Question for you machinist folks about auxiliary sliding extrusion on tablesaw

[TomTrees]

Hello folks, getting back at working on my old Startrite 275 again, as I've acquired some materials what will get the job done...
just about that is, as indeed there be some faffing involved as you would expect, lol.
Sorry didn't get a piccy of the skip, as it was a deep'un.

Now I've got plenty of perspex, which will just about do... well at least until I can find some Lexan, polycarbonate or PETG.
None the less, it'll provide me with a decent mock up for an overhead guard, and is a whole lot nicer to work than any other clear plastic I've used in the past.
Bonded to the stuff (with some tenacious silicone like goop) was this very nice aluminium box profile, which took ages to roll off with the help of a heat gun,
and yes my thumbs are indeed sore whilst typing this!, haha


Though can't complain, as I'm hoping this will indeed aid in saving them from a worse outcome.

To me, the stuff looks just the ticket, that is...once I get the two joined up using some nice angle iron inside,
which will indeed be a troublesome affair, but at least it's a plan, and I shall be plonking ahead with things soon.

So, you could say that's one component of this sliding fence sorted.
Ideally, I'd like some 10mm aluminium plate in-between the stock fence and the extrusion, for the sliding part
though seems I'll be making do with some Trespa material for that.


Difficult to explain, but it'll be a tight squeeze to get space for the slot, which will get bolted to the original fence, with either M8 or M10 fixings with low profile heads...
whilst also allowing smaller fixings to thread above and below the alu profile (the angle iron inside which will be tapped)

Whilst there's ample space for that at the minute...


It only leaves 10mm of lower fence projection....


whilst 20mm clearance looks a whole lot better to my eyes, when configured like so.


My question being, does 20mm provide enough space for use with an overhead guard?
I've been looking at all the HSE and BGHM, SUVA, and similar articles, though can find nothing in that regards.

Disclaimer, yes I believe the rules are that the height of the extrusion needs to be 15mm max height with the lower function,
and I can cross that bridge when I get to it.

p.s before someone suggests to use this approach instead...
There's still the issue of adjustment when the fence is at the high orientation,
i.e like in Roy's video for example


Whilst making a sensible, quick and straight forward ply or MDF box, with high and low functions like Steve's here, isn't viable either... as plywood/MDF and this damp shed aren't compatible, and sorting that out isn't possible for me.
(and I've only got two wee offcuts of this Trespa stuff BTW)

Thanks for reading
Tom

 

[TomTrees]

Hi again, (might edit this with some photos later)
I spent a fair amount digging through my folders, and a bit of searching online.
It's very difficult to get an accurate impression of how much clearance one can get away with,
regarding the low profile fence orientation...
Regardless, I drilled for M10 bolts to join with the original fence, as it seemed about right.
Not too large, though made allowances for M12 fixings,
Perhaps at a later date...

Haven't figured out how much clearance I have yet, as I've yet to rout the slot out, and test fit for round bolt heads
in order get a better idea of how things will look, so holding off on reducing the width of the Trespa stuff just yet.
(besides I have a bolt for the fence rail to make up)

Anyway, this fence below appears like it's got slightly less width?...
well, at least from this angle below, but I'm likely wrong on that, as I've been fooled already!
(they all seems to look taller when seen from the other side of the fence)
Plus I'm kinda guessing they might indeed be all a standard width?

Maybe I'll have a mooch around some cheaper Euro machines to see what I can find.


Tom

 

[duke]

Tom, one thing that I don't understand is the need for a sliding fence. This is not a slight towards what you are trying to do but complete ignorance on my part. Please don't take offence as I am naive regarding this. Please educate me regarding the benefits.

 

[TomTrees]

It's the European rules Duke, and worth knowing if the statistics are even a tiny percentage
of the estimated figures.
Of those estimated fugures, what's albeit a blanket term, those listed as "circular saw accidents",
so that could be 99% handheld and other types of saws for all anyone knows?

If looking for the UK stats, admittedly I can't help you there, but I assume from reading forums like these...
(forums based in the UK, that is) ... I sure ain't getting the impression that the UK was having near the same amount
of "incidents" or "accidents" ..................
The fomer, often stated to be something unforeseen,
i.e, playing by all the rules.

Compared to the latter, and something happening in which, (if playing by all the rules) would have prevented.

Those Circular saw injuries, the ones what gets listed in the hospitals in the USA...used to be in the region
(on average) of sixty five thousand reported cases per year!
I think that has fallen dramatically in recent years, i.e since around 2020 or thereabouts, IIRC,
but that might be where your answers are.

