barrelling machine for cleaning up castings

**Muggins2003** · 18-06-2015, 05:21 PM

Hi,

I have a tumbler that I have used a few times with steel shot and barrelbrite. However, I am unsure what different media I can use to clean up castings and in what order I should use them. I see green ceramic pyramids can be used with a cutting media but could do with advice as to the best way to clean up castings after emery to 1000 grit.

Thanks,

**Dennis** · 18-06-2015, 10:06 PM

I have not done this, but www.eurofindings.com list a range of ceramic cones and chips in order of grittiness:

Green cones with or without cutting powder. (the coarsest)
Red pyramid chips with cutting powder.
White ceramic pins with Barrelbrite.
Mixed shot with Barrelbrite. Their mixed shot is not stainless though and I would not recommend it except for economy.

Now using all this would be tedious, so you have to decide what you will leave out, given the quality of your castings and how many you will be finishing in the future.

If in doubt email them at info@eurofindings.com. You might well use different barrels for the different media you decide to use. Dennis.

**ajda** · 19-06-2015, 06:03 AM

I can't claim to have a lot of experience here, but have been getting good results from these media in a small rotary tumbler, though it does take time as Dennis says. I might use one or more of these in stages, depending on what I'm starting with and what finish I'm after:
1. green cutting cones + abrasive powder + barrelbrite - deburrs and cuts back surface leaving a matt finish - more or less aggressive depending on proportions of abrasive powder and barrelbrite used
2. grey ceramic pyramids + barrelbrite - a gentler process that leaves surfaces very smooth but slightly matt - I guess the white ceramic pins referred to by Dennis would be similar, possibly better at getting into nooks and crannies?
3. stainless steel mixed shot + barrelbrite - leaves a bright finish, but with the potential to cause very fine surface pitting. (This seems to depend on what mix of shot is used, the sharp ended pins perhaps responsible for that pitting effect - I'm currently experimenting with ways to prevent it by grinding the pins and/or altering the mix.)

I keep one barrel for shot only and another for the cones/pyramids, using both for silver only. I keep a third barrel for occasional use with copper.

Alan

**Dennis** · 19-06-2015, 10:11 AM

Originally Posted by ajda

Stainless steel mixed shot + barrelbrite - leaves a bright finish, but with the potential to cause very fine surface pitting. (This seems to depend on what mix of shot is used, the sharp ended pins perhaps responsible for that pitting effect - I'm currently experimenting with ways to prevent it by grinding the pins and/or altering the mix.) Alan

Yes Alan, you might have seen my thread of about three years ago, where I re-sorted my shot and ground the needles individually with abrasive wheels. Then I tumbled them with seaside pebbles overnight. It did not make a great deal of difference to the pitting effect. In retrospect the result might have been better if I had added abrasive medium then.

The problem is that unless your media can reach right into angles, you will get shading due to an incomplete polish. Perhaps you will discover the answer.

Some of our members have changed to magnetic polishers, which also use very thin needles and they swear the result is unpitted.
However this has raised the problem of needles clumping, due to magnetisation, so rendering them useless. Dennis.

**ShinyLauren** · 19-06-2015, 12:24 PM

A very timely post - I was about to ask something similar!

Since I got my magnetic polisher my barrel tumbler has hidden away, unloved, in a cupboard. I thought I might resurrect it and use it to prep castings, rather than doing them by hand.

Would the grey ceramic pyramids plus barrelbrite take the "skin" off castings, or would I need the green cutting cones/pyramids?

How long do you run the barrel for with the cutting cones?

I've been looking at this in Rio Grande: http://www.riogrande.com/Product/EVE.../339502?Pos=45 but it's pretty expensive.

I might try the cones first perhaps.

**Dennis** · 19-06-2015, 12:34 PM

We don't have the answer, Lauren, because in all this timed no one here has written about ceramic cones and abrasive powder. However there is no need to go abroad, as both Sutton tools and Eurofindings stock them. Dennis.

**ShinyLauren** · 19-06-2015, 02:37 PM

I did search the forum, but all I found were posts on steel shot. I'll just have to try them out and see how it goes then

I know you can get the cones and pyramids over here, but it's the silicone stuff that looks like the eveflex burrs that only seems to be sold by Rio.

**Tabby66** · 19-06-2015, 09:54 PM

I'm similar to you Lauren, my barrel tumbler is now under used. I have the green cones........is there a particular abrasive powder that folk would recommend?

Many thanks