Safety: Radial Arm Saw

Greetings, this is my first post :)

I'm employed as a consultant in health and safety and due to a recent mishap, I'm reviewing some practices in relation to the use of radial arm saws.

We've had some debate / disagreement on the width of the slot in the fence for radial arm saws and I was wondering if anyone could provide an answer or guidance?

I’ve been advised by a supplier of radial arm saws and also a contractor who services them that:
• The rear fence should only have a slot cut for the blade to pass through. The slides are designed to rise and fall to pass over the fence and the material being cut.
• If cuts were made in the fence for the sliding guard, they would inevitably get caught up.

This is disputed by a colleague who (like me, doesn’t have a trade background) and is going from what he’s been told / shown in workshops. He believes the slot has to be wide enough for both the guards and blade.

I’ve also seen for myself at some workshops that they’ve cut the slot wide enough for both the guards and blade.

I have conducted my own research, but haven’t been able to find anything definitive.

If you are able to provide an answer, that would be greatly appreciated :2tsup:

Cheers

Mark

welcome.

I'd caution you from relying on "the internet" for a source of guidance, rather than the acceptable OHS guidelines from Worksafe Australia or similar.

Perhaps if you were more transparent on the incident in question or the situation that came up, or even the actual equipment in question, you may get more relevant info

Good luck on finding an answer.

Quote:

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Originally Posted by Baron_Samedi

I’ve been advised by a supplier of radial arm saws and also a contractor who services them that:
• The rear fence should only have a slot cut for the blade to pass through. The slides are designed to rise and fall to pass over the fence and the material being cut.
• If cuts were made in the fence for the sliding guard, they would inevitably get caught up.

---

That is correct

Why would you rely on "a colleague who (like me, doesn’t have a trade background) and is going from what he’s been told" rather than the advise of the manufacturer and a professional who works with RAS every day?

While in this case I agree with the Manufacturers (and they are good for covering legal backsides) we know they are not always "right" and I think the OP has the right to ask the question.


However, as for getting advice from the internet, its a common method used to validate "biases" - don't like an answer or explanation, just look hard enough on the internet and you will usually find one you like :D

Somewhere on the web is a list of 100's of reported injuries with various bits of WW gear. The section on Radial arm saws may be revealing.

If the fence is tall enough that it fouls the guard then it will have been modified and the tool isn’t being used as per the OEM design. Look at pictures of these tools when new, you’ll see that the guards generally come in two forms. Older machines have fixed guards that only cover the top half of the blade; more modern designs have retracting guards. In both cases though, the fence is just low enough to clear the guard and the slot in it is for the blade only. Ideally the gap should be zero clearance so the saw cannot pull anything into it.

If a machine has the fence raised sufficiently that it requires clearance for the guard also then as per general HSE guidelines additional safety measures must be implemented to mitigate against the loss of support for the workpiece such as clamping mechanisms and sacrificial backing.

The most common incidents I have witnessed with RAS and SCMS are the workpieces being grabbed by the blade and pulled into the gap between it and the fence; this is usually caused by two things:

1) The gap in the fence is too large and the workpiece is too short; eg someone is holding onto a small piece with their left hand and are just trying to take off a small slice that isn’t bridging the gap in the fence. Result is the workpiece is jerked violently into the gap and the operator’s fingers are thrown towards the front of the blade. The only safe way to trim small bits is to clamp them into a fixture.

2) The operator is making repetitive cuts against a fixed stop, eg cutting table top mounting buttons. He’s holding the long blank in his left hand and feeding it along the fence until it hits against a stop block he’s clamped onto the RH side of the fence. What can (and DOES) happen here is that once severed the button has nowhere to move other than towards the blade. It then catches on a tooth which tries to force it into the fence gap and ends up being violently pinged across the workshop. The safe way to make these cuts is to position the stop block about 5mm further away and use a spacer piece between it and the workpiece. Insert spacer, slide workpiece along fence until it hits spacer, clamp workpiece, REMOVE SPACER then make the cut. Now the button can move freely away from the blade.

