Newbie with a 3020

[Daven]

Having cut 10mm acrylic I doubt you will get the accuracy due to the taper of the beam. I have not cut MDF other than 3mm yesterday and that took a few passes. I wonder if you could do one pass then adjust the focus and do another pass and so on - may reduce the taper?

Best I can suggest is cut a the shape out larger than required and the use a Dremel type tool to finish off using a template for a trimming router bit.

If you email me a plan I will give it a go for you to see what the taper is like?

Cheers

Dave

[blinky465]

If you email me a plan I will give it a go for you to see what the taper is like?

I couldn't find out where to get the email address, so have posted the files at http://www.nerdclub.co.uk/files/guitar_outlines.rar. They're in wmf and dxf formats. There's a top plate with a cut-out for the neck to fit into - the same shape as for the sandwich filling - and a bottom plate where it's covered.
I'll be making the necks separately - partly because it matches how real guitars work, but mostly because I have to fill them with electronics too, so making them separately and just sticking a different shaped head on at the end seemed the easiest way forward! Thanks for all your help and advice guys!

[Daven]

Sorry I ment to pm you my email address.

Got the files - will have a play in a while and let you know

Interesting project though - they sound great!

Cheers

Dave

[Daven]

OK - tried the 12mm MDF (not laser quality) - best it gets to is 6mm. If you cut one pass and then move the table up by 3mm, the focus at the top of the material clips the edge already cut. If left at correct level 6mm was still the best I could get with just the standard air assist and no additional cooling. Using around 50% and 8mm/s and slower and you can light a fag with the flame

6mm cuts ok on 3 passes on same settings.

Hope this helps

Dave

[PhillyDee]

I could probably offer some assistance with the CNC router you have. I work on CNC machines for a living, and although the ones I work on are £500K machines, the principles are the same!

Of course, the importance of the work and toolholding is of utmost importance, as you have found out!
Next in line, the tools themselves. For cutting woods, I would recommend you buy FC3 cutters, these are 3 flute cutters used mostly for cutting aluminium. They can have pretty high metal removal rates! You want to work on the basis
of around 0.2-0.5mm per tooth. Too slow and it blunts the edge, too fast and it will create too much stress on the cutter and tool.

I have seen a basic pic, and some g-codes, any assistance I am happy to give. I would recommend trying to fit a 'proper' router in there, as the dremel type tools are not really meant for taking a lot of meat off at once.

Oh, and where did you buy the machine, I am after one of them as well . And a lathe, and a milling machine, and a .. . . . .

[blinky465]

Thanks for your efforts Dave - in fact, I've been thinking about "stacking" layers, as you mentioned in your email reply.
I've a very early prototype of the guitar here, which my mate cut on his laser cutter (3mm acrylic, single pass, no problem!).
It's made up of 5 layers of 3mm acrylic, which gives the right thickness, but the final finish isn't what I want for a finished product. (These new instruments are a bit bigger, and have the neck made as a separate piece now)



What I thought I'd try is to make the inner three layers slightly smaller, then run a 9mm veneer/edging over the top of them, to smooth out any imperfections. In fact, I thought I'd make two slightly thinner layers, then stand them off each other with some little round "pillars" made from 3mm acrylic, to give a total thickness of about 15mm (2 x 3mm faces + 9mm sandwich filling)



I've drawn out my plans and tried a paper template mock-up and it looks ok (the red line is just a scratchplate design which I'll make as a vinyl sticker - it's just there to help with the alignment).



So I guess my last question - until something else comes up - is would it be cheaper to use mdf for the inner sandwich parts or acrylic offcuts (they'll be made from 3mm sheets) and which would be quicker/easier to cut? I'm planning on just using coated, printed card for the banding; does anyone have any other suggestions for a nice finish?

For anyone interested, here's the later prototype in action - it's the same approach to make the body, stacked layers, but with an MDF middle (I ran out of acrylic) http://www.youtube.com/watch?v=QGMXdXBNoVs

[PhillyDee]

You could use a plastic weld (Starloc adhesives on here does some good stuff) and then use polishing mops on a pedestal grinder. This should help blend all the edges together.

[Daven]

Yeah when I mentioned a Dremel I was thinking the bits were smaller than on the plans.

I think veneer would be tricky to use. You would have to steam it to get it to bend into the tight curves and then find a way of clamping while the glue sets.

Other options - water jet cut in ally?
Use ply and make a feature out of the edges?

It looks a great project - well done! Are you planning to go to market?

Cheers

Dave

[blinky465]

...then use polishing mops on a pedestal grinder. This should help blend all the edges together.

This sounds like an interesting solution - lookng at the plans, I reckon 4 layers (12mm) might even be thick enough for the body and I could use 6mm mdf for the neck. Then a polishing head on an fixed router table for the acrylic and maybe a sanding head to round over the back of the guitar neck (to take the sharp edges off on the reverse side). I've a router attachment for my Dremel; I wonder if I could make a table to mount it under....

I think veneer would be tricky to use. You would have to steam it to get it to bend into the tight curves and then find a way of clamping while the glue sets.

I was thinking maybe even some 280gsm printed card (I've a Xerox Phaser 7400 here which prints beautifully onto even thick cardstock) for the banding. Or perhaps a thin vinyl, erm, band of something!

Use ply and make a feature out of the edges?

Again, another nice idea - especially if I can finish them nicely, perhaps with a light sanding and either leave as is, or treat them to a lick of paint? The V2 instruments in the video have exposed "scorched" edges on the mdf. They look nice (but don't smell to great!). Would it be cheaper/easier to use ply for the sandwich filling (sorry I keep using that term, but it makes sense to me) or to stick with acrylic?

Are you planning to go to market?

I want to use these as a product range to promote UK cottage industries (not cottaging, that's something else altogether I believe!) I'd like to keep manufacturing inhouse if at all possible which is why I'd like to find out what the LS3020 can and can't do. The instruments have already been evaluated by Mattel - they said they were too complicated for their 7-10 year old target group to understand - and Ravensburger - they wanted to be able to manufacture them for $3-$4 per unit, to sell for $40-$50 each, but couldn't get the manufacturing costs down! So I figured that I'd make them myself and offer customisations via an online editor on the website - http://www.nixshop.co.uk/guitars/. My partner and I are returning to North Wales for the winter (to keep an eye on family up there when it turns bad) and are looking to open a shop in September. So I've an outlet, a website, lots of interest from everyone I've shown and a whole other range of add-ons, sample packs, make-your-own-music-video ideas. Now I just need a way to actually produce the instruments!

[PhillyDee]

http://www.diytools.co.uk/diy/Main/sp-5 ... sander.asp

Plenty of others around for drum sanding. Axminster power tools have similar things.

And as for making the table, you could always use a laser cutter to make the table . . . .