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Making a short fence #1: A good safety feature for your table saw. Questions at the end

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Blog entry by Betsy posted 2433 days ago 5641 reads 0 times favorited 23 comments Add to Favorites Watch
no previous part Part 1 of Making a short fence series Part 2: Used it and have some thoughts »

Well – here is my version of the short fence.

I’d really appreciate your looking at this and letting me know if I’m all wet in my description/explanation or if I’m missing the point or did not explain something very well. That’s the only way I’ll learn – if you tell me.

I sincerely appreciate your honesty and your input.

So here goes.

The case for the short fence is all about safety. When you cut a board you only have complete control of the board as it begins it’s connection to the blade. Once the connection to the blade is made and wood severed, you no longer have complete control – despite using a push stick. The reason for this is that once the board is cut you now have two ends independent of one another and you have released all the internal pressures of the board up to that point. This internal pressure will make both ends act in different ways. The ultimate would be for the board to just maintain a straight path through the remainder of the blade. The second option is for the board to move in toward your blade or out toward your fence. The intention of the splitter is to keep the saw kerf open to keep the board from contacting the blade. However, the board is split into two portions before it reaches the splitter. If the board is going to move it will begin doing so before it reaches the splitter. The board on the opposite side of the blade (typically the waste portion of your board) has plenty of room to move out away from the blade. The board between the blade and the original fence has no where to go – it’s trapped. If the board comes back towards the blade and touches it, the teeth coming up out of the back of the throat plate can pick up the piece and potentially toss it back at you—this is kickback.

The short fence will help stop this by creating a “space’ for the board to move in one direction – away from the blade. It does nothing for the board if it wants to move towards the blade at this point because it has not reached the splitter. I think the hope is, is that if the board is going to move when it is first cut that it will move away from the blade. The space created by the short fence gives the board room to move and not be jammed between the fence and the blade.

The position of the front edge of the short fence should be just past the first tooth that actually cuts the board. Anything past the first tooth or two is defeating the purpose and function of the short fence. The actual physical position that the short fence will rest on top of the regular fence will depend on the height of your blade. Therefore, the fence will be in a different location for ¾” material than it would be for 2” material.

The length of the fence material will depend on your saw. Mine is 19” long. The length, in my opinion needs to be at least long enough to be placed an inch or two in front of the throat plate opening and at least cover the majority of the fence back toward the front of the machine (I consider the front of the saw the edge that you stand by).

The width, or top piece, of the fence will depend on the width of your saw’s original fence.
The fence is made up of 5 pieces of wood or mdf, two knobs or levers, two pieces of metal that the knob/lever will push against and two short pieces of dowel rod.

Of all the short fence materials I have found on the web – Steve Maskery of Woodshopessentials.com has made the most sense to me. You should check out his website and the video that he has put out about the jig. He does a much better job explaining this than I do. But I am trying!

http://uk.youtube.com/watch?v=d7QXIN2X8-w

On to the building. This is really a very simple jig. 5 pieces and some hardway. And no fancy joinery. Mr. Maskery uses biscuits to join his pieces. I don’t have a biscuit cutter worth getting out of the cabinet, so I plan to use screws to join my parts.

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So first – the three main side pieces are the left and right and a pressure plate which goes on the right side of the fence. These three pieces need to be the same height as your current fence.

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The pressure plate needs to have two dowels inserted for placement of the outside right piece. There, of course, needs to be a corresponding hole in the right side to accept the dowels.

The outside right piece also needs to have the screws.
The pressure plate also must have a metal piece that corresponds to the back of the screw – this provides the pressure to hold the fence in place.

I clamped the two right pieces together and drilled the holes for the dowel and screw at the same time – this insured they were located correctly.

The next photo just shows the dowel and the “pressure plate.” I don’t generally have anything metal in my shop that I have scraps that I can use for something like this. So I used a flat washer. I used a spade bit to cut the hole and used CA glue to put it in.

