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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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Plastic roll pin
I want to bid on a part for a floor washing brush. The company made a
bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. |
#2
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Plastic roll pin
On 7/12/2014 1:20 AM, Tom Gardner wrote:
I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. I forgot to mention that one end gets a 30 deg chamfer to aid insertion. |
#3
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Plastic roll pin
Tom Gardner wrote:
I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cheapest = outsource to China/Viet Nam... Slit the tube first, for that a cheap small table saw with guides on both sides and top of the blade and a narrow fin inline with the blade on the outfeed to keep the cut nice and straight. Next, modify a cheap lathe. Make an internally tapered collet that gets placed in the jaws or welded in place on the spindle. Tubing gets compressed as it enters the taper until the slot is closed where it exits the collet. Have a stop placed 4" away with a modified live center with a 2" or so pin that is a tight fit in the compressed tube and a sleeve on the outside the same length. Have the tail stock on a pivot so it can on a pivot away from the operator and a position stop when it comes back. Make a chamfer tool and a parting tool. Mount both on pivots with stops. In use the tubes get slit, then pushed into the "lathe". Quick chamfer on the end. Push through onto the stop set to give you a 4" section. Chamfer first then part off. Part will open but be secured from motion by the internal pin and external sleeve. Operator pivots part and tail stock away while pushing part out of sleeve and off pin into "finished" bin behind the machine. Pull the tail stock back into position, feed in more tube and repeat process. Basically a home brew chucker screw machine. -- Steve W. |
#4
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Plastic roll pin
On 7/12/2014 2:33 AM, Steve W. wrote:
Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cheapest = outsource to China/Viet Nam... Slit the tube first, for that a cheap small table saw with guides on both sides and top of the blade and a narrow fin inline with the blade on the outfeed to keep the cut nice and straight. Next, modify a cheap lathe. Make an internally tapered collet that gets placed in the jaws or welded in place on the spindle. Tubing gets compressed as it enters the taper until the slot is closed where it exits the collet. Have a stop placed 4" away with a modified live center with a 2" or so pin that is a tight fit in the compressed tube and a sleeve on the outside the same length. Have the tail stock on a pivot so it can on a pivot away from the operator and a position stop when it comes back. Make a chamfer tool and a parting tool. Mount both on pivots with stops. In use the tubes get slit, then pushed into the "lathe". Quick chamfer on the end. Push through onto the stop set to give you a 4" section. Chamfer first then part off. Part will open but be secured from motion by the internal pin and external sleeve. Operator pivots part and tail stock away while pushing part out of sleeve and off pin into "finished" bin behind the machine. Pull the tail stock back into position, feed in more tube and repeat process. Basically a home brew chucker screw machine. I see. My first thought was to part and chamfer in one cut then to slit on a router table with an out-feed fin as guide to keep it straight...but I like your set-up. The other thought was to farm out the parting and boring and chamfering and do the slitting in-house. |
#5
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Plastic roll pin
On Sat, 12 Jul 2014 02:56:21 -0400, Tom Gardner Mars@Tacks wrote:
On 7/12/2014 2:33 AM, Steve W. wrote: Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cheapest = outsource to China/Viet Nam... Slit the tube first, for that a cheap small table saw with guides on both sides and top of the blade and a narrow fin inline with the blade on the outfeed to keep the cut nice and straight. Next, modify a cheap lathe. Make an internally tapered collet that gets placed in the jaws or welded in place on the spindle. Tubing gets compressed as it enters the taper until the slot is closed where it exits the collet. Have a stop placed 4" away with a modified live center with a 2" or so pin that is a tight fit in the compressed tube and a sleeve on the outside the same length. Have the tail stock on a pivot so it can on a pivot away from the operator and a position stop when it comes back. Make