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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: Archived bbc programmes available now
13/05/2020 23:37:12

Just followed your hints and found the broadcast. There's certainly similarities with the riff! ,I'm not sure that there's any criticism of Richie needed, the world was a far less litiginous/autoproctological place then.

The fire and smoke were definitely an original piece of work.

Thread: Fixing lenses and mirrors into mounts.
13/05/2020 18:28:40

Have a house point that boy! laugh

These are mounts for mirrors to use with the autocollimator.

The 1976 surplus-from-work surface grinder was used to rough grind the bed plate of the 1952 Hardinge HLV when I was rebuilding it. That needed spot-grinding to get it flat enough (too hard to scrape). Since then I've rebuilt/re-scraped most of the Beaver milling machine (still got some more work to do on the head).

In the process of having a tidy-up in the shed, I realized that the collection of scrap hard disks from work would take far less space in the form of ingots.

Once I'd done that, I made some castings for mirror mounts.

Now I'm working on joining the mirrors to the mounts...

I think I'm heading towards the "sort-of kinematic design", but that's not fixed in stone yet.

12/05/2020 22:34:30

Desired short term (2 hours) stability better than 25nm or .1 Seconds relative to the mounting at constant temperature...

Relative weights approx 750g for mount of a 50g mirror. 16mm thick alluminium and 10mm thick glass.

It would be nice to be able to remove the mirrors without damaging them (eg if they needed re-aluminizing).

Vibration only from careful handling.

Edited By Mark Rand on 12/05/2020 22:38:47

12/05/2020 21:10:57

I have a need to mount two or three 50mm 1/10 wave, first surface mirrors into bored holes in aluminium mounts. I can think of a number of possible fixing methods:-

Nylon screws pressing on the perfiphery.
Shellac, either melted or alcohol born.
RTV silicone rubber.

Do the telescope/microscope/camera... making community have any suggestions for the best low/zero strain option, including all the ones I've missed?



Thread: What Did You Do Today 2020
06/05/2020 00:37:13

Cast a new box for the forward/off/reverse switch on the mill. The latest switch (after the one I got to replace the orignal burned out!) is quite a bit bigger than the original.

Need to work on my sand ramming technique against the sides of the pattern, but for this one the messy surfaces will get skimmed clean on the mill. Very happy with the finish on the inside of the box from the core.





Edited By Mark Rand on 06/05/2020 00:37:48

Thread: Blot On The Landscape
24/04/2020 18:03:42

The West Coast Mainline is already operating at capacity. Actally operating at more capacity that was designed in during the modernisation that caused major disruption to travel over a long period.

Modifying the route to increase the loading gauge is a non starter while it is in operation. There are little things like tunnels that would need to be closed for the odd year or two in each direction to make this happen. Doing so would reduce the line's capacity to about 20% of its current capacity.

Moving over to broad gauge, while an excellent idea, has the problem that you need to do it to every line in the country to avoid the problems that caused it to be replaced by standard gauge. Do you put containers two wide in freight trains?

Double decking might help increase passenger carrying capacity (see note above, why it won't happen)., but it does bugger all to help freight capacity, unless you go to two high container trucks.

The amount of land taken up by HS2 might seem large when viewed from a pedestrian/personal viewpoint, but it is small compared with even something like the A14 or the M1.

The way to improve our 100 year old rail infrastructure is to build new lines that are good for the next 100 years or more. That can't be done over the existing rights of way (in use, built around, croocked), so new routes need to be planned and built.

Instead of pissing and moaning about it because it offends indifidual sensibilities or won't be used by those upset by it, we should be pushing forward to get it done more rapidly so the country can benefit from it. Just like it does from the motorway network, the channel tunnel, even nuclear power stations (we need more of those as well!)

Stop being a bunch of nimbys and get out of the way of progress!

Thread: Machining - free of charge.
15/04/2020 22:41:31

Saying where you are (either in a post on the thread or in your profile) might help with the offer Bill. smiley

Thread: All things Beaver Mill
05/04/2020 22:00:15

Thanks for that. Never spotted it in other pictures I've seen of the Mk11 for some reason!

05/04/2020 18:09:54

I have wondered about fitting tapered alignment pins to my Mk1 along the lines of the Mk11, but aren't sure as yet how repeatable the other parts of the nod/swivel arrangements are even if they seem to be a good fit still.

Out of curiosity, where does the swivel pin live?

