Poor Riving Knife Design (large)

[johnelliott]

John..

given that the OME splitter is alive, well and unmodified in any way, it can't be refitted in order to carry the guard when ripping or cross-cutting... because...??

just curious...

CHJ has explained why he feels it is OK for him to work the way he does. But I didn't get the impression that he's planning to refit the original riving knife anytime soon, did you?
John

 

[CHJ]

just one thought; given that you need to put another mounting hole into the Mk2 splitter, would the blade guard still work??

Yes it does.

The guard will fit but results in a reduction of 20 mm in thickness of stock that will pass under it.

It does not contribute to any severe kickback protection other than would be provided by a long bolt positioned in the fixing hole because it just lifts out of the path, as was the case with the original knife.

I am currently trying to source 6mm Pip Pins to replace bolts and nuts in fixing guards, anything that takes more than a few seconds to adjust or refit will inevitably result in the “not bother for this quick job” syndrome taking precedence.
Alternates will be long bolts drilled to take spring wire retainer clips (anyone know of a good source for either Pip Pins or Clips?)

On reflection I checked the original (fitted) 30 tooth crosscut blade supplied with machine, this has a 3.5 - 3.6 mm kerf, no way was the original 2.4 mm riving knife anything other than a support for the guard with this blade fitted.

I have been checking around to see if any manufacturers supply different thickness Riving Knives for their machines, so far I have found non in the DIY/Site Tools end of the market.

IMHO as the Riving Knife thickness is the main factor controlling the likelihood of kickback I find this lack of support somewhat alarming.

Has anyone ever seen a warning with new blades as to the Riving Knife requirements?

 

[CHJ]

CHJ has explained why he feels it is OK for him to work the way he does. But I didn't get the impression that he's planning to refit the original riving knife anytime soon, did you?
John

Your assumption is correct in as far as I have no intention of refitting the original Riving Knife as it provides no realistic kickback protection with either of the blades I currently possess.

I will however be manufacturing a replacement item for use with the 30 tooth crosscut blade as soon as I can locate a suitable piece of material in excess of 3.6 mm thick.

 

[stewart]

This is taking the thread in a slightly different direction but it is to do with fitting guards to a table saw. i'm in the process of making a cross cut sled. I have kept the original riving knife in place and made the back fence of the sled tall enough for the riving knife to pass through. The original blade guard is of course impossible to keep attached to the riving knife. what is the best solution to use as a guard in this case?

 

[CHJ]

This is taking the thread in a slightly different direction but it is to do with fitting guards to a table saw. i'm in the process of making a cross cut sled. I have kept the original riving knife in place and made the back fence of the sled tall enough for the riving knife to pass through. The original blade guard is of course impossible to keep attached to the riving knife. what is the best solution to use as a guard in this case?

No problems from me with direction, if the discussion leads to more safety awareness so well and good,

The only method that I can come up with is what we used on very old (long time installed) machines, primarily for dust extraction to improve COSH standards, but resulted in about the only way you could remind people to protect their hands other than tying them behind their backs and this was a system like this:http://www.axminster.co.uk/product.asp?pf_id=32672&recno=1

I am currently trying to prototype a version that can be made from easily obtained bits from the local DIY just to meet my needs and pocket thus avoiding having to keep changing setups.

 

[Chris Knight]

Stewart,
Re your cross-cut sled. I find the greatest danger with one I have is the possibility of pushing the sled with a hand in line with the blade such that when the fence closest to you passes over the blade you might neatly saw your hand in half. I have seen pictures of some sleds where folk have put a sort of "lump" behind the trailing fence to prevent this

Danger to your hands between the fences can be reduced by either a fixed or hinged perspex cover that sits above the blade (fixed to one fence or both fences)

 

[Midnight]

<chucklin...

I read Stewart's post an thought..Oh...I know this one...

ummmm.... wot Chris said...

 

[DaveL]

a system like this:http://www.axminster.co.uk/product.asp?pf_id=32672&recno=1

Thats a good bit of kit, LOML bought me one for Christmas.

 

[stewart]

Thanks for the link Chas - i think i could make something similar. i have some acrylic sheets from an old greenhouse - is this a safe material to make a guard from?
Chris, thanks for the tip about the block at the back of the fence - i've got one fixed on at the moment but i do need to fit a block to stop the sled being pushed in too far. I think i'll fit a handle to the fence too which will not be in the blade's path just to guarantee i keep my hand!

 

[CHJ]

Thanks for the link Chas - i think i could make something similar. i have some acrylic sheets from an old greenhouse - is this a safe material to make a guard from?

I would think so, most acrylic (for greenhouse use) is reasonably shatter proof. If you look at several of the "professional" machines in something like the Axminster catalogue (on-line) you will see acrylics of some description used.

I am erring towards a wooden top/front surface to increase protection from 'missiles' myself put am not trying to prevent all debris escapes.

I always treat guards as reminders not to put hands passed them, not to prevent an accident from happening.
I have learnt from a working environment that it does not matter how good a guard system you fit, some idiot will always find a way of circumventing it. Despite the impression I may have given some on this forum, I try hard not to be one of those idiots and place reminders in my way whenever I can.

 

[Noel]

Stewart, here's one of my sleds:

Acrylic or polycarbonate blade guard across the two fences. Best to make the fences good and big to support the two sections of the bed. As has been mentioned a block of timber attached to the rear fence will limit the path of the blade but obviously not stop it. You simply feel the blade begin to cut the timber block. For a truly safe setup it's best to clamp a baton on the outfeed side of the saw table to limit the travel of the sled, or fix a chain or cable to the front fence and anchor somewhere to the saw to keep the sled in check until you are used to it. Advance the sled with two hands placed each end of the front fence, but I'm sure you know that.

Noel

 

[stewart]

thanks for the advice, guys
i'll follow it all!

stewart