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Thread: Sawstop
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28th December 2020, 04:56 PM #46rrich Guest
OK. I don't disagree. But remember that I am the logical idiot in the family.
Please without judgement, can anyone explain how a tape can come in contact with a spinning blade under power. Please don't tell me that people are measuring fence to blade with the saw running. Typically I work to half of a 1/32. That requires measuring from the right ATB tooth to the fence.
I have used a inside chipper from a dado set to locate the arbor flange on my right tilting Unisaw and scribe a line in the table top. (Using a carbide scribe) The line kind of works but the set of most saw blades is about, around, almost, maybe, close to 1/64. OK, I am anal retentive with measurements but let's not let that come between friends.
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28th December 2020, 05:55 PM #47SENIOR MEMBER
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28th December 2020, 06:07 PM #48SENIOR MEMBER
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There are several techniques that use the slider for repeat solid wood rip cuts.
Here is one example from Felder - watch from 9:14
Here is another showing rip options using the F&F jig, including very thin rips. (Note - you will see he has set his fence for a slight taper - many ways of getting an exact parallel cut without having to do any secondary processing)
Or you can use parallel stops as in this video:
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29th December 2020, 03:56 PM #49rrich Guest
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29th December 2020, 03:58 PM #50
Good Morning Lance
My technique is quite different from Riverbuilders and similar to the Felder video referenced by Ross.
Firstly, it should be remembered that with the saw bench about one third of accidents are from kickback and two thirds are from blade contact.
Secondly, a properly set up slider should cut sufficiently accurately and smoothly that jointing of the cut surfaces is not necessary.
Thirdly; my experience is that the Feldar technique works well with large pieces of soft pine, but not with hardwoods with interlocked grain; the wood, itself, may wander. I advocate that you secure timber when ripping; I use either:
- A wedging foot (like in the Felder video) plus one or two hold downs, or
- No foot plus 2 or 3 hold downs.
My technique with the slider for ripping timber is as follows:
- Set blade height so that bottom of the gullett equals thickness of the timber,
- Jointing cut. By eye line up timber on slider so saw takes off thinnest possible cut and clamp with foot and/or hold downs. This joints the first face.
- Set fence just forward of the blade and the desired width from the blade, (NOTE: having the fence ahead of the blade eliminates risk of kickback, and you are not standing in the danger zone.)
- Put timber on slider and against the fence, secure with foot/hold downs,
- Switch saw on and move sliding table to make the cut, (NOTE: Hands are on the sliding table and no where near the saw blade; fingers are safe.)
- Return slider, ease hold downs, reposition timber against fence, secure hold downs and do next cut,
- Repeat untill sufficient cut or timber exhausted.
- The final offcut may be as small as 20mm wide. I often salvage it by thicknessing the uncut face.
This is actually quicker to do than explain; it gives very high quality timber and it is quite safe.
But idiots are very creative; nothing in a workshop is foolproof!
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29th December 2020, 05:27 PM #51
The Felder PCS seems to offer a "better" solution in a number of key areas imo.
- The SawStop relies upon a part of the human body to contact the moving blade to be detected then activate the safety system - a reactive system. There is still a risk that the system may not detect or activate when the user has already made contact with the hazard. If for some reason contact is not detected then the hazard and risk has not diminished at all!
- The Felder PCS appears to detect hand proximity to the blade activating the safety mechanism - blade retraction. It is a proactive system and still has a small safety margin before the user makes contact with the hazard.
- The SawStop "writes off" a cartridge and most probably a blade plus there is the associated down time, loss of production, inventory of spares, replacement of components, training users/staff to replace components etc.
- The SawStop creates very high shock loading of saw components i.e. saw arbor etc, that are potentially damaged after one or more activations. How many activations can those components sustain before they potentially fail?? Answer - unknown, a new/residual hazard!
- The Felder PCS, from their promotional resources, can be reset by the user, no or minimal damage, minimal lost production etc.
It is very good to see such innovation, which has largely been driven by Steve Gass, his lobbying, & his SawStop patents etc. We should thank him for that.Mobyturns
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29th December 2020, 06:01 PM #52Woodworking mechanic
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Regarding the SawStop. I don’t have one but have used the one at my local Mens Shed.
They have wired in big red and green lights and they can’t be missed!!
You are only allowed to remove cut timber, adjust fences etc when the green light is on.
