Brass machining advice

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martin54
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Brass machining advice

Post by martin54 »

Been asked for a quote for some brass rubbings, these would be roughly 100mm (4") square with woodland animal rubbings. Having looked about in the UK there are a couple of specialist companies that cast these & they seem to be just an outline (like a line drawing) so I think I could produce these on the CNC.
It's for a nature trail so needs to be something with good corrosion resistance, Brass like aluminium comes in lots of different grades so looking for the best overall option for machinability & exterior durability :lol: :lol:
I know CZ121 is probably the best option from a machining point of view but there might be something else that machines well but is a better option for external use :lol: :lol:

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Re: Brass machining advice

Post by Leo »

CZ121 is a european standard I believe

In the US Alloy 360 is a good machinable brass alloy
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Re: Brass machining advice

Post by martin54 »

I believe you are correct Leo, funny thing is if I contact a supplier for prices they quote imperial sizes lol :lol: :lol:

Phoned a few places that stock brass & no one could fully answer my questions, some of these were big companies so I would expect them to have a degree of expertise about the products they were selling or is that just me?? :lol: :lol: :lol:

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Re: Brass machining advice

Post by phill05 »

Martin,

I used to use CZ120 half hard brass and put a clearcote on to help keep clean.

You could also use Portland stone stands the weather very well, easy to cut on the cnc and better still not on the list of scrap metals to pinch.

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Re: Brass machining advice

Post by martin54 »

Phill, I thought about using something other than brass but most things I thought of either wouldn't stand up over time or wouldn't machine well :lol:
Stone was not one of them, these will be for brass rubbing, do you think the Portland stone will stand up to that? Do you take any special precausions when machining it?

Customer who is actually the Landlord for my Industrial unit asked if I would be able to do them in wood to keep the cost down but she wants them to last for a lot of years :lol: :lol:

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Re: Brass machining advice

Post by phill05 »

martin54 wrote: Stone was not one of them, these will be for brass rubbing, do you think the Portland stone will stand up to that? Do you take any special precausions when machining it?

Customer who is actually the Landlord for my Industrial unit asked if I would be able to do them in wood to keep the cost down but she wants them to last for a lot of years :lol: :lol:
Martin, Not sure what you have to do for "brass rubbing" to get it onto the the plaque? if it was cutting an outline vector into the stone then no problems you can even cut 2 1/2 D but this needs flooding water and takes longer, using a carbide V cutter and spray some water onto it.

Stone blanks could be cut to shapes of different woodland animals if needed or left square and no protection of the stone needed when finished and it will last many years no matter what the weather.
I could even put you in touch with a company that could give you a price for the Portland cut blanks.

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Re: Brass machining advice

Post by Leo »

I have cut marble with a carbide v cutter. Works OK but it does wear the cutter quickly, fortunalely the cutter does not need to stay razor sharp.

Corian is a VERY durable material and cuts very nicely. Corian is basically a very hard plastic

PVC cuts easily and stands up to weather

HDU cuts REALLY easily paints well and is a best choice

EXTIRA - not Medex - is rated as an exterior grade of MDF. I have had EXTIRA - on outside signs for 4 or so years and showing no signs of deterioration at all.

For Brass - did you try a scrap metal bone yard?
Brass can be bought on Amazon as well.
I just bought some Brass from Amazon and their price was not bad.
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Re: Brass machining advice

Post by Leo »

martin54 wrote:I believe you are correct Leo, funny thing is if I contact a supplier for prices they quote imperial sizes lol :lol: :lol:

Phoned a few places that stock brass & no one could fully answer my questions, some of these were big companies so I would expect them to have a degree of expertise about the products they were selling or is that just me?? :lol: :lol: :lol:
I find with companies, especially big ones, is that those that you "call" are sales or customer support people that may have been dog trainers last week. They don't know, but they will not tell you that they don't know.

If you want technical answers you need to talk to technical people - engineers - to get correct technical answers.

So - NO - it does not surprise me at all.
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Re: Brass machining advice

Post by Rcnewcomb »

CZ120 Brass is also available on ebay.co.uk
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Re: Brass machining advice

Post by martin54 »

Thanks for the replies people, Phill message me details of a supplier please, I am not going to use Portland Stone for this job as I would like to test it first & don't have the time to do that now :lol:

Leo, I looked at other materials & if it was just visual then I wouldn't have a problem using some of the other materials you have suggested but I don't think any of them will stand up to the rubbings in the same way brass will. Yes tried a couple of local crap metal places, none of them had any idea about what grade they had & wouldn't sell me a small bit to test but more importantly none of them had it in the thickness that I eed for this job

Randall, to be honest I hadn't thought to look on ebay, will have a look to see whats available but I may well get it cheaper at a trade price from a Metals supply company :lol: :lol:

Found a supplier of cz121 today with a reasonable price so can base a quote around that & if I get the job & find it cheaper elsewhere then all the better for me lol I was looking for a price for sheet material based on the total number of squares so was looking for a bit roughly 550mm x 350mm & not having a lot of joy. Company I spoke with today said I would have more luck with flat bar & since these are to be 100mm square I got a price for 4" wide flat bar, just a much longer length :lol: :lol:

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Re: Brass machining advice

Post by Ms Wolffie »

Hiya Martin.
What is “Brass Rubbing”?
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Re: Brass machining advice

Post by ozymax »

I can answer that, because it brings back some fantastic memories of my childhood.
Back in the late 60's my family lived in the UK for about 3 years. One of our favorite past times was to visit various churches in the district and do brass rubbings. Under floor mats in these churches laid very ornate brass plaques that signified the resting places of various knights or royalty etc. It was my job as a kid to seek out nice brasses to rub.
We'd lay down a sheet of tracing paper over the brass and using large black or gold crayons, we'd rub away until the image was completed.
Have you ever laid a piece of paper over a coin and rubbed a pencil across it to reviel the image. Well, that's basically the same thing.
I have a 2m+ high rubbing of Robert De Bures in our living room. He's looking at me whilst I type this.
http://www.themcs.org/churches/Acton%20 ... aints.html
Sadly I feel this practice of rubbing the brasses has now halted due to the wear on the brasses.

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Re: Brass machining advice

Post by martin54 »

Well I did some experimenting once the piece of cz121 brass I ordered arrived, think I was initially way out with my speed & feed settings, plus I didn't have a small enough end mill for some of the detail so I used a ball nose for some of it, apart from the fact that I didn't set my z zero that accurately it didn't go to badly, slowly increased my setttings but I think I am still far to conservative, for some reason I seem to be a bit short o small endmills at the moment so didn't want to go breaking the one 3mm bit I had lol, some new ones arrived today so I can try ramping things up a bit :lol: :lol:
Once cut it got a couple of coats of etch primer followed by a few coats of rattle can enamel, filed the high spots when dry to get the brass colour back where it was wanted. Still needs a final clean up :lol: :lol:
brass finish.jpg

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Re: Brass machining advice

Post by scottp55 »

Lookin' GOOD Martin! :)
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Re: Brass machining advice

Post by mtylerfl »

Looks like fun, Martin!

I’m curious what the depth of cut is around the raised areas. I imagine it’s just a small amount needed for the rubbings to come out alright, yes?
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