TVRRUG Meetings on 6th and 20th July

[Malcolm Napier]

In what looks suspiciously like an outbreak of organisation, we have specific activities planned for the TVRRUG ,meetings on 6th and 20th July.

On the 6th July (this coming Monday), Matt and I will be trying a compound called XTC-3D. This 2 part epoxy claims to smooth out the striations in an FDM/FFF print. ABS can be smoothed in an acetone bath but the same is not as straightforward with PLA. We aim to document our experiences for posterity and will hopefully be posting to the rLab and TVRRUG sites. Because of this, I imagine that this meeting will mainly be of interest to people who have a print that they would particularly like to have smoothed. If that is the case can you please let me know in advance? We will be limited by time and there is a finite amount of XTC-3D.

I expect the meeting on 20th July to be of wider interest to the group. The reason is that Richard (Ibbotson) and Ryan have offered to demonstrate where they are up to with their project to (ultimately) build a SLS printer. Approximately 2 years ago I made a post to the Reading Hackspace Google Group, pointing out that the SLS patents were about to expire. Richard, Ryan, Barnaby and others have been beavering away quietly in the background since then.

To quote Richard:

Don't want to raise expectations too high, we are only running 2D so far and barely getting a single layer to hold together. Alex seemed to think we had enough progress to share, and we could do with some help too if we want to speed progress. The biggest technical problem at the moment is the quality of the powder, we need to get a proper atomised spherical powder of consistent grain size, most likely 316 stainless. I hope to get some next week.

 

The laser we have used is the HKR5 laser etcher, because it is in the right power range and type for metals, and has the XY scanning built in. The laser etcher is big, due to old technology. However it is Class 1 laser safe and has space for experimentation. When we get further in testing we will likely go for a much smaller and expensive laser with less support needs in terms of power and cooling.

 

There is information on the HKR5 on the wiki, and I will try to find some time to update the sintering information on the wiki. Also some good discussion and target designs at: www.metalbot.org

Alex on the other hand was more enthusiastic:

Even seeing the clumpy sintered iron filings ring was awesome - it was a successful laser sintering in a coherent shape by CNC control in a Hackspace.  If not a first, there cannot be many precedents and it's such a good first step towards a full metal 3d print.

Whilst respecting Richard's modesty and expectation management, I am with Alex on his assessment that there cannot be many precedents. I am enthusiastic to see the progress that has been made and to see if I can help in any way (not being a laser person).

I hope that others are equally interested. In particular, I hope that this is something that might persuade our members in Surrey and Hampshire to organise a charabanc trip to Reading.

If you intend to come to the demonstration, can you please post on here - so that we can get an idea of numbers?

In terms of practical arrangements, I expect the laser event to start at 20:00 on the 20th. As for the 6th, I hope to be there from around 19:00h onwards and aim to leave shortly after 22:00h. If there is enough interest, pizza can be organised.

Regards,

Malcolm

   

[Stuart Livings]

I'm curious about both and might be able to make both dates. If there's a space constraint I'll happily give up my place due to the uncertainty, but if possible I'd like to be there...

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[Matthew Daubney]

Results of the resin test are here! http://mattmakes.uk/xtc-3d-3d-print-smoothing-resin/ I think I'm going to grab a bottle and have a play. There looks to be a small amount of art in getting the right level of application onto a model.

[Alex Gibson]

Thanks for posting this, I wanted to come along but couldn’t at the last minute.

 

Looking at the results it seems good, but working at a fine level, so would you say there is only a point to using this if already printing at high resolution?

 

How thick was the gunk?  Could it be dipped or sprayed for even, easy coverage?

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[Matthew Daubney]

It's very thick! I doubt you could spray it. It only has a working life of about 10 minutes, after that it hardens quite rapidly and is completley set in 2.5 hours (according to the data sheet). I doubt dipping would help, It's too thick and it dries too quickly!