Why? Apparently, when you turn the saw off, the cartridge is still active until the blade stops rotating completely. In fact the red light stays on until the blade comes to a complete stop, then the green light comes on.
All their firings had been cause by the blade being touched when rotating very, very slowly, just before stopping, because members were removing timber, setting fences etc etc.
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29th December 2020, 06:34 PM #53
Thanks for the detailed response Riverbuilder. I've re-written this several times in an attempt not to come across as argumentative. Please interpret as me trying to get a good understanding only.
My understanding is that this technique is essentially using the slider just like a regular cabinet saw? The only potential differences may be that you're setting the fence end forward, I assume to reduce kickback. I wonder if there is any benefit to this over newer saws that employ a riving knife? Regardless, if so, the benefit appears to be in the fence, which granted, would need to be an aftermarket or DIY effort for cabinet saws.
My comment about unsafe practice was referring to people doing as you say, but getting their hands really close to the blade during the rip, or reaching over/around the blade to collect stock post cut. This is commonly seen on YT with both cabinet saws as well as sliders. Perhaps I'm not understanding correctly, but I can't see anything inherently safer about using a slider in this manner for this operation. I realise that it may seem like I'm cherry picking a scenario, but for me, this is 90% of what I use a table saw for.
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29th December 2020, 06:46 PM #54
After asking the question of Riverbuilder I did go searching for some "official" videos of how it is supposed to be done, and my initial reaction was "that's a very slow laborious process". After a little pondering however I realised that I simply don't make that many cuts in the overall scheme of a project, and so the time difference over an entire project is going to be negligible. I would imagine too that when it's not being explained it does go pretty quickly.
I guess the important part is that with this technique, you really are clear of the blade, in that your only interaction with the saw is pushing the slider through.
Thanks for taking the time to explain Graeme
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29th December 2020, 08:59 PM #55
The "reaching over/around the blade to collect stock post cut" is a very bad habit to develop. It becomes more hazardous, with far higher risk when the operator is not using a blade guard, and a riving knife.
I use a TS250 Woodfast table saw which has a simple aluminium sliding table and no miter tracks in the cast iron table top. The design offers many options for ripping stock, from the traditional fence operation; or as a slider as described above though it has a restricted travel of some 1100 mm iirc. I have a range of sleds that attach to the sliding table which I use for many tasks cutting very small components. One sled is designed to rip thin strips as thin as 1 mm from 19 mm stock x 450 mm long. At no stage are my fingers within 150 mm of the rotating blade.
I also use a GRRipper for some operations. It presents its own hazards and is not my first preference but it does offer a solution for some tasks.Mobyturns
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29th December 2020, 09:13 PM #56GOLD MEMBER
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I use a riving knife,always. I just didn’t mention it because it’s just normal practice, for me anyway.
As for people reaching over the blade or removing stock while the blade is running, well, I think I’ve said somewhere else about keeping fingers away from cutting blades, it really isn’t that difficult to understand, and extremely easy to avoid doing. I didn’t mention using a push stick or similar because it’s just normal practice,second nature to do that. From memory, most all good quality,and most of the cheaper but still good quality sliding saws I’ve seen, have an adjustable fore and aft fence, the only time that I would push the front end of the fence past the centre of the blade would be when cutting laminex or similar thin material. The rest of the time, the end is at the centre of the blade,no further.As you say, this eliminates almost all risk of kickback. The height of the blade during ripping operations is also a big contributor to kickback events. The angle of attack of the teeth is much more perpendicular when the blade is fully raised, which forces the material down onto the table, rather than back towards the operator. It also helps with blade life and cut quality,as the teeth are contacting a much smaller surface.
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29th December 2020, 10:57 PM #57GOLD MEMBER
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F & F jig is the simplist and safest way to rip on a slider. I never use a rip fence and it sits on a shelf gathering dust except for some rare occasions and in it place a 200mm long piece sits in its place. This is used as a dimension bump stop and means I am not forever walking around the end of the rip fence hanging off the table.
CHRIS
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30th December 2020, 09:40 AM #58GOLD MEMBER
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30th December 2020, 09:45 AM #59GOLD MEMBER
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That's a great idea. I don't have SawStop but my blade takes forever to stop. I have on occasion reached in to grab the offcut and realised the blade is still spinning. A big red light would be great addition. Was that a commercially available unit or did some clever member make it?
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30th December 2020, 09:48 AM #60Woodworking mechanic
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One of the members designed it and wired it up.
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