We should be able to CAD a lens holder and get it 3d printed – @andrew_d’s brother made a model before.

In the meantime why not just use the damaged lens? It still works and the risk from the lens material seems to have been a misunderstanding.


@lasertechs what’s the policy on using the laser with the damaged lens? I have a quick router template i’d really need to cut today

They’ve previously said no in the past few days when people suggested this.

Alright. Any suggestions on places I could outsource to that are good?

Is there a reason why a good-enough centre can’t be attained with the 4-jaw on its own? It is rectangular after all

Cut Laser Cut
Good Empire
4D Modelshop

The problem with using the 4 jaw is alignment. The aluminium has two purposes

1) Demonstrate that the lathe can cut to the required tolerance

2) But the real reason is to provide a circular surface to set the DTI against whilst  centring the rectangular holder in the 4 jaw. Once aligned the aluminium  is discarded. The  rear washer ( I'm thinking of using a centre bored penny) is only required to retain the aluminium whilst setting up the 4 jaw.

nb The 20mm aluminium stock is slightly undersized at about 19.8mm so won’t be up to the job, but I have on order some 25mm bar which should arrive Monday or Tuesday.

Didn’t someone design a holder in 3D that we could 3D print?

These are 19.5mm still FYI

Sorry, why is trying to be achieved here? Build a new lense holder to fit an exiting other lens?

Yeah, we bought 20mm lenses but it turns out that Trotec use 19.5mm. The lens needs to be pretty accurately centred and is quite fragile so we can’t just bodge something.

The holder needs to either be modified to accept the new lens, we make a new holder, or we pay Trotec for an official lens which is much more expensive. We’ve done that once already and it’ll add up if we have to keep doing it.

And the problem is centering the lathe on the shape, right?

Yes. The hole is not in the centre, front to back. It’s also a pretty small & flimsy piece of material so there’s the possibility of distorting it just with the clamping force.


there is any way that we can machine a holder for the lens holder?

@3dprinters @metaltechs @woodtechs ? any idea?

It’s a simple shape, apart from the overhang on the guide rails, which would need a special bit to machine.

3D printing is probably the easiest way to make one from scratch.

How much were the lenses? Could we buy a slightly smaller size? It would be easier to print a spacer to mount an 18mm lens in a 19.5mm hole, for example.

The 20mm lenses were quickly available in the UK from Just Add Sharks for £60 each

However! I have just found a UK source for 18mm lenses. Next day delivery for £55

This is 1.5" focal length, so not as suitable for thick materials as our current lens.

Machining that would be difficult, especially in plastic, because its tricky to workhold it with deforming it.

We have the tools though. If the bottom is flat we could try using an adhesive. Might also be easier to machine a metal one and cast it.

We 4 jaw chuck it will be easy to cut out .5mm .
Why don’t we ask frank

Scroll up a bit - he’s thought hard on it :slight_smile:

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