Small box making has become a significant part of my woodworking recently, which requires thin and small sections of wood, meaning quite a lot of wastage as they’re sawn from larger pieces.
There seems no easy way to reduce the amount of this wastage when cutting up one plank into numerous small sections for the wee boxes. But one potential waste reducer might be to use a thin kerf tablesaw blade of high quality. Tablesawn sections can be made consistently thick with minimum saw blade marks on my saw, requiring very little more to be removed (with a plane or sanding block) to obtain the box-ready parts. Bandsawn and handsawn parts always seem to need much more further wood removal to get them evenly thick and free of saw marks.
So, I’ve been looking at thin kerf 10″ tablesaw blades for my tablesaw. The thinnest 10″ blades seem to have a tooth/kerf width of 2.4mm, as opposed to the standard 3.2 mm or the other common thin-kerf width of 2.8mm. A reduction of the kerf from 3.2mm to 2.4mm represents a reduction in wastage (sawdust) of 25%.
My tablesaw has a riving knife of exactly 3.0mm width, made for use with 3.2mm kerf blades. It works safely with a 2.8mm kerf blade as the front edge of the riving knife has a blunt knife-edge profile. The 2.8mm wide kerf seems to slide over the 3.0mm thick riving knife with no noticeable drag or other effects. But would a 2.4mm kerf get past that 3,0mm thick riving knife?
I suppose the only way is to try it. A mental experiment suggests that a 2.4mm kerf 20% (0,8mm) less wide than the 3mm thick riving knife will be much more likely to jam than is the 6.7% % (0.2mm) less-wide kerf from a 2.8mm kerf blade.
My question, though: does anyone have experience of attempting to use a 2.4mm kerf 10″ tablesaw blade with a standard (3.0mm thick) riving knife; and what did you discover?
In addition: is such a 10″ thin kerf blade, with a correspondingly thinner saw plate, safe to use at all in a 3hp tablesaw?
Lataxe
Replies
Hi Lataxe,
The safest way I can think of at the moment would be to pull out the riving knife, make a new zero clearance throat plate, and glue in a splitter to the new throat plate base upon the kerf of the thinner blade.
As for running a thin blade on a 3hp saw, if you're cutting small, thin stock, I can't see where it will hurt. Big, thick stock - no thanks. Of course, all disclaimer apply here ..
I use almost exclusively thin kerf on my unisaw without a riving knife, I see no safety issue , but if you want real thin kerf, and have a bandsaw, get a Laguna Resaw King and you will get 1mm waste per cut with as good a finish as a circular saw.
I have no trouble with thin kerf blades on a 3hp saw. I don't know if it will work with your splitter though.
Are you interested in saving wood on your rip and cross cuts, or is this setup for resawing on the table saw?
If you are looking for truly thin kerf blades, consider the 1/16" (about 1.6mm) options such as those from Total Saw Solutions. You cannot use them with riving knives, so I only use them on smaller wood (Like box making pieces) and pieces I know have straight edges. But in those circumstances they slice with amazingly smooth edges and apply SO little force on boards that I worry less about using a riving knife. Perfect circumstance for them is ripping pieces for Kumiko - when slicing up a hundred strips or so, you save an amazing amount of wood!
Downside? Very expensive, like $200+ expensive. But I have never regretted the purchase and I save it for special uses like those mentioned.
(By the way, if you are looking to save wood on large pieces, I would agree about just using a bandsaw!)
Thanks all for the replies so far.
A good bandsaw + matching resaw blade would be very nice but ..... I have no room for one in the already full-to-bustin' single car garage, even with a car never in it. When we moved to this house from the previous abode, I had to sell my 12" bandsaw, along with many other large power tools, because of workshop shrinkage.
I could risk using a thin kerf blade in the tablesaw without the riving knife mounted, despite my trepidation in doing so, as I also use hold-downs to keep the workpiece down on the table and firmly agin' the (half-length) fence. There's always a risk of kickback without a riving knife if the cut-kerf should close because of stress released in the workpiece by the cut, though. A small risk, especially with a hold down mounted on the fence pressing the workpiece to the tablesaw's deck.
Without a riving knife to worry about, perhaps I could mount a smaller diameter blade (than the standard 10" my tablesaw uses) albeit one with sufficient diameter to still rise high enough to cut 25-30mm max rather than the usual 80mm possible with a 10" blade? A smaller blade could presumably be found with an even narrower kerf than 2.4mm - perhaps that 1.6mm mentioned?
I can also make a tablesaw top insert to match a thinner/smaller blade, to provide zero-clearance for any cuts.
