METAL CASTING WORK

[krow113]

Any one doing any metal casting? My 1/9 Harley Hillclimber's plastic rims crack at the slightest manipulation , they wont survive the lacing procedure. The master and mould I can handle , just need tech info on the metal properties etc.

Prolly will get deep into this , the chains and wheels are major stepping stones in the larger scale classic M/C kits. I have a lot of Protar and Revell kits that all need good 'laceable' rims and hubs and chain sets. The rims and other wheel parts are atrocious in the Freccia Protar kit and its such a cool bike and kit I want to build it one day...and many others.

Proper lacing and chain sets make show stoppers:

Edited June 26, 2016 by krow113

[Rob G]

I'd be more inclined to get a lathe and turn them up from aluminium or ABS plastic tube stock. But that's me.

[krow113]

I'd be more inclined to get a lathe and turn them up from aluminium or ABS plastic tube stock. But that's me.

Looking at production , not one off. I'll use my lathe to make the masters , then cast the product.

More interested in metal casting info or experience.

Edited March 4, 2016 by krow113

[krow113]

No worries , may be a dying art as far as modelling goes. I spent the morning looking at supply sites and tutorial vids.

[Black Knight]

What metal do you want to use?

[colin]

Surely turning them on a lathe(which you have) would give you a better finished product than casting will and be easier than all the effort with molds/casting etc

[krow113]

What metal do you want to use?

This is some of the info I am looking for. I see a number of alloys available , I am not sure which will be best for detail and a polished finish , rather than alclad or waxes or powders.

I want to make rims and hubs to solve the problems associated with kit supplied components. Any one familiar with Protar kits that have spoked wheels will know exactly what I am talking about.

I want to cast a number of copies of masters I will make on my lathe or through other fabrication techniques.

Surely turning them on a lathe(which you have) would give you a better finished product than casting will and be easier than all the effort with molds/casting etc

Read my answer to the first question.

Edited March 4, 2016 by krow113

[Black Knight]

This is some of the info I am looking for. I see a number of alloys available , I am not sure which will be best for detail and a polished finish , rather than alclad or waxes or powders.

I want to make rims and hubs to solve the problems associated with kit supplied components. Any one familiar with Protar kits that have spoked wheels will know exactly what I am talking about.

I want to cast a number of copies of masters I will make on my lathe or through other fabrication techniques.

...

For a silver finish you could use a pewter white metal. A tin alloy.

I use lead/tin/bismuth. I mix my own to suit me.

Commonly available is a lead-free white metal called 5 Star Metal by Prince August of Cork, Ireland who specialise in white metal casting supplies. Things can be bought direct from them or through W.Hobby's in London. [Links at the end]

White metal melts at about 220-240 degrees. I use a camping gas cooker for my melting.

After casting the parts do need cleaning up ~ flash removal, smoothing ; nothing a modeller can't do. The metal is soft enough for files, knives and even wet&dry paper to work on it.

White metal is easy to work with and it flows well, though with some items I have to bounce the mould to get the pewter into the nooks, but thats my fault for not making a good mould.

Commercial users, such as John, Aeroclub, would use a disc shaped two-part mould. The pewter is poured into a hole at the centre and the disc is spun by a machine so centrifuge pulls the molten metal into the cavity.

For one-offs or short runs [up to maybe 6 copies] I use a small oil-sand casting set up. With this the mold is destroyed after each casting and needs repacked for subsequent copies. Not good for items with multpe angles or undercuts.

For something that needs more copies [up to 500] I make a single or two-part mould in a special heat proof silicone rubber

For a lot more copies Prince August will make a vulcanised rubber mould for you but it costs about £80 - £200

Prince August, metal page

http://shop.princeaugust.ie/casting-metals/

W. Hobby's

http://hobby.uk.com/moulding-casting/prince-august-casting-products/accessories.html

http://hobby.uk.com/moulding-casting/melting-pots-casting-items.html?limit=all

ok for now?

more Qs?

want pictures of anything?

