Help requested with casting

[Twincam]

Hi I am from Weymouth U.K.
I have built several 4 stroke petrol engines from commercial castings, Wallaby,Mastiff & sea lion which run successfully.
I’ve now designed my own 30cc inline 4 cylinder OHV engine. I have taught myself basic Freecad (very frustrating) and 3D printed the plugs for making the mould for casting in aluminium.
But here is the problem, I have never done any casting and have no equipment and quite frankly it’s not my thing.
is there any one out there willing to assist

 

[Jasonb]

This foundry is quite reasonable, post the patterns and they will post the castings back. Email them with sizes and they should be able to give you a reasonably close quote

https://www.graydoncastings.co.uk/

 

[petertha]

If you end up getting a price quote & its ok to share, I'd be interested to know just out of morbid curiosity. Or PM if you feel broadcasting is not appropriate. I have similar thoughts in my head. I can CAD & have easy access to 3DP, but the molten metal aspect is a whole new hobby unto itself.

I think 3DP metal might be an option for small, complex pieces like header tubes because they are low mass, but seems like larger parts rapidly become expensive & new issues/limitations enter the picture.

 

[ajoeiam]

Hi I am from Weymouth U.K.
I have built several 4 stroke petrol engines from commercial castings, Wallaby,Mastiff & sea lion which run successfully.
I’ve now designed my own 30cc inline 4 cylinder OHV engine. I have taught myself basic Freecad (very frustrating) and 3D printed the plugs for making the mould for casting in aluminium.
But here is the problem, I have never done any casting and have no equipment and quite frankly it’s not my thing.
is there any one out there willing to assist

Dunno if mr greentwin is so inclined but he might be willing to do such. (He posts here with quite some regularity re: at least casting.)

Possibly there is some equivalent person in the uk that might be willing to assist.
Could also be a way of learning a new aspect or is that a new hobby - - - grin!

(imo - - - knowledge whilst not infinite is just too much fun to pursue - - - - so - - - onwards and upwards . . . )

 

[user 52078]

I have used AJD Foundries of Brierley Hill, UK several times on bronze, cast iron and LM25 Ally. Very pleased with their work and very simple to deal with by post. Here is their website:
AJD Foundries
I have no connections with them other than a happy customer.

Looking at your patterns they are very smooth which is good, but I don't discern any draft angle on them. It would be worth talking to AJD by phone before sending patterns as a conventional sand casting process might not cope with zero draw angle. I think that would apply no matter who the foundry are.
Good luck,
Martin

 

[GreenTwin]

Sending things across the pond is a bit tedious as far as the paperwork that has to be filled out.

Its a shame it is not a more simple process.

.

 

[Jasonb]

As well as draft angle you actually want a negative core box mould for the part on the left which will then produce it as shown in the photo but in sand.

 

[user 52078]

I should also have said that the core for the cylinder bores and crankcase tunnel would normally be made in a corebox. What you have 3D printed is the male form you want, and the corebox needs to be the female of that form, but you only need to make a half box as the core looks symmetrical so you just mould two of them and stick them back to back. Not quite the same sort of job, but I attach a photo showing the male half of a sump casting (on the left) along with it's corebox to make the inside of the sump (on the right) which should give you an idea of what I mean.
A good foundryman would probably take a mould off the core that you have printed, and then make a core out of the mould. The snag is that it is more work which will cost you more.
I would also be a bit wary of supporting the core on 4 prints at the sump end. There is significant "flotation force" on a core, so it needs some firm location to keep it in place. Notice in the photo that there is a fairly large rectangular core print around the pattern. There is a similar large rectangular feature in the corebox. For scale, that is a 1 foot rule sitting on the corebox. If you went with a similar rectangular coreprint, the size of the crank tunnel interior protruding maybe 20 mm into the mould.
Hope that all makes sense and helps,
Martin

Looks like Jason types a bit quicker than me!

 

[Charles Lamont]

If I can take the thread down a side alley for a moment, does anyone know where I can get small quantities of the high-build paint used by patternmakers?

 

[Jasonb]

Not seen it in small containers, usually 5lts. John Winters do it.

I've used various other paints from International blackboard paint, Halfords grey Primer (acrylic) and UPol's "High 5" high build spray and not had any problems with airset sand sticking to them.

This is grey primer on hardwood. back on topic th etwo halves at the back make up the core box, the core moulded from that fills th epattern in the foreground so it is just a thin shel with openings.

 

[creast]

Hi I am from Weymouth U.K.
I have built several 4 stroke petrol engines from commercial castings, Wallaby,Mastiff & sea lion which run successfully.
I’ve now designed my own 30cc inline 4 cylinder OHV engine. I have taught myself basic Freecad (very frustrating) and 3D printed the plugs for making the mould for casting in aluminium.
But here is the problem, I have never done any casting and have no equipment and quite frankly it’s not my thing.
is there any one out there willing to assist

What are the rough dimensions of the crankcase?
Another thing to consider is shrinkage of the casting, I usually scale up the model by 1.015 and also add extra to any surfaces that need finish machining.

Rich (UK Leicester)

 

[user 52078]

John Winters are the only UK supplier I know of and as Jason says, you can have any quantity you like as long as it is 5 litres. My 5 litres of black and 5 litres of red (plus 5 litres of sanding sealer) was eye wateringly expensive, but has lasted about 13 years now and has done quite a lot of patterns.
It is a very high build cellulose based paint, so may not be compatible with 3D prints, definitely try it first on a small piece. However, it is not fundamentally different to any other high build primer, so that would probably do the trick, apart from being the "wrong" colour - there is a convention for pattern colours.
I also underline Rich's comments on machining and shrinkage allowances. I think 1.5% shrinkage on ally might be a bit low, but can't find my crib sheet right now. Allow 3 mm on all machined surfaces - and that is on top of any draw required - that is going to be way more important than shrinkage on a tiddler like yours.
Martin

 

[GreenTwin]

I have used the same shrinkage factor as Rich, which is 1.015 for aluminum 356, and that scale factor has been pretty accurate.

Others experience may vary.

.

 

[creast]

I have used the same shrinkage factor as Rich, which is 1.015 for aluminum 356, and that scale factor has been pretty accurate.

Others experience may vary.

.

Machinery Handbook quotes between 1/8" to 5/32" per foot so my allowance is slightly high but works for me too.
Rich

 

[Twincam]

Well I got a quote from Graydon Casting for £79 Inc VAT.
I decided too keep it simple and forego the internal core and machine out the internals instead.
Took 1 month from paying invoice to receiving casting as per below

 

[GreenTwin]

Nice looking casting.
Finding any foundry to do small work is nothing short of a miracle these days.

.