Everything is synergistic regarding the European use of the tablesaw, or circular saw bench if you will.
The sliding fence for not trapping timber with the back of the blade,
The long pushsticks, not making it possible to place ones hand closer than 300mm towards the blade (IIRC)
The low orientation of the fence, lending itself to the use of the crown guard, what's another piece of mandatory kit in Europe, and the left tilting arbor saws with riving knives which raise and tilt with the blade, (tilting away from the fence)

Along with that, other possibilities include that not many saws with arbors that are long enough to support a dado stack,
and as stated in Roy Sutton's "basic wood machining" on youtube, (fairly dated, but worth a watch)
You'll see that shaw guarding is also mandatory for trenching cuts.
Perhaps PUWER regs like 10 second stopping also plays a part also, and likely other factors which don't come to mind.

I'm not a mathematician, and couldn't do a numerical v geological analysis compared to the UK,
though it seems to me, that I don't need be, to take but a pinch of those figures on the assumption that some might be
tablesaws, is still a massive amount, whatever percentage, even if one is being very conservative on assumption...
that's still likely in the thousands.

There's a few dated UK HSE articles which are worth a look, but there's a far better more up to date guide,
called the BGHM.
Here's a link to an English translated version of the entire German BGHM safety manual, and it's 22.1 MB in file size.
The link is possible to find through this link to the Felder owners group.
One has to sign in to access the link, though it doesn't cost anything to join up.
Quite an interesting read it is.

File /General Information/BGHM_Shaper Training English.pdf uploaded

groups.io

All the best
Tom

 

[wallace]

Hi Tom, I dont get it. What is the purpose of the low fence? is it supposed to reduce kickback?
All that is needed to stop kickback is a fence alligned correctly. The fence plate should not be parallel to the blade but should tow out very slightly.
I'm not a fan of american style long fences but prefer british fence. In addition to a riving knife and crown guard not much can go wrong.

 

[TomTrees]

Hi Tom, I dont get it. What is the purpose of the low fence? is it supposed to reduce kickback?

Hi Wallace, to quote our Steve... (Steve Maskery for those new to the forum)
"The low lip is so that I can get it under the guard if I need to rip anything very narrow."

There's lots of stuff in this dated article which demonstrate this well, and yes indeed...
some pictures seem to be lacking the pair of suitable pushsticks at hand! (might be mentioned though)
and it should answer your question in image format if you want to see multiple examples why.

Broschüre zum sicheren Arbeiten an der Tischkreissäge

In dieser Broschüre finden Sie und Ihre Mitarbeitenden wichtige Sicherheitshinweise und wertvolle Tipps für sicheres Arbeiten an der Tischkreissäge – mit zahlreichen Fotobeispielen.

www.suva.ch

Though some other uses in which I'm sure some here could chime in on, even though I don't need to find more.
It's kinda related to my question on whether 20mm of lower fence orientated projection is enough,
as one can see I've made the decision to break the rules slightly in choosing 20x40mm extrusion,
which is 5mm too tall.

All that is needed to stop kickback is a fence alligned correctly. The fence plate should not be parallel to the blade but should tow out very slightly.
I'm not a fan of american style long fences but prefer british fence. In addition to a riving knife and crown guard not much can go wrong.

That's a debate, which seems like it could be a sharpening thread in the making, though perhaps I'll start one when I make up
some Shaw guarding, something like in Roy Sutton's video on YT.


All the best
Tom

 

[TomTrees]

Might as well give ye an update on how things are coming along..
Had this nice, thin and crisp cornered angle iron which was from an old bed, and started cutting one of the rails up.

Drilled both lengths, and also the underside of the lower one for access, whilst tapping the upper length...
(should've gone to some effort to get rid of the burrs on the inside)


Spent a while fumbling about with being careful trying this method below, and then with magnets which was no good either.
The tools for the job, simply being a long piece of plastic, and a slim ground down screwdriver, what's my "beater chisel" for nails and screws, that's it.



Turns out there wasn't enough clearance made for the bolt heads, but the only grapes were the ones I routed with a 4mm bit.
I thought this would be more difficult than it was, infact effective enough to go through the material on one spot...
Lots of space, for drilling horizontally is needed for this... as my clamps were in the way the last time,
doing so would've solved it from happening.. I'll likely be having another go at this again, for the nuts.


Like so... getting ready to drill the last bunch of grapes at the very end, with plenty of space for sidewards drilling.
Only snapped half of one bit whilst doing the job, and I wasn't being particularly careful.


Just two tools for the job, well and an allen key for shoving it through thereafter.


