FH - cam followers

After a 60 mile round trip on the Square Four which left me worrying about its coupling gears I decided to have another look at the cam followers in the Huntmaster. I had refinished the wearing surfaces to true them up but I knew that one of the followers had worn through the case hardening. I decided to stop messing about and get some replacement followers.

These are available as an exchange part from Draganfly Motorcycles and they came very quickly, in a couple of days. Refitting is very simple and I replaced the barrel with a layer of Wellseal on the gasket.

Before I did this however I wanted to make sure that the cams were going to be properly lubricated on startup so I used my oil can to make sure the channel under the camshaft was full of oil as you can see in the picture below.

With the barrel fitted, I could oil the followers from above:

I threw the pushrods in to start understanding how difficult they would be to fit. I once spent ages chasing a valve timing problem on the Square Four only to find that I had the pushrods in the wrong followers!

FH - rocker box refurbishment

With the cylinder head coming on, it’s time to take a look at the rocker box. We won’t be doing too much, as a number of folk have told me how a BSA A10 rocker box fits straight on and is a much better design - but I don’t have one of those.

We’ll start by stripping out the rocker shafts and cleaning the box.

While the lathe is in action, we’ll replace the 5/16" BSW stud that wasn’t holding the cover on - the covers are held on with a special 1/4" CEI sleeve nut. What we need is a stepped stud, like the original in the inlet side but with a 5/16" BSW thread to go in the aluminium casting. Somebody has already recut the thread in the casting to suit the replacement stud.

We'll start with a bit of 5/16" mild steel round bar. Because it's 1/4" in diameter for most of its length we'll need to be careful when we turn it. What we will do is use the travelling steady on the lathe to support the slender quarter inch section as we turn it to size.

 This turns out pretty well especially when we make a finishing cut with a round nose tool. Cutting the 5/16 BSW thread, I've set the die to its largest diameter such that the thread is a little oversize.

This is where the oversized thread pays off - when it's fitted in the box the the stud fits quite tightly and hopefully won't back out.

The next step is to get the box in the cleaning tank for degreasing; we'll then examine it for damage and polish the outside.

Mini-lathe - boring bar

 

My 0XA boring bar holder fits 1/2" bars or 3/8" bars with an adapter sleeve. Shame my boring bar is 10mm! It currently resides in a 250-001 tool holder, which is a bit of a waste.

Mini-lathe to the rescue! The sleeve on the left is turned from a bit of 1/2" round bar, with a 10mm reamed hole and a slit. Works perfectly, and liberates another 250-001 tool holder!

SQ4 - fuel tank

 Some years ago the Square Four got a new fuel tank in original paint from Yeoman’s Motorcycles. It was pretty shabby but it still had the coach lines picked out in gold paint to show where the Ariel craftsmen put them all those years ago.

As you can see the paint is very faded. The Square Four wore this tank for several years but eventually I decided that it was really too far gone. I didn’t really want to repaint the whole tank and lose all the patina, so inspired by Graham Ham’s book about his Speed Twin ‘Daisy’ I resolved to clean up the paint as best I could and enhance the gold lines a little bit.

The areas that were worse affected were around two weld repairs where the tank badge carriers had been refitted. The paint here was burnt and discoloured and no amount of rubbing down was going to bring that back. I used a matching spray paint (from stock I had accumulated years ago) to blend these areas in to the rest of the paint. Rubbing all the paint back with various grades of wet and dry from 240 to 2000 brought the tank back to life enough. 

I then used some old jet black gold lacquer and some 3 mm PVC masking tape to put the lines back in. When these were mostly dry I rubbed over them with a dirty glove to dull them down. This works reasonably well when I timed it correctly but if the paint was too dry it didn't pick up the dirt from my gloves.

It needs more work of course, but it's getting there for sure.

Mini-lathe - manual drive

 It's useful sometimes to be able to manually turn the lathe chuck, particularly on these little lathes which don't have a lot of low speed torque, for example when thread cutting. Usually I just haul the chuck around by hand, using the chuck key or a bit of bar like this:

It works, but it's a bit ugly and the chuck guard gets in the way.

There are a few designs around for cranks that can be used with an expanding arbour, or the crank can be expanded into a full wheel for better control.

