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Member postings for Michael Cox 1

Here is a list of all the postings Michael Cox 1 has made in our forums. Click on a thread name to jump to the thread.

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Thread: casting small parts
09/03/2011 10:30:11
Hi Gordon,
Polystyrene foam is used for lost foam casting. The conventional white packaging foam is ok for large parts that will be machined afterwards. This type of foam gives a rather coarse finish. The blue closed cell "styrofoam" is much better for for small parts and give a good surface finish. It is available on ebay.
When the alumimium is poured the foam firstly melts and soaks into the surounding sand. As it gets hotter it depolymerises and changes from polystyrene back to styrene. Some boils and exits the mould and catches fire during the pour.
Most of the changes occur at the surface of the molten aluminium from whence all the vapours can escape into the surrounding sand and they are not then trapped in the casting so there is little or no voidage generated in the metal.
Yes, there is some smell and a little smoke when the vapours burn but not that much. Most of the styrene ends up in the sand and is trapped by it.
Polystyrene foam is the only common foam with the right properties for lost foam casting. Polyurethane foams are unsuitable because they do not depolyimerise but decompose producing a hard black char and some very toxic gases. Polyester foams, such as used to make sponges, are too soft to model accurately.
Mike
Thread: Stanley Hand Drill
05/03/2011 14:08:46
You could buy a standard 1/2" chuck and drill out the back. Then make a sleeve internally threaded with 7/16" x 26 tpi. The sleeve could then be loctited ito the back of the chuck.
The other way would be to dismantle the drill and turn down the spindle end to 3/8" and thread this to suit a standard 3/8" chuck.
Mike
Thread: casting small parts
04/03/2011 08:05:52
It is not difficult to melt and cast aluminium especially for relativly small items such as the ones that you show. If you have a big propane burner you can probably get away with a stainless steel mug or pot as a crucible surrounded by insulating brick as a furnace. Thermalite or Celcon blocks from your local builders merchant make good insulating bricks and are relatively cheap.
 
If you can model the parts in polystyrene foam then it would be very simple to cast these by the lost foam method.
 
For details of simple foundry methods see my website:
 
If yyou decide to cast the parts give some consideration to sensible safety precautions.
 
Mike
Thread: Case Hardening
03/03/2011 19:43:22
It is fairly easy to case harden steel simply by packing the pieces in powdered charcoal in a steel tube. If the pieces are small then simply pinch off bothe ends of the tube to exclude air. Half an hour at bright red heat gives a surface which, after quenching , is glass hard. Mixing about 10% sodium bicarbonate (baking soda) with the charcoal seems to speed up the process a little.
 
The active ingredient of Kasenit was sodium or potassium ferrocyanide. This is available on ebay.
Thread: What motor should i use?
21/02/2011 17:43:52
Hi Nic,
I have fitted a leadscrew motor to my minilathe. You can find more details here:
 
 
I hope this helps
 
Mike
Thread: Broaching Keyway
11/02/2011 14:00:09
I made a small hole keyway cutter that was essentially an adjustable broach. I think this would work quite well for what you want to do if it were scaled up in size. Full details are here:
Mike
Thread: Square peg in a square hole
04/02/2011 08:59:38
If you want to make a clock key then I think you could easily form it. For example, if the key is 2 mm square it has a circumference of 8 mm. Take a piece of thin wall tube with about the same internal circumference = 8mm/PI =2.5 mm. Tap a piece od 2 mm square bar into the tube and it should deform the tube to a square shape. It will be a tight fit and to remove it then gently hammer the external faces of the tube and the 2 mm bar should come out. Then braze or solder a handle on the square tube. You may have to anneal the tube during the forming operation to prevent it splitting.
I have made hexagonal steel sockets by this means - see:
Hope this helps
Mike
Thread: Flycutter with 2 Morse taper and M10 thread
20/01/2011 13:48:00
Hi David,
Try this link instead:
Mike
20/01/2011 10:30:57
Hi David,
I too have searched for an M2 flycutter with an M10 thread. They seem to be very rare!
I ended up making a flycutter as shown here:
I guess you were thinking of the 3/8" BSW studding in order to make a drawbar. It would be very quick to single point thread both ends of a piece of 3/8" round in order to make a drawbar.
Mike
Thread: radius dresser
09/01/2011 17:25:44
I  have designed a ball turner, I think the one that TerryD refers to, that can cut right round through 180 degrees swing. It is described here:
The only real limitation is that the ball must be attached to something that drives it during the turning operation. As the cut approaches the driven part then this gets thinner and thinner and will eventually break before a complete ball is actually formed.
Mike
Thread: Diamond tool holder.
01/01/2011 15:02:09
Although the tangential toolholder described in MEW 156 is not difficult to make I have designed a similar tool which avoids having to set up compound angles for milling. The holder is easily made from a piece of 1/4" steel plate. Full details are on my website:
Mike
Thread: Power X feed
21/12/2010 12:13:24
Hi John,
Thanks for your kind words about my minilathe cross slide power feed. I have recently added a power feed to my X1L mill that may interest you. You can find it here:
Mike
21/12/2010 08:47:45
I have modified my minilathe to provide a powered cross feed. I think this would be readily adaptable to other lathes. Details are here:
Mike
Thread: HSS tool inserts
20/12/2010 14:30:54
If you braze HSS won't you ruin the hardness? My understanding is that HSS softens if held for anytime above 500 degrees celsius. Brazing and silver solder  both melt at greater than 600 degress.
Mike
Thread: Cleaning up after Silver soldering (brazing)
19/12/2010 12:30:35
You can buy spirits of salt (hydrochloric acid) from Toolstation (www.toolstation.com). This is a very effective pickle for copper and steel when diluted 1 part spirits of salt to 5-10 parts water. Make sure you keep it in a well stoppered bottle since the fumes promote rapid rusting af any steel around.
Mike
Thread: Fluxes
09/12/2010 13:13:40
I have used borax for flux when silver soldering. My technique is to apply the borax as a paste, heat the workpiece(s) up and when the borax melts to a clear glass then apply the solder.  By heating before applying the solder, then you can bring the borax to its active state before filling the joint.
Mike
Thread: Gauge Plate specs
03/12/2010 20:42:10
Hi Chris,
Guage plate is high carbon steel that can be hardened and tempered like silver steel. It machines reasonably well in the as received soft condition.
The only problem I would forsee using it for gib strips would be that hardening and tempering may introduce distortion.
Mike
Thread: How to determine the pressure angle of gears
19/11/2010 12:38:23
Hi Howard,
I tried the plasticene sausage method and could not get repeatable results. I also had problems on my mod 1 gears with the plasticene detaching cleanly from the gear.
Mike
18/11/2010 22:57:02
Hi Peter,
Thanks for your kind words.
The website is mine.
Mike
18/11/2010 19:11:23
Hi Clive,
I recently had the same problem of determining the pressure angle of a gear. The most successful way is described here:
I hope this helps
Mike
<< First < Prev 20 21 22 23 24 25 26 27 28 Next > Last >>
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