a chamfer tool and a parting tool. Mount both on pivots with stops. In use the tubes get slit, then pushed into the "lathe". Quick chamfer on the end. Push through onto the stop set to give you a 4" section. Chamfer first then part off. Part will open but be secured from motion by the internal pin and external sleeve. Operator pivots part and tail stock away while pushing part out of sleeve and off pin into "finished" bin behind the machine. Pull the tail stock back into position, feed in more tube and repeat process. Basically a home brew chucker screw machine. I see. My first thought was to part and chamfer in one cut then to slit on a router table with an out-feed fin as guide to keep it straight...but I like your set-up. The other thought was to farm out the parting and boring and chamfering and do the slitting in-house. Any CNC lathe with a bar feed could knock out the part bore and chamfer with maybe a 30 second cycle time. No need to build a special machine. My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. Karl |
#6
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Plastic roll pin
On 7/12/2014 5:29 AM, Karl Townsend wrote:
... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob |
#7
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Plastic roll pin
On 7/12/2014 1:20 AM, Tom Gardner wrote:
... Is there a better solution? ... A wooden plug? |
#8
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Plastic roll pin
On Sat, 12 Jul 2014 01:20:29 -0400, Tom Gardner Mars@Tacks wrote:
I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. S/B Delrin, eh? Rather than this kludge, why didn't the labs redesign the brush properly? That seems foolish. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. On a CNC lathe/machining center. -- Liberalism is a pathology. |
#9
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Plastic roll pin
In article , Tom Gardner
Mars@Tacks wrote: On 7/12/2014 1:20 AM, Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. I forgot to mention that one end gets a 30 deg chamfer to aid insertion. This volume (10k units) is on the edge economically, but Delrin can be injection molded. Joe Gwinn |
#10
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Plastic roll pin
Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cut to length with a standard automatic bandsaw if you have one, otherwise use a table saw with a jig to allow fast cutoff feeding from the presumably long stock. Make a custom chamfering head that has a bore to match the OD of the tube and a standard insert to cut the chamfer (look for HSS inserts). Incorporate the depth stop in the head so you just push the tube in until it bottoms out on the flat part of the front. Continue a bore and a side port for chip evacuation and surround that with a connection to a shop vac / dust collector. Mount the whole head on a basic motor so you don't tie up any normal machines. Do the slotting on a cheap table saw, with a holding fixture for the tube. Something with a chamber in the bottom you put the tube into where the tube sits slightly past the bottom of the fixture so you can apply down pressure to keep it from rotating. Position the operator and parts bins so they can pickup a tube, place it in the bottom of the fixture as they slide it over the saw table, run it over the blade between a pair of fences perhaps 2" apart, and as they run it off the end of the table the completed part falls into a bin. Minimal labor and pretty fast. For insertion do a simple pneumatic press setup where you drop a brush and a tube in the press fixture and hit the button or foot pedal to press in to the preset depth. This could be automated easily with some gates to allow you to just load some feed bins and let the cycle work automatically. If the quantity was higher or this was to be a regular job, a lot more automation could be applied pretty easily. |
#11
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Plastic roll pin
On 7/12/2014 9:02 AM, Bob Engelhardt wrote:
On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. |
#12
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Plastic roll pin
On 7/12/2014 9:07 AM, Bob Engelhardt wrote:
On 7/12/2014 1:20 AM, Tom Gardner wrote: ... Is there a better solution? ... A wooden plug? Wet environment. I suggested it. |
#13
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Plastic roll pin
On 7/12/2014 9:26 AM, Larry Jaques wrote:
On Sat, 12 Jul 2014 01:20:29 -0400, Tom Gardner Mars@Tacks wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. S/B Delrin, eh? Rather than this kludge, why didn't the labs redesign the brush properly? That seems foolish. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. On a CNC lathe/machining center. -- Liberalism is a pathology. They did. They don't want to scrap the parts already made. Unless the fix is too expensive. |
