Woodcutting - CAD Files from SketchUp? Or other sources?

[HugoMack]

I don't have the workspace to cut out my plywood pieces - I'm looking at building two Jack 12 Lites and then maybe two T39s. I live in UK.

I've been in touch with a CNC cutting company who require CAD as .dxf or .dwg files . They say this should include a drawing of each piece required as a 2d outline with third angle to show any rebate depths etc if required.

"Explode" on SketchUp doesn't seem to produce any dimensions to each of the parts on the resulting list. I'm probably doing something stupid here....

Very grateful for ideas - as I couldn't see anything recent in this group of discussions, to cover this.

[Charles Jenkinson]

Hi Hugh,

Do you have an outside space where you can cut the wood? I appreciate I'm not answering your question, and maybe going the CNC route for a one pair off is worth it, in subjective terms, but the marking and cutting is a good part of the fun. I would imagine they will charge at least 3x the cost of the wood for CNC parts in your hand. Of course there's handling 4x8 sheets if you do it yourself. I'm just saying, others cut and assemble outside. I put 2 sheets of 6mm (2 cabs) on top of one another and sawed out by hand. A very respectable jigsaw effort can be made on the baffles as well. I've never yet looked down into the throats of my completed jacks, so circular arc perfection is not required.

Charles

[HugoMack]

Hi Charles - very helpful and thanks. Also, I can probably get the square cuts done by the supplier making the sheets easier to handle. The T39 looks much easier to cut and assemble.

[Charles Jenkinson]

Ok.

I have some images of the cutting layout I did on my 4x8 sheets, for the J12L's. I didn't use cutlist, but laid it out on AutoCad myself. If I can attach files to a PM, I'll send them.

The subs are more straightforward. The only thing different, in a tools and set-up manner, is cutting various different angles of mitres on the ends of panels.

[HugoMack]

Huge thanks!!

Ah... the mitres immediately make self-cutting sensible for this. I definitely ought to set up a rudimentary cutting table.BUt that would stack up against the wall outside under a plastic sheet (I live in the middle of Oxford and so have only a very small yard).

I'll have to wait for a dry day - as unlike one of the other members, who I saw with admiration dared to do all his cutting in the kitchen, I'm not that heroic!

Question: what the "Switchable" bit of your J12Ls? I'm wondering about having a switchable option for one of mine to use with a 12 volt 2 channel power amp for outdoors stuff (busking). It would switch from cross-over, two-way (if that's possible).

I've also been thinking about using J12Ls with T39 subs: using a DB Power+ or equivalent to low cut out everything below 75Hz. But I'm still torn wondering if a DR200 might be the way to go (especially if that pair in Huddersfield are still for sale...)

[Charles Jenkinson]

I would only make the array switchable if using for bass guitar. IMO, no real need to switch it off otherwise.

I can't attach images to a PM, so if you wanna PM me a suitable email address...

One's internal debate on speaker choice is agonizing.

[Grant Bunter]

A table saw of some description may be a good thing.

I can tell you all my cabs (see sig) were built without one. Plenty of others have built without a table saw as well.

I also didn't use the table in the panel jig plans.

I used a 7 1/2" circular saw. Rather than relying on the angle setting on the saw itself, I bought a digital angle rule for all of $10. The digital angle rule proved the angle guide on the saw to be woefully innacurate.

Cutting was done on a pair of saw horses. Assembly done on same. It's highly achievable! An extra pair of hands is helpful as you near the end of each cut though...

[HugoMack]

Thanks Grant. You guys are balancing off all those porny shots of other people's hi tech garages!!

[Charles Jenkinson]

Not wishing to modify or add to Grants comments at all, ...but apologies because it is pretty much going to be implicit.

Table saws are good, but i think in a cab building application some commitment is required to also build and use the panel.cutting jigs. I havent done that, and got away with it. Mitring a panel (re: subwoofers) by sliding on the table against the fence has not produced particularly clean cuts for me. Plus, lightweight bench saws need a foot on the support frame brace to stop them tipping. I'd use a bench saw in preference to a loose circular saw and setting guide boards for each and every cut (where if its a square cut i just hand saw it) but i think the catch all solution for the person without a dedicated workshop, just about, is the track saw - raw full sheet and mitres can be cut. ...but everyone wants the tools they haven't got.

Other tools:
Framing square
Pneumatic 18gauge brad/staple gun
Small compressor (borrow one?)
Router; nowt fancy required. Plus Wickes multi bit pack.
Jig saw; again nothing fancy.
Random orbit sanders, handy, but not essential.

...and now I'm going to let others post....Damn it Charles!

[HugoMack]

track saw - something like this one? http://www.screwfix.com/p/scheppach-pl4 ... tAodEU8A3w#

[Rune Bivrin]

track saw - something like this one? http://www.screwfix.com/p/scheppach-pl4 ... tAodEU8A3w#

Yes, but consider Festool, Makita, Hitachi, Bosh or DeWalt. More expensive, but buy once, cry once.

I'm very partial to my Makita SP-6000. Very precise. Very easy to use. Very compentent.

[tomlang]

"Explode" on SketchUp doesn't seem to produce any dimensions to each of the parts on the resulting list. I'm probably doing something stupid here....

Very grateful for ideas - as I couldn't see anything recent in this group of discussions, to cover this.

I use Sketchup to draw many items that I then CNC the panels -- shelves, murphy beds, speaker enclosures, etc. The nice thing about the BFM designs is he includes the completed Sketchup.

IMHO, any CNC shop worth their "salt" should be able to take and use the Sketchup files directly. In a nutshell, you explode the panels, then lay them flat, then using parallel projection, export to a .dxf file (use Sketchup pro or download a plug-in). Dimensions need not and should not be exported. If you do it correctly, the .dxf file will be full size and correct. Then, looking at the Sketchup, the CNC toolpath will have to be created to get the plunging correct for rabbets, etc.

Every CNC file that is created needs some human thinking behind it to make it successful. Exporting a .dxf into CNC software does nothing until you tell it the exact thickness of the material, the size of the tooling, depths of cuts, etc. Expect them to charge an hour or so of programming time in addition to the CNC machining time. Unless you have your own CNC machine, I doubt you will like the price...

[1n3]

... In a nutshell, you explode the panels, then lay them flat, then using parallel projection, export to a .dxf file (use Sketchup pro or download a plug-in).

What plug-in have you used successfully for exporting DWG/DXF from Sketchup?

[tomlang]

Plug in:
https://sites.google.com/site/jimfoltz/ ... ns/freedxf

Sometimes (when the plug in doesn't look or scale "right") I download Sketchup Pro. Pro gives you I think around 500 minutes free. So, I'll download and use it just long enough to export the dxf's I need then uninstall it.

Either way be SURE you choose camera parallel projection for the planar (do not export anything in 3D) object. Then, open in your favorite CAD/CAM software. Sometimes you will have extra/duplicate lines to remove.

[HugoMack]

Thanks Rune and Tomalang. I've gone off the CNC route!!