Title: Emergency Stops for the Hardinge Lathe

Submission Date: 09/12/16

Current Status: Cancelled, pending purchase of lathe more suited to Hackspace needs.

Proposer: David Smith

Description: Provision of emergency stops for the Hardinge Lathe.

Rationale

This proposal is to provoke discussion and, hopefully, agreement on the provision of emergency stops on the Hardinge lathe.

The lathe is a large and powerful machine which, in the event of an accident/misuse could cause considerable injury and/or death. It is the opinion of the proposer and other Hackspace members that the current mechanisms for stopping the machine (one flush “stop” button on the lower-left control panel) are inadequate for stopping the machine in an emergency.

It is appropriate that the decision of what level of provision is sufficient should be decided by the Hackspace membership as a whole, rather than the decision (and therefore the liability, should it be deemed inadequate at a future date) falling on a single individual.

This proposal does not request funding at this stage (although costs are considered). It is purely to gain a group consensus on the appropriate level of provision.

The options below are not considered to be mutually exclusive; in fact, it is expected that a number of them will be implemented (but not necessarily all). In addition, it does not consider where/how (schematically) the stops are wired in, just where they should be physically located and what form they should take.

Please refer to the attached photo which shows each of the proposed positions in yellow.

Option 1: Upper control stalk

A standard emergency stop mushroom could be fitted in a box screwed to the side of the existing stalk.

The advantage of this is that it is directly in front of the user's eyeline as they are using the machine.

It also means that the wiring would be entirely self-contained.

Cost: Low - estimate £10-20

Option 2: Kick bar

A length of box-section steel (the proposer has a suitable piece available) could be attached to a pair of trailer dropside hinges: Example hinges on eBay this would allow the bar to hang across the front of the middle section of the lathe, a small distance (e.g. 2cm) above the floor. Behind the bar would be placed one or two standard emergency stop buttons. Should the user be unable to use their hands, they can stop the lathe by simply kicking the bar, which operates the button(s).

Cost: estimate £25-30

Option 3: Control panel

An emergency stop button on the existing control panel on the lower-left would probably be the easiest to access for someone coming across the room to assist a lathe user in difficulties.

Option 3a: Control panel - replace existing button

The existing “stop” button could be replaced with a raised “emergency stop” mushroom. This would look neat but the current switch uses a 30mm panel hole. Most industrial control switches have now standardised on 22mm panel holes. 30mm switches are available, but are significantly more difficult to find, and are commensurately more expensive. Cost: estimate £20

Option 3b: Control panel - new button

A new hole could be drilled in the panel, and a standard 22mm button fitted. This would be further down the panel. Cost: Estimate £5.

Option 4: Wall

A switch could be attached to the wall adjacent to the lathe. However, it does mean running an extra cable between the lathe and the wall, so this is not a self-contained solution. May require landlord's approval to drill fixing screws to the wall. Cost: Estimate £10-20.

Option 5: Pull cord

A pull cord (typically steel wire, but the Hackspace could choose to use something else like nylon washing line) could be hung across the lathe working area, attached to an appropriate emergency stop switch. The user then simply has to pull on the cord, and the machine stops. This solution does, however, have a few issues:

  • It is not self-contained, requiring wires run from the lathe control box plus the switch and pull cord attached in appropriate places
  • May require landlord approval for wall fixings
  • The switches themselves are expensive.

Cost: £100+

Option 6: Powerfeed Control Module

An alternative to mounting on the wall, a button could be mounted on the top or side of the powerfeed control module. This would allow the wiring to be self-contained inside the lathe. If mounted on the top, care would have to be taken to ensure it does not obstruct maintenance by preventing the saddle being slid off the lathe bed. An alternative would be either to mount the button on the side facing the wall (where it would be less visible), or attach an additional box to the side of the control box, so that the button can be mounted facing the user.

It is the proposer's opinion that options 1, 2 and 3b should be implemented. Cost: Low - estimate £10-20

Budget: None

Funding source/model: N/A

Resources depended upon:

Member supporters:

Committee supporters:

  • botlab/hsproposals/hsproposals_2016-12-09-emergency-stops-for-hardinge-lathe
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