Hand Crafting And Cnc Manufacture

[alex_holden]

I see, so if I told the CAM program the cutter diameter is (cutter dia + line width), that would cause it to cut outside the lines of the design.

[Chris Ghent]

There is no line width in a vector drawing. You get the choice of centering on the line, working on the inside, in which case the program shifts the cutter one cutter radius inside, or on the outside etc. You can also ask for a finishing allowance ie. cut on the inside but leave an extra x mm.

 

There is a 2.5D cam prog called Sheetcam you can download and play with. It will do anything you need for a concertina.

[alex_holden]

The vector drawing program I used to design the bell push end does let you set the width of a line (the control nodes are along the centre of the line), and I designed the curves visually so they look correct when you cut outside the line. In hindsight I could have set the line width to zero (i.e. invisible) and used a solid fill.

[d.elliott]

To me, craft is the intuitive use of personal skill

 

Where as design is the conceptualisation and communication of an end result. A designer may not be able to make, and a maker may not be able to design. An artist can achieve both, with the implicit aesthetic elements of course. I suppose the artisan label is the non aesthetic equivalent of artist.

 

If the intuitive utilisation of personal skill includes the application of powered tools then so be it, my daughter is a stained glass artist, but I dare anyone to take her electric soldering iron off her.

 

Dave

[alex_holden]

Very interesting, Dave. The line between artist and craftsperson is rather blurred and the subject of many a philosophical debate. I suppose one could say an artist is expected to design things but not necessarily make them (other than drawings on paper), and a craftsperson is expected to make things but not necessarily design them. Some craftspeople regularly design new things and make them, for others the aim is to make many perfect copies of (or deliberate small variations on) traditional designs.

[Dana Johnson]

 

I admire good artistry in any craft and the flexibility hand work allows, but I can't see making people pay for your hand work just because you might be able to sell it for more.

That's not really what I was suggesting, though I almost certainly would be prepared to do extra hand-work if a customer specifically wanted me to and was willing to pay for the extra time it took. For example there is the question of hand cut versus CNC cut metal ends. On my personal instruments I would prefer hand cut ends, not because they are technically better but because the tiny variations and imperfections give them more individuality and character.

I would have been of this opinion until my first non hand cut nickel silver end came off my router. All the effort I put into the design just sparkled, kind of like the difference between a freshly tuned instrument and one where everything is only slightly off, but the aggregate effect is less satisfying than when it was new. I use a CNC router with a VFD spindle running 24000 rpm and a 1/32" end mill to cut out my reed shoes. It produces a remarkably clean cut and much better results than the ones I used to punch out. Using some files with the flat sides ground safe and a couple others ground to do the finish of the corners and ends, I get results that are much nicer than the Wheatstone shoes they are mostly patterned after ( punched out on a fly press and broached to size ). With the back bevel and the corners done by hand, the effort here is to get results that are as good as the router produced. Having a clean window with dead straight sides really helps when fitting the reeds.

Back to the ends, I'd still hand cut one off ends since it takes about the same amount of time as making a decent CAD file out if a sketch for me. Quality with practice can be excellent.

[alex_holden]

I would have been of this opinion until my first non hand cut nickel silver end came off my router. All the effort I put into the design just sparkled, kind of like the difference between a freshly tuned instrument and one where everything is only slightly off, but the aggregate effect is less satisfying than when it was new. I use a CNC router with a VFD spindle running 24000 rpm and a 1/32" end mill to cut out my reed shoes. It produces a remarkably clean cut and much better results than the ones I used to punch out. Using some files with the flat sides ground safe and a couple others ground to do the finish of the corners and ends, I get results that are much nicer than the Wheatstone shoes they are mostly patterned after ( punched out on a fly press and broached to size ). With the back bevel and the corners done by hand, the effort here is to get results that are as good as the router produced. Having a clean window with dead straight sides really helps when fitting the reeds.

Thanks Dana, that's useful to know. Which make/model of router do you have? I have been planning to cut out the reed shoes on my Taig mill, possibly with the addition of a high speed spindle (I've heard the Kress routers are pretty good), and get something like a Shapeoko to route the woodwork because of its larger work envelope. Do you relieve the undersides of the reed shoe vents using a ball end mill to avoid sharp steps?

[OLDNICKILBY]

Alex , Why not use a 4 flute cutter with a side angle of 2 or 3 degrees , they are less than a Tenner and will give you a great finish.

[Chris Ghent]

Which make I have been planning to cut out the reed shoes on my Taig mill, possibly with the addition of a high speed spindle (I've heard the Kress routers are pretty good), and get something like a Shapeoko to route the woodwork because of its larger work envelope.

Alex,

The Taig can be easily modified to increase its work space. When bought they have something like 5" of Y travel but 30 minutes work can increase this to nearly 6.5".

 

High speed spindles do not have to be as expensive as the Kress. Search Ebay for "water cooled spindle" (Dana put me on to this).

[alex_holden]

Alex , Why not use a 4 flute cutter with a side angle of 2 or 3 degrees , they are less than a Tenner and will give you a great finish.

Wouldn't that limit you to a fixed angle taper? Perhaps that is good enough, I don't know.

