Thread: brass hardening

I wouldn't think you'd be able to get it harder than the steel in a knife.
Cheers,
Jim

Unless you want to go in for a very expensive preparation, then you won't be able to harden the brass beyond the hardness of steel.
Brass can have a Rockwell hardness in the range of 55 to 85 depending on the alloy mix and the tempering process. However, because of the expense the typical alloy sits at the lower end.

Obviously I don't know what sort of knife you are using but A2 steel has an average Rockwell hardness of 64 when it is air hardened.

You may be able to change your marking knife (or its blade) so that your square is less likely to be damaged.

I've never had this problem as I use steel bladed squares.

Eldanos

Using a marking knife is the best way to get an accurate line to work from, and if the knife is held coplanar to the edge of the square, and the blade of the square is straight then the knife will not cut into it. I would suggest you concentrate on your technique, & how you are holding the knife relative to the square.

Regards

Originally Posted by Eldanos of KDM

Hi everyone, I have a square that has a brass blade, and I was wondering if anyone knows if it can be hardened (at least along the edges) in any way.

Everytime I run a knife along it it shaves some off the brass, then every few months I have to file it straight and square again. The good news is the square is recalibratable, so I guess it could be removed for any process.

I am incredibly happy with the square in every other way and it has exceeded every other one of my expectations, so I am wanting to avoid the name of the maker because it is a product of the highest quality, and maybe I just shouldn't be using a knife with it...

Any info would be very cool indeed, Cheers

Hi Eldanos,

The only way to harden the brass is work-hardening, and it's a bilt to late for that.

Brass tools are usually made so they're sacrificial when used with steel, but I'm telling you something that you already know.

Cheers,

eddie

Thanks everyone for the ideas, methinks I may have to save this square for use with an awl or a pencil, or I may have to get a copper knife

Originally Posted by Basilg

Eldanos

Using a marking knife is the best way to get an accurate line to work from, and if the knife is held coplanar to the edge of the square, and the blade of the square is straight then the knife will not cut into it. I would suggest you concentrate on your technique, & how you are holding the knife relative to the square.

Regards

Sounds like advice from someone that doesn't use avery soft brass square coupled with a knife with super crisp file-hard edges.
I'm very well aware of the features and functions of, and how to use a marking knife.

Eldanos -there aren't many types of adjustable trysquare with brass blades about, so I'm assuming it's the same brand as my favourite trysquare. They've been around for quite a while now, and I've had mine for at least 12 years or more. It's had a lot of use, and so far my blade has remained perfectly straight (and I check it fairly regularly). I must say I was a bit worried about the durability of the brass blade myself, when I first got it, but I haven't encountered any real problems, & certainly not to the extent of shaving bits off it with a marking knife. I use knives a lot, too.

Brass is a 'self-lubricating' metal - you can machine it without needing any cutting fluid, for example. Recently, I made a large square based on the same design, but with a spring-steel blade instead of brass. I know the hardness of the blade in this case is R55, which is what Horaldic says is the bottom of the range for brass (are you sure of those figures, H.??). The stee blade is certainly much harder & tougher than my brass blade, but I can report that it does seem to 'bind' a bit more than the brass when a knife is run along it. Time will tell what it wears like.

Maybe Basiq was a bit blunt with his advice, but it may be you are twisting your knife blade a bit, or perhaps it has a bit of a burr on the flat side?? There are a lot of CC squares in use, and yours is the first post describing this problem, but perhaps it is happening to others, who may come forward, now.....

Cheers,

Eldanos

Originally Posted by Eldanos of KDM

Sounds like advice from someone that doesn't use avery soft brass square coupled with a knife with super crisp file-hard edges.
I'm very well aware of the features and functions of, and how to use a marking knife.

With the exception of two Japanese marking knives, all my other other knives are HSS, one is a Chris Vesper and the others are made by myself. All these I would be confident in saying are capable of cutting brass, and some have been used occasionally for marking out brass when I have made tools. Early in my career in the 1960's I used HSS cutters in lathes, Milling Machines etc. as well as hand tools such as hacksaws and files. All of which cut brass without problem.

My marking knives are sharpened to 8000 grit waterstone then honed with Chrome polish on a hard surface to avoid dubbing the edge.

I have two Colin Clenton squares & two Bridge City squares all with brass blades & I don't have any problems with my knives cutting into the brass blades when using them. The Bridge City squares I have used for around twenty five years. Those from Colin I bought about the time he started producing. I would have no hesitation in buying other tools from Colin should the need arise, as I am very appreciative of the quality he delivers. I have not heard of anyone having problems such as you describe with Colin's squares, which does not necessarily mean there is no-one. However If you are using one of his squares and your certain that is the cause of your difficulty, I would be confident that Colin would prefer you spoke to him directly.

Originally Posted by Horaldic

Unless you want to go in for a very expensive preparation, then you won't be able to harden the brass beyond the hardness of steel.
Brass can have a Rockwell hardness in the range of 55 to 85 depending on the alloy mix and the tempering process. However, because of the expense the typical alloy sits at the lower end.

Obviously I don't know what sort of knife you are using but A2 steel has an average Rockwell hardness of 64 when it is air hardened.

You may be able to change your marking knife (or its blade) so that your square is less likely to be damaged.

I've never had this problem as I use steel bladed squares.

Worth a look at this chart
260 Brass is listed on my chart as 78 Rockwell F. The "F" is VERY important. It is for softer material. Another of the Rockwell scales is used for steels.
For instance Rockwell F 78 = 90 Vickers Hardness.
Tool steel at Rockwell C 60 = 665 Vickers Hardness.
Regards,
Peter...who occasional will loose concentration and cut the steel square or rule with the knife... WOOPS!

