Slotting brass

Matt_50 · Nov 22, 2020

My first thread is about bending brass, and I think because of your help I now have a good idea what I'm looking at to make a shop press fold brass. What to buy, make, costs, ect... plus there is the need to anneal. I think this option costs less and it is traditional for saw backs.

There is a 2nd option I'm curious about. Cutting a slot in a brass bar. Up to 12 inches long in a roughly 3/4 by 1/2 inch bar.

Folded is more traditional but slotted works and looks good. The downside is the need for a mill.

If I save a little more money I could buy a small mill but are mini mills capable of what I'm wanting? For folded I chose 260 brass because it is easier to work with. I'm assuming I wouldn't need to be as picky here?

For a .020 saw plate, I would need a .020 slot.

Shop press experience is limited to automotive bearings. Mill experience is zero so again I will need a little guidance to understand if this 2nd option is an affordable option.

So basically, can a mini mill handle this nicely and accurately? And if yes, which mills should I look at?

Peter from Holland · Nov 23, 2020

How deep ?
On a mill you should use a slitting saw And that needs a stable machine
If on a tight budget a shaper perhaps instead of a mill Although 0.02'' is narrow
I would limit the stroke of the clapperbox to a minimum so the tool stays in the slot

Peter

Limy Sami · Nov 23, 2020

The depth is going to be everything on this job ???

DDoug · Nov 23, 2020

Limy Sami said:
The depth is going to be everything on this job ???

Angle grinder with cut off wheel should doo just fine.....:d

Limy Sami · Nov 23, 2020

digger doug said:
Angle grinder with cut off wheel should doo just fine.....:d

Right, .......tell ya what, best get some samples up to inspection first - you know what the paperwork's like these days.

DDoug · Nov 23, 2020

Limy Sami said:
Right, .......tell ya what, best get some samples up to inspection first - you know what the paperwork's like these days.

No, see I have friends with milling machines...…

Let's let the OP use the cut off wheel eh ?

How many people defended using such tools in Jason's thread ?

Isaac S · Nov 23, 2020

I used to use a Bridgeport to do this, but then built a milling attachment for an old South Bend lathe to do them on. It's driven by a motor mounted behind it. The milling table is mounted on a spare cross slide table so I can remove it when it's not being used.

Here's some of what I've learned from doing this. With thinner blades you'll need to use multiple passes, about 0.10" at a time. The arbor is really critical - I tried a few of the cheap slitting saw arbors before realizing I could do better and started turning my own. If the blade doesn't run dead true, you'll never have success doing this. The blade should protrude from the arbor by just a bit more than the depth of the slot.

HSS and carbide blades can both work well, but carbide definitely elicit a stronger response when they meet a violent and early end. I stick with HSS now. I use something like a 2-1/4" blade with 60 teeth. The teeth need to be sharp, or the cut will start to drift. Fine teeth don't clear nearly as well as the larger teeth. I run them dry, but sometimes they benefit from a bit of wax on the blade to keep chips from sticking to the sides. You'll have to experiment with blade and feed speed as each blade seems to have slightly different harmonics.

mTeryk · Nov 23, 2020

I didn't read your other thread but here are some thoughts on this. It sounds like you are making the backs of dovetail saws or the like. I'm assuming the slot needs to be at least 3/16" deep.

Milling it will be more precise than bending but it is going to take awhile. I'm not sure how many you need to make but I can't imagine doing a large number this way unless you really need the precision.

If you do want to mill it. I'd suggest getting a small horizontal mill such as a Nichols or the like. They can sometimes be found cheap and will give the blade enough support to keep it aligned and cutting straight.

Teryk

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Matt_50 · Nov 23, 2020

The slot would need to be .30 deep. Do those mini mills have the support and accuracy to run a slot .3 deep and 12 inches long?

Limy Sami · Nov 23, 2020

YIKES! that's a depth of 15X width.

IMHO A 20thou EM will take forever over 12'' so that's out, ........ To get a straight slot, your best bet ** would be a 0.020'' coarse tooth (for the gullet capacity) carbide slitting saw on a horizontal, with a a special fixture.

