Thread: Help selecting mill bit

Hi,

I'm helping a mate with his model railway. I need to mill quite a bit of brass (hoarded by my mate over the years) to build his loco shed. But never mind the details.

The brass ranges from 20mm x 5mm bar and lesser. The idea is to cut scale girders from these bars.

My little mill I only ever use for precision drilling. So my question is, would this be a suitable bit to buy for the purpose of both facing and depth cutting.

https://www.endmill.com.au/3-flute-u...r-soft-metals/

Thanks in advance.

Greg

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Probably be okay, you haven't mentioned much about the type of machining you will be doing, HSS slot drill or HSS end mill may suit your task as well, depending on what you are doing will generally govern the type of cutter, you may also want to consider if you will need any long series cutters.

Thanks for the answer,

The idea is to cut the brass bar into I-beams and trusses. At the moment the 3 on the left are (scaled up 160x) 1.6m wide and 0.48m thick. They have to be thinned and diamond or circle patterns cut through their vertical sections.

Basically they have to be thinned down and resemble a truss


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So if you could recommend, then i'm listening

For the I beams carbide slot and end mills are probably a better choice as they are pretty cheap on aliexpress and you will get a better run out of them than the carbon end mills. https://www.aliexpress.com/wholesale...list.1000002.0

For the trusses i would see about getting them done with water jet, if you are going to try to machine all those thin webs you are gunna be taking tiny cuts trying not to bend them away from the cutter, you would need a lot of time and swear words and then finish all the corners with maybe a triangle file depending on what angle you choose and more swear words.

Originally Posted by shedhappens

For the I beams carbide slot and end mills are probably a better choice as they are pretty cheap on aliexpress and you will get a better run out of them than the carbon end mills. https://www.aliexpress.com/wholesale...list.1000002.0

Thanx for this one.

Originally Posted by shedhappens

For the trusses i would see about getting them done with water jet, if you are going to try to machine all those thin webs you are gunna be taking tiny cuts trying not to bend them away from the cutter, you would need a lot of time and swear words and then finish all the corners with maybe a triangle file depending on what angle you choose and more swear words.

For this type we were just going to cut away as much swarf as possible and then finish with triangle files. Brass is easy to file. So I could just use a drill to cut the biggest circle allowed and then file. But it would be handy to slot sideways as well. All the time keeping the bar at max thickness, and only surface thin it after the cuts. Would that work?

Originally Posted by Mutawintji

For this type we were just going to cut away as much swarf as possible and then finish with triangle files. Brass is easy to file. So I could just use a drill to cut the biggest circle allowed and then file. But it would be handy to slot sideways as well. All the time keeping the bar at max thickness, and only surface thin it after the cuts. Would that work?

Yeah that will work, do 10 or so test triangles and that will give you an accurate idea of how much beer you are going to drink while filing

I have to ask what the rest of the model train world does?

Surely they're not all machining sections up?

You could also try using a scroll saw to cut out your triangles.
Kryn

I’d be looking at punching them. Depending on the size you may be able to get a relatively cheap triangle jewellery making punch off the shelf.

Originally Posted by shedhappens

For the trusses I would see about getting them done with water jet, if you are going to try to machine all those thin webs you are gunna be taking tiny cuts trying not to bend them away from the cutter, you would need a lot of time and swear words and then finish all the corners with maybe a triangle file depending on what angle you choose and more swear words.

Hi Mutawintji,

Yes this the way I would go as well ! A sheet of 0.5 mm hard brass big enough for you to get all your parts out of. Using water jet, or Laser for that matter would mean that all your parts would be Identical and uniform in size. You would have to supply a DXF file with a drawing of your parts.

Originally Posted by Mutawintji

At the moment the 3 on the left are (scaled up 160x) 1.6m wide and 0.48m thick.

I assume you mean 1.6cm x 0.48cm?
I.e. 16mm x 4.8mm
I.e. ⅝" x 3/16"

It would be a lot easier to buy pre-made brass trusses. And probably cheaper than paying someone to water jet or laser cut them for you. These are 7.5mm tall. Two of them would give you 15mm, which is close to your 16mm:

https://modelshop.co.uk/Shop/Strip-S...engths/ITM1922

Originally Posted by shedhappens

Yeah that will work, do 10 or so test triangles and that will give you an accurate idea of how much beer you are going to drink while filing

Bwahahaaaaaaa 🙃

Originally Posted by browny

I have to ask what the rest of the model train world does?

Surely they're not all machining sections up?

They're all nutters. They scratch build everything from brass. Some sorta railway disease they've all got

Originally Posted by jack620

I assume you mean 1.6cm x 0.48cm?
I.e. 16mm x 4.8mm
I.e. ⅝" x 3/16"

It would be a lot easier to buy pre-made brass trusses. And probably cheaper than paying someone to water jet or laser cut them for you. These are 7.5mm tall. Two of them would give you 15mm, which is close to your 16mm:

https://modelshop.co.uk/Shop/Strip-S...engths/ITM1922

Wow ... I'll show them to my mate. Thanx for this one

In n-gauge it's 1:160. So the brass rods in the photo are 3mm wide x 10mm (0.48m x 1.6m in real life) It's not that hard to work with brass.

I was buying a few drill bits at Equipment Sales, Kingaroy. When I spied this on the shelf, they appeared to be the only mill bits in the whole place. Dirty, dusty, musta been sitting there for years.

Can anyone recommend the best speed for brass for the 4 mill bit?

Greg

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