I made this expanding mandrel years ago as part of a dividing setup for the lathe. I used it to make a number of splined shafts and the graduated collars for the tailstock and the saddle hand wheel.

The mandrel features a journal at one end to carry a gear which provides the dividing index. An M6 threaded rod passes through the mandrel which connects with the expanding plug at the inner end.

With this mandrel already in the tool box, it makes little sense to repeat the exercise for a crank with an expanding arbour so we'll adapt the one we've got. I've made this boss for the hand wheel - it registers with the expanding mandrel on the journal where the indexing gear normally fits, but I have added a pinhole to that mandrel to enable the boss to drive the mandrel. The boss is provided with a drive pin at one end and a 1/2" BSP thread at the other, to which I fitted a pipe flange to carry the wooden wheel itself.

Here's the wheel - it's simply cut from a scrap of 3/4" plywood. The M6 threaded rod that expands the mandrel passes through the hand wheel boss into a recess on the other side such that the same threaded rod can be used both for the hand wheel and the dividing set.

The nut in the first picture is replaced with this special threaded widget which reaches down inside the boss to mate with the threaded rod and lift the expanding plug, specially designed so that the dividing setup and the handwheel setup can use the same expanding plug and threaded rod.

Here's the manual hand wheel in place with the special nut holding the expanding plug wedged into the mandrel and providing a rigid drive for the chuck.

Here's the other side. It does of course fit with the gear train cover in place.

I've stored the wheel on a little post screwed to the wall - oh all right, it's just a screw in the wall that the wheel sits on:

Lathe - lead screw handwheel

 I made a lead screw hand wheel for my mini-lathe a few years ago. It works, but it's generally a bit wobbly because it's fitted to a very short M8 thread on the end of the lead screw.

You can see it here. The plain section is the tail end bearing for the lead screw and that short M8 thread you can see is the thread for the lead screw end float adjustment. It's very short, probably about 10 mm.

What I've decided to do is to replace this section entirely with a much longer piece that carries the bearing and passes much further into the short shaft I have my hand wheel mounted on.

The first step is to part off the old 8mm section and drill out 7.5 mm, reaming for 8 mm.

Next we will let in a short piece of 8 mm round bar into the reamed hole and we'll retain it with high strength Loctite retainer. This would have been very straightforward had the first piece I selected not been 5/16" rather than 8 mm! Measure twice, cut once as they say.

I put a longer thread on the new piece of rod to retain it solidly into my hand wheel axle.

Here it is in place. It's retained by an M4 grub screw into the plain section of shaft at a point where the end float is minimised. Actually there is no end float measurable in the installation at all.

There are a couple of modifications to the old handwheel here that may be obvious or may not. The wheel fitted in the later pictures is much larger than the old one for better control; there is also a small piece of rubber fitted into a 4 mm hole in the axle which provides a bit of extra friction to the graduated collar.

The collar, by the way, is divided into 62. The lead screw is 16 TPI, or alternatively has a pitch of 1/16" or 0.0625". This means that each division of the collar has an error that amounts to 0.0005" per turn.

Lathe - tool storage

 In a bid to clear up the lathe area a bit, I bought a magnetic knife rack from Amazon. The magnets seem a bit weak but I suppose you don’t want to be struggling to pull a 9” carving knife off the rack and risk it flying across the kitchen.

As you see, it keeps the tool holders neat, tidy and accessible:

A few months later, this kitchen knife rack got replaced with a bespoke tool rack that has much stronger magnets:

I will now stop worrying about my lathe tools falling down the back of the cabinet.

Lathe - cheap collet chuck

 I use my ER25 collet chuck quite regularly, generally because it's more accurate than the three jaw chuck. It's a morse taper fit in the lathe spindle and consequently has a very short capacity - you can't fit more than about 50 mm into the collet holder before the work bottoms out.

Therefore, I thought I'd buy a flange mounted collet holder which would allow me to pass the workpiece right into the lathe spindle. You can buy a lot of stuff online, usually made in China, for little money these days and to be honest that's what's enabled me to develop my machining skills without breaking the bank. However sometimes these things are not quite the quality you would want. 

Here's a little video. Look at the dial test indicator needle waving around all over the place:

The whole collet retaining assembly has a 0.4 - 0.5 mm runout compared to the spindle locating feature on the back. 

