Using 3D prints for casting

They would be anything from 3/4" to 1 1/2" long, I haven't decided on a scale yet.

I reckon it would be possible to print them in quite big batches at a time. As Jason says I could get on with real life while they printed and anyway the length of time is irrelevant as it's something I've been musing on for years - a Vickers Light Tank, My main interest is in making working suspension units, but a bit pointless without a route to a full model!

I also want something a bit more space-friendly than TIger tank.

Neil

Edited By Neil Wyatt on 21/02/2015 12:55:35

Shrinkage allowances are easily catered for, you just draw the part teh size you want it in your CAD package and then hit a button that will allow you to enter a percentage to increase the item by so you just enter a suitable figure for the intended metal. Same with draft angle if sand casting you can enter an angle when you extrude the basic shape. and then if you want to can superimpose the pattern over the part to make sure it will fit and has machining allowance where needed, I do this by making one part semi transparent.

Hello Wallace,

It's simple to draw the draught angle on to the CAD image and as JasnB has said, machining allowance can also be included where required. What is essential is a good 3D printer, better the printer the better the 3D print.

Regards,

Bob Youldon

I am astounded at the response my original posting has made. It has certainly stimulated the thinking of a lot of you out there. If you don't have your own printer, I am certain that there will be companies out there that will 3D print your items to order.

I note that just recently, a specialised tool was needed in the Space Station, and as they did not have this on board, they uploaded the necessary file and just printed out the required tool on their onboard printer.

Looking forward, maybe there should be a databank created to store all the programs for various items. To be downloaded and used by others, maybe for a small fee? Certainly cheaper than shipping.

.

I wonder if Neil conducted his recent survey with that possibility in mind.

MichaelG.

Neil, biggest problem I see with your tracks if printed on a home machine is that the "teeth" that stick up will be very weak as the print could fracture between layers a bit like short grain on wood.

Is it for a static model or RC?

As I said if you are not going for a perfect match (two different drawings) then you can buy aftermarket tracks for the RC tanks, about £10 for a set of plastic and from £40 for metal at 1/16th scale which would fit within your scale range.

Edited By JasonB on 22/02/2015 08:01:41

I printed the 3/8" ratchet that was also printed on the ISS - incidentally it was not needed there, it was an exercise in designing something remotely to where it might be needed. Anyway you would think the 3/8" square drive would shear off easily since as Jason suggested it was printed as layers, but I found that it withstood the kind of force that you would expect to shear the same part if it was moulded. With ABS I often treat the print to an acetone vapour bath which fuses the exposed edges and reduces the propensity to delaminate.

Andrew.

> I wonder if Neil conducted his recent survey with that possibility in mind.

No...

> Is it for a static model or RC?

R/C. The crude drawing was to help me figure out what a link looked like from photos of the outside of the track, the lower drawing is obviously from a contemporary manual. It's surprising how different the links look from the inner and outer faces - the major one being that the central hole is a large round scoop on the outside with another 'layer' on the inside with a smaller, squarer, hole. I misinterpreted this in the pictures as part of the sprocket wheel, and I hadn't understood the 3-D shape of the teeth at all well. I'd obviously have to redraw it in much more detail.

I don't think it would do any harm to make the 'pyramidal' teeth a bit broader at the bottom and rather less hollow to make them stronger

Neil

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Neil,

Just to confirm .. There was nothing accusatory in my 'wondering'.

It could, I think, be a logical extension to the Plans Service [provided that you could get the DRM sorted to everyone's satisfaction].

MichaelG.

You are aware there's an example at Bovington?

http://www.tankmuseum.org/museum-online/vehicles/object-e1952-30

Edited By Peter Bond on 22/02/2015 13:57:26

Thanks Peter

yes, I have lots of pic of the Bovigton example.

Neil

Couple of weeks ago clumsy Son in Law kicked the door off the washing machine, simple accident but he's still a clumsy f@#~>.

