Member postings for John Haine

Well, I have decades of experience with soldering and none of riveting! But Matthys recommends soldering to ensure that the edge of the chop is firmly in contact with the spring. There's some evidence that if there's a small gap then the CD of the pendulum can be unpredictable as the bend brings the spring into contact. I've also just recently replaced the spring on my new pendulum with one that has a wide single leaf rather than a double, and I took more care with soldering, and it looks like this on its own has significantly reduced the measurement noise I was seeing.

What's that FFT of Dave?  Is this impulsed or run-down?

Edited By John Haine on 17/04/2023 21:52:53

Thanks for the input everyone. Actually I have a little pot of rouge somewhere, I'll give that a whirl first if I can find it. Tesco seem to have Tippex so I'll try that if the rouge doesn't work.

How wide is the "hump"? If it's the central "lands" between the tee slots, could you mill most of it on the machine itself with a face cutter?

Is it under warranty?

Or photos?

Could also make from MDF, reinforce when turned with several coats of thinned PVA to soak in, or better West System epoxy.

Thanks Bernard - does it still wash off after heating or does it need scraping?

Corian machines beautifully. Sharp HSS works well, carbide probably better but it isn't that abrasive. As Jason implies, you would need to leave wide lands on the edges at the top of the vees. I have glued it with both araldite and Gorilla Glue clear but if laminating for pulleys I'd suggest some bolts too to reinforce (yes it taps easily).

Not really an electronics question but related. I'm trying to refine my technique for making pendulum suspension springs. Basically these are a strip of beryllium copper about 16mm wide which have thick brass "chops" soldered on each side of each end for mounting. The active length of the spring in between the chops is a few mm. The soldering problem is to prevent solder squeezing out from the chops when molten and forming littlee blobs on the active surface that could affect the uniformity of the bending. So I would like to put something on the spring surface between the chops that will inhibit solder wetting. This is the same sort of requirement as a "solder resist" on a PCB except that I will want to remove it after soldering.

Does anyone have any ideas for what I could use please? I've seen Tippex mentioned I think, I'm not even sure if that's still made! Soldering by the way is using electronic silver solder, either cored wire or paste.

Good.

Modern 3v logic families tend to smoke if supplied with 5v...

The ones that need 2 cells, are they in series or parallel?

If you look at the photos on the lathes.co.uk site it seems to be where the horizontal spindle fits.

Another use for the quill on the VMB. To take a controlled skim off a surface I wind the Z feed down so the cutter is a mm or so off the work, use the quill to bring down the tool so I can feel it just touch the surface, lock the quill and zero the Z DRO. Then raise the head with the feed, move the table to clear the cutter, bring down the cutter so the desired cut is indicated, and lock the slide before taking the cut. May not be "good practice" but works well. Doesn't really affect rigidity because the quill extension is minimal.

As a matter of interest what is the reversing switch doing? It should NOT be in the wires to the motor because if the motor is energised (even if stopped) and you throw the switch the inductive kick from the coils may blow the driver. Reversing should be done by changing the logic state on the DIR input of the driver which only needs a simple one-pole changeover switch, or an on/off plus a pullup resistor.

I fitted a 3 axis one to my VMB 2 years back. Quite easy to fit and has transformed my use of the mill. The mill does have a quill but has fine downfeed anyway. I use the quill for drilling only unless depth is critical when I'll use the z feed.

AFAIK the only difference between imperial and metric S7 is the crossslide and topslide screw pitches. which as Bernard says are both 2mm pitch. The Xfeed dial is marked in mm off diameter however, i.e. t turn is 4mm. The leadscrew is 8 tpi in both but (un)helpfully the handwheel is calibrated in metric! i.e. 3.175mm full turn.

Edited By John Haine on 12/04/2023 15:57:22

One advantage CNC machines have is that the feed rate can be selected to whatever you want within reason, whereas mechanical lathes are very limited. IIRC my S7 only gave two slow auto feed rates. With CNC I now generally use quite a low rate of 5mm/min but never bother with back gear, the cut is much better at high surface speed anyway. I'm sure I could go faster if I wanted to. I never understand why manual lathes still have mechanical auto-act when a little motor would be much cheaper and more flexible. Also why all the bother and expense of change wheels for threading, or worse a gearbox, when a bit of electronics would do the job better and cheaper these days. Doesn't have to be full CNC, but would result in a better and probably cheaper product.

I already use all the edges.