Hi Chris

I believe there will be an electric enclosure that will suit your needs, either in GRP or plastic material, either can be obtained in good IP ratings as long as you use a spindle seal where it exits the box.

Emgee

If I can suggest – the motor on my 180mm diamond lapping machine is tiny, about 60mm cubed, and that uses disk far larger than you plan for your 50mm graver sharpener. It has a belt drive reduction for the large discs to get about 400rpm

Why not look into building a battery-powered machine perhaps using 18660 batteries and a geared DC motor with the disc mounted on a backing plate directly on the output shaft? All you'd need then is a small switch and charging port and mount it all into a plastic enclosure.

1. 20W at 400rpm is on the weedy side, 2000W at 400rpm would be grossly over-powered. 200W at 400rpm has decent poke, should be fine.

2. Cooling depends on the motor. Some are fitted with a fan (impeller), and need a free airflow. Others use the mass of the motor itself to absorb heat, and may be fitted with fins to radiate it. Check the motor rating: many motors limit the amount of time they are allowed to be on and insist on cooling off periods. For example, my hobby grinder's motor is completely enclosed (no air vents) and is rated S3 – 50% for 40 minutes. In other words I can expect 20 minutes worth of hard grinding in any 40 minutes, after which the grinder should be switched off and allowed to cool down. If I overheat it, the insulation will fail. A professional grinder might be fitted with a motor of the same power, but with an 80% or even 100% duty rating – considerably more expensive but it won't overheat in a busy workshop. The 1.5kW motor on my hobby lathe is a fully enclosed 3-phase type with a separate fan running continuously. So far I haven't made it warm! For your purpose, check the motor by hand periodically. When the motor feels hot to touch, it's time to switch off and have a coffee.

3. Much depends on the metal. With sheet clamped between two bits of old angle iron I've managed soft Aluminium for radio chassis up to 3 or 4mm. Mild steel up to about 1.5mm. In both cases it's easier to work with thinner plates! Not all metal sheet is happy to bend: I have tough and springy Aluminium alloy and Stainless Steel plates that resist bending and are reluctant to stay in shape. Avoid bending awkward metals! Not done either myself, but in theory Copper should be easy, and Brass troublesome because it work hardens and might need to be annealed between stages. Car bodies are made from 'Dead-mild Steel', which is malleable. Not found anyone selling it locally, but it must be available to panel beaters.

Dave

Just been watching this video and thought it contained a number of good ideas for fine grinding of carbide with a diamond lap. https://youtu.be/GOBtH4m2TYo

Doug

Are people not over estimating the power needed to sharpen tools for clockmaking with a 2" diamond lap???

I bought a few of these dc peristaltic motors with controllers for £20 off ebay (they cost a fortune from cole palmer,the latest models are almost £1500 for one motor and controller) ,they are only 75 watt and suitable for a lot of smaller stuff. Only problem is overcomming the spiral splined 8mm shaft .

heres one i`ve used for a flexible drive.

Edited By mark smith 20 on 11/11/2019 11:01:54

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One man’s grinding is another man’s lapping

It’s worth looking at this: **LINK**

https://www.eternaltools.com/small-diamond-grinding-wheels

… and especially; noting the grit sizes, and watching the video.

MichaelG.

Once you get down to the 2000g one that is getting into lapping but not as fine a stropping.

Removing metal with a (driven) diamond wheel would be grinding in my book too, however fine the grade.

Ian P

Grinding and lapping are both material removal processes but they are distinctly different techniques as far as I know.

Eze-Lap is just the name the manufacturer chose for the product, I've seen them referred to a diamond 'files' too.

Ian P