Author Topic: Resin Casting, a favour  (Read 537 times)

Offline Joules

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Resin Casting, a favour
« on: May 17, 2018, 01:16:41 PM »
I have just completed a pair of MORRIS badges for a friend.  He is restoring a 1930's Morris, the badge for the grill cost a tidy sum and really too valuable to risk on the open road.  I said I would have a go casting some replicas for road use and the original can be used for shows and judging.   First job clean up the badge and mount it, in this case on some adhesive tape to seal the rear as they seem to be stamped from brass sheet.  I will be making the mould from a material called Gelflex, it's a reusable moulding material made from Vinyl.  My mould used some waste steel banding fixed with masking tape and weighed down to form the dam for the Gelflex, the stuff is poured at around 160℃ so this does some what limit it's use to items that can stand the temperature.  I managed to burn this batch hence the dark spots in the rubber, it will still work, just throw it away when done rather than remelt, and take more care next time.

Once the rubber has set remove the dam and flip the mould over.  The masking tape did its job of keeping the rubber out of the back of the badge, it's then a fairly simple job of teasing out the original.  Gelflex is self releasing and will pick up very small details and defects.  The resin I am using is a polyurethane two part, my first time with this, it's very fluid when mixed and easy to pour but you only have about 7 mins working time including mixing.  The first one I overestimated the amount needed and it over filled the mould slightly, the next pour I got the volume spot on.

The cure time is very quick, but best to leave them on a flat surface once removed from the mould to cure overnight.  Once that was done I could clean up the edges with a scalpel and clean off any residue from the Gelflex using isopropyl alcohol.  Next, outside and spray them...  OK the original is brass, the only spray I had was chrome, I figure if the paint works I can use a yellowish lacquer to seal them and give a slight chrome colour to them.  The results are OK, I could have done a better job cleaning up the castings and maybe mix up some more resin to fill small pin holes, but again, these badges are for rally use not showing.   The whole process was easy with the great benefit of the polyurethane resin having virtually no odour.  I will be using this stuff more often for short runs of plastic parts and even light duty gears as I can make the masters in aluminium.  Hope this is useful information for someone.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline John Rudd

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Re: Resin Casting, a favour
« Reply #1 on: May 17, 2018, 01:28:36 PM »
Nice job Joules.. :thumbup:

Where'd you get your resin from?
eccentric millionaire financed by 'er indoors
Location:  Backworth Newcastle

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Offline Joules

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Re: Resin Casting, a favour
« Reply #2 on: May 17, 2018, 01:35:22 PM »
John, I got it from an outfit in Sheffield.

http://www.mouldcraft.co.uk/shop/4572905647/mouldcraft-a3000-black-fast-cast-polyurethane-liquid-plastic-casting-resin-kit/9474394

Really like this stuff and it seems strong, be great for plastic model parts, trains and boats.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline efrench

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Re: Resin Casting, a favour
« Reply #3 on: May 17, 2018, 08:13:04 PM »
How about plating them.  I don't think you can electroplate brass, but gold would look nice  :headbang:

Offline Joules

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Re: Resin Casting, a favour
« Reply #4 on: May 18, 2018, 06:42:42 AM »
The resin people do metal powders you can add to the resin and then buff up for a true metal look.  The paint I used on the badges hasn't set, looks like it's not compatible with the resin.  Maybe try a primer next time.

As it turned out the paint on this badge set enough to do a test fit on the grill.  I think the chrome plate idea would actually compliment the rest of the radiator.
« Last Edit: May 18, 2018, 07:28:35 AM by Joules »
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline ddmckee54

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Re: Resin Casting, a favour
« Reply #5 on: June 06, 2018, 03:14:53 PM »
What about vacuum plating with aluminum like is done with model car parts to simulate chrome plating?   Or aluminium since you're on the other side of the pond.  It isn't as durable as chrome or nickel plating, but then again plastic isn't as durable as brass either.  Plus it has the advantage of being easy to strip and re-coat.

Just a quick Google search came up with a couple of outfits on my side of the pond that do custom work, I'm sure there are some on your side too.

Don
Too many irons, not enough fire.