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One thing you should know about CA glue. It really does bond skin together. Really, really, really well. Acetone is the answer. The picture police will have to forgive me I was not thinking and did not take a picture of my index finger and thumb stuck together. What was I thinking?

This next picture shows the back of the outside right piece and the back of my T-bolt. Mr. Maskery uses a lever to put pressure on the plate to create the fit of the fence. However, I did not have a lever so I am counting on the snug fit of the fence from the “joinery” and the small about of pressure that tightening the knobs will create.

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After the fact, my screw does little to nothing as it is not the right design to move out and against the pressure plate. When I tighten the knob it just pulls into the right outside piece. So this is my mistake. You have to create pressure – my set up does not create that. However, my fence is snug enough that this may not present an issue. I’m no engineer.

The left piece has a 1½” wide strip attached to the bottom that allows for using a push stick safely when ripping thin strips of wood. I attached these with screws through the back.

The top is just laid on top of the three pieces and screwed to the left and to the outside right side piece. I clamped the three pieces together before screwing the top on – this made for a pretty snug fit.
That’s all there is to it.

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I cut several pieces to test this outfit and it works as advertised. The material moves smoothly through and I have to admit it actually “felt” safer.

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Now the questions: As to the outside “waste” portion that is cut off. As I understand it, this portion of the board is generally not what gets kicked back at you. Is this just physics or because the featherboard (provided one is used) keeps it from coming back? Seems to me that if the waste portion curls in when cut and touches the blade that the teeth coming out of the back of the throat plate would catch it and pull it up and over the featherboard and still throw the wood back.

Seems to me a good blade guard would keep most kickback from actually getting all the way back to the user as it would act as a very loud brake when the wood hits it. The kickback would probably break the guard, but still protect you. Is that right? Just another reason to use a blade guard?

Is this a device that you think you would use? I can see where it would come in handy.

Thanks for looking. Hope this makes some sense. I really would value any comments or suggestions.

-- Like a bad penny, I keep coming back!



23 comments so far

View Todd A. Clippinger's profile

Todd A. Clippinger

8724 posts in 2704 days


#1 posted 2433 days ago

Betsy, to be honest this is the first time I have ever heard of this. I think I understand the concept though. Once the wood is cut it has an open space towards the back of the blade to help reduce the chance of kickback.

I have never heard of the wood kicking back from the waste side of the blade however that is not to say that it would not happen, but is very much less likely to happen.

What could cause this to occur? I have ripped some boards with incredible tension in them that would cause it to curl in the way that you have described. Usually the fence side causes the problem because if tension is released in the wood it pushes away from the fence and into the blade.

Overall, with reasonable attention being paid I would not worry about the waste side.
However, I write this knowing you understand that what we do is inherently dangerous.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Todd A. Clippinger's profile

Todd A. Clippinger

8724 posts in 2704 days


#2 posted 2433 days ago

Anyway I guess I can see the safety benefit of the short fence. I wouldn’t sweat the outside of the blade.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Betsy's profile

Betsy

2913 posts in 2501 days


#3 posted 2433 days ago

Thanks Todd. I appreciate your thoughts.

-- Like a bad penny, I keep coming back!

View Myron Wooley's profile

Myron Wooley

226 posts in 2501 days


#4 posted 2432 days ago

What you have made is a shorter version of the sacrificial fence I use for rabetting. It straddles the fence snuggly, and allows me to bury the dado cutter for fine adjustments.
My old Unifence could be adjusted to do what your short fence does. In fact, a short length of fence was (is?) available as an accessory.
Your idea is sound. I think I’ll make something similar for my Exaktor fence.

-- The days are long and the years are short...

View Calgirl's profile

Calgirl

188 posts in 2500 days


#5 posted 2432 days ago

Todd,
Your reasoning sounds good and I will be interested to read updates from you as to how it performs in “real world” conditions. Because the short fence is so short, I wonder if you will have difficulty feeding a longer piece of stock accurately (straight). Maybe some sort of “pre” fence such as an extension before the main fence, might help on the longer cuts.