Hello and many thanks for the reply...absolutely agree about not being able to rely on the internet...I have read a number of OHS guidelines (safe use of machinery, industrial technology and design guideline, safeguarding of machinery and plant) and none of them give specific guidance on the slot in the fence. I can't give too much information on the incident as there are issues of confidentiality and WorkSafe WA is investigating. I have to conduct my own separate investigation on behalf of my employer and although it appears the gap in the fence wasn't a contributing factor, it is still something which needs to be looked at. I've even asked WorkSafe for guidance and was told: It is inappropriate for me to provide technical advice relating to the saw, particularly while my enquiries and investigation are ongoing. Your best option would be to engage a suitably qualified and competent person such as an engineer or manufacturer of radial arm saws to provide this technical advice (my employer may have to do this, but I still like to conduct my own research). Thanks again and cheers :2tsup:

Thanks and cheers :D

Hello and thanks for the response :2tsup:

I'm not relying on my colleague at all, especially as he hasn't been able to substantiate his opinion with evidence...my posting is part of my research to prove him wrong (if I can) :D

Thanks again :)

Hello and many thanks for the response :)

Not knowing what "vintage" of RAS in use or the task being performed at the time its difficult to give anything other than general advice. Like any workshop machinery there are proven "safe operating practices" which reduce or eliminate hazards, so specific training is important.

I've used RAS's for the best part of 50 years, the first 10 years pretty much as a daily task (timber frame construction then truss plant), the rest irregularly as a hobbyist, and agree mostly with Chief Tiff's response. All of the RAS's I have used are not "trigger switch" actuated like the more modern SCM's.

One thing CT did not mention is the use of the stops on the radial arm - these are usually used to set the width for ripping but should also be used to limit the travel of the saw blade across the width of the table. (edit - we used a modified G cramp as a limiting stop on the radial arm of our DeWalt RAS's)

Most of my experience is with the older style DeWalt RAS's. The RAS is a very versatile machine that can perform a multitude of tasks from traditional docking / cross cutting, ripping, cut daddo's, "pointing stakes", then the various "splayed cuts," & "trenching" - a now pretty much a discontinued practice of cutting in one pass a full width 50 mm x 12 mm deep housing in wall framing top & bottom plates for studs.

RAS's are also designed for "right handers" with the motor mounted to the RHS. This permits the dominant hand to control the saw cut, with the left hand to "feed" stock. Mostly stops are fitted to the RHS of the blade for convenience and under the electric motor, restricting access for fitting work holding clamps to hold short components. Chief Tiff's practice of using a stop plus a spacer is one method to minimize the hazards of a block becoming caught up between the blade and stop then flung out.

Another is to use a simple hinged counter weight arm mounted on the fence; or a horizontal action toggle clamp mounted to the table to hold the cut work piece. Some tasks are best performed, and offer more control if the fence stop is set up on the LHS of the saw, especially small components.

The fence on a RAS must be treated as a consumable item as the saw kerf slot does suffer considerable wear. We made our fences as a two or even three part fence that butted at the saw kerf, or had a swap out centre section when the fence was set up with a measure. As the kerf width widened the fence/s or a section was removed & replaced or more commonly interchanged for another with the two part "old" fence having the kerf ends re-trimmed square and set aside for the next swap out.

The fence height (& thickness) should also match the stock height being used for cross cuts, daddos etc i.e. if the RAS's main task is cutting 19 mm thick stock it is preferable that the top of the fence is 25 mm and no more than 30 mm above the saw table. This allows the guards to ride up and over as designed BUT is low enough to prevent errant fingers from contacting the blade from the side/s and front. A housing (down to the height of the stock) to allow the saw blade and guard to pass through the fence may be one method of achieving this!

"Pointing" of stakes presents a more hazardous situation as a wedge may be drawn into the fence kerf IF the off cuts are not constantly cleared away. The local Endeavour Foundation produced many tens of thousands of survey pegs, survey stakes, gardening stakes without any serious problems through setting up a secondary purpose built fence to align & hold the stock being sawn.

Splayed cuts i.e. truss webs, @ compound miter cuts with very acute angles are best cut using a secondary / auxillary fence normal to the main fence, or at a convenient angle that is ergonomically efficient for the operator and maximizes safety. We often employed a "guard fence" offset and parallel to the secondary / auxillary fence with sufficient clearance for the stock and a waste exit. When employed with the RAS arm stop it prevented contact with the saw blade as the blade was limited to not clear the "guard fence."

There are a number of other simple procedures that improve safety - eg. setting the saw table and auxiliary in feed / out feed tables with a slight fall to the rear of the table - helps to prevent a running saw from creeping forward IF the operator is not holding the handle!

Edited to clarify a few matters.

Tip, a DeWalt RAS I have came from a friends Cabinet Making shop and had a neat feature - a 16 mm wide dovetail slot across the table on the CL of the saw kerf that housed a sacrificial piece. As they cut a lot of panels for shelving this little modification helped reduce tear out on the underside of a board.