Member postings for Gary Wooding

You never mentioned if you're making a piece of jewellery, or something mechanical. If the former, then it seems like a great deal of work to make a pattern that fits sufficiently firmly on the chuck to withstand the considerable thrust needed to move the saddle of a Conquest lathe against a spring sufficiently strong to move it back again. Since you'll end up filing the pattern anyway, why not cut the groove by hand in the first place?

Whatever route you take, you're going to have to do some careful filing. If you do the whole thing by hand, then when the filing is finished, the job is done. If you make a pattern, you also have to make a follower and make a suitably profiled cutting tool to cut the groove. Then cut the groove. For me, it's no contest - unless its for something that needs fine tolerances.

There's a further consideration.The groove in your pictures has rounded edges. If you use a cutting tool in the lathe that also cuts the rounded edges, the groove will be correct at only two places round the ring; it will be lopsided everywhere else, you'll then have to file it to make it even. If the cutting tool doesn't cut the rounded edges, you'll have to file it anyway.

The 16 degree angle of the groove means that its actually an ellipse.For an average sized ring (say 20mm ID) the depth of the groove, measured normal to ring's axis, varies by almost 0.4mm. In other words, the difference in length of the major and minor axes is about 0.8mm. That will make the width of the groove vary very obviously if the cutting tool isn't moved that much radially. Better to do it by hand.

The reason I got into model engineering was the need to make tools for making jewellery. I would tackle your ring by hand-filing the groove after laying it out with a piercing saw. Use the depth of the saw blade as guide to the depth of the groove, then use suitable needle files to curve the edges. Ti isn't hard to saw or file.

I faced a similar dilemma when I added a depth stop to my Centec VH. I used a threaded rod with a pair of Tilt-Nuts for the actual stop. The tilt-nuts have the useful property that, when tilted they "unlock" from the threaded rod and can be moved up and down easily; they re-engage with it when un-tilted. In use, the lower one lowered to the stop block, which orients it to engage the thread. The top one is the lowered until it meets the lower one, which orients it to engage the thread when they can be locked together.

It looks like a wedding ring made of two different metals. I would make each half separately and join them together afterwards. Each half could be turned on the lathe - each "external" end being a simple turning job on a stub mandrel. Each "internal" end would have to be machined on a stub mandrel that was at the required angle - like the picture. Making the mandrel will be interesting.

You can then join them together.

Older Pro versions (V16, for example, which I consider to be one of the very best versions) do just about everything you will need and will be much cheaper than £1500. It works fine under Win10.

JA,

I think there's something wrong with your system. I'm using TCAD 16.2 Pro/Plat on my Win10 x64 system with no problems.

If you upgraded an earlier (Win7 or Win8) system to Win10, then try re-installing TCAD 16.

I can also recommend TurboCAD, which I've been using for many years, and Fusion 360, which is a fully fledged parametric program made by AutoDesk. Whereas older versions of TurboCAD are very reasonably priced, Fusion 360 is totally free for students and home users.

A word of warning though. All powerful CAD programs are large and complex, and take a considerable period to master. Many people are seduced into using one with the mistaken belief that they will be productive in a week or so. For most people it just doesn't work like that. They get despondent after several weeks of encountering errors with no obvious solutions and then simply give up. If you've never used a CAD program before, be prepared for a steep learning curve and don't give up.

If you persevere you'll get there in the end, and the rewards will be immense. I can create rough drawings with TurboCAD faster than I can draw on the back of the proverbial fag packet, then, with a little more effort, transform them into fully detailed and dimensioned drawings in 2 and 3D. But it didn't come overnight. My first set of drawings for a knurling tool took me about a month, I can now do the same thing in an afternoon or so. Practise, and more practise, gets results.

Yes, at tapping speed, ie. less than about 120rpm, switching into reverse takes far less than 1/4 rev. so its effectively instant. At that slow speed there is no perceptible ramp time.

I use an ER32 chuck in my mill that has VFD. I set it to low RPM for tapping, and use the instant reverse to withdraw and/or break the chip. I know I'm tempting fate, but I've not had a tap break - yet. I've broken taps when doing it free-hand but not yet with the mill.

I don't tighten the chuck too much, so, with a bit of luck, it will slip if the torque gets too great. I've been lucky so far.

Here's a photo of a handle I made from a piece of Nylatron rod. As can be seen in the short upright piece, the mottling is not very deep.

I did the mod some years ago and have lost the original drawings, but have re-constructed the attached by direct measurements, all shown in mm. See my album called Stuff. The actual slots are approx 160mm long.

Edited By Gary Wooding on 05/12/2015 11:19:34

The needle can be moved back and forth when the knurled nut shown in the photo is loosened.

Yes, that's what it designed to do.

I'm afraid that my photo was created in a hurry and, to save time I just stuffed something in the 3-jaw. In practise, the workpiece would be in the 4-jaw independent with a centre-punched mark that needs to be centred. The pointed end of the finger follows the centrepop as the chuck is rotated, and if its not truly centred the other end wiggles even more because of the difference in the lengths either side of the support.

Here's a photo of a similar item in use.

Sorry for the typo, for sring read spring

The easiest way is to select the extrusion (the tube), right click to bring up Properties, then, if not already chosen, choose Simple Extrude Shape and set the height (which is the Z dimension) to whatever you want.

By the way, instead of creating a tube by extruding a circle and and then subtracting another extruded circle from it , try drawing two concentric circles and boolean subtracting the inner one from the outer, then extruding resulting torus.

Another way is to draw the two concentric circles as above, then Simple Extrude and then right click and choose Use Compound Profile, then, with the shift key depressed, select the circles, release the shift key, and the extrude will work as before but the result will be a tube.

I was taught...

Some People Have (Sine = Perpendicular over Hypotenuse)

Curly Black Hair (Cos = Base over Hypotenuse)

Though Partly Bald (Tan = Perpendicular over Base)

Funny how these things stick in your mind.

Here's mine that I made years ago. I did an article about it in MEW #72.

an example of output

Edited By Gary Wooding on 20/11/2015 07:16:34

Thanks Andrew, I missed the fact that it was double acting, so I ended up with .093 m³ and couldn't see where I'd gone wrong.

Sorry, can you explain that bit please?