Model A - investigating the rear brake drum

 In common with several Ariels of this vintage, the Model A has a rear wheel sprocket which is integral with the brake drum. This in itself would not be a problem were it not for the fact that the sprocket teeth are worn out.

The whole assembly is far too big to go in my lathe so what can I do about removing the sprocket teeth? Some options:

• Can I spin the hub in the rotary table, mounted on the workmate and remove the teeth with a fixed angle grinder?
• Find someone with a bigger lathe?
• Find a better hub?

We'll have to think about that a bit more. In the meantime, we'll have a look at all the other bits in that area so that we can work out what we are dealing with especially since I'm expecting to place an order with the Ariel Klub Slovakia shortly. 

The brake plate is all present and correct.

The brake plate dust exclusion ring is a bit mangled - I have a feeling you can get these new as they are spot welded in place but since the 1930 Model A doesn't have a plated ring here I may repair it and paint it.

In the brake drum we have the 'new for 1929' ring that retains the spoke heads should they break off. Ariel must have had some incidents with brakes seizing or wheels grinding to a halt through loss of spoke heads. Not a pleasant experience to contemplate! It's all very greasy in there.

Equally greasy is the back of the brake plate but at least we have some shoes which are whole and a set of springs and a cam.

The cam bush is very worn indeed and will have to be replaced.

It's fitted through the brake plate and there is a nice little gas weld on the inside:

Here's the cam. I don't think there's any doubt that we will be buying new ones!

Something else that has caused much discussion on the Facebook group is what brake lever this machine should have. This part is definitely Ariel, but it may not be 1930 - however it's not much later, perhaps 32. Checking the parts lists doesn't reveal very much from any of these years - they all show a relatively short stubby brake lever. The various members that contributed to this discussion revealed quite a variety of brake levers including this long curved one - so go figure.

It did have a lot of bends in it. I've taken one out and this will probably sit better with respect to the mudguard stays - we'll have a look when it goes back together.

Moving on to the frame, we'll take the opportunity to clean out the threads for the chain adjusters

There's something odd here - this looks like a braze repair around the sidecar mount. The mounting should exist as a more or less complete ring without that lump of material between it and the frame lug.

The brake plate torque lug is present on the inside and both of the top hat washers are present.

Moving to the other side of the bike, this all looks good and the stand stops are in very good shape.

Missing from this side is the little flattened tube that's used to protect the wheel spindle thread from the chain adjuster. They are often mangled - we will have to make one of those. 

At both ends of the spindle, the wheel nuts are not in the best shape. The left hand side won't run all the way down the spindle - it looks like it's had a hammering at some time.

Model A - clutch dome screws

 I'm making these clutch dome screws, because whilst such screws are commonly available even as Ariel parts, they are usually 1/4" BSW to go into the later alloy primary cases. These black Ariels with tin primary cases use 1/4" CEI screws which I don't stock.

We'll make a set from this bit of 3/8" round bar:

I used the compound slide adapted for vertical operation to put the slots in the screws. They are cut with a 1/16" slitting saw.

Here are the first two. They still need the raised top shaping, but that will need the milling equipment removed from the lathe so we'll do all the others first.

A couple of days later, with the lightweight milling attachment removed we can put the radius on the screw heads using the form tool:

After that, I've used a piece of 240 grit wet & dry paper on a piece of wood to get rid of that copper plating - the bar I used to make these screws was an old earth rod. I don't think that the chemical blacking that I plan to use to finish these screws will work on the copper plate!

Lovely. Just what I wanted.

Model A - clutch spring screws

 Now that the primary chain guard is finished we'll start on some lathe jobs, finishing the clutch dome when it's screws are made. This will need a change from the three-jaw chuck to the ER25 collet which we will do in a while, but first we'll use the chuck to hold the hexagon stock we need to make the clutch spring screws and perhaps the battery strap nuts.

We have four screws but we need six, so here we go. First job is to turn down the bar stock to a 1/4" diameter for threading, copying one of the existing screws.

After a small problem with a blunt die, I was delighted to find that the torque upgrade that we did on the lathe some months ago enabled this 1/4" thread to be cut under power.

Once you're set up it's dead easy to knock these out. In 10 minutes or so I have two of these ready:

The next step, and for this I need the ER25 collet, is to shape the head to that low radius the original has; then we can think about cutting the screwdriver slot and making the washers.

