Thread: Brass Cutting

Hi SamSlam. Welcome aboard.

I don't know much about CNC but do you have one in mind, if so what sort. Ie milling? More information would help. There are others that will advise re the CNC aspect.

Brass will tarnish on the surface but does not need any corrosion protection under normal conditions. A check on brass 260 with Google will give you a better idea.

Cheers

Dean

Sorry, I meant tarnish not corrode. I will ask my teacher next time I am at school as to the type for CNC.

Sam, brass will be expensive. Unless you need it for strength I would suggest considering an engineering plastic (Australia doesn't help as a location, but if you are in Adelaide, try speaking with some one like Dotmar plastics for example)
You can use a CNC machine if it has a rotational 4th axis but the important thing is the cutter shape/ profile. If you bought 2 involute cutters (one for the 50mm gear and one for the 100mm gear) that would be between $50 and $100. A bandsaw won't give you a precise enough cut for them to mesh well enough - you would have to do a lot of filing to get them even close to correct. You can make cutters yourself that will do the job, but that is more complexity for you again.
I may be jumping to conclusions here but it sounds like at this stage you haven't though/ researched much about gears. This is a university page but will give the basics (and a bit more) DANotes: Gears : Index of topics . Is this a central part of your project or just so that you can get a 2:1 ratio? If you just need a 2:1 ratio, you may be better off seeing if you can buy some gears - typically model shops have them for starters and there is bound to be something on ebay. The other alternative is to find someone to make them for you. Perhaps there is a local model engineering club with a member who can assist if you provide the material. However, you will need to specify more than diameter and thickness. Someone here may be able to help too, but again will need more information.

Michael

It all comes down to the type of equipment you have available to make them.

Brass is expensive and will harden with use, so it's quite durable.

So is machine grade aluminium, and it's relatively cheap and easy to machine.

I have a web blog on gearmaking that may give you some ideas:

Cut a lathe change gear

Involute gear cutters can be bought very very cheaply from CTC Tools.

Rob

The gears are mainly there for style tbh... These gears will be mounted on the exterior so you can actually see them in action.

I am making an alarm clock that rings a 5" brass bell using the two gears.

I used this gear generating program so I did not really have to learn too much how gears work and how to correctly design them from scratch. I planned on just printing out that template or plugging it into the CNC machine to cut the gears.

http://woodgears.ca/gear/


I am very sure the CNC machine doesn't not have a 4th axes I was just intending to cut the gear out following a path around the gear from birds eye view. I asked my teacher and he said the machine will not be able to cut the brass out anyway. Do you think I would be able to cut the gears out using the template and a band saw? What blade would be best if so? Small gear (Driver) will only have 3 of its 9 teeth so I shouldn't have to spend too much time getting them perfect. The way it will work is the little gear will rotate the big gear ~35 degrees winding up the bell then letting the big gear slip once there are no teeth on the little gear. This allows the bell to ring. The small gear then waits there until next time the bell is to be rung and rotates the opposite way back down. So I am only really using 3 or 4 of the teeth on the big gear also. So I only have to file down 6 or 7 teeth so they mesh correctly then the rest can just really be there for style.

Does this sound like a good plan?

Sorry - I thought that you were transmitting power or motion through the gears. Here when we talk gears we mean things with much finer teeth - a 50mm gear will typically have 24 or more teeth as a minimum. 9 teeth on a gear that size could not be cut using the methods we usually use.
Blade size your teacher should be able to advise you on but teeth that large can certainly can be done on a bandsaw.

Michael