Originally Posted by Basilg

Eldanos

However If you are using one of his squares and your certain that is the cause of your difficulty, I would be confident that Colin would prefer you spoke to him directly.

Calling the shop I bought the square from was the first thing I did when I first noticed my problem about 9 months ago and was told no-one had ever called with a similar problem. So... That's why I named this thread "Brass Hardening" and not "I think this particular product is faulty"

Notice how, in my first post and in this one, the good sense and sensitivity I have shown in not blaming the square itself, and not naming the maker? My goodness, the only reason I even mentioned the square is re-calibratable is because it might have been important that it could be removed for any hardening process.
----------------------------------------------------------------------------------------------------------------------------

Well I have been back to the workshop and have cleaned up the back of my knife, which could possibly have been a little burred, good suggestion Ian and well, maybe shaving bits off my square wasn't the best way of putting it, sounds a bit more violent than it is.. I also think I may have cut my knife in a less than favourable design; (I have no Idea about metalwork and didn't think about it at all) th edges are really steep and do pull into the square, and there is only about 3mm of blade back contacting the square. I'll make a slightly wider one, less obtuse at the bottom, so that there's a longer edge contacting the square's blade today and reckon I might sort out half the problem with that.

I will be more diligent and concentrate more on my method though; for what it's worth.


I am now incredibly sorry I posted this thread, and didn't mean for it to get silly.
Cheers.

Originally Posted by Eldanos of KDM

......
I am now incredibly sorry I posted this thread, and didn't mean for it to get silly.

Eldanos - I don't think you ought to feel silly or chastised - most replies have been in the spirit of trying to help, though some may have been a little direct. Anything that provokes a bit of civilised discussion can't do any harm, and others could benefit from it. I think you may have just hit the nail on the head with your last observation. I forgot til you mentioned it, that the angle of the knife bevel can certainly change the way the knife tracks. The first knife I made with a double bevel for left or right side marking didn't track too well until I made the point a bit longer. That's a good point, so to speak.

The knife you show might also have some bearing on the matter - it looks like it has a much longer blade than any I use. I don't know for sure, because I haven't tried to use one like that, but it seems to me it would have a bit less 'feel' for where the tip is & where it's going than with a shorter blade? I prefer a striking knife with a pencil-sized handle & a quite short blade (~25-30mm), held like you would hold a pencil.

Cheers,

Eldanos

If you are only getting 3mm registration between your square and the knife I would say that is where your problem lies. I also find that marking knives with a spear point are not as easy to control.

I have attached a photo showing two knives. The top knife has a single bevel at ~45 degrees which provides a registration of 10mm or so & gives very good control. I purchased a length of HSS which I think was around 2mm X 10mm x150mm cut this in half & ground a bevel. Then fit this into a piece of Rosewood and shaped to my fingers to provide a firm and comfortable hold.

The bottom Knife uses a spent piece of hacksaw blade & is therefore only around 1mm or so thick. I made this specifically for marking dovetails where the pins are very fine and a normal marking knife is too thick. In this case the spearpoint works fine as it has plenty of registration.

I find these knives much better balance & therefore easier to use than a knife with a chisel like handle, & they can also be used for paring in restricted spaces.

Regards

Originally Posted by IanW

I know the hardness of the blade in this case is R55, which is what Horaldic says is the bottom of the range for brass (are you sure of those figures, H.??).

I actually quickly looked it up before making my original post to double check. I did a little bit of Metallurgy in the early '90s my text book is an old McGraw Hill publication, well out of print now I'd suspect. My original post was in the "long and boring" category so I cut it down. Let me fill in a little detail.

Your HRC55 blade will be harder than the HRB55 copper. It's difficult to directly compare commercially available brass and steel because of differing measures of hardnesses, however, the bottom end of steel and the top end of brass do overlap in absolute terms. Manufacturers like to compare the same type of alloy within the same hardness category. So Brass will usually be sold using the HRB classification and steel the HRC classification.

The point I was seeking to make in my original post was that you can obtain a range of brasses in different hardnesses the top end of which is harder than some steels. However, to use the high end brass is pointless as that same alloy would be very expensive and difficult to work, negating some of the benefits of working with brass in the first place. Quality tool steels will be harder than the higher end brasses.

Doing a search of "brass and hardness" on the web yields this you can look through and see the differing specifications on some brasses; it gives you a bit of an idea of the range.

If folks are interested in the various differences in hardness scales (as touched on by lightwood) you can see a translation of the various scales here and here.

A quick translation is that Rockwell F is only one of the scales in common commercial use. There are several scales applied; from Rockwell A through to Rockwell V. Rockwell A is determined with a pointy Diamond being pushed into the material while Rockwell V is determined with a 1/2" steel ball being pushed into the material. Rockwell C is commonly used on tool steels (pushing a rounded conical diamond in) while Rockwell F is used on sheet material; trying to push a 1/16" steel ball in. All these data are commonly aggregated to allow sales and distribution people to work with the materials. In this context HRB is used for the copper alloys and softer steels while HRC is used for Tool Steels.

I don't want to mislead folks. To make it clear, you are very unlikely to come across a brass harder than a steel.

Well, let's just say my confusion is slightly un-confused. So we wern't talking about the same Rockwell hardness scales. I can go back to believing the brass blade of my square is considerably softer than my spring-steel striking knife blade.

Cheers,

Horaldic

Thanks for the information.
I did some Metallurgy about 30 years prior to yours, as part of my engineering studies. I must confess it was not my favourite topic, and it tends to make my head hurt more now than it did then. Like Ian I am more interested in what cuts what, & how well it does so.

thanks again