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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Sacrificial backing material
I am drilling this aluminum sheet:
http://picasaweb.google.com/lh/photo...eat=directlink This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i |
#2
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Sacrificial backing material
Ignoramus30138 wrote:
I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...eat=directlink This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i Get a piece of 3/4" MDF - medium density fibercore - looks like brown paper bags pressed together because that's basically what it is . But it's cheap , it's rigid , and it won't hurt your cutters . And you can buy less than a full sheet at ho-de-po or Blowes . -- Snag Learning keeps you young ! |
#3
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Sacrificial backing material
On 2010-12-17, Snag wrote:
Get a piece of 3/4" MDF - medium density fibercore - looks like brown paper bags pressed together because that's basically what it is . But it's cheap , it's rigid , and it won't hurt your cutters . And you can buy less than a full sheet at ho-de-po or Blowes . I thought that it actually is abrasive and also clogs the coolant pump. i |
#4
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Sacrificial backing material
Ignoramus30138 wrote: On 2010-12-17, Snag wrote: Get a piece of 3/4" MDF - medium density fibercore - looks like brown paper bags pressed together because that's basically what it is . But it's cheap , it's rigid , and it won't hurt your cutters . And you can buy less than a full sheet at ho-de-po or Blowes . I thought that it actually is abrasive and also clogs the coolant pump. i It's not a good idea to use coolant when using a wood / wood product backer. This is one of the many times that it's best to machine aluminum dry and just vacuum up the chips and backer dust when it's done. |
#5
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Sacrificial backing material
Ignoramus30138 fired this volley in
: I thought that it actually is abrasive and also clogs the coolant pump. both. And the statement earlier that "most" woods don't contain much silica is rife with problems. As wood selections get cheaper, and more and more of the scrap is salvaged, more bark, root, and knot sections get included in plywood and press-board products, raising the silica content beyond what you want on your nice tools. LLoyd |
#6
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Sacrificial backing material
On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
Ignoramus30138 fired this volley in : I thought that it actually is abrasive and also clogs the coolant pump. both. And the statement earlier that "most" woods don't contain much silica is rife with problems. As wood selections get cheaper, and more and more of the scrap is salvaged, more bark, root, and knot sections get included in plywood and press-board products, raising the silica content beyond what you want on your nice tools. Lloyd, do you think that I could use 2x4 and 2x6's for this sort of purpose, as a backer on my mill, and with coolant? The wood "chips" would not be so fine as with MDF or some such. Right? i |
#7
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Sacrificial backing material
Ignoramus30138 fired this volley in
: Lloyd, do you think that I could use 2x4 and 2x6's for this sort of purpose, as a backer on my mill, and with coolant? The wood "chips" would not be so fine as with MDF or some such. Right? Right, and you can, but you have all sorts of "prep" work to do to the backing that will generate lots of shavings and dust. Go to a local plastics supply and ask them for some cut-offs and scraps. Just avoid insolubles like PE,PP,Delrin, or Nylon, because you cannot glue effectively to them (well, to nylon you can), and you can't dissolve them off the work if you want to. The more I think about it, the more PVC and styrene have their attractions. For small work, you could even "convert" flat-bottomed pipe caps to work backers. LLoyd |
#8
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Sacrificial backing material
On 12/17/2010 02:34 PM, Ignoramus30138 wrote:
I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...eat=directlink This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. Well, it can be. Finely powdered wood can make a big mess in your coolant system. What I would have done is use a boring process with an end mill. I have a program that writes the G-code to bore out holes like that. depending on the size and thickness, I have versions to either obliterate the entire hole or to just trim around the edge and then let the slug drop out, then finish the OD. I use this technique for almost everything. This is not quite as fast as a twist drill, but if you have to go very easy due to workpiece deflection, then the boring approach may end up almost as fast. Jon |
#9
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Sacrificial backing material
Ignoramus30138 wrote: On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote: Ignoramus30138 fired this volley in : I thought that it actually is abrasive and also clogs the coolant pump. both. And the statement earlier that "most" woods don't contain much silica is rife with problems. As wood selections get cheaper, and more and more of the scrap is salvaged, more bark, root, and knot sections get included in plywood and press-board products, raising the silica content beyond what you want on your nice tools. Lloyd, do you think that I could use 2x4 and 2x6's for this sort of purpose, as a backer on my mill, and with coolant? The wood "chips" would not be so fine as with MDF or some such. Right? i Go down to your local Mal-Wart and get a cheap poly cutting board as your sacrificial backer. And remember, you *do not* need coolant for most machining operations in aluminum. |
#10
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Sacrificial backing material
"Pete C." fired this volley in news:4d0be94a$0$9804
: And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. All the more reason to use a polymer for the backer instead of wood. LLoyd |
#11
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Sacrificial backing material
On Fri, 17 Dec 2010 14:34:57 -0600, Ignoramus30138
wrote: I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...eat=directlink This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i FWIW, I use AL plate. Used stuff taken off a scrap machine. One plate will last for hundreds of parts. Karl |
#12
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Sacrificial backing material
Ignoramus30138" wrote in message
The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. I've had pretty good luck epoxying (5 minute variety) aluminum to MDF then applying heat when finished to soften the epoxy and release the aluminum. I'll clamp up the MDF, and mill it flat, then mill alignment ridges or pockets if needed before gluing the aluminum in place. |
#13
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Sacrificial backing material
"Lloyd E. Sponenburgh" wrote: "Pete C." fired this volley in news:4d0be94a$0$9804 : And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. Not if you are using sharp tools and the correct speeds and feeds. You can also use compressed air to blow the chips out of the way further reducing the risk of chip welding. All the more reason to use a polymer for the backer instead of wood. Either will work, the MDF will be cheaper, though likely to get reused less before being tossed, so probably a wash price wise. |
#14
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Sacrificial backing material
On Dec 17, 4:00*pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote: Ignoramus30138 fired this volley om: I thought that it actually is abrasive and also clogs the coolant pump. both. And the statement earlier that "most" woods don't contain much silica is rife with problems. *As wood selections get cheaper, and more and more of the scrap is salvaged, more bark, root, and knot sections get included in plywood and press-board products, raising the silica content beyond what you want on your nice tools. LLoyd Excellent point. I have seen significant silica in solid wood...knots and bark injury can cause sand to be anywhere in a wood product. TMT |
#15
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Sacrificial backing material
On Dec 17, 2:34*pm, Ignoramus30138 ignoramus30...@NOSPAM.
