Member postings for John Haine

I don't know about bee keeping gadgets, but the usual problem with crowdfunding campaigns for electronics projects on Kickstarter and indiegogo is that they seriously underestimate the cost of developing a new product and getting it to market.

A bit more progress. Have now progressed to the "ways" that bolt on top of the work head base. These are segments of circles, laser cut from plate, with hole positions spotted accurately but a general machining allowance round the edge of about half a millimetre. I started off confidently drilling the mounting holes but soon realised (should have thought before) that actually it is critical to machine all round the edge to get these accurate and there is no obvious datum other than the holes. After a lot of though in the small hours of this morning I've decided this is a job for my cnc mill, but will need a mounting fixture using the accurate (I hope!) drilled holes as a datum. That will be a job for Saturday when I can also take some photos to post. Watch this space!

OK, well I have turned both bits now, holding them as before but with different tools. I still find the material very "sticky" and suffered several dig-in/jams, but no matter, job done. I didn't take any photos of the operation I'm afraid, they would not have been very edifying! There aare now some easier operations to be done, which I will pick up tomorrow and hopefully post some photos.

A bit of feedback to Eccentric: I've done quite a lot of turning steel of around this diameter (50mm) without problems like this, the plate material seems to be very "sticky" and prone to digging in. It might be easier if these two pieces at least could be supplied as blanks parted off from a bit of 2" FC bar perhaps?

Martin W: Ah yes, as I said "as long as no two holes are one" - which is exactly what they have done of course. Silly really, when drilling one extra hole it would be fully balanced.

One of the best bits of engineering I have ever seen was a unit the size of one of those "table-top" pump thermos flasks they serve coffee in, which was a superconducting filter to use in cellular base stations. The superconducting bit was in a small square box at one end with 4 coax connectors; the rest of the unit was a single stage pressurised helium oscillatory Stirling Cycle refrigerator. It was driven using a voice coil to the "piston", excited by 60 Hz AC. The voice coil (in a loudspeaker-like magnet" compressed the gas whilst the resonant oscillatory displacer lightly coupled to it to vibrate in quadrature. The result was a temperature low enough to achieve superconductivity in the thin film filter resonators. I'm familar in my day job with RF filters and how they work, but the refrigerator just blew my socks off! A real bit of yankee know-how.

The people who had disintegrating electrical insulation could have had the copper pipes that an old colleague had in their barn conversion - after only a few months they developed pinholes - might have acted as an impromptu sprinkler system!

Thanks Danny, good suggestion.

You're right Neil! Another project...

Bit of a setback today. Have gone on to making the workhead which involves turning a very shallow shoulder on a couple of circular blanks laser cut from plate. As they are pre-cut the only practical way to hold them is to drill through the centre and hold on a stud into a mandrel held in the chuck. The material is very "sticky" and even taking very shallow cuts I've suffered 3 dig-ins that stalled the lathe, and b******d the tipped tool. So now started on one of those loops where I don't seem to have a spare tip that's sharp for the holder; try a different holder that I made that turns out to be bowed (never noticed before) so you can't easily get the tool to centre height, now I need to make a small mod to a tangential tool holder I made a while back but needs a dimension adjusting which means it's back to the mill....tired and frustrated, taking a break!

Ian, when you say "converted", what do you mean? Even the "new, metric" Super 7 has the standard 8 tpi leadscrew and can only cut approximations to metric threads unless you have the 127 tooth gear.

However, the approximations can be perfectly fine for all practical purposes at least for shortish fasteners, and a short search on this site will find a number of threads with tables, or pointers to tables, for cutting metric threads on the Myford 7 lathes. When you say "just under" 1.25 how much is "just"?

For example see this: http://www.model-engineer.co.uk/forums/postings.asp?th=86738&p=1

It would be a great service to us all if the people who operate this site added an FAQ facility as this is a topic that comes up time after time.

As Michael says, it should be no problem if you adjust the other dimensions...and since this design seems to have an eccentric adjustment on the worm shaft you might not even have to do that! But personally if I wanted to make a rotry table I'd buy a casting kit which would probably come with a worm and wheel; or buy a worm and wheel from HPC. Unless the challenge is to make the work and wheel of course! Actually I have two rotary tables, one small and one large, and almost never use them!

Having drilled and tapped the link joiner the next job was to drill and ream the holes in the links.

Held in my little vice clamped on the VMB table, lined up using a point in the spot provided. Drilled 8 holes 5.9 mm then reamed out to 6 mm and deburred.