I spent some time poking about making sure I wouldn't foul anything, and made me mind up where to drill the M10 bolt hole..
with some allowance for an M12 at a later date, should they suit better.
(I decided that 40.1mm seemed better)


One done, which went smoothly...

 

[TomTrees]

Whilst I spent a fair bit of time with some rod, hoking about to check for obstructions for the other bolt hole.
Noticed some cast iron swarf was appearing, so went about taking apart the fence to see what I was dealing with.
Didn't feel that with the pokie!





No worries, I have just enough space for going up a larger bolt size should it be necessary, phew!.
However...whilst drilling these holes incrementally, I should have got some 6 and 8mm threadbar for checking progress
before finishing to M10, as I had to do a teeny bit of filing on the second hole.

Took some footage of assembling the fence again, just incase I needed to see how things needed be.
Turns out there's a slight bit of length to play with, should anyone not have quite enough meat on the threaded rod
adjuster at end of the fence, which can get mangled pretty bad.

Bored some holes, and got routing, quite an adventure with the bit coming loose, and I thought I cranked down on it fairly sufficiently just a few mins earlier.


First use of the router table, which I thought at the time, was jumpin the gun a little bit?...
Great help with things, so it is, though I need some training and practice with re-setting the height more easily.


Another chance for the router bit to come loose, but better it happening whilst the router is upside down.

Was going to grind the fence bolt heads thinner, but I didn't think it were necessary,
and was deciding on whether to grind them round aswell, or add wings instead.
It seems sound as is... though I'll have to see how things are, once the taller extrusion is bolted on.


Hopefully it'll be rigid enough to keep the two extrusions flush with each other, as you can see some fettling nessecairy.

Not got around yet to seeing how much material I've got to play with, regarding the upper line of bolts to be drilled,
and the amount of a lip for the low profile orientation, should it be even possible, that is...


Tom

 

[TomTrees]

Been eyeing up things, and think I'll be better off not trying to succeed in having the two jobs in one.
Perhaps if I had some aluminium plate instead of the Trespa material, I could open the ends of the slot to enable
sliding the auxiliary fence off, instead of removal with the bolts captured.
That's the long and the short of it, I suppose.

The other little issue, if I found some plate for the job, the space needed for the connecting bolts, which looks like I don't have a millimeter to spare for a maximum projection of the lip of 20mm...

So looks like I'll have to do something else for the job in the meantime.
Well, at least the fence bolts now will simplify things massively, so might copy the low fence design in the photo I posted earlier.



Nothing more to post yet, as only got the place tidied up a bit to take a photo.
The Trespa is rather stinky stuff.

Cheers
Tom

 

[TomTrees]

Hello again folks, might as well post an update on things.
Onto getting the holes marked out, just needed to fettle things first..
I always find bending things a head scratcher, but only a few clamps were needed for this thin stuff.



I fully intended to add a little more depth to this WIP, but my camera/computer wiped the pics,
so you'll have to make do with a mock up for a bit...

Drilled the trespa stuff whilst clamped onto the extrusions, and countered holes thereafter...
(could have done a better job of marking out, as I had to grind a bit of a welded nut later)


The countersinking made alignment more sureworthy, I would've thought...
but some filing was necessary.
A very slow, but brisk job.

One of the bolts required to be inserted from the far end, due to the welded nuts,
hence the long offcut being added to the necessary tools shown below. (the pliers and tweezers wern't of any use)



Had a bit of a job getting those nuts welded, as both of the ends needed grinding off as the bolts became seized.
I ended up using lots of heat sinks after welding, in order to try reducing that.
It seems a bit of pot luck I reckon...
If I were to do this again, I think I'd try welding little plates on, instead of nuts, as I had to do some bending anyways.


Not sure if it might be a good idea sealing the stuff, guessing such won't matter since it's being held tight against the fence.


Rummaged through my metal basket and found two pre-cut welded rings what seemed about the right size,
to make up some fence knobs.
These weren't perfectly identical, and I spent more time on them as a result.

Spun them round(ish) in the end, and then tapered them a bit with the aid of an angle grinder..
They could do with another go, so didn't bother taking a photo since.

 

[TomTrees]

Sure you can buy about 15, M10 star knobs for under a tenner from the big river,
or you can make yer own fugly lookin ones instead!
Though they seem about right clearance wise, and also of suitable width in surface area, as the fence isn't made of very substantial thickness material in that regards, I didn't want to indent it with something less broad,
though likely wouldn't have...
should what's likely a wiser option fit (regarding getting the fingers under)

I suppose/do hope, a bit of black paint might make them a bit less obtrusive to the eye, though not too rushed to paint them yet.
They hold well though, and seems they are happy to stay very snug, and take a bit more effort to loosen than tighten,
which for smaller fixings/knobs would be a bit of a wrestle, so I'm pleased with my decision to go with 10mm shouldered bolts.


