Friday 31 May 2019

Rotabs make the mill go round...

... or how to fit a 190mm chuck on a 150mm (6") rotary table. In reality it is quite easy: make a backplate, fit it on the table. Done.

It's the details that make jobs like this tricky. Originally I attempted to make the backplate entirely on the mill, but the surface finish was rather dissatisfactory.

So first step was to get both sides parallel with each other and correct a spot, where the mill had eaten into the step.

The top side needed a bit of attention too, the M6 bolts are plenty to hold the adaptor to the rotary table. 

Should you happen to know the brand (most likely Soviet-era Ukranian made) or where to get a set of internal jaws for it, please let me know.

The countersunk allen bolts needed a bit of touch up to clear the locking handles in the vertical and a reduction of diameter to reduce the size hole needed to be countersunk.

Vertical runout after all this jazz: 0.02mm between highest and lowest spot. 

I admit, it's quite a bit higher than I had hoped, but to be fair it is massive and it will be perfect for what I have in mind for it. That being said, it might be replaced with two smaller 125 (5") chucks that I have left over from my old Myford. So if you're in the market for a ready made solution for a 6" rotary table...

Friday 24 May 2019

Belts 'n' suspenders - more on the Rhino lathe

The best one can say about an old lathe is probably that there ain't much to say about, because it just does its job. In reality that's pretty much accurate with this old beast. But I have to admit that the lathe belts had a rather nasty tendency of slipping... a lot.

Now in order to swap the belt on this lathe, one would have to take the spindle out. (Which on its own wouldn't be the dumbest move to start with, because the bearings certainly could do with a bit of cleaning!) But what if, there was a way to avoid this?

Bring on the fenner belt or as the seller calls it "linked v-belt". As the name implies, it is comprised of sections that make it possible to lengthen or shorten the belt according to the needs of the situation and also you can link it up in place. 

A thing to note: After running the belt in for a few revolutions, it had to be shortened. A process which I had to repeat quite a few times and I attribute to all the links seating correctly. I was expecting it to run rather roughly, but to be honest, it's not worse than it was with the old belt. Surely you wouldn't do this to some Schaublin finishing lathe or the like, but for jobs like this one: perfect.

Friday 17 May 2019

Everyday TR1 - umpteen little jobs round the bike

Currently I am very strongly aiming towards getting all my two-wheeled junk moving in a direction, which could be summarised as: working condition (with minimal impedencies). The bike that is used the most is, somewhat as implied by the name, the Everyday TR1. Hence the old girl is getting most of the attention.

Four main problem areas have been identified and subsequently remedied, which were

  1. The washer of the oil-pressure switch was a joke,
  2. the Ignitech produced a slightly unclean signal leading the tach-needle to jump around a little,
  3. due to the bad weather and riding in the same, the rear brake axle started to feel sticky
  4. and lastly the bushing for the gear lever was completely worn out, leading the shifter to wobble around in all sorts of directions.

The oil-pressure switch was an easy fix, yet it called for draining the oil.

After some thorough cleaning a bit of flower was sprinkled onto the area and the bike taken out for a spin. If any oil had come out, due to the capillary effect it would have become clearly visible. 

Also whilst I was in there a new set of footpeg rubbers were fitted. (The one in the picture is the better of the old ones.)

Next was the Ignitech swap, which unfortunately didn't fully cure the jumpy needle, but it was well worth a try. The blue dot on the plug is to tell them apart.

The last part was to fit a grease nipple to the brake shaft.

Even though I had the shaft out two or three months ago and greased it up nicely with some GOOD saltwater-resistant grease, there's not much greasyness (pun intentional) left in there... Also rather well visible the adjuster is heavily bent from a previous crash and had to be bent back to stock position.

Originally I wanted to do it in the lathe, but with the shape of the backplate it turned out to be impossible to hold in the lathe chuck without making an adapter. So the trusty drillpress had to be employed for the task at hand.

... and the last bit to tackle was to make some proper new bushings for the shift lever. Luckily I had some 24mm stainless steel barstock sitting around that just had to be turned down to 16mm.

And that's the sideplay and the general indifference of the shift lever taken care of.

Friday 10 May 2019

Aprilia Moto 6.5 - spring maintenance

Lately there was some left-over work to do on one of my dad's Moto 6.5s. The most important one was to do some empirical carb jetting research.

Now as it's a mild pain to get that carb out and the bike was bogging down, it was easier to just restrict airflow and see how that affects the performance as that only meant taking the seat off.

The other source of constant joy on one of these are failing brake-light switches. Turns out you can either buy the 60 or 70 Euro stock part or go to your local electronics shop and get a microswitch for a whopping 1.89 Euros, which in my cases almost puts it on par with the fuel costs, and then just solder it on to the stock cables. 

The only other modification required was a 5mm bearing ball. Now, where do you get a single 5mm bearing ball, if you don't want to go to the shops to buy one...

They say German bikes are built without any hint of emotion, Japanese bikes are fine-mechanical marvels and Italian ones? Well, they need a slightly more laid back approach with built-in ingenuity and creativity. 😉