Milling Machine

Hi,

A gold star for service from Pantograph Services.

The drive belts arrived today, having been ordered yesterday. They have been installed - once I worked out how to adjust the tension - and all is working smoothly.

Richard

adrian said:

Thanks for that - as I have very nice solid Jones & Shipman vertical drill so some pointers as what constitutes "a modern 'no-volt' arrangement" and why I might be "happier" with such a setup would be appreciated.

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The purpose of the 'no-volt' release (NVR) is to prevent the automatic restart of equipment in the event of a supply failure. It's good practice to use a NVR on a machine tool, as in the event of power failure or trip the machine will stop, but if you don't isolate it at the mains, then as soon as the power is restored it will restart automatically with potentially disastrous consequences... Unless a NVR is fitted of course.

A NVR consists of a relay with one set of contacts holding the coil energised. The start button bypasses these contacts when pressed. After the start button is released the contacts on the relay keep the coil energised. The stop button is a normally closed contact that breaks the current to the coil when pressed. More expensive NVR's also have thermal overloads which trip the NVR off if the current exceeds a set value for a period of time. I'm obviously describing single phase switching here, three phase is the same in principle but with more coils etc. Incidentally, you may also see them described as motor starters.

For instance, basic no-volt on/off single phase switch:

Axminster NVR Switch c/w Box 230V 1ph

With a stop button that's easier to hit in an emergency:

KEDU NVR Switch 230V 1ph E Stop

The luxury model with a thermal trip:

Axminster NVR Switches 230V 1ph

Obviously these are retail prices, if you look on eBay you will find the last example available at much lesser prices - this is where I got all mine from. As I also say above; don't forget to check the wiring and motor insulation as well.

Hope this helps.


Andrew

Dikitriki said:

Hi,


..................What milling cutters should I get?
The stylus is V shaped. I presume I need a straight sided one to follow a pattern?
Thanks,

Richard

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For profile milling you'll need parallel cutters so a spindle that takes suitable collets is required.

I use 2 flute, 1.5mm dia. cutters for general work, sometimes 1.0mm for fine work, but cutters are available from 0.1mm. I get mine from www.cutwel.co.uk
Cutter dia. and ratio will dictate the dia. of the follower ( guide pin) so for intance 2:1 ratio with 1.5mm cutter and 3mm follower.

Col.