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Old project - Improved Crown guard for TS200 saw

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Old project - Improved Crown guard for TS200 saw

Postby Robert » 13 Apr 2015, 16:21

These pictures are from 2010 so another thing that was lost. not so many pictures this time so I'll add some words too :)

The crown guard that came with the saw didn't work very well at catching the sawdust coming off the blade.

i tried taking high speed pictures to see where the dust comes from
Image

hard to see but it is in the blade gullets and thrown out all round
Image

the insides of the axminster guard
Image

When further in to a cut the dust is projected forwards more
Image

As this deflected piece of paper shows there is a significant breeze coming off the blade in the direction of travel - and I was getting better at the high speed photography as the blade is spinning here
Image

first mock up using polycarbonate sheet and masking tape. It worked and made a stream of dust backwards.
Image

The finished item. the curved parts are 8mm polycarbonate strips bent with hot air from an electric paint stripper gun
Image

Air and dust flow down the pipe even without extraction running. I connect it to the saw base and have a single larger extraction next to it.
Image

It is still in regular use and the clear sides so i can see what is happening has been a real benefit as well as the near 100% dust collection. The aluminium block at the back fits a slot in the riving knife so it is a simple lift off when not in use.
Image

It also has a much larger nose slope than the original so it self lifts over cuts approaching 40mm.

One of my better contraptions :)
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Re: Old project - Improved Crown guard for TS200 saw

Postby Andyp » 13 Apr 2015, 17:28

Contraption does not do it justice Robert. Looks very close to a production mock up to me and as it is obviously so much better than the original bought item I wonder if there is any merit in trying to sell your design.
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Re: Old project - Improved Crown guard for TS200 saw

Postby tracerman » 13 Apr 2015, 17:36

Robert - the professional construction and detail do you credit .

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Re: Old project - Improved Crown guard for TS200 saw

Postby RogerM » 15 Apr 2015, 17:07

Dunno how I missed this one first time around. That looks like the db's Robert. I can see me having to make one of those for my Scheppach TS2010. Thanks for re-posting.
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Re: Old project - Improved Crown guard for TS200 saw

Postby Wizard9999 » 27 Sep 2015, 22:55

Robert

Really clever design. Well you know how they say imitation is the sincerest form of flattery, well I was thinking of flattering you :lol: .

I had a question or two though. It looks like screws fixing the side and the top/front pieces of the guard, are they actually screwed into the polycarbonate or did you just drill holes and use glue to fix the screws? Afraid I have limited experience of the material, but it doesn't give me the impression of something that will take a screw. Also, did you glue the length of the joint and if so what type of glue did you use?

Many thanks,
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Re: Old project - Improved Crown guard for TS200 saw

Postby Robert » 28 Sep 2015, 09:19

Polycarbonate is one of the materials often used for guards (the other is ABS) as it does not shatter like acrylic or styrene. You can also drill and saw it with confidence. I drilled 3.5mm holes then just screwed M4 machine screws into the holes without tapping a thread first. Polycarbonate will just swell a little if you drive a screw into a small hole not split.

I used to have a business manufacturing lighting and have kept a few offcuts of plastic sheets. polycarbonate is a most versatile material and I often resort to it for jigs and solving problems.

You can glue polycarbonate but to do it properly you need a specialist cement so I use only mechanical fixings - no glue.
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Re: Old project - Improved Crown guard for TS200 saw

Postby RogerS » 28 Sep 2015, 10:47

Very elegant solution.

Am I right in saying that it's quite difficult to remove? That would be a no-no for me as I frequently remove mine for grooving and rebating.
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Re: Old project - Improved Crown guard for TS200 saw

Postby TrimTheKing » 28 Sep 2015, 11:06

RogerS wrote:Very elegant solution.

Am I right in saying that it's quite difficult to remove? That would be a no-no for me as I frequently remove mine for grooving and rebating.


Must be some serious dancing (grooving) you do Roger if you need to be guarded most of the time...

:P

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Re: Old project - Improved Crown guard for TS200 saw

Postby RogerS » 28 Sep 2015, 11:17

TrimTheKing wrote:
RogerS wrote:Very elegant solution.

Am I right in saying that it's quite difficult to remove? That would be a no-no for me as I frequently remove mine for grooving and rebating.


Must be some serious dancing (grooving) you do Roger if you need to be guarded most of the time...