30138.invalid wrote: I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...uTAdxO3bjAhN7B... This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i Ig...since you do know how to reuse materials, try going to the local thrift store and get the $1 picture frames with clear panes of PLASTIC. Works great for sacrificial backings. If you buy the frames that use aluminum extrusions, you will have building stock also. TMT |
#16
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Sacrificial backing material
On Fri, 17 Dec 2010 16:19:44 -0800 (PST), the renowned Too_Many_Tools
wrote: On Dec 17, 2:34*pm, Ignoramus30138 ignoramus30...@NOSPAM. 30138.invalid wrote: I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...uTAdxO3bjAhN7B... This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i Ig...since you do know how to reuse materials, try going to the local thrift store and get the $1 picture frames with clear panes of PLASTIC. Works great for sacrificial backings. If you buy the frames that use aluminum extrusions, you will have building stock also. TMT Cheap dollar store cutting boards provide some useful material too. It machines quite nicely. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#17
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Sacrificial backing material
On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote:
"Pete C." fired this volley in news:4d0be94a$0$9804 : And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. All the more reason to use a polymer for the backer instead of wood. LLoyd I have never succeeded machining aluminum without coolant. Broke a few endmills. i |
#18
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Sacrificial backing material
Ignoramus30138 wrote: On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote: "Pete C." fired this volley in news:4d0be94a$0$9804 : And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. All the more reason to use a polymer for the backer instead of wood. LLoyd I have never succeeded machining aluminum without coolant. Broke a few endmills. i I've never machined aluminum with coolant, and I've machined a lot of aluminum and never had a problem. If I recall you were running with way too low a feed rate at the time causing more rubbing than cutting, chip welding, etc. I use high feed rates and moderately heavy cuts so I get decent sized chips flying away. |
#19
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Sacrificial backing material
On 2010-12-18, Pete C. wrote:
Ignoramus30138 wrote: On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote: "Pete C." fired this volley in news:4d0be94a$0$9804 : And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. All the more reason to use a polymer for the backer instead of wood. LLoyd I have never succeeded machining aluminum without coolant. Broke a few endmills. i I've never machined aluminum with coolant, and I've machined a lot of aluminum and never had a problem. If I recall you were running with way too low a feed rate at the time causing more rubbing than cutting, chip welding, etc. I use high feed rates and moderately heavy cuts so I get decent sized chips flying away. Maybe one day I will try it again. i |
#20
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Sacrificial backing material
Ignoramus30138 wrote:
On 2010-12-17, Lloyd E. Sponenburgh lloydspinsidemindspring.com wrote: "Pete C." fired this volley in news:4d0be94a$0$9804 And remember, you *do not* need coolant for most machining operations in aluminum. But you need _lubrication_, or you get false edges built up on the tooling. All the more reason to use a polymer for the backer instead of wood. I have never succeeded machining aluminum without coolant. Broke a few endmills. Coolant, or lubricant? They're not necessarily the same, although I'd assume your coolant has some lubricity. I've used plain, ol' ordinary lard (Crisco will also work) on aluminum; it works good and smells good too! ;-) Cheers! Rich |
#21
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Sacrificial backing material
On Fri, 17 Dec 2010 14:34:57 -0600, Ignoramus30138
wrote: I am drilling this aluminum sheet: http://picasaweb.google.com/lh/photo...eat=directlink This is a holder for a (almost complete by 1/64) set od DA collets that I have in a bag. Unfortunately, when drilling, it flexes more than I would like. It is under control but I now realize that I should have used some sacrificial backing material, or a step drill. The question is, what material is friendly to the mill. I thought that wood (plywood) was somehow bad. thanks i MDF Top 10 Democrat Party Slogans 10. Bitterly clinging to aborton and taxes 9. We didnt destroy your freedoms, you can visit them at the Smithstonian 8. If you want us to listen to your opinion, move to Europ 7. Someday none of this will be yours 6. We can't tax terrorism, so who cares? 5. Please don't vote us out!! None of us can hold a real job! 4. Why the Founding Fathers limited Government: Racism! 3. Reducing America's carbon footprint, one job at a time. 2. America: We just cant wait to see how it ends!! 1. Making everything in this country free, except you. |
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