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

[Amateur]

I suppose it depends on how many slabs you wish to flatten.
I wouldn't entertain making what you suggest, but rather get a wood supplier that has either a wide sander that will stick it through for you. In fact A lot of places sell slabs this size already converted to show the wood configuration to the buyer.
If I was doing a one off I would seriously look at this method.
However if your going into full blown production runs there are machines out there to handle these sizes.
A lot of posts on YT look ok in the final video, but they never show you the cock ups, time to set up, emptying the chip collector bag, and installing an empty one, rail deflection and especially with a router cutter of max 2 inch diameter the time it will take to reduce the slab to the thickness your looking for.
One person I know who makes kitchen worktops from boards such as this uses a belt sander which has already been suggested.
It also depends what your skill levels are up to?
Is this for internal use in a central heated house?
If so that presents another set of problems with shrinkage and expansion.
I'm sorry I can't be more positive.

 

[julianf]

I'm planning on using 40x80mm for the y axis, with the 80mm in height.

At 1m of unsupported length, I reckon I could stand on that with very little deflection.

The cradle itself will probably be laser cut and CNC folded out of somthing like quarter inch mild steel, which will be overkill for supporting the router but the cost difference is virtually nothing and the mass just makes things jump about less.

 

[Ollie78]

I still say its overkill but you seem to have a plan.
Mine is similar to the one in the video sploo posted, only without the central frame bit, I made mine much longer than that and from 18mm birch ply, it does not flex at all.
I would say a design consideration that has not been mentioned is backache mitigation, like attaching a pole with a universal joint on the router so you can move it easily while standing up. I did a huge slab and it gave me lower back ache for a day or two after.

I hope you show us your final creation.
Ollie

 

[julianf]

Ive kind of made a start on this, but in a very very much more budget way.

I picked up a Hitachi M12V off Facebook market place for £25, and that kind of set the financial theme.

I had a look about here, and found some, i suspect, 2" box section. A couple of, about, 6' lengths, with, maybe a 3mm wall (sorry, im bi-lingual when it comes to measurements!).

This will do for the long rails.

I sanded one up (it had been outside, and was pretty rusty!) and then waxed it with what i had knocking about (briwax) and did the same to a bit of 1.5" (approx.) angle.

The angle slides along the top of the box very well when waxed. Remember, a zero friction router sled isnt desirable for this anyway, so, mostly slidey, and level is absolutely fine.

What i think ill now do is cut some more angle for the y-axis and weld it onto the slidey bits that sit on top of the box.

Ill weld up the two y-axis bits just wide enough to run the hitachi down the center of them.

Im not sure if ill bother with a "ladder" between the long rails. The 6 foot box is weighty anyway, and ill either just clamp it to the top of my wadkin ags table, or maybe even just use magnetic welding clamps.


Ill take the blade out of the wadkin, so its just a flat cast worktop, lay the 6' lengths along the long width of the table, and weld up the y to do the short distance of the table.

This will all just be from stuff i have knocking about here, and, i think, will work well enough for me to test with before spending any more money.

Im not sure yet how ill hold the wood in place. I could put a bit of ply under it, thats fixed to the table, and then screw to that, or i could try hot glue to the wadkin cast, but im not sure how well that will stick to the waxed cast iron (i keep it waxed to keep off the rust)


If i make this in alloy, it will cost about £400 before the sled. I will have paid for the steel im using at some point, but its been in the rain here for at least a year, so its as good as zero cost at this point, i think.

Ill see if i cant take some photos tomorrow, as i cant think many will have followed my late night ramblings above!

Thank you.

 

[julianf]

I've not got the welder on it yet, but -

The X axis movement is surprisingly slidey. As in you can push them and then carry on moving for a bit.

The router on the y axis less so. I mean it's perfectly usable and I guess I could stick some slidy plastic on there or somthing, but I don't want zero friction anyway.


Now I won't pretend that it's as the YouTube one but my total spend so far is, umm, £25.

The long rails are heavy. Their weight keeps them fairly well in place but I'll need to sort out somthing more.

They won't slide outward, as the ends of the y axis fold over them. Which stops the y moving off also.

I need some way of holding smaller bits of wood in place. Hot glue might be enough, but I'll have to clean the wax off the table all the time.

Hot glue is nice though as it "packs out" the underneath of the slab and stops it rocking.


Again, I'm well aware it's not like the YouTube one, and not much of a step up from a standard wood one. But as I say, I'm more at ease with metal anyway, and it's what I had here.

 

[julianf]

Ps

My plan is to Tig the bits in situ.

I don't want to mig anywhere near the wadkin, as, despite the overspray (which will just rub off the wax) I care about the surface some.

If I clean it up and Tig it gently, then I won't get warping and distortion.

 

[julianf]

So, really, all i have is a basic router sled, but just made of steel instead of wood. Its so basic that its not even got sensible clamps to the table...

The steel on steel slides surprisingly well. I did wax it.

Finish is nice "straight from the box"

I had ideas about adding extraction to the alloy plate, but (as will be mentioned below) im not convinced with the whole design anyway.

There are some lines from the cutter, but not much at all, and -

This is about 90 secs with the DA sander with an old sanding pad. No tear out etc at all.

Obviously this is a tiny bit of wood, but it handles larger equally well.

Total spend - £25 on the hitachi, and £20 on the bit.


So, what's not to like?

I think its dangerous. Im normally fairly hardened to these things, but i reckon if somthing caught or slipped or somthing, that 2" cutter could come up and bite me. Im not quite sure how, but id rather not find out.

I could, probably fairly easily, design some linear stuff that will still run on the steel (rather than expensive alloy extrusion) but then the alloy stuff would be easier for the next issue -


Ive just hot glued the job to the cast iron table. It needs something better than this. The alloy ones, i think, have toothed clamps held on with t slot bolts. This would make flipping the job easy.

Im sure i could think up a solution in steel, but i dont know if its worth it.

And, dust extraction.... Its got to have some sort of extraction, otherwise clean up is just so much bother.



But, so far (as i type this will all my fingers still in place) its successful, but, again, no more advanced than a simple sled.

 

[sploo]

For the safety issue, could you do something like this:

The red panel is the base your router's sitting on, and the blue pieces are some metal welded onto the existing angle iron rails. Obviously it's not some fancy linear rail system, but it would mean the router base couldn't tip and allow the bit to dig in too far.