Printed 3D metal better than a Casting

[JasonB]

On JasonB Said:

…part may have a lot of internal cavities that would traditionally have been formed by cores as they are not easy to machine if you can’t get access to the inside.

Like a globe valve:

Inlet on the right, outlet on the left. I plan to try 3D printing, and also investment casting, when I get around to making these.

The CAD model is unfinished; it was primarily created to learn how to create the internal passageways using Boolean operations.

Julie

[DiogenesParticipant @diogenes]

Yes, I agree – should also open up possibilities for doing some of the more ornate ‘frames’ and/or extra architectural details that were either on the engines themselves, or to give fuller context to the setting of a model – floor grills, cast iron steps & railings, etc…

..exciting stuff..

[JasonBModerator @jasonb]

That looks an ideal candidate Julie. Will you print the pattern with something like Poly-cast and use that as the wax for your investment casting? I don’t use Boolean that much but have found it useful for cores and the associated core boxes.

The ornate detail would again be something that 3DMP would excel at, hardest bit is doing the CAD for some of the more organic shapes. The next hot air engine I am likely to make has quite a decorative frame that held it to a wall and allowed the fan to be directed to where you wanted the breeze.

 

[Roy VaughnParticipant @royvaughn26060]

As Jason says, 3D printing enables things which would be very difficult or impossible for a hobbyist to manufacture such as the transfer passages in this crankcase.

 

[JasonBModerator @jasonb]

Another very good use for 3DMP there Roy and on several counts.

– Hard to replicate by machining internal cavities

– Thin cooling fins & reinforcing webs

– A casting that is no longer available.

The latter is one area where I have made use of it. There have been many model designs over the years that were based on available at the time castings but so many of these are long gone. Drawings for many still exist but the lack of castings has meant they no longer get built. Now if you have the CAD abilities or can find someone who does there is nothing to stop the old designs being built once more. Even if no drawings exist, the builder who is familiar with the general type of engine can come up with a very good replica based on old engravings or photos. Couple of recent prints I had done are such a case

Along the same lines there are a lot of untouched or part built kits out there that may have lost castings along the way or old engines in need of TLC with damaged or missing parts. 3DMP is a suitable way to obtain the missing castings. A good example from Sanjay the builder of the Williamson is his ord Stuart 10H. This is to the original design before they went over to the simpler to machine trunk guide so the current castings are not the same. The box bed was missing and chances of finding an original casting extreamly unlikely but he and a friend played around in CAD and did a couple of PLA test prints. Then when happy that their rendition looked like the old catalogue illustrations got the metal print done.

[JasonB]

On JasonB Said:

That looks an ideal candidate Julie. Will you print the pattern with something like Poly-cast and use that as the wax for your investment casting?

I am printing the patterns on my resin printer using Bluecast X-One V2, which has proved to be trickier than standard resin printing. I made some dumb mistakes on part orientation and supports, but the main issue turned out to be buildplate adhesion of the initial layers. I have some ideas to try, but currently I have enough patterns to try the casting process, which is finally set up and ready to go:

I think that the biggest change to be initiated by 3D printing of metal will be the need to transition from machining to 3D CAD skills. Promotion from the shop floor to the drawing office!

Julie

[JasonBModerator @jasonb]

Ah, I forgot you also had the resin printer. I will have a look at that particular resin. At least you should not have the problem of layer lines with the better surface the resin gives.

Yes CAD is the key to opening up a lot of the modern methods.

[Martin ConnellyParticipant @martinconnelly55370]

I think I have mentioned this sometime back in another forum post. I worked in Siemens until I retired and we had a turbine set up for full load testing before despatch in 2017. We had a core that had been built with a 3D printed turbine blade that we swapped out for the customer core and ran the turbine at full load with a printed blade in it.

Martin C

[DiogenesParticipant @diogenes]

I wonder what sort of clean-up allowances one should leave when prepping a part for quote?

[Julie Ann]

On Julie Ann Said:

The CAD model is unfinished; it was primarily created to learn how to create the internal passageways using Boolean operations.

Julie

The neatest way is often to start the model solid and then remove the interior. Take a simple t-piece, for example. If you extrude or revolve two tubes at rightangles, you have still got to ‘drill’ the side port and clean out bits of side tube from the through hole, so it is better to start with two cylinders and then put the holes in. With something complicated I sometimes model the whole of the interior space as a solid ‘core’ and then subtract it.

[JasonBModerator @jasonb]

Charles, that is what Boolean does. You subtract a solid of the cavity from the overall solid.

Not really worth it wil the simple tee in your example but a very good and efficient way when dealing with parts that have complex cavities. The other big bonus is the fact that having modeled the void as a separtate item you can also use that to produce the core box cavities with just a couphe of clicks rather than having to sketch and cut all the shapes a second time. Add to that Parametrics and any change you make to the cavity will automatically carry over to the part and core box files.

Take this replacement cylinder casting for an old gardner engine.

Quire complex cores needed when you see it in section, one for the water jacket, one for the exhaust passage and one for the actual cylinder bore and it’s passage to the hot tube.

All three were modeled and then removed from the overall pattern using Boolean subtract to get the finished casting below

I then used the same three models to produce the core boxes, this is half the water jacket box

And a test of what the core from it would look like again done with boolean

And a test fit of the core in drag again no need to draw things again just use boolean

 

 

All three were modeled

 

[Diogenes]

On Diogenes Said:

I wonder what sort of clean-up allowances one should leave when prepping a part for quote?

