Cnc? laser cut shapes?

[ukracer]

A 1:1 pantograph is easy.

I had a plastic one when I was a kid - pointer on one end and crayon/pencil in t'other.

Looking at that attachment it looks easy. I am actually sitting here and thinking that looks like a direct copy. Bit weird there is not much about it on youtube . If its simple many seem to write about it. Lol

But again here is Joe's latest reply.


I still don't follow him or is it me being thick? (Again)

 

[ukracer]

I see what Joe's is saying....not sure it will matter in many applications but looks like it won't engrave....etc

 

[ukracer]

OK how do I make one then. Lol

 

[Gareth0123]

The clever bit to making a scaling pantograph is ensuring that the following stylus, fixed pivot and torch holder are interchangeable on the beams of the pantograph.......... in other words the pivot bearings they sit in are all the same size.
This can easily be achieved by making a "Top hat" bronze bush with corresponding locking collar.
But with one bush centre to suit a plasma torch, one bush centre to suit a stylus and the final bush centre to suit the fixed point.

So the simplest way for me to describe this is as follows.
This child's Sketch-a-graph shown in the photo has a fixed point pivot, stylus and pencil which are all interchangeable.
As shown it is currently in the X 2, 1:2 or doubling configuration: Fixed pivot at A, following Stylus at B and pencil at C.... Got it?

So, Following stylus at Point A, Fixed Pivot at Point B and pencil at Point C is X 1, 1:1 or actual size.

and Fixed pivot at point A, Pencil at Point B and following stylus a Point B is the X 0.5, 2:1 or halving reduction.

So substitute pencil for plasma torch and we are on to a winner.

 

[slim_boy_fat]

@Gareth0123 I remember having one of those as a kid.

 

[ljgfabs]

Hi Andy,

This is interesting, i made the same at my last company. I intended to make them and sell them, i made a couple of samples that would have been better quality than anyone else's but wouldnt have been able to compete in a product where price beats quality every time, The first ones i made were cut on a laser, 3mm thick is perfect, stainless is an overkill. Anyway, i started my own company last year and got busy with other stuff and never followed through, i bought a 3m x 1.5m bed CNC plasma cutter and could make these shapes for less money, but couldnt get the holes accurate enough for the rivetted assembly , but the perimeter cut edge and shape was very good. I worked out, the plasma cost, a 'rabbit' 300 x 250 in 3mm mild steel blank would cost 2.75 each as opposed to the laser coat of nearer 4.00, if that gives you any idea. So i wouldn't discount the Plasma entirely, it might just mean reaming out holes where required. If you need any help i have dxf files of rabbit, crow, squirrel and rat which will save you a small fortune should you decide to get lasered etc.....

 

[Gareth0123]

Ideally, you want the pivot to always be in the same place, ditto tracer and 'tool'.
That way, you can have a fixed bed with a pattern shelf and a part shelf always in the same relationship.
Scaling is achieved by relocating the moving pivots.

Try this link and extrapolate the given dimensions accordingly: https://www.peter.com.au/articles/pantograph.html