[Alex Gibson]

Hmm.  Wonder if there is a solvent that will not ruin its function?

[Simon Green]

On Tuesday, 7 July 2015 19:59:09 UTC+1, Matthew Daubney wrote:

It's very thick! I doubt you could spray it. It only has a working life of about 10 minutes, after that it hardens quite rapidly and is completley set in 2.5 hours (according to the data sheet). I doubt dipping would help, It's too thick and it dries too quickly!

It looks like epoxy. Does it add anything to the strength of the parts? 

[Matthew Daubney]

probably..... have we got a thing to measure pressure being exerted on an object? could print 2 of the same objects and test it destructively?

[Simon Green]

On 08/07/2015 11:19, Matthew Daubney wrote:
> probably..... have we got a thing to measure pressure being exerted on
> an object? could print 2 of the same objects and test it destructively?

Perhaps print something with no infill and single wall and compare
with/without the resin. That ought to exaggerate any effect.

[Matthew Daubney]

Could just do cubes and stack weights on them? Would that be enough of a comparison?

[Stuart Livings]

Flat-top pyramid or a horizontal bar might be easier objects to test to destruction?  Horizontal bar makes it easy to hang weights off string?

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[richard....@btinternet.com]

I will be down around 19:00 tonight, and we can start at 20:00 as you suggest

[Malcolm Napier]

I will be there as soon after 1900h as the traffic allows.

I am guessing that attendance will be in the 5 - 10 people range - based on minimal response to my posts on the 3 Google groups.

See you later.

Regards,
Malcolm

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[daprigoo]

can't remember if I replied previously, i plan to be there 7-ish
David

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[Matthew Daubney]

I won't be down this evening, but Malcolms resined parts are in the normal drawer for dropping stuff off at the space.

[mikethebee]

I'll be along too.  -Mike   

[Hugh Pryor]

Hi there,

I met a fellow from the Reading Hack Space in the laser tent at the Harwell open day the Saturday before last and I've just found the note saying that you have something to do with laser sintering on tonight between 7.30 and 9.30.

 

Is this the right place? 

I'll be driving form Oxford so I thought I'd better check beforehand.

Hope to see you!

Hugh

[Ryan .]

Hi Hugh, sorry this message ended up in the moderation queue and I missed it!!

Yes, this is the right place, however we only managed to get three of four dimensions right. 

Hopefully more developments in this area will be as widely advertised and demonstrated. 

R

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[Richard Ibbotson]

Hi Hugh,

Sorry you missed our session last Monday.

You are welcome to come down to rLab to see and hear what we are doing on laser sintering at a time of your convenience.

Just post up here some possible dates.

Richard

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[M P]

damn, also missed out on this as I was away.

How did the lazor presentation worked out?

M


On 22 July 2015 at 13:12, Richard Ibbotson

[daprigoo]

It was an intro presentation, no demo as we ran out of time (ideally a
topic for next session), interesting and scary - lots of volts and
radiation.

The setup up with the etching Yag laser to do SLS/SLM needs practical
work on mechanics for the powder management (lifts and scrapers similar
to the OpenSLS design) and software to exploit a Beaglebone + adaptor to
interface a PC to the laser.

The 1.2kW monster is for cutting metal and the fact it is housed in a
sarcophogus is a bet of a give away. Richard is figuring out plumbing,
pumps and large water tanks at the moment
David

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[Eric Rowen]

Re the "cutting metal"  what thickness is possible? 

[Richard Ibbotson]

That's what we want to test. It is not just the laser power ( 1.6kw), but heads and assist  gas which make a difference.

My hope is 6mm steel with a fairly simple setup, and 25mm steel if we got exotic.

[Alex Gibson]

Hi Richard,

 

Do you have the dimensions (or ideally the CAD file) of the base of the newer powder printer?  I’ve got a design in OpenSCAD and want to see if it will all fit together.

 

Cheers

Alex

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