks under the LH and RH ends of the gear-box.
I opted to use screw jacks, only I don't have any! :lol: :lol: :lol:

So, to paraphrase Mrs. Beeton, I had to first catch my mild steel hexagonal bar.
That came to hand quite easily - the shed gremlins must have gone to watch the Rugby! :ddb: :ddb: :ddb:

So, I cut off two pieces about 2⅜" long, chucked one in the 3-jaw then faced and centred one end. I reduced a length of ½" to ½" diameter and drilled a hole down the centre of the bar, opening it in stages to #12 (tapping size for M6 thread) and started the taper tap in the hole. NB. power off, turning the chuck by hand.

Then, I remembered I ought to take some photos, here are a couple of views of this stage:

and

Next operation was to change to a round nose tool, swing the top-slide round 30° and turn a tapered shoulder like this:

and

I reversed the job in the chuck and opened out the hole to just under ½" and deep enough to just leave enough meat to match the reach of the taps. (That doesn't warrant a photo.)

Then I transferred the job from the lathe to the bench vice and completed tapping the hole M6. A quick draw-file on the flats of the hexagon and fitted the screw and it looked like this:

I bought the screws with the wobbly pads - next time I'll buy M8 rather than M6. Now I need to make a second one, you can see the raw material and screw in that last photo.

I think I shall lay a parallel across the top of the gear-box when I do the alignment, it'll save the clock probe from falling down the hole! :lol: :lol: :lol:

Pete W.:
Hi there, all,

And then there were two!!!

Next workshop session will put these to use.

Pete W.:
Hi there, all,

The next stage was to level the gear-box. This is how the Beeston Myford installation instructions tell you to do it:

That picture shows two wooden wedges - the text says you can alternatively use screw jacks.

Having reviewed all my mag bases & fittings, I discovered that I didn't have the means to mount the mag base on the lathe saddle and position the dial indicator over the extreme left-hand side of the gearbox!
:bang: :bang: :bang:

Miking the mag base rods revealed that they are between 9.5 and 10 mm diameter. I'm sure to have a long enough bit of steel rod that diameter, aren't I? No, I hadn't! :bang: :bang: :bang:

What I did have was a shaft from the old ex-WW2 bomb-aimer's computer. That was long enough and had sections at each end that were just over 10 mm OD.
So I turned those sections down to fit the mag base joints (including machining off the rather nice worm wheel on one end!)

That enabled me to rig up the following set-up (it's so wide, it took two photos):

and

I'm sorry that the flash has washed out the clock dial. What you can't see in those photos are the two screw jacks under the gear-box, one each end, in lieu of the wedges.

Once I got that set up, the actual levelling of the gearbox was almost a non-event! Winding the saddle back and forth to traverse the probe of the dial indicator along the parallel and adjusting the jacks accordingly, eventually there was no change of clock reading. I suppose, to be sure, I should have turned the parallel end-for-end and tried again but I didn't think of that until I started to type this post! When I was satisfied with the levelling, I tightened the gear-box fixing screws and checked again. Then I dismantled the mag base & dial gauge and refitted the gear-box lid.

The next stage is to fit the gear back-plate and gear-quadrant and check for freedom of rotation with no binding. Then I have to get some SAE 30 oil and put the right amount in the gear-box. Apparently, it has to be plain oil with no additives (like the detergents in engine oil) and although it's for a gear-box, it doesn't need to be EP.

Pete W.:
Hi there, all,

Here's a bit of an :update: No photos, I'm afraid.

I've fitted the gear quadrant and checked the entire gear train for free running. I did have an initial scare because there was a regular 'thump' when I ran the machine under power. Luckily, that turned out to be a bit of something in one of the gear's teeth, cured with a toothbrush. I don't think it was metallic swarf, more likely a fragment of cardboard from the box it's all been stored in since I bought it.

I went looking for 30 grade motor oil to fill the gear-box, asking for plain oil with no fancy additives. In particular, it doesn't need to be EP oil. I eventually did buy a 1 litre flagon though I'm not convinced it's 'plain'.

Once I've put the oil in the gear-box I can, in theory, use the lathe even though the gear cover is not yet fitted. The outstanding work on the gear cover is to drill and tap the 2 BA hole for the spring catch and then to fill, rub down and paint it. I'm a bit scared of that job, having seen Mick-s results on his L5!!

However, before I can do that, I really do need to spring clean the shed, particularly the bench. Also, if I am to use the lathe, I need to attend to its regular lubrication. That means I need to rehabilitate my two Beeston Myford oil-guns. I think the more modern one is usable but the original, shorter, gun that came with the lathe always leaked oil out of the filler cap. There's a leather washer in the cap but it only has about ½ mm of the wall thickness of the oil-gun body on which to seal. I do need that one because the more modern gun is too long to fit between the workshop wall and the oil nipple in the rear of the saddle. While I'm giving the lathe's lubrication system a going-over, I've bought some 2 BA oil nipples in case any of the originals are clogged.

If any other Modders have succeeded in taming the leak from the original oil-gun, I'd be pleased to hear from you - I hate the feel of a handful of Nuto H32 let alone the waste!

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