Thread: splitter for the table saw - home made - give it a go

Thanks for this Evan, just need to get a decent saw to be able to use it on.
Kryn

So simple and so effective, must do for my new saw when it arrives next week

Thanks for the Evan, I didn't see the thread of your "argument" with BobL but am really glad I saw this thread as to dust extraction hole at the front of the blade makes a lot of sense.
I have been using home-made zero clearance plates using the plastic gripper plug-in splitters which have been great but the dust is a real problem.
Some good ideas here, thanks for sharing.
Cheers Ian

I can't find the thread either, but as always it was a discussion on the usual things that concern us all: visible/invisible dust, collection methods, overall usability etc.

where I became stuck is my little studio is very tight, plus each job is hugely varied, plus there might be three different jobs in the day....so I have to use a more universal setup. Quick changes and jigs and thoughtful swap outs are needed.

I can't have a big overhead collector as my work absolutely precludes it, so I was forced to think it through.

A while ago, BobL sent me a few of his very excellent bell mouthed ends, which are absolutely amazing, but it had me thinking about how I might "use" something like this to overcome the lack of upper collector. Hence the huge holes (2 1/4" Forstner bit).

My thinking was the COMBINATION of:

-- the cut being half way over the hole forces the gullet to descend the dust downwards (it's quite amazing to watch). By keeping the gullet centred it gives the greatest area to be captured
-- the ZCI stops the "rooster tail" of dust from the back (to some degree. The blade will still eject dust caught in the gullets and cabinet floating dust-noise)
-- plus the violent mixing of air down the hole removes the dust from between the gullets (mixed sideways, not down)
-- lastly, by matching the height of the blades back to the height of the splitter, there is very little room for dust/air to be "pumped" up/out of the cabinet.

im uncertain if the holes being radiused would assist, but it sure does do a good job visually.

ill include a picture as to my reasoning.

but, I will say, that these innovations do seem to work very well indeed. I've been astounded by how dust free my work has been over the last two days (plus all the benefits the splitter has had on quality of cut). Mr Howarths video shows this as an example over the last few minutes.

Thanks for the post. Very useful as I had been pondering doing something similar myself after watching Frank's video. My main concern was that an MDF or perhaps hardwood splitter might not be strong enough. But it seems like you're happy with the strength of yours? I use a thin kerf blade so would have to go closer to 2mm than 3mm.

With the ZCIs being reversible you get that large hole at the back. Have you ever tested whether that makes any difference to the dust extraction (good or bad)? On the one hand it seems like a potential place for dust to come flying up the back, but perhaps it's offset enough for this to not be an issue. On the other hand it may help to have some air being drawn in at the back as well as the front.

WoodyNZ, I only made them reversible so I could get four different heights out of two splitters. It was just laziness. Making new blanks only takes a few minutes. Pine as the base is OK, but I'd suppose hardwood would be better, but overall I've found:

-- Pine has lasted for at least two years of all-day daily use. I just sanded it quickly if it becomes manky (I use a lot of pine for kiddies furniture and its gummy as hell sometimes, hence the crappy looking blade!!!)
-- The MDF was simply laziness. The Freud P410T is 3mm and the first thing I had on hand was a 3mm MDF
-- I'd say some other hardwood would be better, but you'd want the end grain up/down, not lengthways (!!)

But, I've found over the last two days that there isn't any appreciable wear, but after a few weeks/months (?) Id say it would be a fair bit. Im not really recommending MDF or anything, it simply was something I had on hand. I also thought the relative surface slipperiness of it would be a good quality to have.

Of note, which is surprising to me, is just how much better these work than the riving knives I suffered with previously. They were "OK" but the really close fit of this has improved the work quality out of sight. Im seriously impressed with the cut quality on both the good bit and the offcut. The slide-past is smooth and the Grrrrippers do an excellent job of arching over the 5mm height.

Attached is a Sketchup you are free to abuse plus some pictures with my thoughts.

Ev

ZCI with splitter - blade proximity.jpg ZCI with splitter - overall.jpg ZCI with splitter - decending into.jpg

edit: here is the Sketchup file. The forum cant handle uploads of sketchups over 200kb (tiny!!!)

edit 2: I'll make some news ones with hardwood and also radius theintake with a 6mm roundover. See if this helps Perhaps it might eliminate the potential of a catch with the leading edge of the workpiece.

An over head BMH on an articulated arm that can be swung right out of the way might be a useful compromise for a standard OH guard and dust collector.

One concern about making the dust clearance hole in the ZCI too large is when using push sticks applying pressure downwards onto a short thin workpiece onto the table.
When the rear end of the piece appears over the hole there is a chance the ends of the pieces will be pushed downwards into the hole and lift up at the back catching the top of the blade.

If this happens when using a blade guard or a long workpiece the risk of the wood lifting and catching is reduced but if not there's a chance the work will be thrown back at the operator.
One modification might be to make a stepped hole so that an insert reducing the size of the hole could be used when working on thin/short pieces.

