Imagine a dowel about 20mm in diameter. I want to cut a goove in each end kind of like this guy has:

But accurately.

The dowel is going to be 8ft long so I can’t use a lathe. And I don’t have a lathe, so I can’t use a lathe.

The best thing I can come up with is to use my table saw, set the blade to stick out just above the table, set the fence and run the end of the dowel over it back and fore whilst turning it – eventually creating a groove. But that’s a bit crap, and very prone to going wrong and making splinters.

super glue a small rod into the top and use that in an electric drill.

You shouldn’t really be taking the guard off the blade to do that, reason to buy a band saw 🙂

You could mount a jigsaw under a piece of wood (with a hole for the blade), and use that?

Or a router+table could probably do it, but not sure of the bit.

Whatever you use, a simple ‘V’ jig to hold it would be sensible.

Use a plumbers pipe cutter.

There are various types (do a google image search) but they all do the same thing – grip a cylinder and score a groove in it as you twist it round

You may be able to get a satisfactory result with a pipe cutter

None of those methods will give me an accurate depth though will they?

There needs to be one in each end, and the thinner section of dowel (ie inside the groove) has to be the same diameter for both.

How about turn smaller bits in a lathe (if you can borrow one) and glue them onto the long bit?

None of those methods will give me an accurate depth though will they?

All will if used with a decent ‘fence’. What about sanding it?

Or cut two grooves with a tube cutter, then chisel out the material?

Don’t suppose it’ll be a useful solution unless you’re doing loads but there must be something here, I can’t look or I’ll end up buying something

http://www.fine-tools.com/duebelherstellung.htm

Why? What do the grooves do?
If you can’t do it, change the design

I think I will have to.

The idea is to support the dowel between two brackets so it can spin and roll up the sheet I am going to attach to it, like a blind, or like a giant one of those kitchen towel roll holders. It’s for a photographic backdrop.

The grooves are to ensure that the dowel doesn’t wander around. I think I will have to put some kind of collar around the dowel instead to keep it in place. A few layers of road bike inner tube strapped around it should work.

Collar is the better idea. More chance of shearing the dowell if you reduce the section near the supports. You also give yourself more options for corrections I.e. zip ties, jubilee clips etc.

I wonder if I can pick up a really big one of those projector screens from some office clearout.. 🙂

It’s for a photographic backdrop.

Arty ones? 😉

Hah, no, no shag pile carpet. It’s a plain white sheet in fact 🙂

Incidentally it has to be accurately made because the sheet has to roll up perfectly without any creases in it.

Making the rig is going to be easy, attaching the sheet onto the dowel perfectly parallel and flat is going to be a bitch. It’s a new sheet, so I’m going to have to hope it’s square!

Even if you get the sheet attached perfectly, I’d be willing to bet that the dowel will sag in the middle over time. That’s pretty slender; 20 mm over about 8 feet long is a small ratio.

Very seriously, might it be worthwhile talking to a blind company? They will be able to provide plastic tube to the correct length, with a method of attachment and end pieces.

A blind 8ft square would cost a bomb. This is ghetto style.

I concur about the dowel sagging.. I might have to go up to the broom-handle sized dowels, they are not cheap though.

I’ll also have to find one that isn’t already warped.

Maybe I’d be better off with a piece of alu tubing… hmm…

You could do this on a router table with a fence and a fixed end stop. Just rotate the dowel against the router bit.

Not sure I’ve described that too well, so here’s a picture.

I concur about the dowel sagging.. I might have to go up to the broom-handle sized dowels, they are not cheap though.

They’re cheaper if you buy broom handles rather than dowels, and strong too.

Shorter though.

Alu tubing is only available from B&Q in 1m lengths.. if there were a smaller dia tube of the right size I could fix two together.. but it’s getting complicated then.

The reason for going to B&Q by the way is that I have a giftcard to use up.

I am now beginning to doubt if I need it 8ft wide. Best do it though as it gives me more options with regard angles and whatnot, and the sheet is that wide anyway.

If you clamp a hand saw and rotate the dowel over the blade you should get a fairly good groove of eaven depth .simples 😀
If you need a guide drill a hole of same dia as dowel in a scrap piece and cut scrap piece in half through centre of hole.lay guide block infront of saw blade and adjust clamped blade to correct hight then ( assuming your right handed ) keep left hand over guide block and rotate dowel with right hand .a new hard point saw will put a groove in a dowel without much pressure in no time

An easier way is to cut off the ends and glue a smaller diameter disc that represents the grooved piece you want on to the cut end and then re-glue the ends back on to the main piece. You should find with a decent glue the overall joint will be a strong one.

won’t the backdrop sheet be sold on a cardboard tube to start with? Just put a length of rope through the tube. Even if its not – get a tube from a carpet shop, they’ll give it you for nowt, being a tube its going to be more rigid than a bit of dowel and you’ll be rolling the sheet round a wider diameter so it’ll drape better when you unroll it.

Well in the end I cut pieces of some old cylindrical grips and stretched them over the dowel, which keep it in place sufficiently.

MacC – the backdrop is in fact a 120tpi Egyptian cotton sheet from TK Maxx, and it was sold folded in a packet 🙂 I got a thick 34mm dowel in the end, it’s pretty rigid and it was easy to make brackets for.

The only problem with rolling it up and down is that the weight of the sheet makes it sag down in the middle slightly, which drags the sides inwards. Not by much, but it’s enough to make small wrinkes in the sides. It can be done perfectly with two people though, one on each end keeping the edge straight.

I’m taking photos now, I’ll try and get some up later for all your criticisms 🙂

Alu tubing is only available from B&Q in 1m lengths

I know you’ve done the job now, but for future, B&Q do 32mm aluminium aerial poles in 6ft lengths.