:P

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Re: Old project - Improved Crown guard for TS200 saw

Postby Wizard9999 » 28 Sep 2015, 11:43

Most helpful Robert. Based on that can I just ask about the extraction outlet, was that glued or screwed as well?

Thanks for your help,
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Re: Old project - Improved Crown guard for TS200 saw

Postby Robert » 28 Sep 2015, 17:37

Wizard9999 wrote:Most helpful Robert. Based on that can I just ask about the extraction outlet, was that glued or screwed as well?

Thanks for your help,
Terry.


Wedged between extended bits of the side panels and kept in place with clear silicone. The silicone also did the job of joining the square hole to round outlet pipe.

I had the blue pipe already so just used whatever I could find that fitted - in this case the barrel of a large syringe.

There is a commercial product that is very similar. I only found it after I'd worked it out for myself and made mine...

Image

found on this US site - http://www.highlandwoodworking.com/saws ... guard.aspx

I also made the riving knife for my saw and sized it so it sinks below the table surface when the blade is down. Doesn't look like this one does that. I would have to take the guard off if I wanted to cut over 2" thick on my saw (but I never have) and need the flush surface when not in use.
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJ » 28 Mar 2017, 11:04

I know this is an old thread, but thought it may be interesting to some of you how I tackled the age old problem of dust collection from the Crown Guard, this is on a TS250-2 so is a bit relevant to this thread.

Image
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Re: Old project - Improved Crown guard for TS200 saw

Postby Andyp » 28 Mar 2017, 11:49

Hi Mike, and welcome to the forum.

that looks to be a well engineered solution thanks for sharing.
cheers

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Re: Old project - Improved Crown guard for TS200 saw

Postby Phil » 28 Mar 2017, 12:25

Made a note of this and the pic when Robert posted it (and yes, it is still in my to-do round-tuit file :oops: )

Where are the kickback fingers with these guards?
My Rockwell has them as part of the guard and the riving knife.
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJ » 28 Mar 2017, 17:10

I use the JessEm stock guides.
Image
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJhn » 28 Mar 2017, 23:10

Kick back fingers are in reality not needed if you have a correctly set up riving knife, or splitter, the JessEm stock guides due to the wheels on them being offset (five deg I think) hold the cut stock against the fence and help prevent kickback.

Mike

Link to manual: https://www.jessem.com/assets/04301---c ... guides.pdf
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Re: Old project - Improved Crown guard for TS200 saw

Postby Phil » 29 Mar 2017, 07:25

MikeJhn wrote:Kick back fingers are in reality not needed if you have a correctly set up riving knife, or splitter, the JessEm stock guides due to the wheels on them being offset (five deg I think) hold the cut stock against the fence and help prevent kickback.

Mike

Link to manual: https://www.jessem.com/assets/04301---c ... guides.pdf



The Jessem guide looks good and a nice setup, not seen them locally and to import will cost about 4.5k

On the Rockwell the riving knife will certainly not stop any kickback.
To make a new guard for dust extraction means building in the riving knife and the kickback fingers.
It is still worth looking at to cut down on dust off the saw.
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJhn » 29 Mar 2017, 08:12

This from the HSE web site:

ACOP 127 At circular saw benches, the risk of kickback of the workpiece should be
reduced by the provision and use of a properly designed and well-adjusted riving knife.
ACOP 128 The riving knife should:
(a) be securely fixed below the machine table;
(b) be positioned directly behind and in line with the saw blade;
(c) be shaped so that the inner edge of the riving knife follows as closely as practicable
the contours of the largest saw blade that is designed to be used on the machine;
(d) be strong and rigid;
(e) have sides with smooth flat surfaces;
27
(f) be kept adjusted so that it is as close as practicable to the saw blade and in
particular is within 8 mm from the blade at table level;
(g) be kept adjusted so the vertical distance between the top of the riving knife and the
top of the blade is no more than 25 mm (except for saw blades that are more than 600
mm in diameter in which case the
extension should be to a height of at least 225 mm above the machine table);
(h) in the case of a parallel plate saw, be thicker than the plate of the saw blade.
129 More information on riving knives can be found in Circular saw benches - Safe working
practices (http://www.hse.gov.uk/pubns/wis16.pdf)

In case you don't know the HSE are the Health and Safety Executive in the United Kingdom and draw up the Regulations for using any equipment in the workplace.

