Just purchased an older Unisaw (34-450) It doesn’t have a traditional type riving knife. From what I can tell, it’s a splitter? Can anyone please tell me more about this as to its safety? Pictures attached
Also, the blade guard? I can’t make heads or tales of it. It doesn’t appear to have points of attachment on the table. It’s probably not the right one. The guy I bought it from said it worked but didn’t know how.
Lastly, the Unifence. It glides across the table ok. Its certainly not perfect. Should it glide perfectly?
Replies
Idk, I’ve never actually seen a blade guard installed on a table saw, the other part is a splitter with the anti-kickback pawls. riving knives are a relatively new invention and most older Unisaw cannot be fitted with a real one.
traditional type riving knife misses the point; traditionally most saws do not have riving knife.
My Unisaw is 1998 or 1999 version. The splitter can be installed easily. It should be a bit thinner than the kerf of the blade. I grind sheet metal about 0.1 inch. The idea is to allow easy entry of the work into the splitter at its front end and allow the splitter's farther end to push the work against the fence, to hug it. I bend the splitter on a vise with large pliers a bit to achieve this slight slant.
My splitter has a slot instead of a hole, so I only need to loosen the bolt but not remove it while I take the splitter off.
The riving knife is a splitter that is 2-3 inches closer to the blade than the traditional splitter, so if the wood opens up due to pressure relief after ripping it would better do so after the splitter. I tend to think this is the advantage.
There has to be vertical downward pressure on the outfeed to prevent kickback, but on the outfeed there cannot be lateral pressure on the ripped side because the wood will bind with the blade. But you need the unripped side to hug the fence. This is really the crux of ripping, and difficulty and danger.
I would check the FWW archives to make sure that you are getting correct information and not just someone's understanding (or misunderstanding) of the differences between a splitter and a riving knife. Forums are great when you ask for opinions, suggestions, etc. but not always correct when you ask a technical question. I've even seen electrical wiring procedures posted on another site that were totally incorrect ("just connect the white, black and green wires together with a wire nut") and presented as gospel by a poster who claimed to be an experienced, licensed electrician and was neither.
Wow, asking questions about a topic in one thread and presenting firm advice on it in another. Pretty wild.
PLEASE do not make changes to your saw's safety features. Most manufacturers work hard to get them right.
Aftermarket solutions are out there also, as MuskokaLayne states.
Hi, I have an older Unisaw (60’s) and love it. I have a few excellent upgrades including a Shark Guard Riving Knife and an aftermarket fence from Busy Bee Tools in Canada - so Grizzly in the US might have an equivalent fence.
The riving knife works perfectly but must be raised and lowered manually, not really a big deal for the safety it adds.
I used to have the splitter that your pictures show and I’m much happier with the Shark Guard for ease and safety. Any questions, feel free to let me know, thanks! Layne
Amen, MJ. Some people just want to hear themselves talk (or in this car, see themselves talk). That's fine if they are just critiquing a design, but very bad when they give dangerous and ill-informed advice.
Sorry to put this person on the spot, but he/she shows no understanding of the function of a splitter or riving knife. If this post keeps just one person from bending the rear of their splitter towards their rip fence, it will be worthwhile.
It will be helpful if you would elaborate on the function of the splitter and riving knife. Discussion is helpful. I like to listen.
Some wood workers have one or more wedged or T-shaped splitters dangling. It is inserted after the cut emerges, on the spot. Is this the manufacturer's design? Is it safe?
No and yes (not less safe) I think. If you don't think so, why?
For the Delta Unisaw and most other saws of original, old design, the splitter is a part of the guard. The sheet metal is quite thin, much thinner than most kerf, and it is uniformly so because it is straight. This type of guard is more for safety than functionality.
To rip with precision, the side that is intended to hug the fence must actually do so. If it is wide enough, one can use friction and slant angle of force to achieve both lateral and downward pressure. If this side is narrow, one can reply on mere downward pressure and just hope that it has not moved sideway--less certain.
If you view using the splitter as an aid to enabling the side that should hug the fence actually does so as abuse or added danger, please explain.
Highdesert, bending the splitter toward the fence to hold the wood you are splitting against the fence is inherently dangerous. As you are ripping the wood this could now allow the opposite side to drift or close onto the upcoming side of the blade thus causing kickback. Some wood will still have enough tension to close or open up around the blade after the cut. All of the manufacturers I' am aware of use paws on both sides of their splitters to stop this kick back. They also align the splitter to the blade.
Kickback will not happen when there is enough downward pressure. Kickback is a phenomenon of a work lifting up; when there is no lifting, there is not enough bite on wood for kickback. To prevent kickback, always have strong enough vertical hold down on both the infeed and outfeed, except for large thin sheet products with plenty of space for hand pressure.
Watch this: https://www.youtube.com/watch?v=CV4uXtxnOdg
In the TS, the spin of the blade as the work leaves is upward, so blade spin is one more reason why rapping with the TS is inherent dangerous when there is no precaution against kickback. Kickback is a great danger in ripping with the TS if one is careless and allows the possibility of the work lifting.
What is the undisputed reason for the splitter? It is to prevent binding of the blade. In the TS, the front side of the blade cuts the wood, either first or the only time. Some fence is deliberately set toe-out by say 0.01 inch. That is, the width closer to the operator is a bit narrower than the width farther away. In this setup, only the front side of the blade cuts the wood; if the lateral force is enough so that fence hugging is excellent.
The other reason for the splitter is that wood is not plastic or steel. Wood has internal stress that can be released by ripping, so the way the wood will split open is not predictable. Some old timers know this and some insert additional splitter on the spot as the wood emerges on the other end. This hand inserted splitter should be the full width of the kerf.
On my Unisaw, same model, I used an MJ splitter in a shop built ZCI. That arrangement worked well for me.
As far as the Unifence is concerned; it is one of the best, most durable, most versatile fences available. A bit of clean up, adjustment, and tweaking should have it operating smoothly. There are those who prefer the Bies; it's a great fence, too.
Good luck with your saw.
The video I cited : https://www.youtube.com/watch?v=CV4uXtxnOdg
has the title "Radial Arm Saw (Safer and Better than a Table Saw)"
It is not my intention to tout the advantages of the RAS over the TS. I cited this video because I feel the author at the beginning has done a fine job in differentiating the three type of danger associated with momentum (the fourth danger is being cut by the blade).
The three types are ejection, climbing, and kickback. A large part of knowledge is differentiation or classification. It would be a mistake to lump all momentum related dangers as "kickback". All these I have long known; I am glad that someone made it clear.
Differentiation leads to better understanding, better awareness, better precaution, better application of countermeasures, and better compliance.
In all illustrations of kickbacks, the work is allowed to be lifted off the table. I have never seen an illustration of kickback where there is robust hold down on the outfeed side. I would like to be corrected if anyone can call attention to illustration of kickback in which there is installed vertical holddown. I really want to see it and to be safe. I almost always have vertical hold down on both infeed and outfeed.
If the matter of splitter can cause jamming, it will be related to the idea of ejection, not kickback. A properly shop made splitter does not cause ejection. Ejection can be prevented by featherboards, which are uni-directional and give very good control. Presumed are also that the wood has been face-jointed and usually edge jointed, and the wood is not allowed to sway laterally.
Whether the RAS is better than the TS is entirely separate and not the focus here.
I will say that the author correctly identified the danger of ripping with the TS, by stating correctly that the outfeed spin of the blade is upward (downward for the RAS), but he has not mentioned any difficulty in countermeasures. Then he went on to mention the larger footprint of the TS as the (one) reason he does not have a TS. Indeed countermeasures exist; here, his bias also shows.
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