# 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 (Oct 15, 2021)

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.


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## YYCHM (Oct 15, 2021)

https://littlemachineshop.com/Reference/CuttingSpeeds.php


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## Marc Moreau (Oct 15, 2021)

Feet  / minute is this the RPM  I never understand this ?


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## YYCHM (Oct 15, 2021)

Marc Moreau said:


> Feet  / minute is this the RPM  I never understand this ?



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.


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## PeterT (Oct 15, 2021)

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


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## Marc Moreau (Oct 16, 2021)

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 ?


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## RobinHood (Oct 16, 2021)

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:


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## PeterT (Oct 16, 2021)

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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## Marc Moreau (Oct 16, 2021)

Thank you very much I will try this  I have to find the way to calculate ?


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## YYCHM (Oct 16, 2021)

Marc Moreau said:


> Thank you very much I will try this  I have to find the way to calculate ?



Calculate what?  It's all here for you https://littlemachineshop.com/Reference/CuttingSpeeds.php


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## Marc Moreau (Oct 16, 2021)

Ho nice  I tought  this was only a page  but it work .  Thank you I will be fine.


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