The raised head is formed using a specially ground tool. It's important to keep this sharp and feed it slowly to avoid chatter marks in the work:

Nicely raised heads:

I used the compound slide adapted for vertical operation to put the slots in the screws. They are cut with a 1/16" slitting saw.

Here's the result, with some old screws for comparison:

A nice little job I think. Still need the washers - those standard ones are too small. The originals are special and are quite tight on the screw.

Mini-lathe - slitting saws and lightweight milling attachment

 Why do I always choose the difficult path? All I needed was some slots in the heads of the clutch spring screws and the clutch dome screws which I suppose I could have made with the hacksaw but no, there must be a difficult way, a better way, a more challenging way - a Simon way. 

The screws looked quite good when they came off the lathe: 

I've had a slitting saw and a suitable arbor for quite a long time, bought for some long lost reason. The problem with slitting saws in the mini-lathe is that is difficult to get work into the right place to use them. Screw heads can of course be slotted with end mills or slot drills or hacksaws but actually a slitting saw is the best way - an end mill or slot drill is always going to be a delicate creature at that size and a hacksaw is not going to produce a very tidy result. 

I thought about setting up a jig and using the milling table somehow but it never really gelled until I thought about holding the work in a tool post and using the compound slide vertically. I thought I could do this with a simple bit of angle so I bought a chunk of 3" x 3" black steel angle, 4" long and set it up on the cross slide with a few holes:

It works rather well and could be arranged to put the work in the right place relative to the slitting saw and to be able to span the slitting saw with the stroke of the compound slide.

You use the lead screw to drive the saddle and get the work centralised - but this reveals that there is a lot of end float in the lead screw which will need to be adjusted out.

I used a piece of scrap hex as a test piece, and you will notice that the chuck has been replaced by the ER25 collet holder which will not only grip the slitting saw arbor more effectively but also allows considerably more space to approach the work.

You set the depth of cut with the cross slide, and make the pass with the compound slide:

The result of the first test was a nice slot that didn't go across the middle of the hex, despite my efforts to line it up properly. The problem is clear once you strip off the tool post and put a square on the lathe bed:

Well you remember I said it was a bit of black mild steel, not known for keeping it's dimensions! I put a shim in the appropriate position to square the tool post to the lathe bed.

For this next test I have a 1/4" CEI hex head bolt in the workholder that I made earlier, centred accurately.

Here's a close up. The slitting saw is set to cut downwards pushing the work into the lathe bed to minimise movement of the saddle, the cross slide, and the assembly holding the compound slide:

This results in very nice cut, perfectly centred. This is actually made with three passes, each of 0.5 mm depth.

The next step is to make a similar cut in one of the real clutch spring screws. This saw is 1/16" wide so will be fine for the clutch centre screws but I think it will be too much for the clutch dome screws.

Other possibilities for this same setup are to use a similar work holder with an end mill and make odd sized hexagon fasteners - for example, CEI nuts in brass which are usually unobtainable.

Model A - mudguard bolts

 Way back in the dim and distant past I made these mudguard stay and rack retaining bolts copied from the ones on the W/NG. I didn't realise at the time that the ones I removed from the W/NG had a thick spacer attached to them - and I had faithfully copied the bolt with the spacer in place.

With the collet still in place on the lathe, we'll remove these spacers:

That's better:

The proper length of these bolts allows the stays for the rear half of the mudguard to sit much closer to the frame such that the one on the near side no longer fouls the brake lever:

Model A - gear control rod

 In the last few years I've made a few bits for the hand gear control, including parts of the tank lever, clevis pins for both ends of the rod and the clevis itself for the gearbox end.

All that remains is the rod itself. This is made from a piece of 5/16" 316 stainless steel which can be made to be very shiny but isn't fun to machine. At least all it needs is a thread and at each end.

We'll use the lathe to get the thread square and to put a small undercut on the short 5/16" thread at the tank end.

This looks quite neat but I'm surprised to see that one of the tank end clevises has obviously been painted - or perhaps chemically blacked. More on that later he says mysteriously!

This is the gearbox end clevis. That reduced hex full nut doesn't look very good - I'll make a new one.

That's a job for later though - right now the gear control rod fouls the carburettor bellmouth. It needs a little bend.

There is always scrap on the bench such as this piece of scaffold tube which is used bending things sometimes.

That's much better. The part that comes down from the tank is parallel to the centre line of the bike and then the rod bends inwards towards the gearbox. It works beautifully.

That's it for the moment - we'll polish up a bit of 303 stainless hex for that lock nut.