Need input! Idea for festool-based panel saw

[johnelliott]

Some of you may know that I am particularly happy with my Festool saw and guide rail set up. It is quick, accurate, gives excellent square, smooth edges and has made my EB sliding table saw virtually redundant.
The system does have one weakness, though. Whereas on a table saw it is straight forward to cut a board to a specific width, ie to rip it parallel to it's other edge (always assuming that that edge is straight) with the Festool system this has to be done by measuring from the existing edge (which will be straight assuming you've trimmed it with the Festool). This measurement has to be done in two places unless you are using a T square, and I've never seen a T square that is that accurate over 1200mm.
Anyway, seeing as I cut a lot of panels for cabinets, and I like my cabinets to be rectangular rather than rhomboid, I've been contemplating making a device similar to the one pictured below.
The essence of it is simple, and 8x4 table with sacrificial top surface, such as I already have, and added to that, a means of traversing a Festool guide across it. M6 thread has a 1mm pitch, so I only need to make a cross cut, then start the motor to traverse the guide, count the revolutions until I reached my desired figure, add the width of the saw kerf, make my second cut and that should produce an extremely accurate panel with its two edges exactly parallel.
So, any comments? Ideas? Problems? (such as where do I find two 3 metre lengths of M6 studding)

 

[Noel]

John, lenghts of studding, 3m or more, shouldn't be a problem. I've a 4m (at least) lenght lying about somewhere. A plumber left it behind a few years ago. Hope your idea works.

Noel

 

[MattMoore]

John, looks like a very impressive idea, i hoep it all works out for you,
a couple of things i do wonder though:
wouldnt the M6 bar bend quite considerable over 3metres? maybe a thicker bar would be more suitable?
will it be possible to adapt this idea for ripping down the 8' length?
i take it that the 2 bars at the end will be stops for the board you are cutting,
so you will always be going from one permanent edge?

apart from that a great idea!!
do you see any possibilty of making it into a wall mounted panel saw style system?

Cheers, Matt

 

[Chris Knight]

John,

You could import it from these folk http://www.keystonethreaded.com/acme.htm

A poorman version might be possible using sets of two spacers made from PVC pipe - cut lengthways to slip over the rods. These could be cut to match the sizes of common kitchen units.

 

[johnelliott]

Thanks for the replies so far, I'm hoping for lots more, and more input on the actual design
Matt, yes I wondered about sag in the studding, thing is that the pitch of M6 is ideal at 1 rev per 1mm traveled. The larger studdings are between 1.25 and 1.75 until either M12 or M14 (my Zeus book is at the workshop, out of reach), so I'd rather cope with the sag than change the thread type.
Also the bars at the end are just there to support the bearings for the studding. I will clamp the board to the table, as long as the two (or more) cuts are parallel that's all I really need at this stage. I'll do the crosscuts on my MFT

Any ideas about a timing mechanism, toothed rubber belt? reynolds chain? how about a revolution counter. it needs to be resettable and to read to .1 of a rev (.1mm)

 

[bg]

John, that’s most interesting indeed. I have been pondering two problems I have when using the Festool guide rails, both for the saw and the router, and that is who best to use the guide rails where the multi-function table leaves off. I find that for both small stock and, like you for larger panels I need a better solution.

For small width stock I’m always looking for similar height scrap stock to provide support for the guide rail, and with quite thin stock those nice table clamps are higher than wood and the clamps and stops can get in the way of the guide rail. I’ve got some very rough hand drawn sketches in front of me of my idea for a jig for this, but how to explain it. I attempt to describe it thus. A box wide enough to support a guide rail, and say three feet long, Another box running alongside this runs on Ttrack and is moved out and back with a vice screw. (in fact the idea is these ‘boxes’ make up a vice with a large top). Where the ‘jaws’ of the vice meet, it is not a solid bit of wood but has strips of wood that meet from both boxes to clamp the wood stock. A vice ‘floor’ on which the wood rests is also made up of strips that inter-mesh with the vice jaws and this floor can be raised and lowered, secured again by bolts running in Ttrack on its side that is secured to this vice floor. The box sides have slots to allow the floor the move up and down and be secured with a knob…. Well it makes sense to me, but I bet it’s a bit of a twister in understanding my gibberish to everyone else.

My ideas on what to do for larger panels are much simpler to explain, and are not advanced. I was considering making a cutting table to which I attach an aftermarket saw fence such as multi-fence I see in the Rutlands catalogue. A long guide rail is attached somehow to the right side of this fence. The scale on the fence would need to be reversed. The fence and guild rail would need to sit flat on the wood to be cut so a mechanism to raise and lower the whole fence and rail would be needed to accommodate the various depths of panel. The idea of a pucker saw fence was the hope that it would keep everything square.

