Metal fabrication advice for roof rack Project

[E-wan]

Hi

I'm currently building a new roof rack and part of the design is going to be a retractable roller.

The roller is going to be mounted to U section aluminium channel
Eg
https://www.aluminiumwarehouse.co.uk/aluminium/channel


I need to find somewhere that can cut an 8mm or 10mm wide slot along the top side of the aluminium channel

Any idea where I could get this done?

I live in Leeds

Thanks

Ewan

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[MikeG.]

You can do this yourself with a winged slot cutter in your router table. It's noisy, and you need to take very small nibbles, but it makes a clean cut.

 

[E-wan]

You can do this yourself with a winged slot cutter in your router table. It's noisy, and you need to take very small nibbles, but it makes a clean cut.

Hi Mike

Thank you for the suggestion but unfortunately I don't have a router table, only a little handheld katsu.

I have a large meddings pillar drill which lets you lock the quill at a specified height but presume the slot cutter wouldn't be too safe to use in this.

For preference I'd like to find somewhere to do this for me but wasn't sure what sort of place to look for

Thanks

Ewan

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[AES]

If the slot is long it'll be a bit boring, but quite easy with just "hand" tools.

Mark the required start & stop of the slot and position a hole (8 or 10 mm as you prefer) making sure that the outer dia (OD) of the 2 holes fall exactly where the start & stop positions are. Then do a bit of arithmetic to work out how many holes you need in between, laying the holes out so that the OD of each hole VERY NEARLY touches the OD of the next hole. Then centre punch every hole position, and this time, as the hole positions need to be pretty accurate, use a pilot drill first (pilot drill dia ABOUT the thickness of the web on the final size drill).

Having drilled all the holes then cut out the in between bits with a thin bladed coping, fret, or other fine tooth saw (3 teeth always in contact), then a smooth file to finish off the slot edges neatly.

You must be an expert on drilling holes in ali by now ( ) and I see from your link that your ali channel has a web thickness of only one sixteenth (inch). So not hard at all, a bit of care needed so that the holes are correctly positioned, but otherwise very easy, but as said, quite probably quite boring (I hope you only have to do 2 channels, and the slots aren't too long)!

Personally I wouldn't pay anyone to do such a job for me, even if I could find someone (bring yourself to Switzerland and I'll do the first slot for you for nowt - you watch, then do the 2nd here yourself)!)

 

[MikeG.]

One sixteenth, or about 1.5mm, is possibly scratchable. If you were to sharpen up a marking gauge with a hardened pin, or make a temporary one with a some scraps and a filed screw, you could probably scratch straight through the alli in a few minutes.

 

[deema]

I used to run companys that made amongst other things roof racks. My advise is buy one. The safety requirements are just too high for anyone these days to knock one up. If it’s a commercial vehicle Van Guard and Rhino are IMO the two best solutions. The Van Guard alunimium range is excellent. Both are genuinely made in the UK.

 

[novocaine]

by hand as AES but with a twist
scribe the centre line
centre punch the ends and drill out
mark every 9mm along centre line
punch and drill out leaving a web between each hole, no need to pilot drill if your on the drill press, this is somewhat easier with a 3 way table but clamping a fence so you have a reference point is just as easy.
stick it in the vice with the edge of the hole at the top of the jaw and use a nice sharp cold chisel to punch out the web. give it a quick rub with a file and Bob is as they say you aunties husband.

for pucker factor
I have a 3 axis table on the drill press with just enough friction on the slides to act as a mill (helps that the quill is locked on mine), using a 4mm 3 flute I could most likely just about get away with taking multiple passes and cut it, but it would be a near run thing. I did it last year for a pinch of a job, there was a good pucker on that day.

For the wood worker trying to do something (bit like mikeg suggested)
I'd also maybe give it a go with the katsu (set slow) and a 6mm cutter to be honest, 2 maybe 3 passes on 2mm with the centre overlapped. You'd have to knock up a jig to guide the router and give you support either side and be ready for lots of hot bits of ali to be flung at you.

you could also do it with a jigsaw and a metal cutting blade.

 

[Fergal]

I used to run companys that made amongst other things roof racks. My advise is buy one. The safety requirements are just too high for anyone these days to knock one up. If it’s a commercial vehicle Van Guard and Rhino are IMO the two best solutions. The Van Guard alunimium range is excellent. Both are genuinely made in the UK.

There used to be a guy in my building that had a roof rack consisting of two 2x2s lashed to the roof rails of his Audi estate with cable ties. They weren't even sturdy cable ties, just the little skinny ones!

 

[AES]

Lot's of options there E-wan.

I'm not arguing with the above, but based on my own experience ("your mileage - and others? may vary"!), a stepped drill can tend to grab as it breaks through - especially when the material thickness is only 1.5mm approx. If using a step drill then, personally I'd advise that the work piece is firmly held in a jig or drilling vice.

And personally I see difficulties with scribing a centre line INSIDE the channel (if I remember, the space inside the channel is only half inch wide?). Can be done with a marking gauge-like device, as already pointed out. And of course you could scribe the line OUTSIDE the channel (with the U facing downwards) but then you'll be drilling from that side too, so deburring the hole from INSIDE the channel will be more fiddly - by no means impossible, but a bit more fiddly.

As to the strength of the finished rack I can't comment, I don't know what load, etc, is involved, and don't know anything about roof racks really (I've never had one). From the little bit I've seen on racks though (just idle glances really) isn't that channel a bit too flimsy? I dunno.

But as someone remarked in the other thread about drilling holes, don't over-think all this, if you take it steady it's a pretty simple job (IMO), and there's not too much to be scared of - ali is pretty simple stuff and if you look out for the couple of whoopsies inherent in ali (which everyone's already pointed out) then it really is a pretty simple job and not hard to do well/nice and neatly.

 

[novocaine]

If i was going to scribe the centre on the inside of the channel I'd find a scrap the right width and drill a hole in the middle of it for the scribe.

 

[autotrans]

loads of small workshops around leeds pal, i am sure one could help just go around the little industrial estates