-- Forget the health food, I need all the preservatives I can get !

View jockmike2's profile

jockmike2

10635 posts in 2851 days


#6 posted 2432 days ago

Why not just leave the fence as is and use featherboards on top and on the outside of the board to eliminate problems. That would also keep your board running straight. Thats what I do anyway. mike

-- (You just have to please the man in the Mirror) Mike from Michigan -

View Thos. Angle's profile

Thos. Angle

4435 posts in 2567 days


#7 posted 2432 days ago

Betsy,
In theory, I think this is a good idea. However, I think I would not go with a short fence that was thicker than about 1/8 inch on the blade side.That would be enough to allow for release of tension but not enough to really allow the board to rotate.. I use Board Buddies when cutting sheet goods and they work well. I think keeping the blade sharp and the fence trued up would be sufficient to eliminate kickback. I use a long push stick that holds small pieces down as well as pushes them through.

-- Thos. Angle, Jordan Valley, Oregon

View Thos. Angle's profile

Thos. Angle

4435 posts in 2567 days


#8 posted 2432 days ago

another problem for me would be the fence rule. I keep mine zeroed in and never measure for the rip cuts.

-- Thos. Angle, Jordan Valley, Oregon

View Betsy's profile

Betsy

2913 posts in 2501 days


#9 posted 2432 days ago

Cal – The fence is short in overall length but it covers the entire fence from just about 2” in front of the throat plate opening back to the very front of the fence. I have the same amount of surface area to guide a long piece through the blade as I would if I was using my manufacturer’s fence as a guide. The difference between the two fences is what happens after the cut. I plan to cut my slats for the adirondack chairs I’m working on using the short fence so we’ll see how it works there. I’ll let you know.

Mike—- featherboards are always good, but they don’t keep the board from getting trapped between the blade and original fence and coming back onto the blade if there is a warping problem when the cut is made. This fence just gives some room for the pieces to “warp out” into an empty space and not be forced back into the blade. With that said, I really think that probably 99% (not scientific by any measure) of the time, good featherboard use and good technique will probably prevent most kickback accidents. I do think that the featherboard on top is a great idea.

Tom – the rotation issue I think is a valid point. I used 3/4” because that is what I’ve seen on other jigs and I had it on hand. I did notice when I ran a few pieces through that there is a tendency as you push the board through the final teeth that it does rotate just a bit. I’m wondering if that is just a technique issue on my part or a shortcoming of the fence.

As to zeroing in the fence guage – I think if I were to use this fence all the time, I would readjust my measure. I don’t plan to do that for a while until I see if I really like the fence or not. If I do decide to use a version of this fence full time, I would be moving my measure tape on the fence.

The fence concept certainly is a thought issue and I think it has its place among the safety arsenal. Espcecially if you have wood with a lot of tension or wild grain that you know if your gut may warp when you rip it. It was fun and easy to build and I will put it through its paces as I build a few projects.

Would be interested to see if anyone else would be willing to give this a shot.

Thanks for all your comments.

-- Like a bad penny, I keep coming back!

View Bob #2's profile

Bob #2

3808 posts in 2626 days


#10 posted 2432 days ago

Betsy, if you can find a DVD on the Grr Ripper hold down device you will find that they have pretty much adressed your concerns as well and providing a host of other benefits in on handy device.
That gizmo you have crafted is not what many would consider as a safety device as it allow the cut end to waddle around in space.

Cheers
Bob

-- A mind, like a home, is furnished by its owner

View Topapilot's profile

Topapilot

164 posts in 2445 days


#11 posted 2432 days ago

I’ve read that in some countries (UK IIRC) the short fence is the only fence that comes with the saw, along with riving knives and other features that have been demonstrated to enhance safety. I’ve also read that the short fence will be mandatory in the US in the future.

Excellent work designing, building, and most importantly, sharing your safety feature. This may help others remain both woodworkers and touch typiests.