Another idea I had for the larger panels was to get some of the ali extrusion Festool sell to make user designed multi function tables. Then make up a large multi function table with a torsion box construction to keep the weight down, and have an accurately set measuring scale set top and bottom. The top and bottom of the guide rail would then have to be checked and locked separately, but using the same mechanism as per the multifunction table. For me this would be no real problem as I’m not into production quantities. The flaw I see in this is how to get a scale that can easily be fixed and read from the guide rail where differing depths of panel have to be catered for as ideally the scale would have to be read from the cutting edge of the guide rail.

OK just ideas so far, but then I see your idea and it gets me all fired up with interest again.

Well your idea is my ideal, but I don’t have enough experience with motors and threads to contribute much. The following thoughts come to mind. How to get a motor to turn so precisely to move everything along the required amount? Is it some sort of computer controlled stepper motor? What sort of tolerances would you get from the top to the bottom of the rail in the linkage, would this better a T square or do you think the linkage from the motor to the bottom thread would be good enough to eliminate backlash. I wonder about the height issue as well, how were you going to accommodate the different depth of panel? Well I hope my comments were of some use to you. Do please keep at it and keep us informed if you take it further. A good workable set up that is easy to use for large panels would just be so useful to all us Festool track system users.

Cheers
BG

 

[MattMoore]

i'm sure somewhere that i have seen M8 and M10 studding with 1mm travel per 1 rotation? but i maybe wrong.
having not used the guiderail before, how are the boards held in place?
is it just down to the shear weight of them?
i did wonder if the bars at the end could be raised, so that the boards can be pushed up against them, and then you know that the cut will be parallel to the fence as it were

 

[Noel]

Should get long lenghts of studding here:
http://tinyurl.com/6tyzb

Noel, who would do tiny URL, if he knew how (Cheers Chris)

 

[Chris Knight]

Noel.

Try this http://tinyurl.com/6tyzb

 

[mahking51]

John

Great idea in principle.
FWIW I work a lot with motion control movie camera systems that allow a camera move to be replicated to an amazing accuracy in up to 7 0r 8 axes at a time. All of this is computer controlled but the mechanical side of things are in essence fairly simple. They use stepper motors, lead screws, toothed belts, cam systems etc.
You may get some help if you check out their site: http://www.motioncontrol.co.uk/ or call them and talk to a chap called Ian Menzies, (Be pepared for detail he's a bloody genius!), mention my name.
Hope this helps
Martin King

 

[Ian Dalziel]

Hi John,
You should be able to pick up 3m lengths of screwed rod at your local BSS (pipe suppliers) check your phone book, this length is common for hanging pipework studs.
Looking at your sketch all parts are easily available from Bearing Service (phone book again) ie timing belt, bearings motors, rev counters, timing belt adjusters etc
Using different studding i.e. heavier you should be able to adjust your rev counter to compensate. I think over a 2.8-3m length the threaded rod would spin itself out of its housings and it would be difficult to support over such a length.
I assume you are using the 1400mm length of rail that came with the saw, splitting the difference on either side of a 1200 sheet only leaves 100mm either side, not a great deal to allow run on and off for the saw and accommodate ‘housings’ for the threaded rod, it just seems a bit tight.
The actual cost of what you want to do might be quite prohibitive unless you are able to get the bits for free, chain or timing belts 2400mm long wont be cheap, motors, rev counter, motor to thread adaptors etc soon mount up
Your drawing resembles a vertical panel saw which is designed for cutting sheet goods and would be my preferred option. A bit of trial and error will give you results similar to your festool saw. I.e. breakout
Steve Maskerys pull down frame is also not to indifferent from what you have drawn. I think its on his web site. Might be worth trying a mod on that
The type of work you do ie cutting of large 8x4 sheets, the saw you have the EB pkf255 is not really suitable for the work you do you, hence you’ve tried to sell it and also looked at the possibility of changing the fence. For sheet work cutting on the flat is really designed for either a very large panel saw with a scribing head and lots of space or a vertical panel saw, hence you see a panel saw in every Band Q Festool use a type of zero clearance insert to prevent breakout, other model panel saws allow the use of throat plates and the ability to be changed to allow the use of zero clearance inserts but these are normally cast iron and reading other posts you have replied to you are not a big fan of cast table saws. Festools saw is good, very good for reducing big panels, great for site work, but slow for repeatability and it is outclassed in comparison to a VPS.
Speed might not be a concern for you but repeatability will be and constantly having to reset your guide rail and remeasure has prompted you to design something to overcome the festools shortcomings for your area of work, this is where a more suitable saw might be worth looking at.
What you’ve drawn and the ideas you have are ‘on paper’ ideal but the practicalities of putting it together and getting it to cut to the standards you have come to expect and want will be very ambitious and would love to see it if you manage to put it together.
Please don’t take this post the wrong way, I have built some strange contraptions over the years, some have been good and others not so good and if I was able to get advice and opinions from others from a site like this then I might not have wasted time monies and efforts, all part of a steep learning curve though,
Good luck if you do decide to go ‘for the build’