******
I have tried the alternative of resawing by hand with a thin-bladed ryoba saw, via a pre-established guide-kerf made with a kerfing plane. It sometimes gets me evenly-thick parts with not too much saw tooth roughness to plane off but ..... not always. It's easy to go wrong when hand ripping a long piece of swirly-grain hardwood. And it can take a long while to get from one end of the plank to the other! :-)
I'll consider the option of doing without a riving knife - just for the box part dimensioning; and look for some even thinner kerf (and possibly smaller) tablesaw blades.
Anyone using a smaller-than-usual blade for such a purpose in their tablesaw?
Lataxe
PS Total Saw Solutions website seems to be denying access "for security reasons" if I try to access it via Google Chrome.
Here is an alternative (although expensive solution).
Bridge City Tools Joint Maker Pro
https://bridgecitytools.com/products/jmpv2-jointmaker-pro
I have never used one but it seems like a sled on linear bearings with a Japanese Crosscut blade as the cutter. I think I've seen 0.4mm kerf.
With all of the creativity in Table Saw Sleds, Shooting Boards and Bench Hooks it seems feasible to distill the essence of this design to a shop made jig with a more limited feature set for small boxes. So Stationary Japanese Dozuki Saw with a Sled.
Hi Gary,
I confess to having looked avidly at that Bridge City joint making contraption, more than once. Should box making become more prevalent in my woodworking adventures, the joint maker would become an attractive proposition, since it not only makes quiet and super thin rips but also various joints!
But what I really need first is a much larger new woodworking shed as even the joint-maker would struggle to find a niche, nook or cranny in the current workshop. :-)
Lataxe
Lat_axe, I understand. I would also have a hard time justifying the cost and footprint of the device.
But the concept of having a shop made jig with:
1. A fixed Japanese Dozuki Saw blade (~0.5mm kerf) rising at a slight angle (front to back) so that it can cut thin stock (less than 1/2") in a single pass over the length of the cut is intriguing.
2 . A simple table saw type sled device on runners would hold the wood to be cut by the Dozuki blade.
3. The fence on the sled would be dialed in at 90 degrees. Other angles are also possible.
There are plenty of small table saw sled designs that would work. The key to me is how to secure the Dozuki blade and dial it in for repeatable cuts? Clamping down the jig assembly to a solid workbench would give it the mass it needs for stability while powering though the cuts.
If they will give you the depth of cut you need, I think that 7 1/4" circular saw blades tend to be thinner.
I agree with the above statement to remove the riving knife and add a splitter of the needed thickness would work just fine.
Another search of the various tablesaw blades easily available in the UK revealed a 200mm diameter blade by CMT having the necessary 30mm arbour hole with the two clamping plate pin holes. It has 36 ATB teeth with a 15 degree hook and a 1.7mm kerf. It costs a mere £17:92 and gets very good reviews
Although undersized for my TS, this would provide a maximum 50mm cutting height and save near to half the saw dust of a 3.2mm kerf blade. It's a combination rather than a pure ripping blade but in my 3hp saw it should still rip small box parts without hesitation; and perhaps also a better quality cut.
As suggested by a number of posters, I'll remove the saw's riving knife and install a 1.8mm thick wooden splitter, probably glued to a dedicated wooden inset plate that'll also provide zero clearance to the blade. I'll make a shark fin style splitter that follow the curve of the blade and always use it with the blade fully raised so that the splitter is just a couple of millimetres from the saw teeth and only a couple of millimetres less high than the blade.
Thanks for all the help.
Lataxe
You have ended up where I would have sent you. 8" blade, zero clearance insert with splitter custom made/shaped for how you plan to use the blade. There was an article in a recent FWW on how to make a splitter for a new insert. Helpful for me when I did it.
JHB,
Yes, it seems to be a well-known technique for getting thin kerf rips in The USA. I looked up a few magazine articles about use of a splitter (rather than a riving knife).
The consensus seems to be that the splitter should be glued into a zero clearance throat plate, behind the blade, but only 1" high by 3 inches long, in an extension of the blade-slot immediately behind the blade and of the same width/kerf.
I'm seeking a very straight-grained piece of hardwood that's stiff but not brittle, as a 1.7mm thick splitter of wood is likely to be rather flimsy. Any suggestions? I have oak, ash, cherry, sapele, hard maple, southern yellow pine, poplar, butternut, black walnut and a few smaller pieces of various exotics such as leadwood, african blackwood and ebony.
I did think about a metal splitter but what if it got grabbed by the blade, snatched out of the wooden throat plate, then shot back at poor ole me standing in the firing line!
Anyroadup, I've made the throat plate and ordered the blade.
Lataxe
Before we get on wood selection: it is important that the splitter have its grain running vertically. Otherwise it is very weak and prone to breaking off.