No good for low profile cuts though, so not a total success.
Suppose I might be better off to wait for a bit, should I trip across something in the meanwhile, which might clip onto the extrusion from either end perhaps, as removing the sliding fence for the job seems a bit of faff.

It would be interesting to see some designs out there, which might do this a bit nicer than what comes to my mind.

Cheers for reading folks.
All the best
Tom

 

[TomTrees]

Hello again folks, I've been pondering a bit more about the job, as space is so tight in there at present,
it's hard to think straight when yer standing on a lawnmower, lol.
Seems that I've got some luck, in such that the trespa being a bit shorter than the extrusion, it might lend itself nicely
to some sort of drop down/slide down low profile fence....
Likely easier to show what I mean...

There's plenty of area for some sort of a claw on each end, which could hopefully be a snug fit without the need for fixings to go missing.
Be nice if it didn't score the extrusion too, and I guess some 5mm aluminium plate might be just the stuff for the job.
Some hardwood might be acceptable for this purpose, though not decided on anything yet, and not in any rush to do either.


Which gets back to something like the original question

How much space would you opt for, bearing in mind I don't wish to remove the 80mm tall fence?
Perhaps one for Mr Steve Maskery?

The one in your old video, the "lip" looks to be about 40mm away from the fence...
Has this proven to be sufficient for your overhead crown guard?

The same question goes to those who might have done the same or very similar,
or indeed for some who felt their HI/lo fence extrusion left a little to be desired in this regards.


Cheers
All the best
Tom

 

[Cabinetman]

Quite an involved job but worth it I’m sure. I too have wanted to compare uk and us injury rates, but I found the uk ones difficult to come by.
The us ones are pretty horrific.
Don’t know if you saw this sliding fence for my combination mc, made from Ash and works a treat, as a combi mc it meant a lot of faffing around between operations this has already paid back the time spent making it, I solved your dilemma on bolt heads ( if I’ve understood it correctly) by using trapped Coach bolts.

 

[TomTrees]

Hi Ian, I was referring to the low fence orientation what's mentioned in the SUVA manual,
titled Arbeiten an der tischkreissäge.
I tried finding the date of publication just now, and cannot open the file for some reason.

Now I'm not sure if what's mentioned is strictly referring to use of a sliding saw, or if it's a universal guide for all circular sawbenches?
I tried putting the manual into google translate, which seems easy to simply drag downloaded files into the box,
but my laptop driver software is now unsupported, so don't know if it'll work for others, I guess so.

I did translate the paragraphs beside the pictures, the hard way, just to see if it mentioned sliders specifically?
which it didn't, but this could be mentioned elsewhere, as I haven't gone to the effort just yet!

This reads...
"To ensure that the guard can be lowered onto the workpiece without hindrance,
The stop or shim in the guard area must be no more than 15mm high"



And on the next page or so, it mentions ...
"When cutting a workpiece with an open kerf, the stop must be adjusted as shown in the image.
With this adjustment, the workpiece cannot jam and will not kick back."



So I looked at some more of Steve'svideos, as I recall he made a new fence which lended itself nicely for use with an auxiliary fence, and noted it seemingly has more or less the same amount of clearance provided,
That is of course, with fence knobs included.


So it seems that 20mm wouldn't have been suitable, though I asked again just to see before I started making a suitable
add on "lip", just for interest sake....
Should even more than 40mm? be desirable in use, which may well be a compromise of sorts regarding ergonomics,
whilst not being utilized on the other side of the fence, or indeed simply for storage, which I haven't looked to see
if there be a nice little place somewhere on the machine where it could go.

Hope that might explain things a little better.
Cheers.
All the best
Tom

 

[Jar944]

Tom, one thing that I don't understand is the need for a sliding fence. This is not a slight towards what you are trying to do but complete ignorance on my part. Please don't take offence as I am naive regarding this. Please educate me regarding the benefits.

Great for being able to pull the fence back away from the blade for crosscuts with a sled/miter gauge or slider. The delta unifence is a euro type design that had the same ability.

High/low is nice for narrow rips

 

[Jonathan]

Tom the lip on my sliding fence is 42mm.
Once you have had this set up there’s no going back to a fixed fence.