Regards
Ian

 

[Steve Maskery]

Hi John
Whilst I'm grateful to get a plug from Ian, I'm afraid that the frame is not (yet) on my website. But, satisfied as I am with it, I don't actuall think it would solve your issues regarding accuracy and reproducability. Whilst using my frame with your Festool may be better than I have at present, I don't think it will be significantly betther than you have right now.
The answer is of course to buy a Stiebig
Ok lets get real.
Do you jave space to have this as a permanent fixture or does it have to be packable awayable? And do you really need accuracy to 0.1mm? Nice, I know, but essential? I'm thinking here of building a wall saw along the lines of the old school drawing boards, where the T-square was fixed to the board on a continuous wire, crossed at the back, so that both sides went up or down together. It could be clamped in place with trigger clamps. Two vertical members, one each side, could have T-slot up the front face, to take stops. The guide could be lifted right up out of the way, load your board, then the guide lowered to the stops again and clamped in place. Reproducable. Tape measure on each side member. Accurate (to the accuracy of a rule anyway, and what else are you going to use to measure with?).
If you really do want this threaded rod system, consider M16, which has, IIRC, a 2mm pitch. It will be much more rigid and faster to travel. Easy to read to 0.25mm at least (1/8th turn).
Hope this is food for thought.
Cheers
Steve

 

[johnelliott]

The type of work you do ie cutting of large 8x4 sheets, the saw you have the EB pkf255 is not really suitable for the work you do you, hence you’ve tried to sell it and also looked at the possibility of changing the fence.

Can't really agree with you there, Ian, the PKF255 is fine for cutting large sheets, the problems are the same as any other table saw and that is
a) getting the sheet onto the saw due to the weight and size
b) the amount of space needed for traversing

The main reason for wanting to sell the PKF255 is space. Now that I can cut sheets sucessfully with the Festool equipment I would sooner use the space the saw takes up for other equipment, especially my 3 table routers which at the moment have to be moved in and out of the store room.

As for cast iron, I have no objection to the stuff, only to people claiming that cast iron saws are better, which they aren't.

For the guide rail ( I have several, including a 2.7) I would use a longer one and cut it to a convenient length

For a traversing motor I might well use a cordless drill, even a mains one if I needed more speed, and when I was nearly at the correct distance then slow down, maybe wind the last bit on by hand.

I don't think a vertical saw would suit me, first of all it's not the way the Festool stuff is designed to work, and there would be the problem of securing smaller pieces. The thing with the festool stuff is the way the rubber strips on the guide rail grips the work, frequently not even necessary to use the clamps

Steve,
no I don't really need .1mm accuracy, but it would automatically be available using the threaded rod system. For years I used something like it with an overhead router I made (back when I was making solid electric guitar bodies), and it was very convenient to be able to skim off another .5 or less of a millimetre
The M16 would in one sense be more rigid than M6 but would weigh a lot more, so I expect sag would still be a problem. One possibility would be to use M6 but put it under tension.

Keep the critiques coming, guys. Also, if anyone has some definite info on timing chains, belts pulleys etc I would be grateful

John

 

[Ian Dalziel]

John,

) getting the sheet onto the saw due to the weight and size
b) the amount of space needed for traversing

This was one of the points I was trying to put over, tablesaws are difficult at handling 8x4’s with or without masses of space, I owned a PKF 255 for a short period, I sold it because I should have bought the V8 with the scriber and hadn’t realised the amount of space it required, I almost always got rough edges whilst sawing ply . I replaced it with a TS2500 but didn’t like it either, then I got a cast machine because I could fit in a zero clearance insert to help with any breakout and fit a scribing blade as and when I need to but the insert does the job 9 times out of 10 … now I would never go back to aluminium, not because of the sturdiness of it but because I can use magnetic hold downs, aftermarket mitre gauges,, it is just far more versatile than the aluminium top. Maybe this is why the saw manufacturers are slowly changing to cast but that is another issue.
I now have a panel saw and don’t need to cut full 8x4s at the tablesaw, this was done as a GWW project and a back saver

Have you considered building a twin router table or should I say a table with routers mounted at opposing sides, this might help with your space issue.

The guide rail point was merely an observation, I am fully aware of the lengths of rails that festool supply and the way they work.

Drill idea sounds good but I would prefer to have a pushbutton of sorts while standing in front of the workpiece whilst aligning, maybe something you could incorporate.

When I was referring to a Panel saw I was meaning something like the Jet one available from axmister, these cater for small bits as well by mounting them halfway up the saw. They also take up minimum space, I am only recommending you give one a try, you might like it, you tried the festool saw and soon converted to that.