Next, the work head swivel. This goes at the other end of the pantograph and allows the work head to be turned to the required cutting angle and clamped. The large hole in the centre as supplied is about 36.5 dia and needs to be bored out to 38. The spottings for the screw holes are accurate in the cut blank but nothing else can be relied on. So I cautiously filed the straight edge next to the spottings smooth to the outline (which is laser marked on the edge, with about 1 mm machining allowance), and set it against a straight edge clamped square to the table. Then aligned the mill spindle to one of the spotted holes by holding a point in the chuck and adjusting the point so it entered the spotting accurately as judged by eye and feel. Then I clamped everything down, so we have the spottings aligned square to the table and the spindle axis aligned with one of the spottings. Then I moved the table Y by 15 mm which places the axis exactly halfway between the spottings; and X by 27 mm which places it in line with the centre of the big hole. Locked the slides, fitted the boring head, it needed 4 cuts at about 100 rpm to take the hole diameter to 38.02 mm - not bad.

Then I could drill and tap for the link pivot bolts and make a trial assembly, as shown here.

I'm struggling with this I have to admit. If two hole patterns which are individually balanced are superimposed, as long as no two holes are one, intuitively you'd think the superimposition would also be balanced. Another way to think about it is to imagine the plugs of material you take out in their relative locations. Again, if they retain those locations the 3 plugs pattern and the 4 plugs pattern would be individually balanced and if superimposed you would thing the whole would also be balanced as long as no two plugs overlap. If the whole plug pattern is balanced you'd think that what it leaves behind would be also. This is making my brain hurt...

What is red?

Kevin, I don't understand what you're asking in your last post, please could you clarify? Myford "metric" lathes are identical to the imperial ones except that the cross and top slide feed screws are 2 mm pitch. The leadscrew remains 8 tpi.

This is the clamp block that goes on the top edge of the table. Supplied as a laser cut disc of 8mm steel with hole positions spot drilled. Centre hole is drilled out 5 mm and tapped M6x1. The other two holes are for the shoulder screws that form pivots for two of the parallel links. There is a 4mm step which has to be milled off the surface, parallel to the line of the pivots. I clamped the drilled part down to the mill table and set the shoulder screws square to the table edge using a big combination square - a bit tricky. The only way I could make my VMB reach the part was to use the longest cutter I had, which isn't over sharp so the finish is not wonderful. Now a problem I found was that the table material, nominally 4mm thick, is actually 3.85 so a 4 mm step is too large for the clamp to work. So I had to turn a shade off the top surface to bring the actual step down to 3.75 mm. Best to measure the table first and cut the step to suit. To turn the top and the sides I bolted the item to a short length of steel with a 6 mm hole drilled through, a bit like this...

This actually shows the sandwich of the clamp washer that forms the other part of the clamp and the pantograph joiner. Two ~41 mm laser cut discs are supplied with the latter having the hole positions spotted. I marked the centre positions thus:

popped the centres and drilled 6 mm after locating the centres using a point in the drill chuck. Then I turned the outside surface to clean up, and drilled and tapped the 4 holes M4. Next photo shows the clamp fixed on the table edge.

I need to shorten the threaded portion of the clamp bolt so it's flush with the top of the block when tight. Next, the pantograph links...

Here is a picture of the assembled base.

The table is supplied finished except for cutting out a gap to go around the wheel. The brackets and struts are ready made and drilled with pilot holes that need to be enlarged to clear the bolts. The kit includes 2 lengths of 1 inch ali to make the big spacers - these need to be faced to length and drilled 6mm through. One small problem, the drawings specify that one of the bolt holes in each bracket is slightly smaller than clearance, 5.8 or 5.8 mm, to lock the bolt from rotating. I found this impossible to achieve, so have added lock washers under the bolt heads so that they can be tightened with the handle alone.

You also need to make the big "washers" that go between the adjustable handles and the struts/brackets - these are 5mm thick and have a radial groove ion one face to locate an O ring that provides a little bit of pressure to assist in smooth adjustment when the handles are slightly loosened. Two laser cut discs of MS are provided for these, but I thought it was easier just to turn and part each one from an MS bar. Once assembled the base is very rigid when locked, but easy to adjust when slightly loosened. Next job - the pantograph that carries the tool holder and clamps to the table. Watch this space...

An interesting concept, a colour camera that can "see in the dark". Below a certain light level human colour light receptors (rods or cones? - can't remember) do not respond, which rather begs the question, what colour are things when it's dark?

Well, my kit for this arrived last Friday, delivered by Hermes in the form of a Vauxhall Astra rather than a winged chariot! My first impression - what a lot of bits! And more work than I expected, but none of it looks hard. Seeing it "in the flesh" I am even more impressed with the quality of the design, and there will be some interesting machining challenges, mainly in setting up (as always).

I will try to keep a photo blog of progress and post here. So far I've assembled the base and table and made a start on the work arm, with no major issues.

Apparently first batch despatched to UK beginning of last week, must have arrived quite quick because Hermes says mine has been collected by courier yesterday and is somewhere in their system I guess.