For wood, you are looking for a wood with good grain strength, wearability, and not brittle. Probably the best two of the domestics would be either ash or hard maple. If you plan to shape the front edge to the curve of the blade, maple would probably be best, as it is less prone to short grain splitting (at the tip of the curve.) It's easier to come up with a really straight grain piece of ash than of maple; in the 1.7mm thickness, ash would likely be more reliable. Even tho oak seems pretty similar to ash, they make baseball bats out of ash, not oak. The ash just doesn't seem as brash as the oak. The best woods would probably be the dense woods that don't even split, like elm or dogwood. Not easy to find. I'd probably use a rectangular piece of ash, and lean it forward a bit to bring the upper front edge a bit closer to the blade. I would consider that close enough to a riving knife, esp. as you can determine what you expect to be the maximum height you will use the blade at. Let me know how it comes out.
Harvey
For completeness' sake, there are a couple more possibilities:
Most engineering shops and pretty much all saw specialists can machine any blade to take the hammer/felder fittings.
They could also make a riving knife for you, probably very cheaply, and sized to suit your blade.
If you can find such a shop then there may be a few additional choices there for you.
The new 200mm diameter 1.8mm kerf CMT saw blade arrived at lunchtime so it was into the workshop to complete it's installation.
Firstly, out with the standard blade and on with this new item - a perfect fit on the 30mm arbour and two-pin stiffening/clasping plate.
A quick run shows no wobble or other worrisome behaviours. I do notice that this much lighter new blade (compared to the standard 250mm diameter 3.2mm kerf blades) soft-starts to full speed very quickly and also stops very quickly when the saw is switched off and the electronic blade brake is applied. The standard blades take 2 seconds to stop rotation but this new fellow stops almost instantaneously - well less than one second from full speed to stopped.
As you can see in the pics, the standard riving knife is not just too thick for this skinny new blade but much too far back and much too high. So, off it comes and in with a new blank throat plate which will take a wooden splitter instead.
The blade is raised through the new throat plate as it rotates, so cutting a zero-clearance slot.
Next post - making and installing the splitter.
Lataxe
To make a slot for the splitter in the throat plate, behind the blade, I used the TS fence set in line with the blade-cut slot in the throat plate and a zero-set cut-off saw against the fence, to make two parallel cuts. That 1/16" Iles chisel I bought was just the job to chop out the skinny bit of waste. It's fourth use in only 6 months! :-)
There's a set of vertical cardboard tubes in the workshop stuffed with dowel rod, stringing and thin offcuts that I often plane down to thicknesses of just a few millimetres, to use as stringing or plain banding. I pulled out a piece of 30mm-wide, 3.2mm thick sapele to try as material for a splitter. (See next post).
Lataxe
I set the small Bridge City thicknessing plane I have to 2mm - 0.2mm thicker than the blade kerf. The strip of 2mm thick sapele resulting was surprisingly stiff for such a thin section.
This particular stuff is very stiff and close-grained. It's grain structure is highly interlocked (making it a difficult stuff to plane) but it doesn't split or shatter easily. So ....
....despite the advice to orient the splitter's grain vertically in the throat plate (presenting long grain to the blade) I decided to try presenting it end grain-on. In addition, a taller splitter seems only to offer more likelihood that it might snap off, so I made it very low profile.
It seemed a more secure design to make the splitter follow the blade closely, with a minimum gap after the rear rising teeth of the blade and the start of the splitter. AFter all, the job of the splitter is to prevent kickback from a wrokpiece turning slightly into the rear rising sawblade teeth, so any gap between splitter and blade would seem to entirely undermine the splitter's function.
So I made the splitter over-length then raised the rotating blade slowly into it, once the splitter was well-stuck into the throat plate with super glue. This seemed to work without issue.
To ensure that the workpiece soesn't catch on the corner of the splitter as the cut-kerf reaches it, I added a chamfer to both sides of the splitter's leading edge; and waxed the splitter with a particularly hard and slippy wax (Alfie-shine).
Time for a test cut!
Lataxe
A piece of 32mm X 32mm ash was lying about (a remnant from some table legs) that had a few traces of worm-dust in it. This seemed an ideal test piece to see if the new blade & splitter would work wothout binding; and if the new 36 tooth saw blade would give a decent cut.
Well, what a fine performance! The ash sailed through the blade at a rapid rate; the splitter seemed to offer no drag; the resultant cut surface was very smooth indeed - that legendary "glue-line" I often read of but rarely see in practice, with no saw marks discernible to the naked peeper.
Success - and lots of box-making wood of the future saved from an early grave in the dust extractor!
Lataxe
Lataxe, Outstanding! Thank you for your detailed documentaion of your process. Gary
That sapele seems perfect for the job. The interlocked grain/lack of splitting removes the requirement to have the grain vertical. And I like your method of cutting the slot for the splitter, rather than trying to align the fence so that the cut slot from raising the blade lines up with the blade. When I did it, I had to "adjust" the result. Thanks for documenting your process, and congrats on your success. Happy boxing!
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