I've been using DuckDuckGo for over two years now. To quote Phil Robertson from Duck Dynasty, I've been "Happy, happy, happy" with it.

FISHTURE?   Stuart, I believe you have something else on your mind, but opening day isn't for another 19 days.  


Or, are you just trying to see who reads your post? 

Either way, I enjoyed the read and the pics. Keep 'em coming!

Dammit. OK - ditching firefox. Thanks for the heads up. Guess I'll try duckduckgo.

Very sad to hear this Terry, it's always tough to help them to the next stage, but as you say, it's what we sign up for. All the best.

I made a thing.

I had some communications with a writer at Model Engineer, and was discussing the shortcomings of the base casting on this model. In the end, rather than wait until later, I went ahead and completely removed the circular boss and the two rails next to it. Those features are way off center and will look horrible if left in place.

As a result, I needed to either make the boss as a new disc on its own - or do as I ended up doing and incorporate the disc into the outboard head.

The head is a circular wedge shaped item - you can see it here in cross section, at the bottom of the cylinder.



I made mine like this, to replace the boss at the same time.



Before I go any further, I want to make it clear that the approach I have taken is one of achieving best accuracy I can, because I felt like it. The wedge feature can be achieved by simple marking out perfectly well - in fact I'm sure the engine would run fine if the head was just made with a flat, non angled face. I just decided to go this route because I find it satisfying.

So first off a piece of 2" steel rod went into the lathe. 2" is the largest diameter I can fit through the chuck and spindle, but that's pretty good - saved me having to saw off a lump and make more scrap. That was turned to a top hat shape at final OD of the part that fits in the cylinder - at .0005" under the nominal diameter of the mating bore (when I get to that).



Incidentally - and this is a bit extravagant but REALLY nice - the domestic authority desired a new TV in the house so I repurposed the "old" one as a monitor. It is in full view of lathe and mill. I didn't really think it would work out so well but it is unbelievably nice to have drawings magnified right there in view.



So then that was parted off, turned around and the dowel hole put in the back side.

And there is the top hat - all very simple. A fun bit of turning.



So, the fun bit is getting the angled face on it at the right height and clocked correctly to the bolt pattern. Not all that hard - and as mentioned, if one were to eyeball it and mark the height front and back, paint some blue on, scribe a line etc it would all work out.

But I decided to make a holding fixture out of a piece of scraptonium, including a mating dowel pin hole at the center, the bolt pattern in the head / ring and another dowel pin for a tooling ball. The tooling ball acts as an easy to establish reference, the holding fixture is then angled making use of a sine bar.

I'm changing all the BA threads over to UNC or UNF threads which are easier to deal with stateside. There are close enough sizes. Not equivalent – they won't play together – just similar physical sizes. I tabulated the whole arrangement. I was surprised I couldn't find anything already done, figured that must surely have been done and shared before.

Anyway – the fixture block was all squared up and the center hole drilled and reamed, and bolt pattern added. Here it is tapped with my home-made small tap holder.



The idea of using a tooling ball to establish location actually came to me after making the fixture to that point. My original plan had been to use a dowel pin, but it would have been difficult to keep perpendicular to the vise jaws. The tooling ball is easy – here is a reamed hole being added. I'm using a kool mist mainly to blow chips away so nothing gets jammed in the reamer to make the hole go oversize.



Tooling ball fitted – a nice close, slip fit.



So, this drawing helps to explain the point of the ball.



The drawing has the dimension from the top of the ball to the finished wedge surface – so now you can see that it is possible to set up the fixture in a vise on a sine plate, touch off an end mill on top of the ball (by way of a feeler gauge so as to not damage either end mill or ball), and then bring the tool down (actually the mill knee up) until dimension from top of the ball to finished surface is reached. Now the wedge is very accurately created.

Although I have CAD and it's easy to measure the dimension needed, I like to do the trigonometry. I'll show the triangles here and how that works for the fun of it. I feel like making the effort to do the maths increases overall understanding of geometry – and it's just a bit of trigonometry. I drew this up to show the relevant calculations and geometry.



Hopefully that's self-explanatory. For anyone interested in the details I will go through the calcs on the video I am putting together for this, but basically the numerical dimensions are the known values – dimensions desired on the final part etc, and the dimensions in letters are what have to be calculated to get the vertical dimension that references from the top of the tooling ball to the finished angled face, when the part is set up in the milling machine.
So OK – with that known here is the set up – using a sine bar to get the angle as accurate as possible. Yes – more trigonometry! I expect you all know this. The center distance of the pins on the sine bar are 5" apart, so to set the angle calculate the height of a stack of gauge blocks to put under the rear pin. Sin (5.572) X 5.0" is the calculation.
Enough waffle – pitchers here.





So then after touching the face of the end mill off on the top of the tooling ball (using a feeler gauge) it's just a matter of raising the knee gradually and carving away the material.







Simple enough and quite satisfying.

2 parts down, lots more to go.

Definitely have plenty brewing. Too much probably - ah well. So many projects. Happy Birthday.

We've been here one year as of today!! 

Time for me to get serious about posting some relevant material and I've got a few things brewing. I hope some of you do, too.

Thanks for being here, all of you!!



I also said there is some news, so I suppose I should elaborate:

Machinist's Gazette disappeared because we did not have a backup administrator that was familiar with all of the behind the scenes stuff and could not access the server or our accounts. We really do not want that sort of thing to occur here, so we are adding a second administrator. Jimmy (Piggiron) has agreed to take on that role. He does have some background with administering a website which is a plus. The rest I can teach him in a rather short time. Over the next few weeks Jimmy and I will be working to get him up to speed with everything on the backend.

Welcome to your new role, Jimmy!

I was thinking. It doesn't need to be for an indicator. You could use it for holding a magnifying lens, safety shield, blue print, camera...whatever. Maybe I'll make a strip of that dovetail so I can mount stuff on it.

Hahaha!  I picked up a Noga post a couple years ago and mounted to a magnetic base I had as a spare. It's almost as big yours. Really too big for my machines  too.

Holy Hannah, that is big!!