A couple suggestions, first, as long as your reed shoes do not include your sheet edges, you can save yourself of creating a perfectly square sheet. Your locating pins are all you need and if you can touch off them, as long as the sheet is touching them, you’re good. Your tool path doesn’t care what the sheet looks like as long as it is somewhere inside it. Accuracy is great where you need it, but costs you time and labor where you don’t. Second, I used to use .093 C353 engravers brass and like you found it no longer available. I used .063” for everything C3 and above, and only used the .093 for clamp blocks. When I was still punching out reed shoes instead of milling them out, I used the C510 Phosphor bronze in spring temper and it worked very well. When I couldn’t get the 353 brass in the right size any more, It is free machining like the 353 brass, but has sulphur instead of lead to accomplish that characteristic so it is safer as well. I bought a sheet of the p bronze for clamp blocks. I had no trouble drilling my sheets of clamp blocks with a 1/16 clearance drill ( 800 holes / sheet ) plunge 10 ipm at 20000 rpm with a light coat of cutting oil spread on the sheet because I didn’t want to deal with the mess of flood coolant. Once the holes were drilled, I switched to a 3 flute Kennametal .063 carbide end mill with a 5/32 loc. to cut out the blocks. That worked fine for me, I file my relief angles, so I don’t need an accurate Z 0 and just need my cutter to break through. I use a holding jig that has the middle milled away to about 3/8” deep so cut scrap can fall away into it. When I cut my lever posts, ( also C510, ) I fill it with cutting oil and let that lubricate the tool which is a .032 3 flute carbide end mill. Without the oil, it raises a burr and the p bronze tends to make a built up edge. With the oil, I can do a 7x12” sheet of posts with all very clean edges. And still have a pretty sharp cutter. I do plunge cut 2 holes for each post using the same cutter. All part of the same tool path and it does just fine in the p bronze where 260 brass wouldn’t let you get past one hole without breaking the cutter. A kazillion years ago in the 60’s my teacher showed us how to “lip” a drill so it wouldn’t try to screw itself into brass, but you can’t really do that on such tiny cutters.
Hey Dana, thanks for the input, very insightful indeed! Yep, pretty much the only reason I got the tormach was for the flood coolant. Being able to evacuate chips effectively, and lubricate/cool the cutter, renders 260 brass similar in machinability to 353. I haven't broken an endmill since I upgraded, whereas before I was breaking many, and spending a pretty penny to replace them. That's a good idea about the phosphor bronze, I never considered that. Maybe I'll look into that and see if I can get some to play around with. I've been considering pouring my own brass ingots. I'd have to make an ingot mold the size/shape of my sheets (4"x6"x.093"), but then I'd be able to add my own lead and make it free-machining, not to mention find a use for the many lbs of brass scrap I've accumulated over the years!
@@CrookConcertinas online metals carries the p bronze in .093. Various sheet sizes available including cut to length. Not sure you could plunge a 1/16 end mill into 260 brass even with coolant. When I was in High school, in the 60’s I watched a 1 inch drill try to screw its way through a block of brass. Making a small 90 degree rake flat on the cutting edge cured it. But not practical on tiny cutters. Anyway, pre drilling starter holes works just fine. My clamp block sheets only had a plunge at the start of each row, and I ended up pre drilling those. The rest was. Side cutting which went fine. I really missed the 353 though. It cut burr free. I liked being able to cut it dry. Fortunately, scrap yards seem happy to take brass scrap, but I’m not sure they’ll take a box of near microscopic chips! I think the reason 353 is hard to get now is because the lead content is a pain to deal with pollution wise. Lead is happy to vaporize at molten brass temps, so you have to deal with that. My friend said most of it is done overseas now. I’m glad you are making concertinas. Most of us old farts are hanging it up now but there is still a good market for good concertinas.
This is all so cool to see, really appreciate you sharing!
A couple suggestions, first, as long as your reed shoes do not include your sheet edges, you can save yourself of creating a perfectly square sheet. Your locating pins are all you need and if you can touch off them, as long as the sheet is touching them, you’re good. Your tool path doesn’t care what the sheet looks like as long as it is somewhere inside it. Accuracy is great where you need it, but costs you time and labor where you don’t. Second, I used to use .093 C353 engravers brass and like you found it no longer available. I used .063” for everything C3 and above, and only used the .093 for clamp blocks. When I was still punching out reed shoes instead of milling them out, I used the C510 Phosphor bronze in spring temper and it worked very well. When I couldn’t get the 353 brass in the right size any more, It is free machining like the 353 brass, but has sulphur instead of lead to accomplish that characteristic so it is safer as well. I bought a sheet of the p bronze for clamp blocks. I had no trouble drilling my sheets of clamp blocks with a 1/16 clearance drill ( 800 holes / sheet ) plunge 10 ipm at 20000 rpm with a light coat of cutting oil spread on the sheet because I didn’t want to deal with the mess of flood coolant. Once the holes were drilled, I switched to a 3 flute Kennametal .063 carbide end mill with a 5/32 loc. to cut out the blocks. That worked fine for me, I file my relief angles, so I don’t need an accurate Z 0 and just need my cutter to break through. I use a holding jig that has the middle milled away to about 3/8” deep so cut scrap can fall away into it. When I cut my lever posts, ( also C510, ) I fill it with cutting oil and let that lubricate the tool which is a .032 3 flute carbide end mill. Without the oil, it raises a burr and the p bronze tends to make a built up edge. With the oil, I can do a 7x12” sheet of posts with all very clean edges. And still have a pretty sharp cutter. I do plunge cut 2 holes for each post using the same cutter. All part of the same tool path and it does just fine in the p bronze where 260 brass wouldn’t let you get past one hole without breaking the cutter. A kazillion years ago in the 60’s my teacher showed us how to “lip” a drill so it wouldn’t try to screw itself into brass, but you can’t really do that on such tiny cutters.
Hey Dana, thanks for the input, very insightful indeed! Yep, pretty much the only reason I got the tormach was for the flood coolant. Being able to evacuate chips effectively, and lubricate/cool the cutter, renders 260 brass similar in machinability to 353. I haven't broken an endmill since I upgraded, whereas before I was breaking many, and spending a pretty penny to replace them. That's a good idea about the phosphor bronze, I never considered that. Maybe I'll look into that and see if I can get some to play around with. I've been considering pouring my own brass ingots. I'd have to make an ingot mold the size/shape of my sheets (4"x6"x.093"), but then I'd be able to add my own lead and make it free-machining, not to mention find a use for the many lbs of brass scrap I've accumulated over the years!
@@CrookConcertinas online metals carries the p bronze in .093. Various sheet sizes available including cut to length. Not sure you could plunge a 1/16 end mill into 260 brass even with coolant. When I was in High school, in the 60’s I watched a 1 inch drill try to screw its way through a block of brass. Making a small 90 degree rake flat on the cutting edge cured it. But not practical on tiny cutters. Anyway, pre drilling starter holes works just fine. My clamp block sheets only had a plunge at the start of each row, and I ended up pre drilling those. The rest was. Side cutting which went fine. I really missed the 353 though. It cut burr free. I liked being able to cut it dry. Fortunately, scrap yards seem happy to take brass scrap, but I’m not sure they’ll take a box of near microscopic chips! I think the reason 353 is hard to get now is because the lead content is a pain to deal with pollution wise. Lead is happy to vaporize at molten brass temps, so you have to deal with that. My friend said most of it is done overseas now. I’m glad you are making concertinas. Most of us old farts are hanging it up now but there is still a good market for good concertinas.