Ripping sheets is best done on their edge; it’s also easier to handle like this. You will know this because you handle worktops, one man can safely carry a 3 metre worktop in its vertical position but bring it round to horizontal and both man and worktop will get damaged. It’s the same for working any sheet material…..you carry it on its edge because its easier……. so work it on its edge at least until its size is more manageable unless you have no alternative.


Ian

 

[Anonymous]

John

You are in my area of expertise now, so watch out :lol:

First of all, I do not think that 6mm rod will be any good over this huge distance; it will sag and whip all over the place if spun quickly. The 1mm pitch is nice but they length is too great. You will be lucky to get positional accuracy of 0.5-1.0mm never mind 0.1 with 3m of M6 stud flapping around!!!
If you really want accuracy to 0.1mm, then use an incremental encoder on your drive system and feed the signal to some display or into a PC. I personally would use two guide rails (16mm or preferably more diameter) with linear bearings on them to provide smooth motion and maintian squareness of cut. Drive the Festool along the guides using two toothed belts with good tension.
Stepper motors to drive it are the best choice as long as they produce enough torque to deal with dust build up on guides and any crabbing - typical resolution of a hybrid stepper motor is 0.9 degrees adn so you will easily be able tpo move it to with in 0.1mma ssuming the belts are tight and stiction in the guides is low

If you want info on how to (cheaply) drive steppers from a PC or how to read encoders into a PC, or how tpo write soem software to control the position of the Festool along the guides, then pm me

 

[Chris Knight]

Tony,
I guessed you would be along! Are we talking the sort of money a humble woodworker can afford (say one that only owns two or three LNs?) :lol:

 

[mahking51]

Tony
Sounds like you too, work with motion control systems. Do you get involved with motion capture as well?
martin

 

[johnelliott]

Intersting stuff, Tony. I thought you would have something to say about this.
Actually, I'm not so much concerned with accuracy of .1mm absolute, so much as I am with keeping the motion of the guide rail perfectly parallel. I would certainly like to get better accuracy than can normally be achieved with a T square or even a fence that works on the same principle, in other words, a right angle from a bar that runs along the front of the table.
What attracted me to my original idea was having a mechanism that would ensure that the other end of the fence would move exactly the same distance as the front. The accuracy available from turning the threaded rod was a bonus.
Anyway, I'm still thinking about it. BG's idea about using an existing table saw fence such as those sold by Rutlands is interesting too. Still got the problem keeping the motion parallel though

I'm glad this thread is generating some interest.

John

 

[Michael S]

Hi John,

Like some others I'm a bit sceptical about the threaded rod approach, but it seems that the major part of your ideal solution is all about keeping consecutive cuts parallel.

Having seen your setup with the sacrificial horizontal table, I would think that Steve's idea of the the "drawing board" style parallel would have been a decent and fairly simple solution. It has been quite a while since I used a drawing board but if I recall correctly the spindles on which the guide wire run are fairly large diameter threaded nylon or aluminium (maybe 50mm or so diam). The wire gets wound round the spindles a few times so that there is enough friction to keep the wire from slipping round the spindle. Add to this to the fairly large travel required and these spindles would need to be quite deep. If you know someone with a metal working lathe you ought to be able to lash this sort of contraption up for a fairly small outlay and you don't need to get involved with control systems :wink:

-Michael

 

[tim]

John

Happy Christmas to you - I saw this post when it first started and wanted to ponder before responding.

I have a similar issue to yours (i think) in managing a lot of 8 x 4 sheets without too much space or a full panel saw (I have a sheppach 2500) and I looked at your plan with great interest. The biggest problem I faced was tipping the full sheet onto the table since human arms aren't 6 feet long but apart from that I can get a pretty accurate cut which I then run through the saw again to trim to size - I use cutlist plus to work out my panel layouts and it allows you to add in a trim margin.

Once the sheet is basically anything other than full size I find it much easier to slide it through the table saw rather than use a sacrificial top and circ saw (admittedly I don't have the festal so I don't know just how great it is although threads suggest its pretty damn good!). Anyway my point is that your plan looks great for that first cut of maybe even a couple of big cuts but won't it be a pain for the smaller stuff - my impression being that you are planning to get rid of your TS and therefore won't have this as backup?

I did build a flip top cart to solve the over reach problem and I'll post a pic if you are interested. Its good in a bunch of ways - it locks horizontally at any height so it can hold several sheets and these can be jacked up to slide each one through the saw but like a lot of homemade stuff its massively overengineered and quite space hungry but I cut 12 full panels last week in one day using it and didn't knacker my back in the process.

Sorry if this isn't helpful but I thought I'd offer some feedback from someone who shares your pain! BTW I have to ask - what on earth do you have 3 table routers for - I'm dying to know. :?

Cheers

Tim