Model A - Kickstart Shaft, setting up for milling

 After a turn on the railway and with the grandchildren coming for the weekend there's not much time for workshop stuff, but I'm inching closer to finishing the setup for milling. 

Some countersunk M6 screws have arrived to clamp the right angle plate to the cross slide, underneath the rotary table:

Using the slot that we milled a few weeks ago, we can adjust the rotary table to align with the centre of the lathe spindle: 

The tap follower I'm using as a pointer here looks like it might be useful for marking out the parts of the work we are going to mill away.

A little while later, after all the preparation for the visiting little ones is done, I venture back to the workshop. I've reduced the diameter of the 2" section to the required 1.990" to match the original, and increased the length of the 1 1/8" section by about 0.040" such that it protrudes from the kickstart shaft bush by 0.020" rather than hiding inside it. I've also changed the carbide tool inserts for new ones.

I've also made a new set of clamps, but I've made them a bit big - I think we might have to do that again... That's development work for you!

In the same package as the M6 screws for the right angle plate came some button head M6. These are to replace the cap heads on the cross and compound slide handles to avoid skinning our knuckles: 

They look a lot neater as well.

Model A - kickstart shaft inches closer

 First job today was to drill a 5mm hole in the 2" end of the fledgling shaft to prepare for the trial fit on the rotary table. That done, I discovered that the end face isn't quite flat, so that will need correcting before we start milling - it's difficult to get in close to face of the end with the revolving centre in the way - maybe I will use my half-centre.

Anyhow, I think I have enough bits in the milling clamp box to hold it together:

The work is located on the rotary table with this little 5 mm pin:

I'll probably improve the security of the clamping arrangement, like this:

In other news, rooting around in my collection of adjustable reamers revealed an H8 reamer, perfect for the kickstart lever.

It's now a perfect fit:

Model A - kickstart shaft and a big milestone

 Today I was pleased to make the last few cuts on the main 1 1/8" diameter part of the kickstart shaft. With carbide tooling, the right geometry and the right speeds and feeds the finish comes up very well and the fit is spot on.

The next job is to mark out and cut the 3/4" diameter for the kickstart lever:

I cut that in about 8 passes and followed it up with my form tool to generate the gentle radius on the end:

Unfortunately the inside diameter of the kickstart shaft is not round - I guess this is to be expected as it has been fitted with a cotter which pulls over to one side and has probably distorted the eye. I may have to obtain a 3/4" expanding reamer to sort this out - you can get cheap ones for about £15.

I'll probably leave ordering that until I've started milling and have worked out what other cutters I might need to buy. 

Fitting the kickstart shaft from the right side of the gearbox and cover reveals that it fits nicely:

I didn't expect this snag though. What we looking at is the stop that limits movement of the shaft - the bit I didn't expect was that these stops are riveted in place and cannot be removed, which means I can't check the length of the 1 1/8" section until I've milled the slot that this stop fits in.

Some measuring suggests that the length is acceptable - maybe even a little long, but only a couple of millimetres at the most. 

So the next step is to start thinking about the milling side of the work and to do this we need to have a flange machined into the waste in order to retain the shaft on the rotary table:

Second thing we need here is a 5 mm hole in the end, where the revolving centre is at the moment, to locate the shaft centrally on the rotary table. We will probably have to make some special washers to hold the flange to the table but more of that later.

So that was a good day of progress.

And the milestone? O yes! This week the blog has passed a million hits!

Mini-lathe - still making chips

 You might be wondering what happened to the Model A kickstart shaft project: well, despite various distractions we are still making chips. 

As you might imagine it's taking a while to reduce a 2-in chunk of EN16 to the main shaft diameter of 1 1/8" but we are getting there slowly. 

Currently I'm troubled by the finish I'm getting as I rattle through hogging out the material. I'm running at 700 rpm taking 15 thou cuts with a carbide tool - actually a selection of carbide tools. Yesterday I locked down the compound slide and tightened the gibs on the cross slide and we'll see if that improves matters. Right now the finish looks like a very coarse thread: 

Since we are not in any hurry for this part I think I will look for play in the saddle. Others have suggested removing the compound slide, checking the tool height - suggesting it's too high, changing the revolving centre for a carbide tipped fixed centre, and changing the tool for one with a wider tip, like a parting tool.

The tool height appeared to be the problem - this is much better:

Charlie's Shed - Chemical Blacking

 Way back in the dim and distant, when I was rebuilding my SQ4 in fact, I had an incomplete set of engine bolts so the SQ4, like the FH years later, wears stainless steel fasteners everywhere. That incomplete set was chemically blacked, a process which was almost universal for protecting fasteners from corrosion until the 1940's, when Cadmium plating became popular.

Cadmium is pretty toxic, and by the mid 1980's most fasteners were zinc plated - a process very much in use today.

However! Our Model A is not going to be wearing shiny fasteners, which raises a little machining challenge! The issue is, when we are missing fasteners, the ones that are commercially available are either stainless or zinc plated - and will probably not be the right pattern - we don't want nuts with both sides chamfered or bolts with stamped text on the heads! Secondly I don't want to spend hours removing zinc plating, so we will make the missing fasteners on the lathe.

Here's a batch of 1/2" CEI nuts I made earlier:

So here goes. This is the GP Cool Black Metal Blackening Kit from Gateros Plating, and if I recall correctly this is the 1 litre kit.

Here are the instructions:

For the first try I followed Process 2 in the instructions, with 3 minutes in Cool Black solution and drying the Rogard Supreme Seal with the hot air gun. A bit patchy but an online video for another manufacturer's kit suggests that 5 minutes in the alkaline cleaner is required, not the quick dip & wiggle that it got from me.

For the second job, I used Process 1 with two minutes in the Cool Black solution:

Third job: a wash with carb cleaner, 2 minutes in the alkaline cleaner, 2 minutes in the activator, 2 minutes in the cool black, 2 minutes in the oil. Much better:

The ambient temperature here is about 5°C, and I am doing this in an unheated workshop!

I think I'm getting the hang of this now. This is a spacer for the frame stud near the top of the gearbox, and after a dose of carb cleaner and a rub over with a rag and a brush dipped in alkaline cleaner it was unable to pass a water break test. I dipped it in the alkaline cleaner again for 5 minutes after which it successfully passed the test. This was followed by 1 minute in the activator and 2 minutes the cool black - this picture was taken after the first 30 second dip in Rogard: 

This is the finished spacer - which ironically I'm not going to use - it's now had three dips in Rogard and one dip in dewatering oil.

I'm calling that a success.