For folks with OH guards with efficient dust collection there should be no need for large ZCI holes especially because this may cause a competition for air/dust between the guard and the cabinet.

With the ZCIs being reversible you get that large hole at the back. Have you ever tested whether that makes any difference to the dust extraction (good or bad)? On the one hand it seems like a potential place for dust to come flying up the back, but perhaps it's offset enough for this to not be an issue. On the other hand it may help to have some air being drawn in at the back as well as the front.

I can't be certain but I reckon those holes are far enough away from the blade to not be a problem. The easiest way to test that would be, given that fine dust goes where the air goes, to tape a couple of streamers to the sides of the hole and test to see which way the streamers point with the saw running , with and without the DC on.

Originally Posted by WoodyNZ

With the ZCIs being reversible you get that large hole at the back. Have you ever tested whether that makes any difference to the dust extraction (good or bad)? On the one hand it seems like a potential place for dust to come flying up the back, but perhaps it's offset enough for this to not be an issue. On the other hand it may help to have some air being drawn in at the back as well as the front.

I didn't answer this, but BobL has. My thoughts would be that the "reversed" hole is underneath the good side anyway, so its covered.

My cutting, I have the "good" piece on the right of the blade, scrap on the left. I use an Incra fence, so it measures from the blade. Since I'm mostly left handed, this works quite well.

There is no fear of it being suctioned down either. My 2hp DC is so weak that its barely adequate let alone for anything creating real suction! I did however cover over all the gaps in the cabinet with sheet magnet roll that was cut up (buy off Ebay in 300x2000 rolls), so the air is being let in where I want it to... at the back, the side opposite the dust port and the holes in the ZCI's. I haven't put BobLs 6" BMH on yet!!! I will get to it one day....

Also, I might mention, that the splitter works really quite nicely with the mitre gauge too. I just cut to the right height and it slides right over. I thought it might get stuck or bind, but its very smooth and haven't caused any kickback disasters.... of which, I have had two events in 5 years and it gives me the willies every time. Each time its been the same... tired, became inattentive and moved the post-cut bit across behind the blade without fully clearing it. The edge of the piece catches the tip of the blade and BAM!

mitre fit 2 (1024x685).jpg mitre fit 1 (1024x590).jpg

The splitter stops this naughtiness as the piece is fully cleared and can't "back blade catch".

BobL raises another good point on suckjing small things down the gaping hole. I dont really have an answer for this, but it is something to be cognisant of. But as an alternative, I still intend using my sleds, for they are amazing devices and a lot safer than this idea....

One thing I have noticed, which is bad (see, not everything is perfect-rosy!) is that when using the mitre gauge, small offcuts can get caught as pictured. Avoid this by pushing all the way through and raising the blade. This happened a few times when trimming ends yesterday. It necessitated turning the saw off to retrieve the offcut.. lesson learned.

mitre catch 1 (1024x685).jpg

What do you do if you want to do mitre cuts as your splitter won't move with the blade?

Its interesting you mentioned this.

Over the years his table saw has given me TERRIBLE mitre cuts. Just terrible. I cut the good side on the left, as the right burns.

It was pointed out by others how I need to adjust the table top by lifting it a smidgen with a shim under each back bolt. In reality its cutting a compound cut I've yet to do this....

You will notice on one of the inserts, Ive already made a 45°cut. I was thinking of adding on the fin and seeing how it goes. Last night I was thinking of how this might stop the burn occurring on the waster.... perhaps not!

It makes using my mitre sled different.

Tomorrow I'll give it a go and report back.... but this is so easy to do you should all give it a go!

I'm greatly intrigued by the hole for dust removal. It's a smart idea and seems quite logical, but doesn't it sort of defeat the main function of a zero clearance insert - minimising tearout by supporting the material immediately adjacent to the blade?

Rex

Originally Posted by Rex Ashwell

I'm greatly intrigued by the hole for dust removal. It's a smart idea and seems quite logical, but doesn't it sort of defeat the main function of a zero clearance insert - minimising tearout by supporting the material immediately adjacent to the blade?

Its all based on a few small ideas I saw and jam them together. BobL sold me a few of his bell mouthed hoods for 4" dusting and the discussion around that had me thinking. I also thought about the old VW Golf that I turbocharged with a SU carbie... I made a BMH for that back in 1992.... it made a huge difference.

With a tablesaw I raise the blade only 1/2 way up the gullet of the blade. For me, tearout occurs at the back of the timber, not the underside, so I move my fence across a tad for a fresh cut if I change the blades height. New fences are just 18mm MDF and take but moments to make.

It may be inconsequential, but I use the Freud high ATB blades, specifically the P410T and P412.....

I thought to update on the idea in that I've been using it now solidly for 2 weeks.

Its fantastic

One of the best things I've ever done.

-- Superb cut quality
-- No potential of catches
-- No nasty tail catches after long sessions and reduced concentration
-- No apparent wear on the upright despite it being only MDF and making hundreds of cuts