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Re: Old project - Improved Crown guard for TS200 saw

Postby RogerS » 29 Mar 2017, 08:23

My understanding is that the riving knife should be slightly thicker than the blade. This means that as the work passes by the blade, the riving knife keeps the two pieces on either side of the cut apart from each other and stops (a) binding if the tensions in the wood are trying to close the gap and (b) the rising teeth at the back of the blade 'collecting' the wood and throwing it back at you.

The other thing not mentioned as yet is to make sure that you use a short fence that ends roughly at the back of the blade so that the wood has 'somewhere to go' for want of a better description especially if, as already mentioned, there is a lot of tension in the timber that is released as the wood is cut.
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJhn » 29 Mar 2017, 08:28

According to the HSE the riving knife should be thicker than the blade body, but not thicker than the tooth width.

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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJhn » 30 Mar 2017, 00:04

A bit of confusing information on the HSE web site, for a tall fence its shows in diagram form the fence being level with the front face of the blade and describes it thus:

A rip fence or a cross-cut fence should be used to
give adequate workpiece support during cutting (see
Figure 2(a)). To prevent kickback, the front of the fence
must be set no further than the base of the saw blade
gullet at table level. When cutting shallow or angled
work, the normal fence may need to be replaced
with a low fence to aid the use of a push-stick and to
prevent the canted saw blade touching the fence (

When cutting a shallow piece it shows in diagram form the low fence being at the back of the blade, personally I use a full length fence with the JessEm guides and have never had a problem before I installed them or since, I have never experienced any kick back on any of my table saws, but then what do I know, only been playing with these things for fifty years.

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Re: Old project - Improved Crown guard for TS200 saw

Postby Phil » 30 Mar 2017, 10:35

MikeJhn wrote: I have never experienced any kick back on any of my table saws, but then what do I know, only been playing with these things for fifty years.

Mike




Mike I respect your view and experience regarding your use of table saws. (that is about 49 years more experience than what I have)

However, I can assure you that my Rockwell riving knife will definitely not stop any kickback.

The RAS has to have the fingers down for ripping, personal experience.
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Re: Old project - Improved Crown guard for TS200 saw

Postby RogerS » 30 Mar 2017, 10:42

Phil

A RAS is a different beast to a table saw and the mechanics of operation etc are different.
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Re: Old project - Improved Crown guard for TS200 saw

Postby Phil » 30 Mar 2017, 11:11

RogerS wrote:Phil

A RAS is a different beast to a table saw and the mechanics of operation etc are different.



I agree Roger, the RAS is very different.

I remember watching a YT on kickback where the chap demonstrated cutting a plank without the splitter/riving knife or fingers and it threw it back across the room.
He then fitted the splitter and did the same cutting exercise.
The plank cut nicely all the way through, but the waste piece went flying back across the room which could be prevented by the fingers.
I think a lot depends on how you are also feeding the timber into the saw.
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Re: Old project - Improved Crown guard for TS200 saw

Postby MikeJhn » 03 Apr 2017, 07:25

Interesting article on the dangers or ripping on an RAS here: http://www.sawmillcreek.org/showthread. ... -rip/page2

I thought this post was enlightening, having never ripped or even considered ripping on an RAS.

Although rips can certainly be done on a RAS, they are messy and can be dangerous. Unlike crosscutting, where the blade either climb-cuts or is pushed into the stock while held against the fence, ripping must be done with the blade rotating directly toward the user. The blade guard must be tilted so its rear just clears the stock being ripped, preventing stock being lifted off the table. While this adds safety, the front edge of the blade facing the operator is exposed, and LOTS of sawdust is thrown directly into his face! Ripping on a RAS is a nasty operation!

Ripping is what table saws were designed for. They do it best! Crosscutting long stock on a TS is as awkward as ripping is on a RAS. Many forego the RAS in favour of sliding miter saws, but those often lack rock-solid stability to deliver perfect crosscuts or mitres. I Love My RAS's!


I disagree with the last sentence, my Makita LS1013 cuts perfectly whether crosscuts or mitres, but this is way off subject, back to the table saws.

I am considering lowering the angle of approach to the guard to 35deg to make the guard easier to lift over the stock being pushed into it, the guard is supported by a long cantilever arm and this moves when the guard is being pushed by the approaching stock, my preferred alternative is to put a counterbalance weight on the rear of the guard attached to the upper parallel guide arm, any thoughts?

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