[alex_holden]

The Taig can be easily modified to increase its work space. When bought they have something like 5" of Y travel but 30 minutes work can increase this to nearly 6.5".

Certainly worth considering, and a lot cheaper than a second machine, though I fancy the idea of putting all my dust-producing woodworking and grinding machinery in a separate room to metalworking and assembly.

 

High speed spindles do not have to be as expensive as the Kress. Search Ebay for "water cooled spindle" (Dana put me on to this).

When you add a VFD they come out to roughly the same price as a Kress router, at least in the UK. The cheap Chinese water cooled spindles are (or at least claim to be) around three times as powerful as the Kress and probably run a lot quieter, but I wonder about the build quality and reliability (having recently been bitten by cheap Chinese stepper motor driver boards).

[Dana Johnson]

There are enough challenges in making a concertina; labour saving devices which do a better job than I can do by hand are not to be scorned.

AMEN brother! ( or is that an Americanism?)

[spindizzy]

Some interesting thought s in general about craftwork

 

http://www.robin-wood.co.uk/wood-craft-blog/2014/11/17/real-craft-alienation-labour/

(from another field, I was surprised to find that you can call garments knitted on a knitting machine hand knitted - until you reach the level on knitting machine that you can walk away from and leave knitting)

[alex_holden]

Thanks, I saw that and as usual I find myself in agreement with Robin. Nice movie clip too!

 

I didn't realise some people call the use of manual knitting machines hand knitting. It's an interesting question as it's clearly a very different process to knitting with just a pair of needles, though in most cases it involves a skilled craftsperson (especially if they design their own patterns), a hand-powered machine, and a fair amount of hand-finishing work. My mum used to knit clothes on a machine and sell them at craft fairs in the eighties, but she gave it up because there wasn't any profit in it and it was sucking the enjoyment out of her hobby.

[Sunny Jim]

 

There are enough challenges in making a concertina; labour saving devices which do a better job than I can do by hand are not to be scorned.

AMEN brother! ( or is that an Americanism?)

 

 

"There's naething the public'll pay you quicker or better for, than for daein' wi' your legs what an engine'll dae faur better"

 

Dan McPhail Engineer SS Vital Spark.

[Dana Johnson]

I use a Techno CNC gantry router (servo) but the taig will do though you might consider ball screws. Or you'll have to be compensating for your backlash. This really counts when you are milling CNC profiles going in multiple directions.. Techno makes a small "DaVinci" model but I think if you've got the Taig, you'd spend your money more wisely improving it with a VFD spindle and ball screws. You can check out my website photos to see the stuff I use. You can get non water cooled spindles, but they don't reach the same power level. Still, you don't really need that much power for concertina part making. High RPMs help though.

I cut my shoes out from the top and do the back bevel on my roller guide vice thingy with a file. It is fast and easily adjustable and I don't have to worry about lots of depth cuts to clean up the steps. You would need a ball end mill for that on the CNC, but I don't think is is worth the extra time and cutters ( not cheap) tapered mills from the back would work, but you need to be able to vary the angle. Filing is easy fast and I get a near mirror finish without much effort. Save your bearings for the things your machine can do better.

[alex_holden]

I use a Techno CNC gantry router (servo) but the taig will do though you might consider ball screws. Or you'll have to be compensating for your backlash. This really counts when you are milling CNC profiles going in multiple directions.. Techno makes a small "DaVinci" model but I think if you've got the Taig, you'd spend your money more wisely improving it with a VFD spindle and ball screws. You can check out my website photos to see the stuff I use. You can get non water cooled spindles, but they don't reach the same power level. Still, you don't really need that much power for concertina part making. High RPMs help though.

Very nice. Probably out of my price range though. I see they use the 800W Kress router spindle on their benchtop model.

http://www.technocnc.com/cnc-router-systems/bt1212.htm

 

Some people have upgraded Taig mills to anti-backlash ball screws, though I understand it isn't an entirely trivial conversion due to lack of space under the table for the recirculating nut (I think you need higher torque steppers too because they are typically higher pitch than the standard ACME screw). You can get the backlash fairly low with the adjustable nuts, though they do wear and need periodic adjustment. The problem is if the leadscrew wears more in one area then you can't tighten the nuts to compensate for the backlash in the worn area without it binding in other areas. This is something I haven't really researched in depth because so far I've only used it as a manual mill.

 

I cut my shoes out from the top and do the back bevel on my roller guide vice thingy with a file. It is fast and easily adjustable and I don't have to worry about lots of depth cuts to clean up the steps. You would need a ball end mill for that on the CNC, but I don't think is is worth the extra time and cutters ( not cheap) tapered mills from the back would work, but you need to be able to vary the angle. Filing is easy fast and I get a near mirror finish without much effort. Save your bearings for the things your machine can do better.

Thanks for the advice! I will have to figure out how to make one of those filing jigs when I get to that stage.

[conzertino]

I would certainly call the old concertinas "hand crafted"!

 

I bet that nobody ever made a concertina without the use of some kind of power-tools:

 

https://www.youtube.com/watch?v=4LFBNlildjA