A Question for Darren - CNC Machining sheet metal

[pre65]

The figure i saw for black Delrin was 500v/mm.

So for what i am using it for there should be no probs.

Thanks Darren for alerting me about a potential problem.

[Darren]

Yes it does look like you would be ok Philip.

At 250V I don't think you'll have any problems. Though I would suggest using natural in the future.

I was contemplating using it for around 2KV at the time which is why it probably stuck in my mind.

In the end I bought a rod of Teflon to be on the safe side which seems to be fine in my application.

Also be be aware that most plastic absorbs water to some extent. Though again I don't think you'll need to worry about this at 250v.

[Darren]

Yes no problem, send the CAD file over to we4212 at gmail dot com and I'll sort out a price for you.

BTW, please don't supply the copper sheet. You will probably already have it to size required? The machine has to cut the outside edge in order to know where to cut the internal holes. If the copper is already to size it can't do this. I don't believe any CAD machine can. It's just the way they work.

Secondly we won't know exactly what composite your copper will be, this does make a difference and they do vary a quite a bit.

We only charge the true cost for the materials. ie we do not make anything on it.

But I would suggest that you think about using Stainless Steel. You can give it a brush effect finish with aluminium oxide paper quite easily and it will never tarnish, thus keeping it's good looks.

We can cut almost any sheet material except acrylic, this just shatters.


Best wishes
Darren

Hi Colin,

Sorry to take so long to get back to you on this, it's a small order so I had to push it a bit. But they are OK and will do it for you.

The price for a 400x320x2mm fully cut out section with all the holes you require comes in at £25 for the copper and £12 for the cutting. Total = £37 + VAT. Much cheaper than you paid for a blank piece.

My charges for traveling to collect (it's a 70m round trip), sorting the CAD file in preparation for the machine, and my time would be 20% at £7.40 in this case.

But,

We have to buy a sheet 1x2M at a cost of £301 + Vat. So doing just one piece is really out of the question.
However, we can get 12 plates from one 2m sq sheet.

If others want something similar then I think we are onto a winner.

each cutout can be different btw, that's not a problem.

If ten people can club together a sheet would cost £30 each, cutting around £12 each and a small charge for my trouble.

Let me know what you all think.

[Toppsy]

Darren,

those prices are certainly very attractive and as you say cheaper than I could buy the basic material for. So in essence a bargain I do need a front and rear plate also but these are likely to be around 300mm x 75mm and as yet are not CAD'd up.

However, without others here on the forum to use up a full 1m x 2m sheet........

I know Paul Bannister is interested and is CAD'ing up a copper chassis so anyone else out there I can do the CAD drawing for anyone who hasn't the skill or access to a CAD programme.

I could always replace the chromed tops of my gm70 monoblocks with new pristine CNC cut copper plates. That would reduce the number of addition guys to the list to around another 7-guys.

EDIT

To put Darrens prices into context I have just recieved a quote from a local Engineering firm that specialise in CNC punching sheet metal. For the CNC punching only the 400mm x 320mm copper sheet the quote was £65. I would have to supply the oversized copper.

Colin[/u]