Not-a-number
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Posts posted by Not-a-number
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Did bit of a time laps video of the camtree casting. Not great but its a start.
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1 hour ago, 00quattro00 said:
Whats wrong with using 350 as opposed to 250?
Nothing, just that it will be harder to do by hand.
6 minutes ago, anglia4 said:Its higher tensile material. Nominally 350MPa yield strength as opposed to 250MPa.
To form it over the mandrel you need to be able to "yield" it, so the higher tensile would need more force to bend to yield.
@Not-a-number will you be heating it to form?
Hopefully not but probably. Ive heard if it was G350 that would probably crack and distort it. Since it would be locally annealing.
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32 minutes ago, anglia4 said:
what thickness is the chassis that you have to form over it?
4mm mild steel.
Though they did them out of G350 by accident. So that may or may not suck. Hopefully they can replace them with mildsteel.
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The mandrel is spaced apart like that so that if we cant form it by hand and need to make hydraulic tooling theres some room to put it behind the rail.
Ideally it would only be 100mm apart. Save some weight!
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Chassis mandrel finished!
Exciting stuff.
Brunton Engineering in Palmy did an awesome job. If you need fab work Id definitely recommend.
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5 hours ago, BlownCorona said:
shit that's going to be a large motor!
i had in my head that those parts were the profile of the crankcase and that part housed the crank gear like a standard engine would have a timing gear case on the front of the block
Yeah its pretty big.
Banana for scale.
Also mm for scale. Its about 1020mm long.
About 700mm tall
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Another 2 done. Worked well.
I think 4 paper weights is enough for now. Time to move on to something big!
For reference of where it goes. Houses cam gearing.
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Well is sold for a bit under $20m NZD. I forgot to bid!
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Finished up 2 more.
Added chill blocks to the bigger top bosses and also a bigger flat one to the middle (instead of the tapered one).
Still have the same risers.
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So the only issue was the back face.
It looks like a crack. But what I think happened is the tapered 'disk' type chill blocks have no where to expand to. They are also in really thin sand. So when the chill block started doing its thing and getting hot it expanded, cracking the sand and pushing it into the face that hadnt solidified.
The front did the same looking at the sand mould after the pour but it wasnt on a flat face so it didnt matter.
May look at changing it to more of a boss like the others.
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1 hour ago, sheepers said:
Yea the old "suck it and see" method of production improvement, 60% of the time it works every time.
And yes you'd be hard pressed to find a foundry they you could just walk up to the door and get your mould poured straight away.
Definitely open to some advice on the big stuff if you want to help?
Im getting a better understanding of the runner system but on the big stuff like the crankcase theres so much going on (and its so big I dont want to mess it up too many times)
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29 minutes ago, sheepers said:
excellent news on the good casting result.
have made many patterns and tried to get castings to work in various sizes and levels of complexity before and i know how hard/frustrating it can be so great work man.
the foundry you're using look like they know their shit too which always helps.
They know what theyre doing so that does help. Usually the answer is "you could change X Y and Z and that might help, or it might make it worse you just gotta try it."
One of the awesome things with the foundries over here is they are pouring 24/7. I just drive up and take the mould right to the furnace and fill it up straight away! NZ wasnt quite like that!
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Well it worked pretty good!
Only real defects are on the face with machine allowance.
The volume of the chill block didnt really seem to matter so I think going forward I'll size them to at least 100% of the volume that needs chilling.
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3 minutes ago, Matt G said:
Fascinating brilliant to know! Keep up your excellent work. How much does a complete engine weigh?
Not sure to be honest. Atleast 250-300kg.
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Basically I find it pretty hard to justify spending $thousands on one off parts. I might as well spend that money on a tool I can use for lots of parts.
Example. To pay someone to make regular patterns for just the crankcase (MDF cnc) was going to be $13K. To pay someone to print just the crankcase patterns was $10K.
So instead I bought a massive printer for $10K and printed every pattern for the engine for about $1000 material.
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13 hours ago, Matt G said:
Apologies if youve been already asked but, is it not economic to just 3D print the metal parts?
so much time making those molds i bet.
Possibly on some smaller parts like the supercharger or waterpump. Maaaaybe!
I dont know the cost of Aluminium printing now but when I was doing SS printing it was about $1000/kg.
The sump/crankcase are around 20-30kg and would have to be done in multiple pieces and welded together.
This camtree part is 5kg and cost $100 to pour. Means once its right they are super cheap.
A rough estimate on the cost to do this part:
- Modeling and pattern design - 250hrs
- Pattern Printing - $50 material
- Pattern /corebox prep - 50hrs & $100 material
- Sand Mould making - 15hrs
- Sand Mould cost - $20
- Pour part - $100
So total its taken about 300hrs and $200 to make 1.
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Got the next one ready.
Now have 4 chill blocks, 4 risers, 2 main in-gates and 2 small gates.
One of the chill blocks didnt pack very well so we'll see what happens there. The sand around that area is pretty thin so theres a chance itll get super hot and fall apart.
Bigger problem is I had an issue with the sand strength for some reason and it cracked when bolting up. Hopefully it doesnt fall apart when filled!
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So the plan is to add 4 risers to the thick top areas.
Then add chill blocks for the bosses in the middle. Couldnt find info on sizing a chill block so Im going to go with making one set total the mass of the boss and the other set twice the mass. See if they are any different.
Also doubled the ingate area (back to what its meant to be in theory) and made it feed from both sides.
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Made a cool paper weight!
As I thought, the in gate was too small and it filled too slowly causing some cold shuts/holes.
Also the thicker sections in the middle shrunk and caused some tears.
Other than that it looks reasonable.
So the plan is to increase the ingate area (maybe add another gate on the front)
Then to sort the shrinkage I need to learn about adding heat sinks into the sand mould.
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New core done, ingate and risers added. Sealed and bolted up ready for the foundry. Made a mistake on the size of the ingate unfortunately and since its glued closed Im sh#t out of luck.
So we'll just have to see how it goes.
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Busy weekend. 2nd half worked well. Little removable corner inserts look clean.
Next I need to make a new inner core and figure out where to put some risers. Should be close to going to the foundry!
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Putting the sand in the freezer before adding the catalyst has given me a good 15-20minutes work time (instead of 5!)
Did the outer mould today with 30kg of sand no issues.
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Since I plan to ship these back to NZ I want to make as few sand boxes as possible. So Im making the patterns removable from the boxes. Usually I just glue them down.
Threaded insert
The removable sections. Still need a bit of cleanup.
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Outer pattern with runner system.
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Bugatti T57/59 engine
in Project Discussion
Posted
Haha. Low 30s... In the shade.