Tweaking Castle Conway 3 speakers

[pre65]

Originally Posted by bob orbell

Richard, it is the weight that holds the cab. solid, I made some for a pair of transmition lines, god knows the weight but they were 12" x 10" x 3". If you ever need imfo on drill and tap size, just shout, metric is easy, just deduct the pitch from the tap size, and that is the drill size, for example, 8mm tap with 1.25 pitch = 6.75 drill, 6.80 will do. BOB

I wasn't sure about Bobs logic re the M8 x 1.25 tapping drill size, but according to all my drill charts 6.80mm is the correct size.

Certainly for metric coarse it seems to work out correct.

[Richard]

Thanks both Bob's last ones would have been 44Kg each

Thinking about it steel would be good, it could be powder coated or etch primed and spray smoothrited which should be tough enough to fend off attacks from the hoover. Not sure I could lift 3" plinths into place with the cabs(!) do either of you have a source for 1" mild? Preferably cut to size!

I'm ok with tidying the edges using the angle dangle but it would be nice if they were milled. Drilling and tapping is ok too, got a pillar drill and taps, 6mm metric coarse in this case if I went that route.

It was the drill type to use for marble or granite I was thinking of before, carbide of some sort I imagine. There must be plenty of off cuts from those trendy black granite worktops I could persuade them to trim and polish.

[bob orbell]

Ahh, you question my tapping size calculation Phillip, 6.80 is the size listed in charts, this is because not many workshops hold a 6.75 drill you can buy that size, but it is expensive, and more to the point if you need that size of hole you use a broach, not a drill, no offence taken. Richard do you have a place local that dose lazer cutting, they can usualy cut up to 30mm, we have two places here, I can get a price for you if you give me all the dimentions, and I can radius the top corners for you on my mill, only thing is I am about 60+ miles from you. Sadly gone are the days when I could get the steal for nowt. BOB

[Richard]

Hi Bob, I would like to do this and had been looking up the materials on eBay. If you know a place that can cut and supply and you will mill the edges that would be brilliant. I would pay of course and you aren't far away to drive over. I used to be down your way every week in a life gone bye

[bob orbell]

OK Richard, give me dimensions and I will get a price for the steel, I bet it wont be cheap if you agree with the price I can put all the holes and threads in for you. BOB PS I dont charge any thing, you will only pay for the steel.

[Richard]

Bob that would be fantastic, we will argue about the price later I'll need to up-end a speaker to get the dimensions so will get a drawing to to you soon. Many thanks indeed!

[Richard]

Hi Bob,
Took the dimensions and some pics. Any of this you can help with would be really good. I don't want to bog you down with it, getting the metal cut to size would be a big help if you don't have time for the machining




top face radius on front corners and front and side edges



6mm spikes and recessed 8mm mounting screws

[Richard]

25mm diam washer shown against corner and bevel radius



no radius on rear corners or rear top edge

[bob orbell]

Thanks Richard, I will go and see the man tomorrow or friday and get a price for the steel cut to size, machining is no problem, but I may not have an exact size corner mill, but I think that I have something close, will let you know. BOB

[Richard]

Thanks Bob, yes any similar radius on the edges and corners will be fine