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When cutting off a short amount from longer stock (say cutting 1/4" off 3/8" round or square stock) the bit sometimes gets caught between the teeth and the ZCI and gets fired at the wall of the shop. The bit gets mangled. Blade is a WWII. The blade looks good and cuts smoothly. Clearance to the ZCI is about 1/32" Happens with or without a sled. Is this blade unsuited to this kind of cut?
Maybe a new insert so the clearance is actually zero? Same with the sled, let in an inlay to tighten up the kerf. The blade is not an issue.Quote:
Originally Posted by Tom Bender
I agree with Kevin...it's not the blade. Many folks also do these small cutoffs using a sled because they provide positive back support for the material which helps avoid the situation where the small piece rotates into the teeth as it gets to where it's released from the larger piece it's being severed from.
Do you have a band saw or a radial arm saw?
Easy enough to find out.Quote:
Is this blade unsuited to this kind of cut?
Just try to duplicate the problem with a different blade.
If you can duplicate it, then it not the blade.
If you can't, then it might be the blade - or - it might be the way that blade interacts with the whole saw/ZCI/clearance setup.
+1 to the idea of using a sled.
I agree with the sled option that Jim mentions. When you make the sled, you can cut the groove in the sled with your WWII and it will work like a ZCI and of course like Jim mentions, will have the back support to push the small cutoff past the blade.Quote:
Originally Posted by Jim Becker
Check with the people that do segmented lathe turning. They deal with tiny cutoffs by the hundreds. They often use a slightly elevated cutting surface with a ramp for the offcut to slide away from the spinning blade. Most likely not your blade as most segmented turners have the problem and are using a number of different blades.
A miter gauge fence that extends past the blade will also work.
An acute wedge fixed to the table with magnets can divert offcuts from the blade. You can see an offcut diverter at about 15:30 in this video https://www.youtube.com/watch?v=h1OLlqB6-x8- not too useful for one very short offcut, but good for multiples dancing around near the blade.
Taking 1/4” off a 3/8” round is a bit hairy, even on a band saw. Angled ramp as mentioned helps, and I’ve also rigged a dust collector fitting with coarse screen that I use at times to suck the off cuts away from the blade. For just a few pieces of dowel or pvc, i have a v-grooved board that I use with a back saw or dozuki…quicker to set up than the ramp & vac.
Bullets is the right term, for sure!!
earl
No ZCI is truly Zero clearance. The teeth are wider than the plate of the blade so there will be a very small gap. But, I’m not sure how a 1/4” cutoff would cause a problem. I trim stuff like that and don’t have the problem.
I use a little ramp on the bandsaw when cutting small round pieces. I use 1/4" brass rod for tone rings on banjos and cut the scraps into less than 1/4" lengths to use for fretboard dots. I cut a 45 degree slope on a piece of scrap wood and then cut into the wood so that the blade is sitting just inside the ramp. Then I clamp the piece of wood down and freehand cut the dots off the brass, and each dot rolls or falls down the ramp as soon as it's cut, out of the way of the blade. This would be a little harder to do on a tablesaw unless you used a sled with a built in ramp, it seems like that would be very handy once you got it made.
Sneak up on the cut. Trim the waste into dust. It might mean rough cutting closer to finished length, or making two passes on the sliding table. My miter saw will slam off cut triangles into the wooden fence. The extra time to nip the end saves the sweet sound of slamming scrap.
A shop vac hose mounted up close will suck those cutoffs away before it gets stuck in a tooth.
Andrew Klein recently posted a video showing a shopvac cutoff collector for this type of cut after he'd been hit in the face:
https://youtu.be/F2J0fw_VlmM?t=421
One issue with ZCIs is the teeth are wider than the blade body, so you will pretty much always have some gap, except at where the teeth themselves are.
Matt
True, but at the teeth is where any throat plate generated kickback happens. If the zci is replaced frequently and that gap kept to a minimum the risk will be minimized.Quote:
Originally Posted by Matthew Hills;3158056[URL="https://youtu.be/F2J0fw_VlmM?t=421"
The various ramps and shop vac solutions are certainly useful for repetitive cuts but unlikely to be set up for the occasional small offcut.
I make 1/2" cutoffs using a small sled for a particular small part I cut for a non-profit. Never had a problem with the the offcuts getting shot back at me. Until recently, when I went with a newer Freud rip blade. Same part number as the old blade, but there is a difference in the shape of the gullets. That blade threw 3 or 4 of those cut offs at me in short order after starting a session. The blade was the only difference so I put the old rip blade back on and no more problems. So, a long winded way of saying, it could be the blade. As suggested, try a different blade if you have one.
Someone posted a link to a small parts cutting sled here, within the past couple of weeks.
Have you tried a deflector wedge to push cuttoffs away from the blade? Very handy, I use one all the time.
I always just make those cuts in more than one pass. I actually have hash marks on the ZCI to delineate the problem length. I can see in a glance when I need to do a double cut.
Thanks for teaching me something new.Quote:
Originally Posted by Brian Tymchak
I agree with those stating that a sled carries the off cut away from the blade and eliminates the problem. An alternative to this is something like the Grr-ripper which carries the off cut away from the blade as well. I use both but not at the same time :-)
Thanks for so many good replies. I took a look at my ZCI and found that it is actually more like 1/8" from the WWII. I may replace it.
However, I recently made a small parts sled and made the clearance cut with this blade so it is as tight as possible and it does the same thing.
Now it's time to experiment with another blade.
Watch your blade height, too...if it's too low, it can cause interesting things to happen because of "lifting", etc.
Was not me but the one I like the best and use was found here.Quote:
Originally Posted by Tom M King
I used to get wood rockets launched when beveling the bottom of sash. Switching to a dado blade made the projectiles into shavings.Quote:
Originally Posted by Tom Bender