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Need infos for working bronze or brass ? this week I try to work brass or bronze I don't know how to reconize i

Marc Moreau

Marc Moreau

Marc Moreau
this week I try to work brass or bronze I don't know if it is the same thing ? My question is how to do to get the write RPM ? What is the best coolant for this ? I was working with a 3/8 bit with small carbide. May be I should use high speed steel ? I find some info for aluminium 'steel ' stainless stell but nothing for brass. I work a lot on aluminium and this is very easy for me . Brass scare me for tapping or drilling. If you have a chart with RPM this will be good for me.
 
Marc Moreau said:
Feet / minute is this the RPM I never understand this ?
Click to expand...

Nope.... use the FPM value and tool dia. to enter the parameters at the bottom of page to calculate RPM.

I have found brass very sticky to drill, as in grab and stall my lathe. One trick is to stone the edge off your drill bit. I have no experience with bronze.
 
Brass & bronze are different alloys to one another & there are many sub-alloys within each family. So you probably need to be more specific. What makes them somewhat similar to each other is relatively high copper content, but altering secondary alloy types & percentage give them very unique properties. Generally the common brass & bronze alloys turn & mill quite nicely. What can cause grief is hole drilling & sometimes reaming. Yes, 'grabby' is the right word. What Craig is talking about is sometimes also called 'dubbing' which is changing the rake angle. Some people say to 'dullen' the drill but I disagree. Dull to me means rounded over, not sharp. Sharp is fine, actually desirable. What is required is the correct rake angle so tool doesn't dig in & feed on itself. Clickspring video describes this well.

Some material links. Brass & Bronze fall under the Copper alloys title
https://www.makeitfrom.com/

Bronze specific
https://www.advancebronze.com/alloy-charts.php
https://www.dura-barms.com/Products/Bronze/Wrought/C54400-Phosphor-Bronze

 
But what I try to understand dependind on the bit size do you work high or low RPM for steel usally is low RPM aluminium is high RPM or my best is to try different RPM I am planning to shave a part for my lathe attachement and would like to use a 3/4 bit. Should I try fast RPM first or slower ? Do you use coolant ?
 
Hi Marc,

Use the link that Craig provided in post #2.

Scroll down to “drilling & reaming”

Look by “bronze”

Enter the surface speed (feet/min) into the calculator and select drill size 3/4 (0.75)”. The result shows as 662 rpm for your drill. In your case, since you are using the lathe, turn your work piece at around 660 rpm and use the drill to make the hole.

Here is a screen shot of the website:

C5AD93AA-A675-4035-B037-AC229EB0EBAE.jpeg
 
The rpm & feed is always a good starting point to know. But specific to brass & bronze at 0.75" hole diameter, you are in the range of potential grabby surprise. Even opening a hole from say 0.50 to 0.75 ID. So if dubbing the drill edge is not appealing to you, or not practical in this case, consider a single point boring bar as an alternative.

I've found WD-40 helps high copper content alloys, but many alloys actually cut fine (or better) without. So kind of depends. Its not a surefire solution that solves the issue.
 
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