#14
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Plastic roll pin
On 7/12/2014 5:29 AM, Karl Townsend wrote:
On Sat, 12 Jul 2014 02:56:21 -0400, Tom Gardner Mars@Tacks wrote: On 7/12/2014 2:33 AM, Steve W. wrote: Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cheapest = outsource to China/Viet Nam... Slit the tube first, for that a cheap small table saw with guides on both sides and top of the blade and a narrow fin inline with the blade on the outfeed to keep the cut nice and straight. Next, modify a cheap lathe. Make an internally tapered collet that gets placed in the jaws or welded in place on the spindle. Tubing gets compressed as it enters the taper until the slot is closed where it exits the collet. Have a stop placed 4" away with a modified live center with a 2" or so pin that is a tight fit in the compressed tube and a sleeve on the outside the same length. Have the tail stock on a pivot so it can on a pivot away from the operator and a position stop when it comes back. Make a chamfer tool and a parting tool. Mount both on pivots with stops. In use the tubes get slit, then pushed into the "lathe". Quick chamfer on the end. Push through onto the stop set to give you a 4" section. Chamfer first then part off. Part will open but be secured from motion by the internal pin and external sleeve. Operator pivots part and tail stock away while pushing part out of sleeve and off pin into "finished" bin behind the machine. Pull the tail stock back into position, feed in more tube and repeat process. Basically a home brew chucker screw machine. I see. My first thought was to part and chamfer in one cut then to slit on a router table with an out-feed fin as guide to keep it straight...but I like your set-up. The other thought was to farm out the parting and boring and chamfering and do the slitting in-house. Any CNC lathe with a bar feed could knock out the part bore and chamfer with maybe a 30 second cycle time. No need to build a special machine. My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. Karl I did talk to a guy that make CNC parts for me and he doesn't want to deal with the plastic swarf. |
#15
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Plastic roll pin
Any CNC lathe with a bar feed could knock out the part bore and chamfer with maybe a 30 second cycle time. No need to build a special machine. My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. Karl I did talk to a guy that make CNC parts for me and he doesn't want to deal with the plastic swarf. I've not done 10K parts but I found a shop vac to work real well for plastic swarf. Maybe you don't want to go there, but this might be a good time to buy your first CNC lathe. Karl |
#16
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Plastic roll pin
On 7/12/2014 12:43 PM, Karl Townsend wrote:
Any CNC lathe with a bar feed could knock out the part bore and chamfer with maybe a 30 second cycle time. No need to build a special machine. My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. Karl I did talk to a guy that make CNC parts for me and he doesn't want to deal with the plastic swarf. I've not done 10K parts but I found a shop vac to work real well for plastic swarf. Maybe you don't want to go there, but this might be a good time to buy your first CNC lathe. Karl No, I'm at the stage in my life that it's time to divest rather than buy stuff...except fishing rods and reels and pistols. |
#17
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Plastic roll pin
"Tom Gardner" wrote in message
... On 7/12/2014 9:02 AM, Bob Engelhardt wrote: On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. [/quote] So when you say they will supply the Delrin, does that mean they supply tubing with the correct id and od, or what? If the outside is going to need turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide each piece onto a SS tube mandrel (have to experiment a bit on the size) and toss piles of them into an oven at 425F or so for 30-45 minutes. The Delrin will anneal and relax and take up the new ID of the mandrel +/- a bit, so you get your correct od without turning the full length. Two sets of mandrels so while one batch is baking the other is cooled, finished tubes removed, new ones loaded on the mandrels and the mandrels loaded into a crate maybe standing them on pegs or whatever, so the entire oven can be unloaded and reloaded quickly. Anyway, just a suggestion. ----- Regards, Carl Ijames |
#18
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Plastic roll pin