I say best bet because the process will take a lot of refining, and will depend highly on the quality of slitting saw you use (and the gooduns are NOT cheap) etc etc

I'd say stick with your original folding idea, ....much easier to refine and fine tune.

Strostkovy · Nov 23, 2020

Definitely need a slitting saw, and no, a minimill won't do it.

Matt_50 · Nov 23, 2020

Limy, I was pretty sure you guys would say a good (expensive)horizontal mill would be needed for this. I was hoping this might be fairly simple job but thats why I asked for your opinions.

Strostkovy · Nov 23, 2020

A slitting jig on a linear rail might work, but I'm not sure of the power/rpm requirements of a slitting saw.

I have used a slitting saw in a die grinder and it was... interesting to say the least.

fciron · Nov 23, 2020

Horizontal mills are considered somewhat old fashioned, so they're not necessarily expensive. The drawback is that a decent running machine can be hard to find, especially in the smaller sizes.

L Vanice · Nov 23, 2020

A thin circular saw blade for metal is often called a jeweler's saw, which gives you a search term if shopping for one. These are different from horizontal milling cutters.

Sawing brass is a lot like sawing wood, to the point that a woodworking saw can saw brass at the same RPM as it saws wood.

There is a cool old saw that was made for precise cuts in metal called a Hammond Trim-O-Saw. It is able to saw wood and is well known for specialized wood projects.
FS Hammond Trim-O-Saw

Larry

boslab · Nov 23, 2020

Did a job for a firm making terminal bars from brass, the things with grub screws, anyway they were slotting brass on a little horizontal mill, lever op machine, think 25 thou, it fair zipped through, however the guy said that an undersized cutter was better mainly because of wobble in the arbour ( can’t argue, never seen a straight one yet), he started the firm in his shed, he said he was slitting bars on a table saw, feeding the bars into a tunnel guide bar pushing bar, I beleive he changed the drive pulley to get the surface feed for a 6” slitting saw, good bit the swarf dropped away so not to jamb up in the cut
Mark

Peter from Holland · Nov 24, 2020

Or you could assemble it out of 2 pieces and soft solder it
The soft solder with some silver in it is pretty strong

Peter

Limy Sami · Nov 24, 2020

L Vanice said:
A thin circular saw blade for metal is often called a jeweler's saw, which gives you a search term if shopping for one. These are different from horizontal milling cutters.

Sawing brass is a lot like sawing wood, to the point that a woodworking saw can saw brass at the same RPM as it saws wood.

There is a cool old saw that was made for precise cuts in metal called a Hammond Trim-O-Saw. It is able to saw wood and is well known for specialized wood projects.
FS Hammond Trim-O-Saw

Larry

I've used one of those Larry - or the British version?? and they're as sweet as can be, ............never managed to find one for myself

mTeryk · Nov 24, 2020

Matt_50 said:
The slot would need to be .30 deep. Do those mini mills have the support and accuracy to run a slot .3 deep and 12 inches long?

A Nichols isn't really a mini mill. It's a small horizontal designed specifically for slotting. It could cut that slot as well as a larger horizontal except for the length. Believe most Nichols came with 9 or 10 inches of travel.

Teryk

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richard newman · Nov 24, 2020

L Vanice said:
There is a cool old saw that was made for precise cuts in metal called a Hammond Trim-O-Saw. It is able to saw wood and is well known for specialized wood projects.
FS Hammond Trim-O-Saw

Larry

I have a Hammond, its one of my favorite machines! They were originally made for trimming lead type and plates, used to be rows of them at newspaper & printing plants. Very heavy, with a really precise sliding table. They take a 7" blade that is held by a few screws around a stub arbor, but I remade mine with a 5/8" arbor and cut some cast iron away to take a stock 8" woodworking blade, also upped the speed. You could certainly fixture the sliding table to hold your brass and slot with a saw. Might also consider using a luthiers fret slotting blade, made in .023" and I think .020" width. Much coarser teeth, might be better for clearing chips at that speed?

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