Best method of making accurate bevels.

[Eric The Viking]

Ah, so it's Stonehenge he'll be wanting then...

 

[simonms]

Thanks Eric,

Disinclined to get into horn theory here and the horn I am looking to make is a pre existing creation as stated back in thread, so I am essentially trying to copy it hence the discussion on how it might have been made.

Keeping things practical i.e looking at the curve I am trying to create in the materials pre decided is the question. I think it's time for practical work now. Jacob, I have a plane, a bench and some poplar, thats it. I may get the form work cnc'ed as it's easy, free and convenient so no gadgets.

I think the way forward is to do exactly what Mike and Jacob have suggested a few pages back, you're right I am over thinking it.

Oscar, these horns any very efficient only a few watts is needed, 11 would dangerous.

I will post back with my efforts so you can point and laugh....but remember a student is only as good as his teacher so when this goes horribly wrong the blame will be entirely on you

 

[OscarG]

Ha.. I know my guitar amp, Fx pedals stuff but "proper" high-fi and the uber technical stuff Eric the Viking is talking about actually makes my brain hurt!

I'm a complete newbie in terms of woodworking, so I bow to the vastly superior knowledge of the others on here but I think if you are gonna paint this this I would consider the router option.

You've already got the CAD drawing of your exact shape, if you can print out lifesize (on several bits of paper) stick it on some thin mdf, cut round it, slowly sand to the lines.

I mean you've only really got one tricky bit which is making that template, the rest of it will be tedious repetition making the duplicates. It's not the "cleverest" option but in some ways it takes the thinking/guess work out of it and turns it into a low-tech production line job.

It's easy to get bog downed with over thinking something, sometimes I think you've just gotta crack on and get started. If you mess up it's only a bit of poplar right. Not like you've wasted some precious rare wood.

 

[thetyreman]

I'd be concerned about harmonics coming out from the solid wood, because it resonates and creates unwanted harmonics in the sound, have you considered using MDF instead? may as well if you are CNCing it.

 

[simonms]

Thanks,

As I have said the materials (poplar) have been chosen for me by virtue of the speaker I am copying but have no fear, they sound fine.

I drew up the former for the initial curve last night but again, having not done this before I wonder if anyone would be kind enough to comment on my initial idea, feel free to suggest alternative ideas or areas where this might be improved. Obviously this needs to stay square and that is the area of concern.

Thanks again.

 

[worn thumbs]

Good luck with the 934.33mm.If that sort of accuracy is required you might have to tell your pal with the CNC router to make sure his chordal deviation settings are set to suit.You don't mention whether there is any allowance for trimming the length later,or if you intend to use slightly overlength staves and trim them to the former.I think you might do yourself a favour if you add a triangular web in the corners to maintain the squareness too.

 

[simonms]

Thanks,

I will tidy up the drawing once I have the basics down, yes the idea is to overshoot the curve by a few mm at each end and trim to fit.

I am not sure what a triangular web is, could you expand?

 

[MikeG.]

For the initial curve? No. Make it in one piece. Again, you are over complicating this. A pair of formers fixed by some battens at right angles and parallel, and off you go with the plane.

 

[simonms]

Thanks Mike, sorry this former will be for a complete curve, there is another to do with a different profile after this one so yes I will be doing it as we have planned i.e doing the entire curve over a former fitting as I go.

So you are saying just the 2 guides with some battens in between.

 

[worn thumbs]

Something like this to stop the former lozenging. Its a quick approximation only.

 

[simonms]

That's great, really appreciate that.

 

[BigMonka]

Thanks,

As I have said the materials (poplar) have been chosen for me by virtue of the speaker I am copying but have no fear, they sound fine.

I drew up the former for the initial curve last night but again, having not done this before I wonder if anyone would be kind enough to comment on my initial idea, feel free to suggest alternative ideas or areas where this might be improved. Obviously this needs to stay square and that is the area of concern.

Thanks again.

Your former looks like a single curve, whereas I thought from your earlier cross-section on page 2 that it was due to be more like an s-curve?

 

[simonms]

Hi,

Sorry for the confusion, there are 2 curves, one is, as you say an s curve and the other is a c curve for want of a better term.

I think I can make my former do both, one on the top and one on the bottom, see pics.

 

[simonms]

 

[MikeG.]

Oh for goodness sake, this is starting to drive me potty.

Simon.......draw out your full curve full size on the top of two bits of ply or mdf clamped together. Cut this out. Get some scraps of wood to hold them rectilinearly. Start work on your staves.

Why in the name of sweet baby Jebus would you do anything else?

 

[simonms]

Hi Mike,

Thanks for your comments, with the greatest of respect that is what I am doing albeit with 3 guides and ply cross bracing , I posed the question on how to keep the form work square and on the advice of BigMonka (thanks!) drew up a design that would do 2 curves for the price of one i.e it can be flipped through 180 to give me the 2nd form. The staves are 1100mm long, I wanted to be sure that everything stays alligned. I posted my form work to invite comments on whether or not it was suitable so I am assuming you do not believe it is and from what I can ascertain you might think it's a bit OTT for the job at hand? Again, I am a total newcomer please bare that in mind and I am sorry you find this so frustrating.

 

[MikeG.]

Right, so this form is for the (complete) piece we are discussing on one side, and some other unrelated curve that you've not mentioned before on the other? Can you see why that might be causing confusion?

 

[MikeG.]

.....you might think it's a bit OTT for the job at hand?......

I don't think I've ever seen a bigger mountain made of a more insignificant molehill.

 

[Inspector]

Simon I know you are trying to get a handle on how to make your project but because you have a goal and a start point and basically nothing in the middle at how to, you are over complicating things somewhat. What you are attempting to do is basically coopering, the trade of barrel making. Look at some Youtube videos on coopering barrels or buckets and you'll see what the guys are trying to get at when they say to plane an edge and eyeball it for fit as you fit the staves. You have a form you want to follow which makes it easier since you can lay the two staves together to see how they fit. You can even put a light under to locate the high spots. Now put some masking tap across that joint and put the glue on the joint and close it up in the form. Soon you can do the next when the glue sets. You go down the line until you are done. It's that simple. Mike, having the skill could probably do it by standing the ends on a line drawn on the bench top. The form you're making is overkill and will work fine, especially if you want to make a few hundred over the next few years. :wink: It's your overthinking that has the guys a little exasperated.

Have a look at this video. Around the 5 minute mark the gent starts shaping the edges and offering them up to each other. That's basically all you need to do except you are moving the plane rather than the wood.
https://www.youtube.com/watch?v=v4kB7JO ... Jtj-xDMHCa

 

[Jacob]

......
https://www.youtube.com/watch?v=v4kB7JO ... Jtj-xDMHCa

Excellent vid!