How large should i build a router sled? (or what size are most tables)

[julianf]

I'm going to build one of those router sled jobs, made out of aluminium extrusion.

This chap on youtube has a video on them -




Now, obviously, the size is directly dependant on your stock, and what you are doing with it. I dont have a market for large resin tables or anything like that, so my plan is a work area of about 170cm x 100cm (table footprint 2m x 1.4m)


Its a bit of a pin-the-tail-in-the-donkey thing, as who knows what the future will bring, but that works out at about 5.5 feet. Im wondering if i shouldnt just make it large enough to do 6 foot jobs and be done with it.

Its not money on extrusion, so much as being increasingly awkward to set up, store etc.

What do you reckon?

Again, noone will have that much of a solid answer, but the question is, is 6 foot such a standard length for "stuff" that i would be shooting myself in the foot by not building to accommodate it?

 

[XH558]

Mine has a working area of approx 1000x600. Stands vertically and is about 80mm thick including the bed and ali rails. Cross sled is detachable and made from ali angle. Does the job.

 

[custard]

Sure you need one?

I make quite a few pieces from big, waney edged slabs. Things like desks and dining tables. They're way too wide to process through my 405mm wide planer/thicknesser. So I finish them with an old wooden jack plane. And that includes ultra hard tropical timbers as well as temperate zone hardwoods.

I used to work in a workshop that had a regular line in massive Oak Hayrake Tables. Same story, too big to be processed through the machinery, so they were done with a bench plane. Okay, it's a bit of a work out, but no where near as gruelling as you might think, bottom line is it's eminently do-able.

 

[julianf]

I have physical skill in two areas -

I can manipulate a spray gun, and I can plaster a wall.

Beyond that, I'm a machinist. My main trade is CNC work.

If I could handle a plane with even a quarter of the manual skill that I see in others then your comment would be valid.... The reality, however....


But, there's another aspect - I can do this at the moment on the CNC machine, but what I'm looking for is a quick, thoughtless roughing job to normalise the timber before I CNC cut it.

That way I can get a proper look at it, and lay out the CNC tool paths according to the grain. Rather than flattening it on the machine (slow, and the work area is not huge) and then finding out that, if I'd made the cut 20mm to the right, I could have utilised the grain so much better.

My plan is to be able to chuck large bits on, whizz over them as quick as possible, then cut them into smaller chunks for CNC cutting once I can see what's what.

But the 6 foot question is still valid. I don't have enough experience to know if, for example, stock often comes in 6 foot lengths, and I'm often going to end up wasting 6 inches to get it into my 5'6" table.

 

[Sachakins]

If your using extrusions, surely you could use extrusion joint braces to extend the lengths to suit as an when needed. So use say 4 foot to suit most usages, then have 2 more 4 foot sections to add on to make 8 feet, or whatever you want?

 

[Robbo60]

I'm going to build one of those router sled jobs, made out of aluminium extrusion.

This chap on youtube has a video on them -




Now, obviously, the size is directly dependant on your stock, and what you are doing with it. I dont have a market for large resin tables or anything like that, so my plan is a work area of about 170cm x 100cm (table footprint 2m x 1.4m)


Its a bit of a pin-the-tail-in-the-donkey thing, as who knows what the future will bring, but that works out at about 5.5 feet. Im wondering if i shouldnt just make it large enough to do 6 foot jobs and be done with it.

Its not money on extrusion, so much as being increasingly awkward to set up, store etc.

What do you reckon?

Again, noone will have that much of a solid answer, but the question is, is 6 foot such a standard length for "stuff" that i would be shooting myself in the foot by not building to accommodate it?

I would make it the size of your work bench?

 

[marcros]

you could either make it oversized and use it for a few months. you will then know how much you really use and could cut down the extrusions and rejoin.

Or make one from timber as a prototype. It is only a frame/couple of runners with a non sagging sled that runs across it. a few lengths of 4x2 and an offcuts of ply. then either keep it forever, or build the second version with the lessons learned from the first.

 

[Essex Barn Workshop]

I feel sure I've missed a point here, or will have my naivety shot down having never used a sled (but liking the idea of making one) but surely you could have, say, a 3 foot long sled and put a 6 foot workpiece underneath it, flatten the 3' then move either the sled or the workpiece (assuming it and the sled were on a stable work bench) and finish off the remainder? The reference point would be the sled onto the bench?

 

[julianf]

I feel sure I've missed a point here, or will have my naivety shot down having never used a sled (but liking the idea of making one) but surely you could have, say, a 3 foot long sled and put a 6 foot workpiece underneath it, flatten the 3' then move either the sled or the workpiece (assuming it and the sled were on a stable work bench) and finish off the remainder? The reference point would be the sled onto the bench?

Possible, for sure, but if neither side are flat to start with, you have to manually re-align the job with the cutter, which is time consuming to get spot on.

Its much easier (and i know this from smaller bits on the cnc machine) to work the whole surface in one pass, and then just be able to flip the job, and THEN know its not going to rock about or anything.

What youre suggesting is not impossible at all, but my whole reason for wanting to build this is to be able to load up a slab, quickly flatten it, see whats what, and then spend the time on it. Its supposed to be a labor saving device, and, for the sake of a bit longer extrusion (and having to store it - which is the important bit!) id rather it was as quick as possible.

