Posted By Stevenb I came across a grinding machine that is used to grind insoles that are then placed in patients shoes to aid there walking. The grinding machine is used around 10 -15 times per week for 1-2 minutes. The run down time is 30 seconds and there is no emergence stop. The machine is operated via a small joystick type switch (left fast, centre off, right slow) and it would be difficult to switch the machine off if the operative became accidentally entangled. No obvious CE mark but as the machine is bolted to a bench cannot view the bottom. Essentially the machine is safe, although if someone where to become entangled (although unlikely- uniform is short sleeve & training and warning sign suitable) the consequences could be server. I have not found much in the way of recommended rundown time? I understand that the machinery require that the machinery must be equipped with an automatic brake that stops the tool in a sufficiently short time if there is a risk of contact with the tool while it runs down. This is a requirement unless the emergency stop device would not lessen the risk or would not reduce the stopping time. obviously we have duties under PUWER as well Would appreciate your thoughts

Posted By Paul Skyrme Steven, First the previous post has some good suggestions. I doubt that the machine is CE marked as if so according to the machinery directive it should have a type of contactor control or no volt release, so that if the power supply fails the motor would not be able to restart on the power resuming. In my opinion it does NOT need a brake, and as the other poster said this could actually be dangerous unless correctly applied. This does not mean it cannot be braked, but I have not yet seen such an application as you describe with a brake fitted. They are present on some larger grinders with wheels around 36" to 42" in diameter, but these are for other reasons and the wheels are fully enclosed when being stopped. To convert this to contactor control would be expensive, as it is a two speed motor. Your description of the switch being a toggle type suggests to me that it does not have a suitable control system, see PUWER regs 14 - 19, HSE ACOP L22 paragraphs 239 to 282. A 2 speed motor controller for a small motor would run typically from my preferred supplier to £268 list price, plus fitting, adding a DC injection brake such as is found regularly retrofitted to hand fed wood working machinery would start at around £336 list, for a single speed motor, dual speed would be more expensive. So you should look carefully at what is needed first to comply with the guidance. However, is should have an emergency stop button and really should have a no volt release control.

Posted By Paul Skyrme Hi Peter/Steven I agree wrt the dc braking, however, it is generally cheaper and simpler on large induction motors than converting to inverters and you can retain the star delta thus giving good starting torque. The large market for this is retrofits to hand fed wood working machinery for PUWER compliance. Small single phase and 3 phase inverters are available as you are no doubt more than aware Peter, going by your email address ;-) I know your Altivar comes with an inbuilt power supply for auxiliaries, but you still need isolation, and contactors, my guess would be around £600 list for a 1 phase, or around £900 list for 3 phase in a panel with buttons isolation etc. plus installation and commissioning? Obviously this depends on the motor rating, but it sounds like a small machine as it is working from a toggle switch. I would love to fit inverter controls as braking retrofits for my woodworking customers, but they would not entertain the cost! It is difficult to persuade them to upgrade the machine to meet the braking requirements of PUWER, let alone the control voltage guidance given in the ACOP, adding in the cost of an inverter and the technical complexity... In this case think of the complexity of this for such a small simple machine? I have in my mind a double ended bench mounted grinder with a wheel of 150 - 200mm in diameter each side? The larger grinders I mentioned earlier were regeneratively braked but not with the energy dissipated via braking resistors, but true regeneration back into the mains supply with some clever control electronics and an active front end. Perhaps the most cost effective option would be to replace the unit with one which is CE marked i.e. complies with the machinery directive etc., then undertake a PUWER assessment once it is installed and commissioned to the correct standards. This could be a replacement grinder, or a linisher/belt/disk sander. Careful on selection of units though as some manufacturers sell equipment which is CE marked, but does not meet all of the requirements of PUWER98. This is aimed at the DIY market where PUWER does not apply. The pricing normally reflects this, if it seems very cheap or is sold in a DIY type outlet then in my experience, there is a good chance that it will not meet PUWER. We see this very often across our customer base unfortunately. Don't forget COSHH & LEV though as your operatives could be exposed to or be breathing in the material removed from the insoles, and that which emanates from the abrasive, do you know what it consists of?

Posted By Paul Skyrme Peter, I realised that you were not trying to advertise! Hence the smiley. I think pretty much we agree on the crux of things. I know there is a safety standard for drives my previous employer was a competitor of your employer, so I am used to the concept! I also appreciate that the cost of "drives" has fallen. PM me if you would like as I would be interested in discussing possibilities. I would pm back but you've turned it off now!