Member postings for Ian Robinson 4

Thank you. Is zirconium oxide going to be very much better than aluminium oxide for this? They are a lot more expensive!

I understand that you can 'sand' mild steel on a disk sander to round/chamfer edges reasonably satisfactorily [?]. What grits would be best to initially remove metal and then bring it to a finish.

I would just go and buy some disks and try it for myself but the only source for 300mm dia, self-adhesive, zirconium oxide disks (which I am told would be best) and which I can find is £33+ for a minimum order of 10. I would like to avoid the expense of trial and error if possible.

The question related to the feasability of bolting 65mm x 1200mm x 5mm plate to the ends of 125 x 65 x 9.5 parallel flange channel to create a rectangular frame. Working to 2 diameters would mean the bolts could be only 2mm to the flanges [9.5mm thk] and 1mm to the web [5.5mm thk ] which intuitively would seem too small. I think I may have to use corner angles instead.

I will do a stress analysis calculation as Jeff suggests [if google comes up with an explanation as to how to do so].

Ian

Hi Michael

Thanks for clarifying this and apologies for my delaying in replying.

Ian

It will depend upon the material in question, the diameter of the particular screw and the loads involved but are their 'rules of thumb' for deciding how close to the edge of a particular material one can drill and tap to leave sufficient material for a secure fixing?

Thanks for posting this EB - v interesting.

Edited By Ian Robinson 4 on 18/05/2013 09:57:12

Thanks for posting this EB - v interesting.

Thanks for the replies and for V8Eng's liink.

Apparently this Myford lathe had approx 6" centres and were specials made for the brake company, Ferodo in the 1950's.

Going back to my original point/query; when you say you don't think you will be trying it on your ML7, does your concern relate to damage that might result to your lathe or to a likely lack in rigidity or both?

There is an interesting video on You Tube - "Using the Spindle Raiser on a Myford Super 7" (David Piddington 1.10.12) - that doubles the centre height of the series 7 lathes and allows components of upto 14" dia to be machined. Sounds great but what are going to be the long term implications for the lathe bearings, slides, motor, drive etc, etc from the increased loads that will result?

THANKS JD & Rufus et al.

The problem with the flat spring idea is that the crown of its arc increases as the latch is retracted and hits the metal plate approx 1mm before the end travel of the latch. Unless the spring can be bent to eliminate this arc it isn't ging to work. I will explore the effects of the bend a little more but it looks as though two torsion springs may be better.

Ian

I think that 2 would better. You have also bent the end which, looking at the photo of the old spring [see album], there is a slight suggestion that this is perhpas how it was. As an alternative to a wire spring, I was thinking that a flat spring might be an improvement to the design - similar to the one at the other end of the lock but not wrapped around the pins - so it has some freedom to move?

Hi Bear - I thought that this might work but having just measured the inside dimension of the latch case it is 8.86mm so a 10mm wide spring + the end loop of the helical spring is going to be too wide. Thanks anyway - very much appreciated.

I'll go to a shop that sells clothes pegs and see if they can be adapted as Neil suggests. If not, I'll have a shot at making some.

Edited By Ian Robinson 4 on 17/04/2013 08:48:04

I have added copy of the dimensioned drawing of the spring I sent to various suppliers to the album. It has one turn only.

I dont think it is difficult but I do think the latch is poorly designed - particulary the way the spring [which seems undersized for what it has to do] acts on the latch. I just want to replace it with something that isn't going to fail in 5 min.

Edited By Ian Robinson 4 on 16/04/2013 07:31:57

Thanks Stick. I tried the Spring Man [and also Johnstones Tools which Springman links to] without succes.

Edited By Ian Robinson 4 on 15/04/2013 19:10:59

Your right , it is a mortice latch - but with a snib lock, operated by turning one or other of the square spindles on either side of the handle spindle. The latch is part of a plate below the top plate - you can just see it in the photograph but the two plates are independant. It is the latch that 'flops about'.

I thought it would be easy to find a generic spring but so far all enquiries have drawn a blank. A supplier has offered to make some but at a min charge of £60 for 10. I have found something similar but with 6 turns rather than 1.

MG's suggestion is a very good idea - though I think I will try and cold form a few so I have some spares.

Reeves sells 20SWG stainless steel spring wire which hopefully will be suitable?

Herewith a photo of the lock. I have added in red [on the opposite side] how I think the spring fits. I am not entirely clear how the latch actually works. You would think that the 2 no. helical springs would suffice but with them in position and working, the latch itself just flops about. You can see the rough broken end of the spring in the photo. It lasted perhaps 2 - 3 years.

Thanks for the replies to date which as always are very helpful.

Edited By Ian Robinson 4 on 15/04/2013 16:30:35

I suppose what is worrying me is whether 1mm stainless will have a sustained springiness? The door/lock is used fairly heavily.

A small, one turn torsion spring in a door latch/lock I have, has broken. The lock supplier can't provide a replacement spring [but will sell me a replacement latch for £100!]. I cant find a matching, off-the-shelf spring anywhere

I thought therefore, I would make one but have a few questions. The wire diameter is 0.95mm. The spring has one 7mm [int dim] turn with 20mm arms. I assume I need spring steel but have been offered piano wire. Are they the same? I assume it will be better to heat and form rather than cold form? Will I need to temper/harden the spring before use and if so how? Stainless steel may better as the environment the lock is in is damp.

Thankyou

Ian R

Firstly, thank you for the replies to date - much appreciated.

Milling flat edges and longitudinal slots [round and square] on [say] 1200mm lengths of Mild Steel/Stainless Steel/Aluminium flat. Milling a 1200mm long rack. Being flat, the pieces should be easy to clamp and advance against guides but will simply stopping and starting show in a milled face? A good visual finish will be needed for many pieces - which includes aluminium parts that are to be anodised.

Ian

I am wanting to buy a milling machine and I'm looking at the Warco VMC Turret Mill. Whilst most of what I want to do will be within its longitudinal/cross traverse capabilities (370mm x 152mm) some will not be. How practical is it to stop & move the position of a piece during milling to allow a longer piece to be worked and can an acceptable finish & accuracy be achieved doing this?

Ian R