Quick strip down and turns out to be a couple of simple hinges with a bit of needed detail and also some not needed to save material on the original moulding.

So quick visit to Thingiverse.com so she if there are any free files there. Quite a few but none for this model.

At the moment I still suffer from not getting started on 3D CAD because if I was able to draw this I could make it, and after I have drawn it I could also upload it to thingiverse so someone else in the same boat.

As it was, because the washer was needed, had to nip out into the workshop and make two up in brass as I know that technology.

The other hinge was non existant.

Something I'd like to mention as it has been brought up before but with this Makers hobby there are two sides to it.

The side where they make everything and give all the designs and software away and the buy already done like the UP printers.

The later falls into the category of what I prefer to call Cheque Book Engineering where you know what you want, want it now and need it to work. Andrew is a very good example of this.

The first part is why Thingiverse exists and the open source software to run the home made machines.

However because of these two extremes, free or nearly so and commercial units with sales aimed at small industry or really serious hobby there will never be a middle ground.

It simply can't exist as there is no profit margin between free and an already saturated commercial market.

So will we see the likes of Warco / Chester / Chronos /ARC / Amadeal selling these ? My take is no because you can't make money at it which is what these people do and they will leave it to the likes of Mapin / RS and the dedicated manufacturers and concentrate on markets they do know.

My 3D printer actually falls more into the home made category. I made the extruder from scratch and used it to optionally replace the woodworking router / outrunner spindle on my ex-education CNC machine running under Mach3. Total cost for the 3D printer option - stepper motor, driver, heaters, controllers and bed etc. was no more than £100. After a couple of months I have still not made anything genuinely useful that I could not have made by turning and milling. it is very satisfying though to make a 3D design one evening, then during the following day it is manufactured (less fettling) whilst I am at work.

Darn it, my cheque book is under the misaprehension it has been insulted, and has spent all day sulking in the corner as a result.

Andrew

Having just acquired a 3D printer thie last 7 days has been a big learning curve but also great fun. I am looking forward to developing the prints as patterns and core boxes for sand casting. The photo shows my efforts with parts for an IC engine ( a flat six) . The engine was a "theory" design and was never made but it's good to see it in 3D.

George.

My interest in casting has led to an interest in using 3D printing to make patterns for sand casting. There are some caveats. The machine at the price I am likely to spend will probably break from time to time and will also probably need some sensible modifications. Going on results produced by various people there is clearly a learning curve as well especially related to machine settings.

3D printing can be used to make all sorts of things. It's another area where just like a lathe it fits in with an interest in astronomy. That's just a for instance. I'm also interested in model aircraft and helicopters at times. From my product design days I know that ABS is one of the more interesting plastics but it seems nylon and polycarbonates are also possible but have their own problems.

The main problem with 3D printing really is that it's incredibly slow otherwise it would probably be used to make all sorts of things. As it is it's basically most suitable for prototyping.

Looking at previous posts - pay some one to do it. I suspect that would be a none starter compared with owning one of the cheaper one such as rep rap etc. The process also has some limitations on what can be printed but things like twin extruder printers are available - I wonder if they are any good. I suspect I may be finding out at some point but gluing 2 parts together is probably a more sensible approach.

John

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I often stick parts together, its a benefit of using ABS. Just coat the two parts with acetone and hold together for a few seconds. They stick like the proverbial!

Gluing sounds preferable to risking a twin extruder putting down soluble and then accurately putting something else on top.

ABS has some bad press now - nano particles, all over the web. That sounds more worrying than what it really produces - smoke. Clearly breathing in smoke is best avoided what ever it's from.

John

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There are many companies providing 3D printing services. You upload the file, they print and send it to you. Never used them myself but if you want to avoid the expense of buying a printer and messing with it for weeks, this may be an attractive option.

There are now some affordable SLS printers about now apparently. Some interesting resins available for them too, including "castable" and "tough" versions. The former suitable for investment casting and the latter having decent strength.

As you say, John, there's no such thing as safe smoke.