Thread: The Workshop Progress Thread 2020
05/04/2020 17:59:36

To Dave, John MC and thaiguzzi:-

Yes, I'm certain that they are an aluminium die-casting alloy. The density is approximately 2.7.

Coincidentally, Compac server disks used a magnesium alloy caddy for some unknown reason. I've quite a few of those as well. They (unlike the other bits) corrode quickly if left out in the weather. I have milled enough of one of them to make a respectable pile of fine swarf and tested it on an insulating firebrick with a torch. In that form, it oxidises readily rather than melting, but it will not burn unlike purer magnesium. In bulk, it melts in the furnace well and produces clean ingots. I just haven't got any projects for it in the pipeline.


I've spent the week making patterns for five different castings, varying from simple to adventurous and have spent the last couple of days making flasks. There's vastly more woodwork in this casting game than anything else. surprise

Edited By Mark Rand on 05/04/2020 18:00:54

Thread: Myford Mk1 Super 7 restoration
05/04/2020 17:42:50
Posted by V8Eng on 05/04/2020 13:47:35:

Please Please promise that you won’t connect that lathe up to power again before you’ve had those electrics professionally checked out!

Looking at your pictures I am sure you have some serious safety issues!

Edited By V8Eng on 05/04/2020 14:04:20

Edited By V8Eng on 05/04/2020 14:08:51

Why do you think that? Yes it's old. Yes there isn't secondary isolation over the wiring. Yes it certainly doesn't comply with the 18th edition of the Regs, but there is no intrinsic danger visible...

Thread: New design of mains plug?
31/03/2020 00:57:18

Just repeated what others said, so deleting it!

Edited By Mark Rand on 31/03/2020 01:02:17

Thread: The Workshop Progress Thread 2020
31/03/2020 00:40:46

Having melted many, many disassembled hard disks, plus a couple of decent sized castings last week, I've now got 75kg of aluminium ingots in three different alloys. Spent today starting to make wooden patterns for some bits I'd like to cast.

It would be far cheaper and quicker to buy some large lumps of aluminium and mill the bits from solid, rather than making close-to-size castings and cleaning them up. But where's the fun in that? laugh

Thread: band a bond belting
30/03/2020 03:17:50

Use a fairly substantial piece of gauge plate or CRS. Heat it until it is hot enough to melt the belting after no more than a couple of seconds. Hold the ends of the belt at right angles to it for four or five seconds to get them well melted. Now hold the ends of the belt together firmly, without moving for a minimum of five minutes, preferably ten.

It's most important to keep the pressure on and avoid movement for far longer than appears neccessary. It takes time for the centre of the material to solidify and it takes more time for it to cool enough to have any strength.

Then leave it for a while longer, trim the flash off the joint and it should be ok.

Thread: A free ride to hospital
12/03/2020 23:24:55

But the coolant on the surface grinder washes all the fines into the tank anyway. There isn't anything left to catch fire...

Thread: Chronos multifix toolholder
07/03/2020 00:21:21

The photos on Chronos's web site show a tool system that may well be sourced from Create Tool. It would be nicer if they stocked more than one type of individual toolholder and also if they used the standard Multifix part numbers, the same as everyone else do (so you know that a 150-300mm swing is really a type A, etc)

Thread: DVLA Scam
29/02/2020 21:12:54

Note that when the DVLC (or A, nowadays) send you the letter telling you that you neer to re-licence/tax your vehicle, there is a URL on that letter that will take you to the relevant web site and also a reference number that will link them directly to your vehicle. They do try quite hard to make it easy for us

Thread: All things Beaver Mill
27/02/2020 21:45:02

It doesn't do any harm to use some low strength 200 series Loctite on the two locknuts. Torsional vibration from a worn drive spline (especially with a shell/face mill) can rattle them loose.

I guess that Beaver were pretty limited for choice in making space for the 40 taper spindle in the existing quill. Opening the bore out to take the more common 80mm OD bearings would be very marginal.

Thread: Coal being phased out
21/02/2020 23:53:13

To the last two posters, you wouldn't show your bare arses and balls in public. Please desist from showing your ignorance in public as well.

Thread: Trolleys at Lidl/Aldi
20/02/2020 21:22:05

Or at least spray 2/3 of the number with Ensis, LPS3 or Rustillo so that they would be usable when the first part of the delivery had died. laugh

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