Which round-over bit for mdf disc

[@if]

Good morning

I'm in the middle of a project to build a subwoofer (50cm cube using 25mm mdf) and will also be using the same 25mm mdf for the speaker grill. I would like to create a circular grill so I can show off some of the walnut veneer I will (try to!) cold press on to it.

I have not yet bought a router, but have decided on getting a 1/2" jobbie. I've already pulled the trigger on a 1/2" straight bit from Wealdons - but don't know what to get to round over the speaker grill. I would like to round over the outside, top and bottom, to get a nice disc-like finish to then wrap some cloth over it. The width of the grill will be 1" so I can accomodate five 10mm wide (5mm depth) magnets without any risk of splitting etc. (I would like to actually go for a slimmer width - would you say it would be safe to do so?)

Wealdons have the Queen Anne, which seems to be what I need, but is also a tad pricey - so any advice would be most appreciated.

I've attached a little diagram of the subwoofer - I can't post any links yet, but if you Google round speaker grill, then you should get a good idea.

 

[kostello]

I'm not really sure what it is you want to do exactly as I have no idea how to build speaker cabinets.........

But a picture or quick sketch would help us help you...........

Or consider this a bump to the top of the list

 

[carlb40]

I think by the sounds of it you need a half inch round over bit or there abouts. I know what you are trying to achieve.

You need something like this, but bearing guided
http://www.axminster.co.uk/axcaliber-ro ... -1-2(127mm)-prod828920/
Such as
http://www.axminster.co.uk/axcaliber-ov ... rod807115/

Depending on how soft a round over look you require, either the 1/2'' or bigger will be needed.

 

[carlb40]

I'm not really sure what it is you want to do exactly as I have no idea how to build speaker cabinets.........

But a picture or quick sketch would help us help you...........

Or consider this a bump to the top of the list

Basically something similar to this, but to go over the speaker

http://www.google.co.uk/url?sa=i&rct=j& ... 9075174004

- made in mdf and then grille material over the top of the mdf to cover the speaker.

Pretty much standard type of thing in ICE builds

 

[@if]

Thank you Carl (and kostello ) - I will place the order when I am back from holiday.

Also, my joining up of the box has not been as tidy as I would have hoped, so now I have some lips/overlaps that I would like to smooth....if that makes sense.

And while I'm at it...reading Ron Fox's book, I can use the straight bit for trimming excess veneer - is this the best/easiest/safest way to do it? Do you have any tips apart from going in "reverse"?

 

[Muswell]

Have you planned some handles into the project? With that size box in 25mm MDF it will be pretty heavy by the time you get the drives in and quite hard to move. Even with handles I got an arm injury shifting 4 into a club. That's when wheels were added. The ones I made had vents to allow the drives to breathe and the draught was enough to make the carpet move.

 

[@if]

Have you planned some handles into the project? With that size box in 25mm MDF it will be pretty heavy by the time you get the drives in and quite hard to move. Even with handles I got an arm injury shifting 4 into a club. That's when wheels were added. The ones I made had vents to allow the drives to breathe and the draught was enough to make the carpet move.

I haven't - I figure without the driver I'm looking at around 30KG (which is manageable) and with maybe 45KG. As it is for home use I won't have to lug it around too often, although we are planning to move home. When it comes to that I could simply remove the driver as I'll be using tee-nuts. Also the amp is external so will also keep the weight down.

Did you double up your baffle? If so, did you glue together first and then cut the holes, or cut the holes and then glues up?

The ones I made had vents to allow the drives to breathe and the draught was enough to make the carpet move.

8)

 

[Muswell]

I realise I wrote drives before. There was only one per cabinet. Fair point about the moving. It's a combination of the weight and shape that's the problem. Your arm is quite extended and I damaged the muscle anchorage. But there were 4 bass cabinets, and the amp racks etc.

The design my son gave me was taller than it was wide. The extra height came from 2 rectangular "tunnels" of a specified length which formed the vents.This was all built in as part of the construction rather than formed after. I seem to remember a certain amount of calculation went into the design: overall volume, proportions,length and aperture of vents etc. It wasn't just a box to contain the drive.

We had a couple of previous builds before settling on this design and that's when I developed my procedure. Biscuit joints leaving 1 to 2 mm projection to be taken off with a trimming bit, don't try to get the joint perfect when you make it. They were going to have a hard life so all external edges were rounded over.

 

[@if]

My sealed cube is only 2.6ish cubed ft, around 70-something litres, internally - if I remember correctly. I suspect your vented boxes are a fair bit bigger to make use of the vents. If it gets a little to much when it comes to moving, I can always get one of those trolley things

I'm sticking with straight edges for mine as I want to try my hand at veneering.

 

[@if]

The Axcaliber bit linked to above and this Wealden seem (to me) to be the same: http://www.wealdentool.com/acatalog/Onl ... o_187.html (T1339-1/2)

From what I have read, Wealden bits are highly rated for value and quality. As the price, after delivery, is more or less the same - which would you go for?

 

[carlb40]

Yes the wealden bits are really rated and i would have linked to their bits. But for some reason i cannot right click to copy/ paste via their site

 

[Gary Morris]

if you use a half inch round over on a one inch piece of wood, do you risk marking the piece with the straight sides on the router bit? Only my novice thoughts, but I did something similar.

Gary

 

[@if]

Any marking wouldn't matter too much as it will be painted black and then have cloth stretched across it.

 

[carlb40]

Any marks made especially on mdf will sand out very easily. I find i get less marks when using a router table. I guess hand held we put more pressure on to keep the router upright and tight to the work.

 

[@if]

The worst thing about holidays is long journey back home .......

I dont have a router table -this shouldn't cause an issue with the rounding?

 

[carlb40]

The worst thing about holidays is long journey back home .......

I dont have a router table -this shouldn't cause an issue with the rounding?

No not at all. I usually do all my round overs hand held

 

[@if]

So I've pulled the trigger on the Triton MOF01 router - I sent the first one back to Argos as I thought I could get better for the money. This one is coming via Amazon thanks to a voucher I've received for £50 off

I've got an eye on this: http://www.ebay.co.uk/itm/151020566719? ... 1438.l2649 - which I will bid on for no higher than £15 inc...but I can't get my head around the numbers. If I don't win, then it'll be the Wealdon bit.

 

[carlb40]

I think that bit is 47mm overall diameter or the height with a 17mm radius on a 1/2'' shank

 

[@if]

Ahh..too big either way! Off to Wealdon it is..