Member postings for Michael Cox 1

I finished my clamp-on soft jaw project. Full details are given here:

http://mikesworkshop.weebly.com/soft-jaws.html

Mike

Try ball point pens or disposable lighters. These are full of small springs that might be suitable.

Mike

If it is only 8 weeks old it is still under guarantee. Have you talked to Chester?

Mike

I have read Harold Hall's articles on his website about soft jaws and their uses. They seem to be very useful for some types of work holding. My mini-lathe only has a cheap 100 mm imported chuck and there are no soft jaws available for it..

I have an idea that enables soft jaws to be clamped onto the outside jaws of the chuck.

The photo shows the soft jaw on the chuck.

This shows the soft jaw removed from the chuck. Note the M6 grubscrew on the right hand side. This is used to clamp the jaw onto the outside jaw.

The soft jaw clamps onto the outside jaw as shown above.

This shows the underside. The milled step clamps against the first step of the outside jaw.

So far I have only made one prototype jaw to test the concept and it seems to hold well. I have ordered material to make a full set of 3 jaws.

Is this a new idea? Does anyone have any comments? Can anyone see any pitfalls?

Mike

Using plastics for machining practice is a good idea. My first tries at single point screw cutting were carried out on 20 mm plastic (PVC) conduit just to discover the potential pitfalls. This size fits nicely in the spindle bore of the minilathe.

The big difference between plastic and most metals is the low modulus. This means that thin sections bend much more than the same thickness of most metals so the protrusion from the chuck must be much less or else the material moves away from, or worse still over, the cutting tool. Plastic also do not like the use of normal steadies as these tend to score or scratch the surface. Steadies with ball bearings on the ends of the arms are OK.

Acetal (Delrin) is one of the easiest plastics to machine in my experience but PVC and nylons also machine well. Thin sections of polyethylene and poly propylene bend very easily making them difficult to turn accurately. Plastic kitchen chopping boards (these are mostly polyethylene) are a good source of sheet plastic for milling practice.

Sharp tools are essential and water is a good lubricant / coolant. Blunt tools and high speed will cause some plastics to melt rather than cut.

Mike

The chemistry of case hardening is quite simple. You seal the component in a container with carbon donor material such as charcoal and heat it to circa 800 degrees or so. The source of carbon is not so important it can be leather, bones, charcoal etc. It is useful to add barium carbonate or sodium carbonate as an activator (circa 10%). The longer you heat it the deeper the case. Like most diffusion processes the depth of the case will depend on the square root of the time. Thus it will take 4 time as long to double the case depth.

Kasenite and similar materials are slightly different in that they contain both carbon and nitrogen both of which are hardening agents for steel.

Mike

Borax has been banned in consumer products by the EU so I suspect that it is no longer available.

Hi Geoffrey,

There is much general information about the WM180 on this website:

http://andysmachines.weebly.com/

Unfortunately, Andy passed away last year so you cannot contact him for advice.

Mike

Just a thought but you could try a 90 degree carbide router bit.

Mike

I bought the mini mole grips last week. I am very pleased with the quality of the grips. How can they make three pairs of grips for £4?

Mike

My first attempts at milling were carried out on my minilathe using the Seig milling attachment. This is not a very satisfactory milling attachment. A good criticism of it is here:

http://andysmachines.weebly.com/the-vertical-milling-slide---criticisms.html

I persevered with it for some time and managed to do some milling but in the process I broke/chipped several milling cutters. These breakages were partly due to the sloppiness of the milling attachment, cross slide and coarseness of feed but mainly due to inexperience. The lessons I learned from this were:

a. I needed to buy a milling machine

b. I needed to make a cutter grinder in order to recover broken/chipped milling cutters

I purchased an X1 milling machine from ArcEurotrade and almost instantly milling became much easier.

At around the same time there was an article in MEW by Ralph Sparrow (MEW 117 July 2006) entitled "Sharpening with diamond discs". In this he described a jig that held the head of a flexible shaft, attached to a rotary tool, at an angle that could be readily set. This was designed to fit on the bed his Unimat lathe and using this set up and a small diamond disc in the flexible shaft head he was able to sharpen lathe tools, milling cutters and twist drills. These diamond disc are readily available from several suppliers including Arc Eurotrade. This all sounded very good and I went on to build this lathe attachment and various jigs to hold tools, milling cutters and drills. My rotary tool flexible drive was from ALDI and the head had much end and side play. I had to rebuild the head of the flexible drive in order to be able to rotate the diamond disc reliable without wobble or end play.

I used this arrangement on my lathe for some time and produced some good results sharpening all my broken/chipped milling cutters. It was even possible to sharpen cutters as small as 3 mm diameter because the diamond discs had a very well defined edge. The only thing I did not like about the arrangement was all the dust flying about so close to the lathe.

I had made a lower base for the topslide of my minlathe and I had the old one spare. I also had the old minilathe milling attacment and I started to think about making a dedicated cutter grinder based on these components together with the Ralph Sparrow attachment. I ordered the the top part of the topslide from Clark (it is a Clark minilathe) . I used the milling attachment to provide the infeed and the topslide to provide the crossfeed and made a small fabricated track for the Ralph Sparrow part.

The completed cutter grinder is shown here:

The milling attachment and the topslide are clearly visible. On the topslide is a rotating table that holds the jig that holds the cutter. The rotating table has a an angular scale and it can be locked at any angle by pinch screw. The Ralph Sparrow attachment is on the right hand side carrying the flexible shaft head. This sits on the fabricated track.

The unit is small with a footprint of about 300 x 300mm.

I hope this is of interest to others.

Mike

Neil - white led viewed through a CD?

Mike

Hi Ed, Soft soap will reduce scaling but not eliminate it entirely. You will probably need to re-polish the knurls after the quench. It is only necessary to re-polish one side of the wheel in order to see the colour change.

Alternatively you can temper in a bath of hot oil at a controlled temperature and no polishing would be necessary.

Mike

It always surprises me when manufacturers choose odd sizes for components.

In the case of small drilling machines 46 mm for the support tube seems to be common to a number of manufacturers. But why iuse a non standard size? A standard size like 45 or 50 mm would seem much more logical. I did think that maybe 46mm was a metric conversion of a common imperial size but it works out as 1.13/16" which does not sound particularly common either.

Mike

I think that the voltage from the transformer and on the capacitor is more in the region 1.5 kV not 150 kV. This is still very much a lethal voltage so care is required. After a few days of not being used the capacitor will be discharged in my experience but I still wear thick gloves and short out the capacitor before dismantling, just to be sure.

Mike

The owner of the toolandmods website is Jose Menezes. He is a Portuguese, a perfectionist and a professional photographer. His site was very active until about 3 years ago. Since then nothing seems to have been added.

Jose also hosts all the drawings prepared by Ralph Patterson of the modification he made to his minilathe. This is a useful resource.

Mike

I too have used ABTEC. Very friendly, good helpful advice, good prices and fast delivery.

Mike

Have a look at this:

http://www.toolsandmods.com/lathe/mini-lathe-spindle-nuts-wrench

This could be easily scaled down to suit your application.

Mike

Hi Dias,

I bought the ice stick tray in Continente in Espinho (near Porto). They were in the 1€ promotional bins with other household items. I bought them about 8 weeks ago. I was in Espinho last week and managed to pick up one more.

Mike

The same supermarket did sell some very cheap, good wine which made it all worth while!

Mike