 

[julianf]

you could either make it oversized and use it for a few months. you will then know how much you really use and could cut down the extrusions and rejoin.

Thats really not a bad idea at all. Ill probably never bring myself to cut down a larger unit, but delivery on the extrusion wont be cheap, so its better to do it your way. Thank you.

 

[Trainee neophyte]

Given that this is a) only initial flattening and b) to speed up the process, have you considered the same jig but for an electric hand plane?

 

[TRITON]

Router sled - Very handy for doing concave and convex surfaces.

Not just for routing for flat things

 

[sploo]

I'm going to build one of those router sled jobs, made out of aluminium extrusion.

This chap on youtube has a video on them -

That's a great sled. The fact it's on round rails (meaning it's held in place well) makes me think that a pulley/cable system with stepper motors would be a good addition - basically automate a sweep across the plank, then slide forward a bit of each sweep.

 

[sploo]

Router sled - Very handy for doing concave and convex surfaces.

Not just for routing for flat things

Many, many moons ago I build a jig like that, but with a motor at one end to spin an axle; so it could be used to make spherical or "torpedo" shaped objects. My main memory of it was dust. Lots, and lots of dust!

EDIT: Found the images

 

[julianf]

That's a great sled. The fact it's on round rails (meaning it's held in place well) makes me think that a pulley/cable system with stepper motors would be a good addition - basically automate a sweep across the plank, then slide forward a bit of each sweep.

I'm a CNC operator. I specifically want to build this so as I DONT have to use CNC...

CNC is great, but, for some jobs, working by hand is just quicker and easier. This is one of those jobs.

As an example on a bendy slab, it may not be clear what the low point is exactly. And then there's no point in working the whole slab in all the step down increments - you may as well just skim the high bits first and then step down and skim the next high bits.

You could generate a tool path to just skim where needed skimming, but then you would need to probe the whole job first.

And by the time you had done all that, then generated the tool paths, you may as well have just done it by hand.

I'm wanting this for rapid flattening so I can see grain patterns etc before loading to the CNC router.

 

[sploo]

I'm a CNC operator. I specifically want to build this so as I DONT have to use CNC...

CNC is great, but, for some jobs, working by hand is just quicker and easier. This is one of those jobs.

As an example on a bendy slab, it may not be clear what the low point is exactly. And then there's no point in working the whole slab in all the step down increments - you may as well just skim the high bits first and then step down and skim the next high bits.

You could generate a tool path to just skim where needed skimming, but then you would need to probe the whole job first.

And by the time you had done all that, then generated the tool paths, you may as well have just done it by hand.

I'm wanting this for rapid flattening so I can see grain patterns etc before loading to the CNC router.

Good point

I was just thinking that a simple (even mechanical) system could do the boring job of sliding the router back and forth. No point if it's mostly just taking out high spots before chucking it on a CNC.

 

[Ollie78]

I made a U shaped "trough " from plywood, the width of my router, the sides are about 100mm high which keeps it nice and flat, it has a slot for the bit to plunge through then put the board or slab to be flattened on the floor.
Either side of the slab I get 2 paralell bits of wood which I have thicknessed so they are smooth.
I just rest the jig on top and move slowly down the slab. Flip it over and repeat. Then belt sander (Makita 9404) job done.
Using a big 25mm bit it is quite effective.

It cost zero because I made it from scrap bits. It works in an almost identical way to the contraption in the video and took about an hour to make. Also pretty much infinitely variable size.

If I was doing slab tables every day I would build a cnc machine big enough, for the programming on stuff like this you don`t have to get fancy, zero Z to the high spot and let it run, it will cut a bit of air on the first passes but you can go for a cuppa. Depending on the machine you have you could use a massive bit to save time.

If you are just removing humps before another process it is amazing what a 40 grit on a belt sander will remove sharpish, it might be a quick and easy method, or even an electric hand planer for roughing big lumps off.

Ollie

 

[XH558]

That's a great sled. The fact it's on round rails (meaning it's held in place well) makes me think that a pulley/cable system with stepper motors would be a good addition - basically automate a sweep across the plank, then slide forward a bit of each sweep.

That sounds like it's heading towards becoming a 2 axis CNC machine...... crack on my good man and tell us all your pitfalls so we can skip those. Ta muchly.

 

[sploo]

That sounds like it's heading towards becoming a 2 axis CNC machine...... crack on my good man and tell us all your pitfalls so we can skip those. Ta muchly.

I'd think of it as a Heath Robinson thicknesser

I'd love the space to be able to work with such large slabs, but I suspect that regularly flattening big slabs with a handheld router could get a bit tedious (hence the thought of a simple bit of automation to sweep the router back and forth).

I do have a CNC machine, but like the rest of my work space it's way too small for such slabs, so it sounds like I'm at a rather smaller scale than what julianf is using.

On the original question, Marius Hornberger had a design that could be stripped down for storage, so might be an option:

 

[Terrytpot]

Tried making one myself a while back and found it all very messy and also a job where if your "cradle" for the router isn't substantial but your router is you need to be prepared for it to dip a bit in the centre which will leave the middle of your board thinner than its edges...sounds obvious but in my case the spread wasn't particularly wide at roughly 14" and I was quite surprised to find I didn't get the result I'd hoped for as you couldn't see the carrier deflecting at all and it was only evident by the marks left by the cutter and with checking with a straight edge afterwards.