[krow113]

Excellent , let me digest the info and check the links.Prolly have more q's then.

Please feel free to post pics if you feel they will be helpful. I am gonna cast rims and hubs , the spoke locations will be small indents and will need to be drilled by the end user as well as axle locations. The spinning may be helpful with the rim part of the work. I did cast rims and hubs for the bobber pic shown , cleaned up with that model , winning BIS at our IPMS 2010 show. However the lacing creates tension in the wheel ,5 years later the wheels are not quite true anymore! Anyone familiar with Protar kits can almost see the progression of wheel parts as they tried to figure out a way to do the wheels in a way that modellers could succeed building them, prolly 3-4 different attempts.

Here are the bobber wheels , hubs and rims cast by me, Harley lacing procedure used , on top of a spray can lid 'jig'. You can see the '10 sets of 4' spoke pattern as opposed to trapping spokes in a radial pattern between 2 rim halves and the ugly seam created. After parts prep it takes around an hour to lace a wheel , following the HD procedure ,well within the home modellers ability:

Those were black in finish , chrome parts represent a whole different ball game.

Now we are on track!

Thanks muchly.

Edited March 4, 2016 by krow113

[vontrips]

Looks good!

I cast mainly with pewter. The best stockists (in the UK at least) is this guy:

http://www.carnmetals.co.uk

This is my go-to casting rubber for pewter/white metal. Again, a UK supplier:

http://www.tiranti.co.uk/EdgeImpactShop/subcatdivision.php?Division=173&Content=RTV-101+Silicone+Rubber+

Trade secret; coat the mould with chalk powder before use! Protects the mould, aids release and often gives a higher definition to the casting. Why, I don't know!

Edited March 4, 2016 by vontrips

[Black Knight]

Just to add.

I build but do not cast white metal figures. Knights.

The bare metal can be buffed up to a shine and a metal cellulose lacquer put on it to prevent tarnishing.

The silver can be very shiney and bright.

[vontrips]

Showing off here, but here's one I made earlier!

[ICMF]

Do they have to be white metal? Resin (with or without an additive if you want to add strength) would be easier to cast.

If you're planning on selling them but don't have any experience casting white metal, you might want to look at outsourcing the casting. I know Tameo do commission work (and are very good). John might, as well. It will be more expensive per unit, but you won't have the expense of the learning curve and/or equipment set-up.

[krow113]

Here are my rims and hubs for the Hillclimber and a link to the thread.

http://kitmaker.net/modules.php?op=modload&name=SquawkBox&file=index&req=viewtopic&topic_id=240355&page=1

The parts are from Italeris Yamaha Trials bike, used for the knobby tires.

The rear rim seems to be ok but the front cracks when I look at it. I also glued in a 'c' channel to the inside of both rims so they look more like Harley rims from the '70's.

The cracks around 4-5 now:

[krow113]

Do they have to be white metal? Resin (with or without an additive if you want to add strength) would be easier to cast.

If you're planning on selling them but don't have any experience casting white metal, you might want to look at outsourcing the casting. I know Tameo do commission work (and are very good). John might, as well. It will be more expensive per unit, but you won't have the expense of the learning curve and/or equipment set-up.

Read the whole thread please. Resin is out.

I dont mind buying tools and equipment , and am skilled , the procedures are simple. I want to do at least 6-10 different sets of rims and hubs over the next few years.

[ICMF]

I did.

Now I wish I hadn't.

[krow113]

I did.

Now I wish I hadn't.

Why? If you have relevant info or are interested in the work its all good.

[vontrips]

Those rims would be tricky to cast. I'm guessing the outer profile is needed for the kit tyres? You may get away with a two part mould, but not sure how long red rubber would take being pulled around to clear the profiles...it also tends to harden after multiple casts.

The hubs faces would be a doddle if you're prepared to turn the centre section from bar. They require two seperate open moulds; or one if they are identical.