Duke as Jarr944 says it’s a must for a slider, use mine loads,set back from the blade as a bump stop

 

[Jar944]

Tom the lip on my sliding fence is 42mm.
Once you have had this set up there’s no going back to a fixed fence.

Duke as Jarr944 says it’s a must for a slider, use mine loads,set back from the blade as a bump stop

That extrusion is likely the best value of anything felder sells separately.

 

[TomTrees]

Thanks Jonathan, that is a rather nice hefty walled extrusion, looks like a Felder machine, if the paint is anything to go by,
and looks to be compliant with the Euro regs what's seemingly at 15mm max height.

I guess I have my answer then, and 42mm should provide ample space.. otherwise they wouldn't be making them, which appears to be largely an unchanged design for a long time, so it must perform very well,
though worth noting if there were more space offered, it would then make the fence when in it's "upright" position,
likely too tall...

So I suppose, I'm still asking the question, since I have to make do with making a separate fence, which isn't optimal...
as then I'll have to find somewhere on the machine to stow it away conveniently, where it won't get damaged,
and I haven't looked into that yet,
but wouldn't be at all surprised if there were some cubby space which might provide some maximum dimensions,
should someone suggest they like using sheet goods offcuts for low profile cutting jobs, i.e wider than 42mm.

p.s, as I'm asking that question, I would be also interested if there are any downsides (obviously, only on occasion)
to having such a low profile...
should the timber one as shown in the SUVA article be of a preferable shape?,
Or if it's merely taller on the infeed, due to being more structurally sound than a thin strip

Cheers
All the best
Tom

 

[TomTrees]

That extrusion is likely the best value of anything felder sells separately.

Now you tell me!
... and there was me like an eejit, questioning the Sawstop reps if they were gonna introduce one with their
venture into the UK market, seemingly those folks aren't too worried if someone gets a very nasty kickback!

I did look into Grizzly tools for such an extrusion (in the spares section), and a few others in the more affordable
category of machinery,
though shied away from the likes of Sedgwick due to some mentioning the price of spare parts.

Good for others to know Felder will sell one, and it's likely as good of an extrusion, as can be obtained from anyone.
Thanks for the pic Jar944.

Cheers
All the best
Tom

 

[Jonathan]

Tom the 42mm works well on my machine with the stock Felder crown guard.
Now should you have a wide crown guard (we see them on Roblem machines) the 42 mm would need to be much bigger.
I would suggest setting up your crown guard and seeing what width lip works for your machine.

p.s. the lip on the Felder is 11mm high, if I was a Felder designer I can’t see why I would change it, unless Martin was doing something special I wanted to copy…..

 

[TomTrees]

Tom the 42mm works well on my machine with the stock Felder crown guard.
Now should you have a wide crown guard (we see them on Roblem machines) the 42 mm would need to be much bigger.
I would suggest setting up your crown guard and seeing what width lip works for your machine.

p.s. the lip on the Felder is 11mm high, if I was a Felder designer I can’t see why I would change it, unless Martin was doing something special I wanted to copy…..

Thanks for the additional measurements Jonathan,
I forgot that I'd been expecting such elements would be brought up!,
but thankfully not before I'd got some measurements first.

My saw having a left tilt arbor, an old Startrite 275 that is, being preferable it seems...
Not seen which way the arbor tilts on Robland or Rojek's machines, and only started looking at the latter now,
should that explain why, as to the extra width of them?...
That might indeed be the answer, or explain a red herring should I have stumbled across such low profile cutting
somewhere.
An interesting point which I'll be looking into, even though I've been looking at plenty of guards before, (overhead types)
well, on some of the older Robland's anyway, and not noticed this, perhaps on another model if so.
(always interested in seeing other ways things are done)



So it seems, (unless I'm mistaken) that I have some leeway in which design of overhead crown guard I'll be choosing,
in attempt to replicate,
and hopefully it should have sufficient adjustment whichever design that be.
Only the post is made so far, what's adjustable in a housing, and not planning on using the saw for a good while yet, i.e a year or longer,
as too much metalworking what I'll be doing, in order to get the shed somewhat functional enough,
what one could call a reasonable enough space to work in.
It also needs some Shaw guarding, whilst also infeed and outfeed supporting needs sorting.

Cheers again.
All the best
Tom

 

[Jar944]

My saw having a left tilt arbor, an old Startrite 275 that is, being preferable it seems...
Not seen which way the arbor tilts on Robland or Rojek's machines, and only started looking at the latter now,
should that explain why, as to the extra width of them?...


Cheers
All the best
Tom

My Rojek and Martin saws are both right tilt.