View Todd A. Clippinger's profile

Todd A. Clippinger

8724 posts in 2704 days


#12 posted 2432 days ago

Betsy, you have sparked some good conversation here. I have enjoyed following this. Previously I had never thought of or heard of a short fence for safety.

Bob #2 brought up the GrrRipper. I bought two of these and use them quite often in my shop. I am working out of my brother’s shop and currently do not have them with me though. They are adjustable and ride over the blade nicely. They work better in pairs than alone and so I bought two.

I have to admit that I do not use a blade guard or a splitter. I know that I am flirting with disaster but I can’t help myself. The generation of Jet cabinet saw, that both my brother and I own, was not designed to quickly and easily install or remove these safety features.

Thos. Angle – I had often wondered about the board buddies. I also have to add that my rule is always zeroed in. No adding an inch or 3/4 inch for extra thickness.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View Mark Mazzo's profile

Mark Mazzo

352 posts in 2517 days


#13 posted 2432 days ago

Betsy,

Looks good!

I think that you’ve hit on all of the right points for the short fence. They are indeed standard issue and required for all European table saws – they have a much higher standard for safety than the US currently does. However, standards in the US are changing toward more safe safety devices for saws (primarily a riving knife).

One point here that you alluded to but is worth repeating is that a short fence does not take the place of a splitter/riving knife – they are each used for different conditions. The splitter/riving knife is there to keep a piece from closing on or pinching the blade and hitting the back teeth and thus causing kickback. A short fence is primarily used for problems with reaction wood where stresses in a board after it’s cut may cause it to warp toward the fence resulting in binding (which could then also cause kickback). A short fence does not allow this to happen.

-- Mark, Webster New York, Visit my website at http://thecraftsmanspath.com

View Bob #2's profile

Bob #2

3808 posts in 2626 days


#14 posted 2432 days ago

Just toss up a 4×8 panel of 1/4” on the table saw and talk to me about short fences.
If you want a thrill a minute try cutting a 4×8 of styrofoam.
I understand the concept as old NYWS Norm uses a similar setup often ( the sacrificial fence).
Without a riving nife and an adequate bladeguard we are just fooling oursleves again.
I watched the video regarding the short fence mentioned here and the fellow lauding it was standing directly behind the stock as he fed it to the blade.

That makes me very suspect of anything else he had to say.

Cheers
Bob

-- A mind, like a home, is furnished by its owner

View Betsy's profile

Betsy

2913 posts in 2501 days


#15 posted 2432 days ago

Thanks for the various comments.

Bob—- I appreciate the link to the gripper video. I’m going to try to get a copy soon. I must admit that I was a bit taken aback when I saw the Maskery video and he was standing directly behind the workpiece. I’m not for that one bit. I don’t think that’s safe.

I’m not sure that I would ever use a short fence for plywood applications. Plywood does not have the warp factor that typical lumber has. Or let’s say I’ve never experienced ply acting as typical lumber when cut. I suppose it is possible. I just don’t think a short fence is necessary for ply cutting. Secondly, being a single woodworker who does not often have shop help, I have never cut a 4×8 sheet on the table saw. I’ve always have had to cut it down to rough size with a circular saw or jig saw before hitting the table so I can’t speak to that. Just manhandling a 4×8 sheet into the shop is enough work for me.

Now I’ve got a design question. Whether you agree or don’t agree with using a short fence. How would you fix my problem of not having a lever to push my right outside board against the pressure board to make the jig rock solid in my desired location? Right now it’s pretty snug without the mechanical fastener, but I’d still like to know how you would fix this issue. I was thinking that I could switch out my T-bolt for a carriage bolt that I can screw in as I go – of course, I would need a threaded insert so that it would work.

What are your ideas?

I’m going to put this jig through a few paces as I work my way through the adirondack chairs I’m making. I’ll try to be objective in my final thoughts on if I like it or not and not let the fact that I spent time making it influence me!

Thanks for all your posts on this subject. Sometimes I think shop safety sparks as much controversy as how to sharpen a plane iron or finish a project.

-- Like a bad penny, I keep coming back!

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