Monday, 15 July 2019

CX500 - Indicator Stems on the Mini-Lathe

Updated: First published 24th June 2019

The latest family acquisition is this 1978 Honda CX500, bought from eBay by son Thomas, and a very fine machine it is too.

The previous owner was, like me, quite short and had lowered the seat producing a very strange riding position; Tom has fixed that now with a new foam and cover.

You can see from the previous pictures that the bike is missing it's grab rail, which includes the proper mounts for the rear indicators and the tail piece. It's absence means the tail piece wobbles and the indicators don't earth properly.

So, a new grab rail appears from eBay but we need some indicator mounts. The ones fitted to the grab rail are wrecked:

We'll make some new ones from a stick of 19 mm grade 303 stainless round bar I have knocking about. We'll start with the end with the bolt recess:

I've drilled this part way through, 6 mm, for the indicator cable.

Then we'll swap it end for end in the collet chuck and machine the smaller diameter, which fits in two top-hat rubbers in the grab rail. We'll need a 10 mm diameter for the thread retaining the stem into the grab rail:

We'll thread these in the tailstock dieholder:

The tubes that carry the indicator stems have a small tongue, to stop the stem turning. The stem has a slot to receive that tongue which we can mill out:

That's two done, ready for the splines:

We'll cut 45 splines to match the original, using a tool ground at 80 degrees and taking 5 thou cuts to a depth of 15 thou. Here's the setup, using the indexing attachment I made; the lathe is used like a shaping tool in this configuration. The machine is out of gear and the E-Stop is locked off.

Here's a close-up of a few splines, cut to depth:

Here are the two stems, with splines complete and polished up with some 240 grit emery.

Next job was to turn up some isolation bushes in black acetal:

And here's the first one fitted to the grab rail:

And with an indicator test fitted:

Saturday, 29 June 2019

Pillar Drill

I've had a small pillar drill for about a year, and pretty cr@p it is too - but it was very cheap and it's a whole lot better than what I had before, which was a hand-held power drill in one of those bench stands.

This one works well enough, it has the usual stack of five pulleys and belt drive, belt tensioner, convenient power switch etc and you can set the table at an angle. But it is very flexible - the base and the table are pressed steel and the pillar is very thin - the whole thing will bend when you put any feed on.

The spindle is mounted in sealed bearings but once the quill descends it has quite a lot of play.

Here's the depth gauge and guard - this is hard plastic and broke almost the first time I used it. The depth gauge requires you to fiddle with those two nuts:

I decided to make a new mounting for the guard and depth gauge, but mostly because I want to do some boring in a big-end type arrangement (like a locomotive eccentric strap). The new mounting is made from two lengths of 10 x 30 mm aluminium bar, screwed together with two M4 screws and shaped to match the old one. Here, I am aligning the components with the lathe centre prior to drilling and boring a 40 mm hole to suit the journal on the pillar drill. The two halves of the clamp are spaced 1 mm apart, so they clamp securely to the drill:

Here it is in place, along with the broken bits of the original:

Thursday, 27 June 2019

Mini Lathe Updates

Readers might be interested to know that the mini-lathe page:

has been updated this week, with a few new bits:
  • a 3D printed apron gear cover
  • a modification to the tailstock die holder
Thanks for reading, and I hope you find it useful.

Dry Build - Siting the Oil Filter

These plain journal engines run close tolerances and need a decent oil filter. Modern oils keep the dirt in suspension and if there is no filter, the oil becomes contaminated very quickly.

The SQ4 has a Norton commando oil filter, like this one, fitted under the gearbox where:
  1. you can't see it
  2. you can get to it easily
  3. it doesn't ground on kerbs
We'll need a similar site for the filter on the FH.

There's a lot of space behind the engine, between the engine/gearbox plates - but not for this filter, which is marginally too big for this location.

Beneath the swinging arm and in front of the mudguard is a likely location used by many FH owners. I'll need to find a location where I can easily mount the filter and where the oil lines will be able to get to and from it without kinks - and it must also fulfil the other criteria I listed above.

This is probably no good - there is nowhere to mount to and the oil line routing could be a bit tortuous:

This is an example of a mounting used in that area:

This one is on AOMCC forum member Steve Carter's Ariel Cyclone.

And another - this is AOMCC Kieth Mettam's filter:

Another one from Steve Carter, this well used Huntmaster carries a Morgo filter - these are smaller than the Commando filters and easy to place - but they are quite expensive and it makes sens to me to use a unit I already have elements for, commonality of spares and all that:

This is my choice. I'm using a mock-up bracket, made from a bit of 20 swg sheet, welded to an old footrest bar sleeve nut and placed in the sidecar lug beneath the swinging arm:

It's too far back, and the oil lines foul the gearbox casing:

Time to cut it up and shift it around:

To become this ugly but effective thing, including a bit of butt welding practice:

Also pictured is the beginning of a special bolt that will locate the filter bracket in the sidecar mount.

