am making a router sled and wonder what type and thickness of metal will be best for the runners?

vale

apologies if this is a bit of a newbie simple question, but i have never really used metal before apart from fixings and aluminimum pedal cases.

i want to make one of these and am shopping for the metal runners to fit my router in.
https://i.pinimg.com/originals/49/b2/c6/49b2c6e4c46e822e0c71d289d48cfd1e.jpg
i want something robust as my handheld router is the regular 'horns ether side type' so weighs a bit, which means if i used wood and routed a slot for the bit
a) it might dip a bit in the middle of the router 'bridge' and give me a slightly concave type of flat (so not flat then!).
b) i wouldn't be able to see what i'm doing much.
c) to make it non bendy i would have to use thick wood and lose potential router cutting depth.

so metal seems best for the bridge bit that goes across the guitar (to be rigid and not bow in middle) while the sides can just be level wood.

the one in the pic looks like aluminium 2.5cm x 2.5cm (ish) but not sure about thickness.
as aluminium is bendier than steel maybe i should go steel? or just thick aluminium.
in which case would 3mm thick aluminium be good, not enough or overkill?

my span will be about 50cm to do 40cm wide bods with buffer room at the edges.
so 2 x 50cm (1 metre) of 25mm x 25mm x 30mm (thick) should be about £8.50 here.

https://www.ebay.co.uk/itm/ALUMINIUM-ANGLE-EQUAL-10-x-10mm-25-x-25mm-30-x-30mm-40-x-40mm-50-x-50mm/192454984028?var=492752715677&hash=item2ccf36015c:m:m4WGwdDPn5tZw-oLBaeBWVQ

many thanks if you can advise.

Corvus

Angle steel usually has a fillet in the inside corner, might not be a problem depending on the router, or it might want to ride up that. Also unless it's a big old section it might not be that straight, it comes in big lengths and can take a set while it's sat around waiting to be cut up.
The thicker the ally the better. I'd think 3mm wouldn't be strong enough against sag and vibes/chatter, thicker wall means wider sections. Or rivet two thinner sections back to back, would be strong if done right. All depends how accurate you want it to be, you can flat out a slight imperfect finish with a big ol' sanding beam and some elbow grease.
Ally angle tends to be straighter when buying cut lengths.

btw I use a bowl cutter on mine - it's shaped sort of like a mushroom head, it doesn't leave furrows that need sanding out, just a nice flat surface.

Roland

I’m always worried about aluminium flexing. L section is a good idea because it limits bending. Box section is better for the lower runners because that bends even less.

My own router sledge has a 2x2” wooden frame, with a metal running surface for the sledge. The  sledge is L section steel, with a plastic running surface for the router.

The other thing which is useful, although not shown in your picture, are long machine screws coming in through the sides of the frame to hold the guitar body in place and stop it lifting.

Sporky

I used box section ali for mine. 

vale

Corvus said:

Angle steel usually has a fillet in the inside corner, might not be a problem depending on the router, or it might want to ride up that. Also unless it's a big old section it might not be that straight, it comes in big lengths and can take a set while it's sat around waiting to be cut up.
The thicker the ally the better. I'd think 3mm wouldn't be strong enough against sag and vibes/chatter, thicker wall means wider sections. Or rivet two thinner sections back to back, would be strong if done right. All depends how accurate you want it to be, you can flat out a slight imperfect finish with a big ol' sanding beam and some elbow grease.
Ally angle tends to be straighter when buying cut lengths.

btw I use a bowl cutter on mine - it's shaped sort of like a mushroom head, it doesn't leave furrows that need sanding out, just a nice flat surface.

thanks for the info Billkat. ok will look into 4mm or 5mm and watch re the fillet. i'll probs buy a 1metre strip to cut into two, so maybe the length thing will be ok. i suppose i could even tell the seller i only need 50cm length and they could use up some offcuts to make my 2x 50cm  for the metre.
thanks for the tip re bowl cutter. will investigate.

Roland said:

I’m always worried about aluminium flexing. L section is a good idea because it limits bending. Box section is better for the lower runners because that bends even less.

My own router sledge has a 2x2” wooden frame, with a metal running surface for the sledge. The  sledge is L section steel, with a plastic running surface for the router.

The other thing which is useful, although not shown in your picture, are long machine screws coming in through the sides of the frame to hold the guitar body in place and stop it lifting.

hey Roland, thanks for the tip. for the bridge bit i think it would have to be L nor box or the router bit would barely reach the wood. i have some straight wood for the sides but if some alumium turns up at a leter date will sub on your advice. less chance of splintering and wear too.
machine screws sound a a good idea for me to bear in mind. in vids i've watched people use double-sided tape or wedges, but screws better still.

Sporky said:

I used box section ali for mine. 

thanks Sporky. didn't this make the bridge bit (in which the router slides) too thick for the bit to reach? maybe you have a long chuck bit. i'm wary of using very long bits if i don't need to as the cutting stress on them is more the further they get from the chuck.

Corvus

I made my sled out of welded steel tube, it does put the router higher off the deck but you can size the side rails knowing all your measurements inc the reach of the router bit of choice.

Teflon tape where theres metal-metal sliding.

My base is thick MDF with steel box lengths underneath making it and keeping it flat. Oiled the base and use hot glue spots to fix a blank down, they pop off cleanly from base & blank. Quite handy cos any shape can be held.

Roland

Corvus said:

Oiled the base and use hot glue spots to fix a blank down ...

Have you ever found a blank coming loose while you’re working on it?

WezV

Mines two  1/2” thick steel bars welded to a 4” bit of L section at either end.  The L section goes lower than the bars to stop me going off the rails .  A few counter sunk holes through the steel allow the router to be attached.

the rails are 2 Long lengths of L section mounted either side of an offcut of kitchen worktop. These can be shimmed in various directions for subtle angles.


weighs a ton and looks ugly as sin, but it’s helped make a lot of guitars

Sporky

vale said:

Sporky said:

I used box section ali for mine. 

thanks Sporky. didn't this make the bridge bit (in which the router slides) too thick for the bit to reach? maybe you have a long chuck bit. i'm wary of using very long bits if i don't need to as the cutting stress on them is more the further they get from the chuck.

I think it was only 15mm or so. Easily rigid enough, and the side rails were the right height for it all to work. 

Corvus

@Roland no problems yet, dabs all round does OK. Because it pops off OK I can dab as many blobs or short beads as I feel needed.

I also have a mini sled which I screw different height rails onto for thicknessing direct on the bench which is kitchen worktop, making like 2mm veneer type things. The hot glue works there too.

Roland

@Corvus ;I’ll try that. I’ve had problems with double sided tape giving up under vibration.