Any experiance using 3-d printers for parts?

[Jim Burrill]

Hi folks,
traditional route for some parts has been to borrow an original from a friend and then have a pattern made and then have the part cast at a foundry.

Damned expensive for things like a gun mantlet. Some smaller parts can be done with home hobbyist sand casting material and an Oxy Aceteline torch to melt some brass.

With the 3-d printer tech that has developed int he last 10-15 years, we can have stuff laser scanned into a file (that can be shared!) and someone nearby with a printer spit out the parts.

In theory.... that is.

ANyone done that? Any land mines to watch out for?

Any printer materials useful to substitute with? ( if the part can be painted , can it be a resin part instead of metal? )

All comments welcome!

[45jim]

Jim,

Most 3D printed parts will not be of any use to you. if you are replicating a cast part then the final part needs to be cast. The value of 3D printing is that you can scan an existing part, then you can account for the shrinkage (depending on the material and shape of part being made) and print a pattern. This pattern can be use to make a mould of the part you wish cast. The 3D process allows speedy production of the pattern, not the part when dealing with cast items.

Here is a primer on 3D printing, its not really our friend as metal parts that are currently made from mild steel are not the target of additive manufacturing. Low strength plastic parts like knobs are certainly possible, but expensive as you pay for time on the machine rather than materials.


http://3dprintingfromscratch.com/com...gies-overview/

[jdmcm]

I would have to disagree, my brother and I have spent the last 3 years in the 3D metal printing business and have one of the few machines capable of production on the west coast. It is true it can be used to make simple patterns for casting, you can also 3D print entire sand cast molds. The real beauty is you can take a part from CAD file to holding it in your hand in a matter of hours, these parts can be drilled, machined, welded and polished...and a part that would be ridiculously expensive to cast unless you were making hundreds of parts, can now be reproduced for a few hundred dollars. And if you are worried about tough, Paccar uses our parts in their trucks and Boeing flies you through the air with 3D metal printed parts...my two cents

John

[David Herbert]

It is also possible to 3D print a pattern (from which to cast a metal part) in wax. This is then used in a lost wax casting process where a ceramic coating is used to cover the wax which is then melted out and the metal poured in. No 'draw' or loose cores required and almost any shape is possible with hardly any more effort. 3D printing in wax is about the lowest tech form of 3D printing as temperatures and pressures are obviously much lower than in PVC and in a different world to 3D printing in any metal.

David

[Lauren Child]

I haven't had much luck with hobbyist printers, but the tech looks promising for the future. I have ordered good prints from professionals.

3d scanning opens some interesting possibilities, if (as has been said) you upscale to account for shrinkage before making a mold.

[maple_leaf_eh]

Originally Posted by David Herbert

It is also possible to 3D print a pattern (from which to cast a metal part) in wax. This is then used in a lost wax casting process where a ceramic coating is used to cover the wax which is then melted out and the metal poured in. No 'draw' or loose cores required and almost any shape is possible with hardly any more effort. 3D printing in wax is about the lowest tech form of 3D printing as temperatures and pressures are obviously much lower than in PVC and in a different world to 3D printing in any metal.

David

I would echo this concept. My understanding of hobby and low-end 3D printers is the limitation is the medium. What I've seen lay down some heat based plastic compound. I have some hunter safety education dummy rounds for example, but they are no comparison to John's example of aerospace parts.

However, if you had a laser scanned file of the original piece, it could be laid down in casting wax. With your complex shape literally in-hand, you could make a metal casting.

[45jim]

jdmcm you are missing my point (unless I missed the point of Jim's request, but I don't think I did) you cannot REPLICATE an original cast part using a 3D printer. If you are trying to replicate the fit and finish of the original cast part so it appears totally original you can't just print one off, the finish and the mechanical properties will be different from the original. Not to mention no one is printing grey iron, bronze or brass (why would they want to?). If you want to print in wax and do a "lost wax" process then you will get good results, printing saves you several labour and talent intensive stages.

Given that this forum is for based on the restoration (ore resurrection) of old military vehicles, I believe that is the point of the question.