This is better. It's further inboard to allow the oil lines to pass the gearbox outer casing, and further forward to guarantee the filter clears the mudguard and rear wheel:

The next step is to replace the bracket with one made from 3-4 mm sheet, and finish the special bolt that holds it in place. I'll use the same old sleeve nut, but I will probably machine a journal in it to fit in the hole properly.

Here's the finished bolt:

It's in the wrong side, but I'm just testing for fit. I wanted to make it look like the swinging arm nuts.

More later.

Tuesday, 25 June 2019

Dry Build - Fitting & Repairing the Rear Mudguard

Updated: first published 27th April 2019

The whole point of a dry build is to trial fit parts before committing to an expensive paint finish that you might ruin with any remedial work you have to do, and the rear mudguard was a good example. Aside from the moth damage at the join, the mudguard wouldn't fit with the oil tank in place.

You can see the back of the oil tank bulges and pushes the mudguard to the nearside:

The centre bolt won't line up:

And here is the problem - the back of the oil tank is supposed to be flat:

Five minutes with a dead blow hammer, working around the edges has it back in shape. There is clearance between the back of the oil tank and the mudguard now, and the mudguard's centre bolt is in place.

Having got the mudguard to fit, we now need to repair it. It's not the worst I've seen.

This is the rear end of the main section showing the rust damage to the bridging piece, to which the tail section is bolted:

This is what it is supposed to look like:

And here is the front end of the tail section:

Again, this is what it is supposed to look like:

I cleaned this up with a wire brush a while ago to get an idea of what I was going to be dealing with - those holes are in the main blade section as well as this joining panel. Notice how the joddle that lives in the mudguard rib is rather deformed - it's flattened toward the rear end. It's quite square at the front and is clearly supposed to fit inside the rib, with the rear light cable below it - the cable does not go between the mudguard and the joining rib. We'll need to remove that, make a new one, and repair the guard as well.

Here's the blank, sliced from a quarter sheet of 20 SWG CRS. It's 3" wide and about 15" long.

Here it s again, with a datum edge trued up on the linisher. It's marked out with a Sharpie against the dimensions of the old, moth-eaten one.

Here are the first two bends going in:

And joddling the top hat section in the middle:

Next step is to fold the two lower channels that fit around the rolled edge of the mudguard, then we will make the main bends. When that fits, we will cut out the old one and repair the main blade.

Here's the first bend of the two side channels:

To make the next bend, the work has been inverted from the previous shot, and it is clamped to one of the folding bars using a piece of 25 x 4mm flat bar. The second folding bar has been raised by the depth of the bend:

Here the work has been folded down over the raised folding bar, producing a joddle:

And here, the joddled section has been clamped behind a 1/2" bar and bent again, producing a shallow channel:

That done, we joddle the last bend and repeat the whole process at the other end to produce this.

I'm very pleased that it sits flat on the bench, with it's datum edge remaining straight and proving that all the bends are square.

Next we need to make the curves, and for that we need a former which is where this empty gas bottle comes in. These were a very expensive way to buy Argon that I used to use before I rented a refillable bottle:

A line drawn parallel to the axis of the bottle, and another square to the datum edge ensures the bend is square:


And it even fits. The marker line you see in the holes is drawn 1/2" from the datum udge, copying the hole positions from the original:

I've drilled the top two holes 9/32", to clear 1/4" screws which we will use for the next steps. These screws will ultimately be 3/8" (for my 5/16" threaded bobbin), but drilling them smaller allows me to move them a little if I need to. The bobbins look like this:

Having a quick look at the side pieces and the holes reveals I have been generous with the length of the blank, and the rolled edges of the tailpiece prevent the over-long bridging piece sitting in the correct position.

The next job therefore is to cut away the old bridging piece from the front section of the mudguard, so we can edge a bit closer to having the bridging piece in the right place and trimming it up. The old one was not too difficult to remove as it was extremely weak; I could see where a couple of the spot welds were and I removed these with a special spot-weld cutter which has been knocking around in my sheet-metal toolbox for decades:

It's a small, double ended saw blade (imagine a 5/16" hole saw) mounted on a mandrel. You can cut right around the weld:

Here's the end of the front section with the bridging piece mostly gone:

I'm going to cut it away back to that black line and let in a new piece of steel, like this:

I'm very happy that I've finally found a decent bi-metal blade for the bandsaw, as it makes life very easy when you want to cut out bits of sheet. This is the new panel - I used a similar technique to before for the centre rib; the curves are bent by hand:

Tacking up. I have a narrow dart in either side to let the new panel curvature match the old guard:

And here is the joining piece, with similar darts. Here it is bolted to the rear section:

These are skin pins - I have a bout 15 of these 3/16" pins, used for holding sheet metal parts together before welding:

Here's a couple of pictures of the mudguard bolted up:

From the inside, the bridging piece is approaching the final shape. We need to machine the weld nuts on the lathe and get those in next.

This view shows the mudguard with the bobbins in place and bolted up. I made them 1/4" BSC, to give myself a bit more wiggle room. I may make up some special 1/4" bolts with 5/16" size heads, domed and polished.