On 7/12/2014 1:06 PM, Carl Ijames wrote:
"Tom Gardner" wrote in message ... On 7/12/2014 9:02 AM, Bob Engelhardt wrote: On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. [/quote] So when you say they will supply the Delrin, does that mean they supply tubing with the correct id and od, or what? If the outside is going to need turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide each piece onto a SS tube mandrel (have to experiment a bit on the size) and toss piles of them into an oven at 425F or so for 30-45 minutes. The Delrin will anneal and relax and take up the new ID of the mandrel +/- a bit, so you get your correct od without turning the full length. Two sets of mandrels so while one batch is baking the other is cooled, finished tubes removed, new ones loaded on the mandrels and the mandrels loaded into a crate maybe standing them on pegs or whatever, so the entire oven can be unloaded and reloaded quickly. Anyway, just a suggestion. ----- Regards, Carl Ijames They will supply tubing 1.040" UD x .500" ID and want it bored to 11/16". I wonder if their original size of 1" OD x .75" id could be stretched open to provide more holding power? That would eliminate yhe boring op. |
#19
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Plastic roll pin
On Saturday, July 12, 2014 6:07:45 AM UTC-7, Bob Engelhardt wrote:
On 7/12/2014 1:20 AM, Tom Gardner wrote: ... Is there a better solution? ... A wooden plug? Yeah, with some foaming/expanding glue. Delrin is EXPENSIVE! |
#20
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Plastic roll pin
On Saturday, July 12, 2014 8:53:34 AM UTC-7, Pete C. wrote:
Tom Gardner wrote: I want to bid on a part for a floor washing brush. ...involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long Cut to length with a standard automatic bandsaw if you have one, otherwise use a table saw with a jig If you're getting 10,000 or more, ask the plastic supplier to supply it in the lengths you want. For them, it's a simple adjustment. |
#21
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Plastic roll pin
On 7/12/2014 11:53 AM, Tom Gardner wrote:
On 7/12/2014 9:02 AM, Bob Engelhardt wrote: .... BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. Yeah, I was just commenting on the price, not suggesting a source. |
#22
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Plastic roll pin
"Tom Gardner" Mars@Tacks wrote in message
... They will supply tubing 1.040" UD x .500" ID and want it bored to 11/16". I wonder if their original size of 1" OD x .75" id could be stretched open to provide more holding power? That would eliminate yhe boring op. FWIW, 3/4" pipe and PVC electrical conduit is 1.050" OD by 0.824" ID. -jsw |
#23
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Plastic roll pin
"Tom Gardner" wrote in message
... On 7/12/2014 1:06 PM, Carl Ijames wrote: "Tom Gardner" wrote in message ... On 7/12/2014 9:02 AM, Bob Engelhardt wrote: On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. [/quote] So when you say they will supply the Delrin, does that mean they supply tubing with the correct id and od, or what? If the outside is going to need turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide each piece onto a SS tube mandrel (have to experiment a bit on the size) and toss piles of them into an oven at 425F or so for 30-45 minutes. The Delrin will anneal and relax and take up the new ID of the mandrel +/- a bit, so you get your correct od without turning the full length. Two sets of mandrels so while one batch is baking the other is cooled, finished tubes removed, new ones loaded on the mandrels and the mandrels loaded into a crate maybe standing them on pegs or whatever, so the entire oven can be unloaded and reloaded quickly. Anyway, just a suggestion. ----- Regards, Carl Ijames They will supply tubing 1.040" UD x .500" ID and want it bored to 11/16". I wonder if their original size of 1" OD x .75" id could be stretched open to provide more holding power? That would eliminate yhe boring op. [/quote] I figured I better check if you are going to try this, and my memory was a little off. Here's a table I found online for lots of different plastics, handy as a guide http://www.boedeker.com/anneal.htm. I was using 1/32" thick by 1" Delrin strip that was straight, cutting 9" lengths, coiling them inside a 1-3/4" od stainless steel tube, putting four side by side and four layers. Any more layers and the id was too small. Put that into a toaster over that is room temp-ish, set to 325F and turn it on. It was a big oven that could do a 12" frozen pizza so it had a decent amount of heater power. I used the convection toast setting so the fan, upper heaters, and lower heaters were