I have found that you don’t need to leave much. On those couple of engine frames I allowd 0.5mm on the surfaces I wanted to machine. On that column 1mm each end but that could have also been 0.5mm as it came out so close to size and with flat ends.

[DiogenesParticipant @diogenes]

Thanks, I thought they’d be pretty good.. ..I see from the ‘Core’ illustrations above I need to get my head around that process too, only this morning I was head-scratching over port passages ‘inside’ a cylinder..

..back to the chain-harrows whilst the sun’s out, first tho’..

[JasonBModerator @jasonb]

The Postie dropped off the printed pipe fittings that I showed the CAD image of in this post.

Very pleased with how they have come out, no pattern shift or flash that you get a bit of with teh PM Research castings and they are also ready bored. I’ll be separating and threading them over the weekend, I may maake some simple nesting jaws to hold them in while face off the ends and thread them.

[Michael GilliganParticipant @michaelgilligan61133]

Impressive !

It will be interesting to see how well they machine.

MichaelG.

[Swarf MakerParticipant @swarfmaker85383]

I have had some parts printed from what I suspect is the same aluminium powder (AlSi10Mg), which is supposedly similar to a casting alloy.

They machine beautifully – but different from any other aluminium alloy that I have used.  If cut dry, the finish is smooth but dull, but with cutting oil it is almost a polished finish. Single point threading is a breeze!

[JasonBModerator @jasonb]

I am expecting them to be just like the previous items I have posted which like Swarf Maker says is very easily and with a good finish.

[John HaineParticipant @johnhaine32865]

http://The Metal 1.0 LPBF 3D Printer Launches on Kickstarter – Hackster.io https://share.google/z3m4wcxLOQVG81EKt

Buy your own…

[Adam HarrisParticipant @adamharris13683]

What are the limitations of 3D steel printed parts other than size? Can you machine down a 3d steel printed surface to the smoothness of a slideway? How do 3d printed moving parts fare with friction abrasion? And when under increasing bending stress or torsional stress do they bend steadaily or snap suddenly? Just a novice’s curiosity…

[Adam Harris]

On Adam Harris Said:

…machine down a 3d steel printed surface to the smoothness of a slideway? How do 3d printed moving parts fare with friction abrasion? And when under increasing bending stress or torsional stress do they bend steadaily or snap suddenly?

The article I am currently writing for consideration by the editor of ME&W will answer most of those questions. However, it wouldn’t be fair to reveal the answers at the moment.

Julie

[JasonBModerator @jasonb]

Adam, I’ve bored printed stainless steel trunk guides and got a very good surface. Not run the engine for hours on end but seemed fine with the running I gave it.

Similar with the aluminium prints, they machine well and I’ve has oscillating cylinders running against the printed port faces at 3K plus rpm without issue.

If you want to send me £50 I’ll order something and do a destructive test on it for you😊

[JasonBModerator @jasonb]

I did not get round to machining the pipe fittings today as the prospect of getting another engine complete and running seemed more appealing. However I did get as far as sawing the strip of fittings apart.

It was interesting to see some internal supports that had been left inside the larger 135deg bends. They broke out quite easily with long nosed pliers and a small screwdriver.

[Russell Eberhardt]

On Russell Eberhardt Said:

On Diogenes Said:

 

The biggest bugbear I can see is how the authorities will respond to the problems of policing ‘mail order’ engineering..

Probably my introducing taxes.  France has just imposed a €2 “Taxe sur les petits colis” (TPC) on non-EU, low-value (under €150) parcels, targeting Chinese e-commerce like Shein and Temu. This mandatory, temporary, and separate administrative fee applies to each item category, not just the package, with an additional €8 fee for non-compliant shipments.  I’m sure others will follow.

Russell

Unfortunately, the aforementioned tax is not an EU wide tax, it is down to individual countries tax decisions.

In the case of Italy who was first,  the tax has been bypassed as Shein and others just now fly cargo to Poland which has no “EU import from non EU” tax, and Shein ship from there to the rest of the EU by post or carrier.

 

“However, Italy made a critical miscalculation: the €2 tax applies only to parcels entering Italy, not the entire European Union. Once goods clear customs anywhere in the EU’s borderless Schengen zone, they can move freely to any member state without additional checks. This created obvious arbitrage opportunity where logistics companies simply land cargo planes in neighboring countries, clear customs there, then truck parcels to Italian addresses—avoiding Italy’s €2 fee entirely while adding minimal transportation costs”

 

How Italy’s Tax Disaster Drove Shein Shipments to Poland

 

[JasonBModerator @jasonb]

With the latest engine running by lunch time I had a go at the pipe fittings this afternoon.

A simple pair of nesting jaws was made by drilling a bit of scrap aluminium with the right size hole and then sawing down the middle. A vice stop ensured the part was always held under the spindle. In the end I opted for M10 x 0.75 as my M10 x 1.0 tap is an old taper tap which is fine for spark plug threads which it was originally bought for but not so good for blind holes so out with a spiral point tap with it’s much shorter lead taper. This also meant I had to drill out the printed counterbores to 9.3mm but that was easy enough just swapping between a drill bit and the tap guide as I did all four of the larger 135deg bends.

Quite pleased with how they look up against the commercial 90deg elbows and will be hard to tell any different once they have had a coat of matt black.

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for sharing that experience, Jason

… it all looks very promising indeed

MichaelG.

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