Edited March 4, 2016 by vontrips

[krow113]

Those rims would be tricky to cast. I'm guessing the outer profile is needed for the kit tyres? You may get away with a two part mould, but not sure how long red rubber would take being pulled around to clear the profiles...it also tends to harden after multiple casts.

The hubs faces would be a doddle if you're prepared the turn the centre section from bar. They require two seperate open moulds; or one if they are identical.

Just heading out now , I'll be back in a few hours. I'll put up pics of the bobber moulds for the wheels and hubs , they were fine. But metal is a new game, may need a centrifugal casting procedure. I cant abide kit supplied wheels with spoke flash and heavy detail!

Positive input relevant to the subject most welcome!

Thank you.

Edited March 4, 2016 by krow113

[Black Knight]

I think there just might be enough flexibility in the red silicone for a two part mould

[krow113]

Thanks , I'll hafta check the red rubber specs against the Smooth-On specs as that is what is available to me.

Here is the masters and mould for the bobber wheels they turned out to be workable. My first master and mould so be gentle...

[Black Knight]

There is no reason why you cant translate that into the heat proof red silicon rubber

[vontrips]

Thanks , I'll hafta check the red rubber specs against the Smooth-On specs as that is what is available to me.

Here is the masters and mould for the bobber wheels they turned out to be workable. My first master and mould so be gentle...

Rim should work OK with the big pour sprue like that. I'd be tempted to add extra runners out of each side of the rim (90 - 120 degrees from pour sprue). These will need to have a 90 degree bend to bring them back up to the surface either side of the pour sprue. This is sometimes essential as you're pouring hot metal very quickly into a small air filled void. The runners will act as vents to reduce pressure and aid material flow. Don't forget you'll need to grind away all this material as the moulten metal will run up the runners!

Heating the mould before pouring helps as the heat will be retained and airflow will increase and the material will stay moulten for longer.

Not sure about the hub. The design shown will give you trouble. At the least; you'll need a larger pour hole, which will be much larger than the spindle - again more hand finishing and grinding. I'd also suggest two more runners again, which will be a pain to remove as the best place is either side in the narrow middle section of the hub. I suggested two sides earlier given your supplied pics. It would work as open moulds in that instance because the backs were flat. These hubs in the later pics are swaged into the centre. If you can live without that hourglass shape my open mould suggestion would be perfect...pour into open mould and wipe with a straight edge - all you need to do is flat sand the backs and turn the centre from bar.

I also think you'd be wasting time and money looking at spin casting for this, especially if you're looking at small runs for yourself. It's generally used for making multiple castings at once, dependent on how many multiple masters will fit within the machine. Making multiple spin cast masters is an art itself. I'd stick with the basics first.

Edited March 5, 2016 by vontrips

[krow113]

Cool .That setup was with resin in mind. The flat bar was the top of the mold, so when I poured I was able to have lots of venting for the air displacement. I'll do the molds one at a time. And some like Harleys have the same hub and rim front and back , Protars Freccia Celeste is like that too. I wouldnt go out of house for the casting , quite capable of doing it.

Mostly was looking for the metallurgy side of the material

IE: -

Which alloy will polish up best.?

Which will render the most detail?

Suppliers has been dealt with so any info on the metal itself is needed.

Thank you.

[Black Knight]

I only have experience with my own mix and the Prince August metals.

They will all copy the detail you want.*

The metals with the greater amount of tin will polish up better I think. That would be the 5 Star, or the Model Metal

My mix is about 45 lead/45 tin/10 bismuth ~ too much lead for your use I think.

* I made a piece out of Sculpey clay. I left a bit of a finger print on part of it. The red silicon rubber copied even this, and the castings copied it too. When I was cleaning up the first castings I was wondering what these fine lines showing on them were. By back tracking I found out.

All the metals will shrink a bit, no worse than your resin, so just have plenty in the top pouring hole.

White metal is helped into the mould by its own weight. Put a much deeper pouring hole, so as it fills its weight will push the rest into the cavity.

That was one of my mistakes, not having a deep pouring hole, so I need to bounce that mould a bit as I pour.