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Member postings for Mark Rand

Here is a list of all the postings Mark Rand has made in our forums. Click on a thread name to jump to the thread.

Thread: What Did You Do Today (2017)
30/04/2017 20:47:52

Tried out a new box of 2.5mm Murex Ferex 7018LT electrodes in practice for welding feet on to some 100mm square columns for a crane in the shed. They were spitting and crackling and making an attrocious bead, almost like wet 6010 rods. Dried them in the oven and tried again. Slightly better but still wrong. Used nearly 20 rods trying to work out what I was doing wrong. Then went on to the Murex web site to look at the specs for these particular rods. It actually says DC-ve preferred for these rods, which is odd. I thought I'd try that as my only other option was to chuck the lot and get some more.

 

Turns out that when I'd made sure to change over to reverse polarity, I was already on reverse polarity, So I'd been using the rods on DC Electrode Negative (like they allegedly prefer). Swapped to DCEP and they started to work as I expectedembarrassed. Slapped myself severely upside the head and gave myself a good talking to!

 

Then cleaned up and spent a couple of hours cutting up timber to make shuttering for a greenhouse base. That did go ok, even if I had to use the wood-spoiling bandsaw, instead of the proper bandsaw with coolant.

Edited By Mark Rand on 30/04/2017 20:49:43

Thread: Which is the best diameter for an ML7 Leadscrew.
30/04/2017 20:31:04

The long bed ML7 always had a 3/4" dia lead screw as opposed to the 5/8" standard lenght bed.

Thread: Accuracy of an old machine
23/04/2017 19:38:41

If you're not paying for your own time, then returning a machine to original specifications is not expensive. So far I've done a 1952 Hardinge HLV and a 19?? Beaver turret mill. 1976 Surface grinder will be done after I've re-lapped the surface table...

Thread: Even with New Tool Fever At its Height...
22/04/2017 21:41:39

At £30/ton, the scrap thieves are raiding stationary cupboards all over the country and the paperclips are ending up turned into container ships...

Thread: MEW 254
20/04/2017 20:40:15

By the way, did the 'On the Editor's Bench' have anything to do with the issue-number/10? ...

Thread: Any Chemists (rust)
18/04/2017 20:01:00

The active ingredient in the VPI products may well be sodium benzoate or another benzoate. Camphor is alleged to work as well, but it's not so good if you object to your products smelling of moth-balls.

I've tried some camphor blocks in my file draw but it's inconclusive, since the workshop normally has a low humidity and a temperature that rarely changes by more than 3°C in 24 hours. Files haven't gone rusty though!

Thread: Restoring Beaver VBRP Mill
15/04/2017 23:30:38

I've got a task that will need a 6" or 8" riser for the Mk1 VBRP. I've noticed a firm on EBay that will cut 'washers' from 15mm mild steel. my thought was to get a couple of plates cut to the right dimensions, approx 14" OD-10" ID, then weld 6 or 8 segments between them for the height, After that, they can be milled flat, then mounting holes drilled and tapped using a rotary table.

ISTR there was an article once in MEW about a chap that had made a riser block using a similar technique, but using rolled plate to produce the centre cection in a cylinder. I'll just use flat pieces of 10mm plate to produce a polygon by welding them together.

Thread: Rusty lathe for sale
15/04/2017 22:59:56

hey, I found a Griptru chuck tnat will go with it. Now the owner can be assured of precision results...

Thread: Exhibitions ,shows, etc in europe
12/04/2017 21:32:47

There's also the Birmingham Science Museum.

Thread: CCMT Carbide Insert PLAIN
10/04/2017 18:20:38

MSC/J&L and Cromwell both have them. Look for inserts for cast iron.

Thread: What Did You Do Today (2017)
07/04/2017 20:02:16

Finally passed my Level 2 City & Guilds MMA (stick) welding course. Took me 12 1/2 days instead of the nine that it chould have, but the college really didn't want me to fail. smiley

Thread: Cross slide adjusting collar myford super 7
06/04/2017 21:43:00

Old Super 7's didn't have power crossfeed. cheeky

Thread: ER40 Collet run out.
28/03/2017 22:23:28

Have you made sure to hook the extractor groove of the collet into the protruding section of the extractor ring in the nut?

That's the most common cause of alignment problems with ER collets.

Thread: Continuous use of a phase convertor.
26/03/2017 23:09:34

On the switching problems. is it possible to use a 'debounce' circuit or software in the PLC (if used) to reduce the strain on the supply/contactors/motor by generating a single turn-on rather than rattling everything untill things settle down?

PS:- Sorry to have dragged your thread into talk of inverters, but I've used/worked with ones that expect to be abused like any other source of supply. smiley

26/03/2017 21:11:00
Posted by Muzzer on 26/03/2017 19:35:36:

Indeed they would be - but they are far from commonplace. Care to share details of a real example for our reference?

Murray

The one I referenced in the first post:- a Danfoss VLT 5000 series. In this instance, it's a 23kVA one that I've down rated to feed from single phase.

There were three similar ones on EBay a few weeks ago.

26/03/2017 10:42:53

See my comment above. An inverter with no limitation on downstream switching does not have this issue.

25/03/2017 22:02:07

My Danfoss VLT 500 series inverter supplies three phase to all the 3ph machines in the shop. No separate controls, just plug the machines into the wall sockets and run them. Currently one lathe, one mill and one surface grinder, with nine motors between them. It just works and powers any or all of them together (With the limitation that I can only run two machines at a time, unless the lad is there to run the third).

Remember, inverters are made from a few Watts up to hundreds of MW, you just have to get one with a suitable specification.

Thread: Tailstock Turret Plan from MEW 253 - FOR DIGITAL SUBSCRIBERS
23/03/2017 00:12:06

Just noticed that the (printed) drawing shows an M12 thread for the MT2 arbor and angle piece that it attaches to, whereas the article text quotes M10 for both.

Not near a measuring stick at the moment so haven't attempted to scale from the drawing.

Thread: Won't be long before this lathe goes.
22/03/2017 17:24:31

Every machine tool seems to be an 'Ex school machine' even when it spent all its life in a steel mill. angry

Thread: Armoured cable - what size would you reccomend
21/03/2017 00:07:46
Posted by Martin 100 on 20/03/2017 21:49:59:

It used to be 4% in the 16th Edition of BS7671, but the 17th edition (2008) altered that to 3% for lighting circuits and 5% for 'other uses'

Bear in mind you not only need to consider the votage drop but the earth loop impedence and the electrical protection for the cable (MCB /RCCD/RCBO) to ensure suitably fast clearance of any credible fault. Also the export of an earth from the main premises may not always be advisible, and you may need to leave the armouring isolated at the remote end and use a local earth spike.

 

Bugger, you're right. I was mentally conflating the 2% frequency stability requirement on the grid. blush

 

Earth loop impedance comments very relevant. ISTR that the advice is now for RCBO for all ground floor circuits, but I only have them for the garage and an outside circuit.

 

Part P of the building regs will require inspection of the work for it to be cosher. (Bah! Humbug!)

Edited By Mark Rand on 21/03/2017 00:08:23

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