To fix this little problem I initially removed the collet nut. The first step was to rebore the 16° cone that receives the collet; that helped a little bit but didn't give me the accuracy that I was looking for. 

The cone in the faceplate is mirrored by another cone in the nut. The collet itself is suspended effectively between these two cones centralising the collet to the lathe, so the concentricity of the nut becomes critical - and was eccentric by something like 0.5 mm. I'd have to recut the thread and hope it would retain enough strength.

I used the Little Machine Shop gear calculator to set up the lathe gear train and set about cutting the thread. The first attempt didn't make enough difference - I still had something like 0.25 mm run-out.

I changed tools and turned the outside diameter such that it was concentric, taking the minimum amount off, and recut the thread again.

By the time I'd finished I had taken 0.5 mm out of the thread diameter, biased to one side as I expected. Another test showed it could be improved a bit more, and I removed another 0.05 mm to get this:

No runout at all. Better than I dared hope for!

FH - indicators

 I've decided, mainly at the behest of my son that the Huntmaster is going to have indicators. I've bought some small circular indicators from eBay which will look the part but I'll need to make some stems to put them in the right place and to fit them to the bike. I made this drawing to show what I wanted to machine and I'll do that on the mini-lathe.

We'll start by cutting four blanks from 0.515" hex bar stock. This is EN1A.

With the first end faced and centred it's time to put some marking blue on the far end in order to turn all the blanks to length. We'll start drilling the 3 millimetre hole for the cable at this point as well. I've got some long series drills just for the purpose.

The next step is to face the ends to length, centre drill and drill 3 mm through the length of the blank. Then we'll turn the M8 thread for the indicator lamp and start reducing the hex to the final diameter for the stem. We'll do this in two halves because we'll want to switch ends in order to turn the 5/16 CEI thread that holds the stem to the bike.

With the outer end of the stem finished on all four examples it's time to look at the inner end. This has a 5/16 CEI thread to bolt into the original fastenings on the Huntmaster. In most cases there is sufficient hexagon left available for us to be able to hold the stems in three jaw chuck. 

First we need to use the height gauge to mark off the length of the 5/16 thread and the height of the nut that we will need to fit the stems to the bike. I painted all the stems with Dykem to facilitate the marking out.

I've got the 5/16 thread now on all the stems, and I've drilled through 3 mm for the wire to pass through from the indicator lamp. 

For the next step I wanted to hold the stems in the collet chuck to avoid damaging the fine 5/16 CEI thread. The next step is to finish the main stem length turn it to size and then to turn a feature in the end to give the stem a little more shape.

There are three examples of the finished article you'll notice the feature that I was talking about and you're probably also noticed that the hex element is not the same length in all of those examples -  we'll have to refine that later.

Here's one of the short stems fitted to the lamp and fitted the front of the bike - it's looking pretty good I think. 

Now, there's a bit of refining to do on the height of those hexagon sections but then we'll assemble these to the lamps, degrease them and paint them.

I'll use a little bit of wood as a jig while I paint them:

Not too shabby.

Charlie's Shed - clutch holding tool

 One of the problems that you can have when you're working on a bike is trying to undo nuts from components that spin around such as the clutch or the engine sprocket. 

Today I'm going to show you how I make a tool out of two clutch plates to hold the clutch in place while we undo the centre nut or conversely do it up again. 

Regular readers will know that I've built several clutches over the last few years and have a number of old clutch plates knocking about. To start with I've taken a friction plate and removed all the old worn cork inserts. Then I've added a plain plate and placed the two over the top of each other in the way they would appear in the clutch using the TIG welder to fasten them together.

Once you've got your two clutch plates together you'll need a handle - there's no point having the clutch basket and centre fixed together if it's still going to spin. In my case the handle is made from a piece of old door threshold - effectively a rough piece of 20 mm by 5 mm flat bar. I've used the TIG to place a fillet weld around the base of the flat bar and attach it to the clutch plate assembly.

I used the TIG torch to heat the handle and form a local bend as an experiment. The problem I have with forming hot bends by my usual approach - a MAPP torch - is that the heated area is so big, the bend is anything but sharp; OK if you want it like that, but this one needs to be in just the right place.

It's worked rather well I think. Here you can see it in action, helping put the FH clutch together.