all on. Reached temp in about 20-30 minutes and the timer turned it off after 45 minutes so 15 minutes at full temp for the soak. Let cool to under 175F, maybe 45 minutes, so I could grab it barehanded, pop out the coils and reload. That gave me coiled rings I snapped around 3" iron pipe as trim rings that would grab tightly enough to stay put but if the annealed diameter got too small they wouldn't lay flat and look good. I wasn't going for a perfect anneal, I just needed them to hold the coiled shape. Anyway, that table recommends a much slower heat and cool, soaking at 300F, but that is a general recommendation for machined pieces up to 1/4" thick. Your pieces will be thinner and I don't think need the greatest precision so you can rush it a good bit. Yes, I'm sure the 1" od would work fine - you can even make the slit 1/4" since it will grow about 1/8" when you anneal to the larger dia. ----- Regards, Carl Ijames "Tom Gardner" wrote in message ... On 7/12/2014 1:06 PM, Carl Ijames wrote: "Tom Gardner" wrote in message ... On 7/12/2014 9:02 AM, Bob Engelhardt wrote: On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. [/quote] So when you say they will supply the Delrin, does that mean they supply tubing with the correct id and od, or what? If the outside is going to need turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide each piece onto a SS tube mandrel (have to experiment a bit on the size) and toss piles of them into an oven at 425F or so for 30-45 minutes. The Delrin will anneal and relax and take up the new ID of the mandrel +/- a bit, so you get your correct od without turning the full length. Two sets of mandrels so while one batch is baking the other is cooled, finished tubes removed, new ones loaded on the mandrels and the mandrels loaded into a crate maybe standing them on pegs or whatever, so the entire oven can be unloaded and reloaded quickly. Anyway, just a suggestion. ----- Regards, Carl Ijames They will supply tubing 1.040" UD x .500" ID and want it bored to 11/16". I wonder if their original size of 1" OD x .75" id could be stretched open to provide more holding power? That would eliminate yhe boring op. |
#24
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Tom Gardner wrote: No, I'm at the stage in my life that it's time to divest rather than buy stuff...except fishing rods and reels and pistols. You kinky lesbians, and your sex toys... -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge. |
#25
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Plastic roll pin
On Sat, 12 Jul 2014 15:24:10 -0400, Tom Gardner Mars@Tacks wrote:
On 7/12/2014 1:06 PM, Carl Ijames wrote: "Tom Gardner" wrote in message ... On 7/12/2014 9:02 AM, Bob Engelhardt wrote: On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob Their lab tried that size and it's too small. [/quote] So when you say they will supply the Delrin, does that mean they supply tubing with the correct id and od, or what? If the outside is going to need turning to size, use the 1" tubing, do the cut/deburr/slot ops then slide each piece onto a SS tube mandrel (have to experiment a bit on the size) and toss piles of them into an oven at 425F or so for 30-45 minutes. The Delrin will anneal and relax and take up the new ID of the mandrel +/- a bit, so you get your correct od without turning the full length. Two sets of mandrels so while one batch is baking the other is cooled, finished tubes removed, new ones loaded on the mandrels and the mandrels loaded into a crate maybe standing them on pegs or whatever, so the entire oven can be unloaded and reloaded quickly. Anyway, just a suggestion. ----- Regards, Carl Ijames They will supply tubing 1.040" UD x .500" ID and want it bored to 11/16". I wonder if their original size of 1" OD x .75" id could be stretched open to provide more holding power? That would eliminate yhe boring op. The more you tell us, the more I see why they're still looking for a supplier. I'd run away if I were you, Tawm. P.S: What's their lab guy's name, DeweyBob? (as in "Hey, hold my beer and watch this!") -- Liberalism is a pathology. |
#26
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Plastic roll pin
On Sat, 12 Jul 2014 11:58:31 -0400, Tom Gardner Mars@Tacks wrote:
On 7/12/2014 5:29 AM, Karl Townsend wrote: On Sat, 12 Jul 2014 02:56:21 -0400, Tom Gardner Mars@Tacks wrote: On 7/12/2014 2:33 AM, Steve W. wrote: Tom Gardner wrote: I want to bid on a part for a floor washing brush. The company made a bunch of PVC tubes 1" ID X 1.375 OD x 12" long. It's covered with a material that looks like carpet...'kinda. It works great until it gets hot then it gets bendy. The company's lab came up with a fix that involves a taking a Derlin tube that's 1.040" OD x .75" ID x 4" long with a .312" slit along the side and pressing it into the middle of the 12" tube to act as a stiffener. What's the cheapest way to make these? Is there a better solution? They need 10k+ of these. They will supply the Derlin material. Cheapest = outsource to China/Viet Nam... Slit the tube first, for that a cheap small table saw with guides on both sides and top of the blade and a narrow fin inline with the blade on the outfeed to keep the cut nice and straight. Next, modify a cheap lathe. Make an internally tapered collet that gets placed in the jaws or welded in place on the spindle. Tubing gets compressed as it enters the taper until the slot is closed where it exits the collet. Have a stop placed 4" away with a modified live center with a 2" or so pin that is a tight fit in the compressed tube and a sleeve on the outside the same length. Have the tail stock on a pivot so it can on a pivot away from the operator and a position stop when it comes back. Make a chamfer tool and a parting tool. Mount both on pivots with stops. In use the tubes get slit, then pushed into the "lathe". Quick chamfer on the end. Push through onto the stop set to give you a 4" section. Chamfer first then part off. Part will open but be secured from motion by the internal pin and external sleeve. Operator pivots part and tail stock away while pushing part out of sleeve and off pin into "finished" bin behind the machine. Pull the tail stock back into position, feed in more tube and repeat process. Basically a home brew chucker screw machine. I see. My first thought was to part and chamfer in one cut then to slit on a router table with an out-feed fin as guide to keep it straight...but I like your set-up. The other thought was to farm out the parting and boring and chamfering and do the slitting in-house. Any CNC lathe with a bar feed could knock out the part bore and chamfer with maybe a 30 second cycle time. No need to build a special machine. My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. Karl I did talk to a guy that make CNC parts for me and he doesn't want to deal with the plastic swarf. I can see his point. It's extremely statically charged and sticks to everything. I've slit PVC pipe and don't think I want to try THAT again. -- Liberalism is a pathology. |
#27
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Plastic roll pin
On 7/12/2014 8:02 AM, Bob Engelhardt wrote:
On 7/12/2014 5:29 AM, Karl Townsend wrote: ... My *guess* is pre sltting would not be any easier and would slow down the CNC lathe work. The trade off is slitting 15 4" pieces vs 1 5' piece. BTW - I found a source for 1" x 3/4" Delrin that prices it at $37 per 5' piece. $2.50 material cost for each 4" piece! 'Course when you're buying 2500', you'll get a better price, I hope. Bob One would think filling it with a fast setting epoxy / resin would be as good or better and cost less. Buy by the 55gal drum and inject. When they installed a new telephone pole in my side yard - I have 1800 foot of 2-phase HV to the house and shop. :-) They had the pole set and the hole a bit large but not much. Before setting, they dumped a mixed up resin and poured it in the hole. Then dropped the pole and another 5 gallons of the stuff was poured around it. The two men then did heave plenty of dirt atop of the hole and stood atop that! They rose by maybe 6" as the plastic resin expanded and filled every crack. It also helps protect the pole from insects. No hidden holes to allow the pole to lean after a rain storm. Martin |
#28
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Plastic roll pin
On 7/12/2014 11:52 PM, Martin Eastburn wrote:
One would think filling it with a fast setting epoxy / resin would be as good or better and cost less. ... I like it! 1" dia x 4" long = 3 cu in = 2 fl oz. |
#29
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Plastic roll pin
On 07/13/2014 7:55 AM, Bob Engelhardt wrote:
On 7/12/2014 11:52 PM, Martin Eastburn wrote: One would think filling it with a fast setting epoxy / resin would be as good or better and cost less. ... I like it! 1" dia x 4" long = 3 cu in = 2 fl oz. The overall piece is 12" and this is a retrofit kit to existing customers, too? Would take a plug inserted unless going to fill whole thing. Cost of even a cheap epoxy?? Anyway, I'd wonder if they wouldn't be better off financially to just scrap current inventory and go to a stiffer piece unless there's a very large number in stock it could end up being cheaper than the retrofit...unless they think this is really a long-term solution which I wouldn't think would be the case, surely? -- |
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