This has nothing to do with the wonderful things made with 3D printers today (and the many things you cannot make with them) this has to do with the replication of antique parts that look and perform the same as the original part.

Can you print Ti hex tiles, 20mm across and 6mm high, with similar properties to Norsk? Could you print a sheet of them 250x300mm? If so I have a proposition for you.

[Jim Burrill]

Maybe I should say what I am trying to make....

The Humber Armoured Car uses two, two-peice cast pot metal triggers - one for the BESA remote fire and the other for the remote 37mm cannon to be fired.

The triggers hang off of some steel bar stock mounted to the side of the 37mm receiver, and were used by the Driver to grab onto to pull himself up from the side crew door. Obviously, they had a hight rate of breakage!

My HAC came without the mount or the triggers.

Clive Hughes had a project to cast repros up as a "back burner, get around to it someday" project.

A friend imported a DAC that had both triggers and let us borrow one to use for a sample.

We let the project slow-track as we had a unplanned majorengine rebuild take prescidence.

Original plan was to take the two simple halves of the trigger itself and cast a few replicas ourselves. Aside fromt he cast handles, the inside has a folded metal bit to be what your finger pulls on, and a couple of springs and alignment pins.

Technology seems to have jumped past our plan to make a mold and hand pour a couple.

It looks like a laser scan, a computer to adjust for size shrinkage, and a 3-d printer that can use something that qualifies as 'Pot metal ( or stronger) and try to order 4 of them.

If the metal looks like silver-ish pot metal, and we can smooth out the "layers" by sanding, we would call that a win. If we need to paint it to get it to look appropriate and be as strong or stronger than the original, still a win.

We also would like to have a gunsight mount scanned int he UK and the file sent to us int he States to be printed. (There are several Humber Mk4 owners that are also missing this part, so we could split the costs by 4 or 5.

OK, now who can I contact to a) gets scans made, and B) get a couple of prints made?

[jdmcm]

point taken 45Jim, may have misunderstood your original point, my apologies

[Alex van de Wetering]

Maybe I should say what I am trying to make....

Jim, your description of your actual plan makes all the difference in my opnion. I mean anything is possible, but finding out what technique works best and is cheapest will always depend on the specific part you want to replicate. Some parts are easily measured and quickly reverse engineered in 3D CAD, while others are complicated and scanning will be easier or cheaper. Other parts are so simple that some wood and a few hours work will give you a pattern that might still be cheaper than the cost of scanning.

In your specific case of the grips I would personally still consider reproducing them in a sillicone mould and resin. Some resins have very limited shrinkage or filling material can be added to reduce shrinkage. Once painted you won't see the difference as casting texture and parting lines will also be transferred ....it might be stronger than normal pot metal and spares can be easily cast if it breaks.


If you want a more authentic effect you could scan and print in metal. I had a boiler for a prototype coffee machine printed 10 years ago, which was done in Selective Laser sintering. The "look" was comparable with pot petal, but it was in fact metal dust, combined with resin....and not water tight as we soon found out . Techniques for printing metal have come a long way since and I am sure John can tell you more.
The scanners nowadays are so accurate they will also scan weld texture, parting lines and any defects, so the printed end result will look very much like a cast part.

Scanning, than printing a master and than casting might give the result closest to the original, but I think it also the most expensive. I think that's the way to go if you want to make a whole series of parts....for instance if you want to make reproduction tracks.

I have had things scanned here by a company called Geopoints. http://www.geopoints.nl/ They have several scanners and scan all sorts of stuff like car parts for reverse engineering, but also art, airplane cockpit elements, complete car bodies.....but also a Fiat 8V engine for reproduction! etc.
I am sure there will be similar firms on your end of the pond, but if not, you can always contact them.....send the part (or a copy in resin!) have them scan it and the file will be sent through WeTransfer. They can also scale the file and either prepare a CAD file for further work in 3D CAD or a file directly suitable for printing.
There are plenty firms nowadays that offer printing services. Some are not very willing to work for hobbyists, but others do.

Alex