The Home Machinist!

Mostly, I have written on various live steam locomotive construction projects but there are other things which come through the shop from time to time.

These photos relate to a friends 1966 175 cc Bultaco Mercurio two stroke motorcycle project which he is re-building from the frame up. It was one of the first motorcycles which he owned.

The new additional part (the original is the black painted piece sitting on the top of the vise) is being machined out of alloy aluminum.

One needs sharp cutters and light cuts. There are other ways to do this but...

Cool....I had a 1968 Bultaco Matador! They were a 250cc ISDT bike.
Never had to worry about my friends borrowing it. The brake was on the left, and the shifter on the right. Kinda threw 'em.....


Bill

Yes Bultaco reigned ! Gosh they look like bearing caps.

spro wrote:Yes Bultaco reigned ! Gosh they look like bearing caps.

Yeah.....I keep lookin' at the pic's....but I'm not sure where it fits? Little help there Carrdo??
Maybe something my Matadors didn't have....???

I did modernize.... I bought a new Matador when the MK4 model came out....'70 or '71 give or take.
Always wanted a Sherpa T. Never got one, but I did buy a TY250 Yamaha trials bike. Not a Sherpa, but was a fun ride!
Bought a TY350 later too....that was Sherpa plus some.

Neat!

I don't think they are the bearing caps on the conrod as a u bolt goes through them. Perhaps something that goes on the bikes handlebars? Anyway, I will ask when I see him next.

Carrdo wrote:I don't think they are the bearing caps on the conrod as a u bolt goes through them. Perhaps something that goes on the bikes handlebars? Anyway, I will ask when I see him next.

Could be....if so, not like a Matador.....but a '63....hard to say. I am curious....
Matadors had two separate handle bars, a left & a right. All steel, with a 4-bolt clamps on each that clamped them to the fork tubes.
I modified my triple clamp, and made some mounts, to use normal handlebars like any other dirtbike.
Bultaco parts were pricey...no doubt unobtainium now.

Now, I know what I am machining; it is the upper clamp section which fits the top of the fork assembly and steering head to clamp the bike's handlebars.

a little further on.

Here are the final two photos.

Making all of the bits and pieces as seen in the last photo to hold the part for machining was much more work than the machining.

Great work and from what I see, Better than the original . Looking back, I understand the set ups. To make these custom parts required a lot of thought. It isn't like jigs where you are making 100's of them. Cool stuff for a cool machine.

A couple of months ago I made a short presentation on this to TSME (when the part was half finished) and got raked over the coals by the members on how I was doing this the most difficult and time consuming way again. There is always an easier, faster and better way!

Specifically, if one was to make this part again, first drill the holes in the part lugs undersize, then thread the undersize lug holes and mill a flat on the bar which holds the part out from the chuck. This way you can obtain a very solid positive grip on the mounting bar and as a result be able to take much heavier (and faster) cuts than I was able to do by relying on a friction grip only. Afterwards, when finished milling, the lug holes can be drilled out to their final size. Totally logical, but that escaped me...

Recently, I had to make some tapered adjusting screws for some that were missing in my split and adjustable threading dies which had been lost or had disappeared over the years. Of course, the manufacturer's use special, fine tapered 40 TPI threads not made to any known standard so they don't make it easy to find any replacements - one has to make them.

The first job was to make a drawing of the missing adjustable set screw(s) using one which I had. They are so small, it is difficult to measure all of the dimensions precisely so I ended up with two sketches of possible dimensions. Of course, the first sketch used turned out to be not the correct one.

Fortunately, I have a taper turning attachment for my lathe which is needed for a job like this. Also, I had never done tapered threading before but it turned out to be just as easy as parallel threading - the secret is to get your initial setup right.